Why do heat exchangers fail?

Why do heat exchangers fail

Why do heat exchangers fail? I have been called out to many homes to troubleshoot why a homeowner’s furnace isn’t working. I’ll get in there and find a part that has failed and needs to be replaced. As an experienced technician, I always make sure I inspect the firebox or heat exchanger inside the furnace. The reason why every good technician does this is to make sure the furnace is safely operating to factory specs. The manufacturer would never send out a cracked heat exchanger, so we want to identify to homeowners when we see something like a cracked heat exchanger.

So, how & why do heat exchangers fail? It can be a bunch of different reasons. Operating a furnace in any of these conditions can cause a heat exchanger to fail because it puts a lot of stress in the form of expansion and contraction over several years. Knowing that, you can surmise that cracks and breaks will form over time because of the constant bending of the metal.

  1. Why Heat Exchangers Fail - Serpentine designsFurnace is Oversized – It’s normal for the cool metal firebox, or heat exchanger, and a hot flame to temporarily create a bit of condensation inside the tubing or chamber of them. An oversized furnace will not evaporate that condensation completely because oversized furnaces tend to short cycle. They turn on and off more frequently than they should because they’re so powerful they warm the house up very quickly. Too quickly! Too much rust over time will drill a hole in the tubing or chamber, and you’d have a failed heat exchanger.
  2. Not Enough Return Air – The system wants to give you a certain amount of air to warm your home. The furnace will only give you what it gets from the return duct (the duct or plenum attached to the grill where you change your filter). Those of us in the industry know that a lot of systems installed before, let’s say, 2015, were installed with return ducts that were too small. The heat exchanger is designed to see a certain amount of air pass over it with the correct amount of gas input and heat the heat exchanger emits. Too small of a return duct will restrict the amount of air that can enter the furnace and cause the firebox to expand and contract too much, causing it to break sooner than it should.
  3. Dirty Filters – Another way to slow down the proper amount of air flowing across the heat exchanger is to have a dirty filter. Filters come in several thicknesses. 1″ all the way to 5″. You can have any size and thickness for a filter. But if it becomes impacted with dirt, dust, skin, hair, and whatever else clings to it, the filter restricts airflow like the return duct we discussed in number two.
  4.  Check out our blog on how the newer MERV 13 filters can cause problems for your heat exchanger and the rest of the system
  5. Why Heat Exchangers FailHousehold Chemicals – Believe it or not, corrosion can form on the heat exchanger. Things like hair spray, fabric softeners, and bleach can enter the air stream, pass the filter, and attach to the heat exchanger for good. Over time, the chemicals bore a hole through the metal and cause it to fail.
  6. Off-Gassing – Let’s say you have a home remodel or new construction. Running the furnace during the construction and even afterward will expose the heat exchanger to off-gassing. What is off-gassing? Like the smell of that fresh paint? Off-gassing. New carpet smell? Off-gassing. And many of those new products keep off-gassing long after that new smell wears off. It’s just more subtle. And just like household chemicals, it will contribute to the overall degradation of the furnace heat exchanger. Frozen Evaporators Coils – Ever had a refrigerant leak cause your air conditioning system to freeze up? Vertical furnace/evap coil combos leave the heat exchanger below the evap coil drain pan. When a frozen evap coil melts, it tends to melt rapidly enough that it overflows or straight drips right down onto the metal heat exchanger. And that causes corrosion over time.
  7. Missing Eyelet on Serpentine - Why Heat Exchangers FailPoor Manufacturing Design – There are clamshell, serpentine, and tubular heat exchanger designs.
    1. Clamshells tend to fail in the back of the chamber. But it’s tough to get an inspection mirror back there for inspection purposes. A process called hydro-scan is used to identify cracks in these types of heat exchangers. And it’s very effective if done right and if the professional is looking in the right spots. It takes a trained eye!
    2. Serpentine designs are pressed together with the middle areas held together with rings or eyelets. The eyelets on serpentine designs tend to deform, pop off, and crack. And if the manufacturer wouldn’t send a heat exchanger out into the field with cracked or missing eyelets, a technician who later finds them like that should fail your heat exchanger for not meeting the manufacturer’s specs.
    3. Tubular designs are a newer design and, in my opinion, superior to clamshell and serpentine designs. They are usually made with stainless steel and bent into form at the factory. The ends of those tubes are stamped into the collector box and faceplate of the burner compartment. At that connection is where some tubular designs fail. Corrosion plays a big part in tubular heat exchangers failing. Eventually, that moisture, condensation, chemicals, and gasses we discussed earlier can infiltrate the tubes and cause them to fail. And 90% of the time, those failures happen at the back of the tubes on the first bend.

Gas furnaces are very safe. Most people prefer the warmth emitted by gas furnaces. They’re cozy! Ensuring the furnace is installed correctly is almost 100% of the battle. Choosing a reputable contractor is important because they will read the manuals and abide by the building codes that mandate a proper installation. Homeowners need to make sure those filters are replaced regularly.

Hopefully, this helps you understand more on “Why do heat exchangers fail?”

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The Easy Guide to Diagnosing a Bad Furnace Inducer Motor

Inducer Motor Troubleshooting tips

Today I want to expand on our recent gas furnace troubleshooting series. “The Easy Guide to Diagnosing a Bad Furnace Inducer Motor” will fill you in on what the inducer motor does, why it’s important, the most common of ways I’ve found inducer motors fail, and how to let the customer know what you’ve found. That’s coming up here on Fox Family Heating & Air.

First, I want to give fair warning to anyone watching this that is not already an experienced technician in the HVAC industry.  This video is for educational purposes only.  Fox Family Heating and Air does not recommend anyone other than a professional to start opening the furnace up and trying to diagnose the failure going on with your system. 

There are high and low voltages that can shock a person.  There are also lots of moving parts that can damage body parts—namely, hands and fingers.  The furnace also produces hot surfaces within the furnace compartments and around the housing, which can cause severe burns.  An actual flame produced by the ignition and startup of a gas furnace can cause severe burns and damage to a person or property.

First, as a technician, you must know the sequence of events that occurs for a gas furnace to start up properly. It’s straightforward, and you should have this memorized before you can even consider being qualified to troubleshoot.

  1. Power to the furnace control board
  2. Thermostat signals the call for heat
  3. Inducer motor kicks on
  4. Pressure switch proves the inducer operates correctly
  5. Ignitor activates
  6. Gas valve energizes
  7. Flame pours across burners
  8. Flame sensor proves all burners are lit
  9. Blower forces air through the ducts

When a furnace begins a new cycle, the inducer motor is the first thing you should see kick on.  120 volts are applied through the wires coming from the control board.  This starts the furnace inducer motor for up to 60 seconds before anything else even happens. It’s a safety feature that creates a negative pressure or draft that purges the heat exchanger of any poisonous gasses, namely the combustion’s biproducts.  It makes the air inside the heat hollow tubes of the heat exchanger cleaner when the flame kicks on. With cleaner air inside the heat exchanger at the time of combustion, the furnace’s efficiency increases.

Without going into it too much, a safety device called a pressure switch activates when the diaphragm inside of it recognizes the suction or purging action of the furnace inducer motor. There’s another video called The Easy Guide to Diagnosing a Bad Pressure Switch, and I’ll make sure it’s attached to the end screen so you can check that out.  But first, you want to know more about the inducer more and how to troubleshoot it.

If the inducer motor doesn’t turn on when it’s supposed to, the furnace will recognize this and shut down.  It will wait a bit and try again.  If the motor doesn’t start after 3 to 5 tries, the control board will stop sending voltage to the inducer motor, and essentially locking it out from attempting it anymore.

Why Furnace Inducer Motors Fail

If the correct voltage is applied to the inducer motor and it’s not turning on, something’s not right. Let’s dig into why:

Unplug the furnace, which removes power to the system.

Is the base of the motor warm or hot to the touch?  This means it’s been trying to spin, but something is holding it up.  Is the flywheel on the motor or the actual squirrel cage unable to spin when you manually try to turn it? This can be a reliable indicator that the motor is bad and needs to be replaced.

Why is this happening?

One reason the motor’s shaft locks up is that the motor’s bearings may be seized, preventing it from turning.  Another reason has to do with the windings inside the motor.  One of them could be open—usually, the start winding in this case.  And finally, some motors have a capacitor that starts the motor and regulates the voltage while it’s running.  If it is a bad capacitor, a new one should get it going again.

One of the first indicators that a furnace inducer motor is on borrowed time is if it’s making odd noises.  Sometimes it’s a rattling noise, a clanking noise, chattering, pinging, shaking, a wobbling noise – you name it!  If it comes on and runs any other way than what you interpret as normal, based on your training and experience with properly operating furnaces, you can see if it’s something you can physically adjust.  If not, the inducer motor should be considered bad.  Why?  Because it’s not running to manufacturers specs.

Think Like the Furnace Builder

Think about it like this. Would the furnace’s builder, who takes a ton of pride in their system’s operation, send this out into the field to be installed, knowing the inducer motor is making a god-awful noise?  The answer is a resounding no!  And you should know that and be comfortable telling the customer this. 

Because many inducer motors are nearly impossible to rebuild, an entirely new unit must be purchased in most cases when one wears out. One of the exceptions to this is the occasional Carrier or Bryant units.

Ordering the Furnace Inducer Motor

So at this point, this is what I need my technicians to do. Inducer motors are ordered through the manufacturer. And since we have flat-rate pricing, which includes the cost of parts, labor, and warranty, if the motor is less than $100, it is a level 7.  Above $100 is a level 8. $200 and above, they need to call a supervisor for pricing.

Be Prepared with Information

You want to know the pricing and availability before you talk to the customer because you want to minimize the number of times you need to bring the customer information.  Coming to them and telling them the inducer motor is bad just to hear them say, “Okay, how much is it?” then means you must find out, come back, and tell them it’s the such-and-such price.  You get their approval on the price, but they want to know when the repair will occur. You’ll need to call back to your parts warehouse to ask when the part will be available.  You then must go back to tell them the part will be in around 5 to 7 business days from the factory. 

All of this back and forth can be avoided if you have all the necessary information upfront before even telling them about the diagnosis.  Even if they don’t go with your repair, you have the information and can log it in your file for the customer if they call back, approving the repair a month from now.

Communicating with the Customer

Once we determine pricing and availability, it’s time to talk to the customer about our diagnosis.  We explain what we found, let the customer know the price, and let them know when we can come back to repair the system.

Just a word to the wise:  good communication between you and the customer would mean telling them they need to change this part on the furnace before seeing if anything else is wrong with the system.  Sometimes you’ll get a customer that asks, “So this will fix my system and get it going again, right?” Well, you don’t really know because you haven’t seen what the rest of the startup sequence and the cycling off of the system is doing, have you?  

It’s very likely the rest of the system will work since multiple failures are pretty rare, but you’re going to feel like a jerk if you forget to tell them you have to see how the rest of the system operates after you replace the inducer motor.  Coming back to them after you’ve replaced the motor only to say, “Oh yeah, now your gas valve isn’t working, that’ll be another $600.” So just remember, without a properly functioning inducer motor, there’s no way to tell if the rest of the system is working to manufacturer specs. 

If it is a part that’s available for pickup, call the office to determine a date to pick it up and return and complete the replacement.  If it is a part that needs to be shipped, we want to let the customer know that the part should be arriving at said date and that we’ll call to schedule the appointment when the part arrives.  You’d also want to communicate to the customer and the office how long the repair will take. 

During the inducer motor installation, we need to either replace the gasket (usually comes with the new motor) or make a gasket with high temp silicone. Once installed, a good technician will test the system for proper operation to ensure there are no other issues with the furnace.

Diagnosing a Furnace Inducer Motor: A Recap

So, just to recap, inducer motors pull the flame through the heat exchanger and vent the exhaust through the roof. To determine an inducer motor’s failure, we need to verify the proper voltage is being sent to it. If the motor has proper voltage, the capacitor tests good and is not turning on, the motor is bad.  If it’s making a lot of noise, the homeowner should know the part is working but is on borrowed time.

Thanks so much for stopping by, and we’ll see you on the next blog post.

Don’t miss our video series on this topic:



What to do When Your Heater Stops Working After a Storm

Heater Stops Working after a Storm

Heater Stops Working after a StormIt’s that time of year again when severe weather is a possibility. One of the dangers of thunderstorms is the potential for lightning strikes. A lightning strike can cause all sorts of problems for your home, including knocking out your furnace or heat pump. If you find yourself in this situation, don’t panic! Here are some troubleshooting tips to help you get your heater up and running again when your heater stops working after a storm.

Is Your Thermostat Displaying Properly?

It doesn’t mean your furnace should be working properly if it does still display right; it’s just where I always start. Some thermostats only run on the 24 volts provided by the furnace, and some thermostats have AA battery backup. (I just want to know if the system is calling for heat or not.) You’ve probably already tried this, but if you haven’t, observe what condition the stat is in. Is it blank, looks normal, and calls for heat? If it’s blank, the thunderstorm could have taken out the low voltage to your furnace. But before opening up the furnace or air handler, let’s check the high-voltage power source.  This can also be a reason your heater stops working after a storm.

Check the Main Electrical Panel

Your furnace is supposed to receive 120 volts from the breaker panel on the side of the house. (Some people have high voltage panels located inside the house.) Heat pumps have 240-volt power supplied to them. As a reminder, the air handler or furnace will be located in a closet, the garage, the attic, or maybe you have a package unit on the roof or side of the house. But the first thing you’ll want to do is check to see if the power to your furnace is turned off at the breaker box.

If the breaker is “Tripped,” flip the switch to the “Off” position, then to the fully “On” position. Wait a few minutes to see if the furnace turns on. If it doesn’t, there may be an issue with the power supply to your home. In this case, you’ll need to contact your HVAC contractor to investigate and make any necessary repairs.

Inspect the Furnace for Damage (Charring, Soot)

A bolt of lightning hitting near your home can send an enormous amount of damaging heat and energy through your home’s electrical system. If the breaker is still on, but there doesn’t seem to be any power flowing to the furnace, the next step is to inspect the unit itself for damage. Start by looking for any signs of damage to the exterior of the furnace, such as burns or melted plastic. If you see any black charring or soot, it’s possible one of the components inside the unit blew, like a control board, relay, or safety switch. If you see any damage, it’s probably best to call in a professional heating and cooling technician to take a look and perform any necessary repairs.  Fox Family can always help finding out why your heater stops working after a storm.

Check for Error Codes

While you’re checking the unit, see if there is a sight glass, maybe an inch wide, on the front cover. Without opening the cover, see if any red or yellow LEDs are flashing. Count those flashes and make a note of it. Your HVAC contractor will thank you for having that flash code. Maybe it blinks three times long and two times quickly. That would be an error code of 32. Maybe you just see five steady flashes. The error code would be 5. Each brand is different in how they display error codes, but once the outer panel is removed, a sticker is usually attached to the inside that identifies what those error codes mean. You should really know what you’re doing before removing any panels, though. You have to think about your safety first.

Reset the Furnace

What to do When Your Furnace Doesn't Turn on After a Lightning Storm

If you’ve checked both the power supply at the main panel and the furnace itself for damage and error codes, and everything seems to be good, the next step is to reset the furnace itself. The easiest way to reset the furnace is to unplug it from the outlet, wait for 30 seconds and then plug it back in. While you’re doing that, observe the condition of the outlet cover and plug. If it has burning and soot around it or on the plate, the wiring inside of it could be charred. If you feel comfortable, take a small screwdriver and take the cover plate off to inspect the wiring. If it looks clean, it’s probably okay, but I would still replace the plug and cover plate as soon as possible. The cord that leads to the plug should not be melting or discolored either. If it is, that’s another thing I would consider having replaced soon.

After you plug the furnace back in, make sure the thermostat is still calling for heat and wait up to five minutes to see if the furnace turns on. Some types of systems have protection that forces the system to lock out for up to five minutes. To us technicians, this can be the longest five minutes EVER!!!

DIY Troubleshooting

Some people are brave enough to move on with troubleshooting their heat pump or heater is not working after a storm, but I have some pretty good articles and videos already posted about how to do that.

Lightning strikes can cause all sorts of problems for your home—including knocking out your furnace or heat pump. If this happens, don’t panic! Follow these troubleshooting tips, and you might be able to safely get your furnace up and running again in no time. And remember, if you’re ever unsure about what to do or how to fix something, it’s always best to call in a professional who can help. Stay safe!

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The HVAC Industry Continues to Experience the Effects of COVID-19

HVAC and covid 19 Featured image

HVAC Supply Pricing Continuing To Rise

Folks who purchased their new AC system at the beginning of the year should be singing their praises.  The industry continues to see rising costs of materials combined with a shortage of workers.  

A colleague of mine said, “When something like COVID interrupts any part of the supply chain system, including how those parts get shipped from there to here. We’re experiencing a weird dynamic right now with worldwide stress, but also with a high demand for our products and services. Also, considering the low numbers of employees working in these factories, the only thing to expect is chaos. The scenario is creating an almost panic for our industry to perform.”

Halfway through the summer of 2021, things haven’t gotten any better.  We continue to be frustrated.  Selling equipment is tough enough, but to get the okay from a customer and potentially not have their equipment is challenging.  It’s the toughest thing I’ve had to deal with since becoming a contractor in 2015.

What happens is, when we order our equipment online in the past, we could see the inventory levels of our distributor.  We would look up a particular furnace that matches up with a condenser and evaporator coil and see that they had 20 of those furnaces.  Now when we win a job, we have to submit the order and wait for the distributor to get back to us and let us know if they have the equipment to fill that order.  If they don’t, we have to call the customer back and let them know.

On a few occasions this year, we have had to offer the customer an entirely different brand than Trane, which has always been our equipment of choice.  This has worked out for those customers, and we appreciate them being flexible enough to understand.  

Every HVAC contractor in the United States is dealing with this equipment situation.  Manufacturers say they can’t get equipment out fast enough for the rising demand for new equipment.  This has created the highest rate of price increase we’ve seen in a very long time.  Each year, we typically see a 4% to 6% increase in the cost of equipment.  

attic furnace unit

This year we’ve already seen a 21% increase in that same equipment. This has resulted in your basic $10,000 HVAC system increasing by $2,000 in just one year.  Higher-end equipment has grown exponentially.

With a few to several more months of rapid inflation in the world’s economy, we continue to brace for whatever price increases we may see. These price increases ultimately get passed along to our customers. 

So, like we said this time last year, as we’re getting close to the end of the hottest time of the year, local suppliers should have an easier time restocking their shelves as demand goes down.  Winter months are relatively mild around the Sacramento Valley, so that we won’t get that high intensity of equipment change-outs experienced in other areas of the world with longer, colder winters.

Let’s keep our fingers crossed America get’s back to normal soon.  People need heating and air conditioning. It’s not a luxury for some people.  With continued demand and lower inventory of equipment and the parts that make that equipment up, inflation continues, stressing this contractor out.  

Stay safe and follow CDC guidelines so we can get through this sooner than later. Thanks so much for stopping by, and we’ll see you next time.

Furnace Repair Company Sacramento

Furnace Repair Company Sacramento

Furnace Repair: Common Furnace Problems We See This Time of Year

Furnace Repair, Common Furnace Issues

It is good for homeowners to have a basic understanding of what could be wrong in case the furnace malfunctions. This knowledge will enable the homeowner to fix the defect himself or herself in case the defect doesn’t require an expert. The discussion below explores some of the common furnace issues that Fox Family Heating and Air, a Sacramento heating and air conditioning company, often has to deal with when called by homeowners.

No Heat Coming From My Furnace

Several defects can stop the furnace from producing any heat once it is turned on. For example, a defective pilot light will stop the furnace from generating heat. Similarly, any defect in the thermostat (wrong settings, for example) can also prevent the furnace from heating your home.
The specific remedy selected will depend on an accurate diagnosis of the problem. For instance, you can follow the instructions in the user manual to check whether the pilot light is on. A clog may be preventing gas from reaching the pilot light. Clear the clog and the furnace will work as expected. Get help from a furnace repair company in Sacramento if the problem persists.

Insufficient Heat Being Produced

The furnace may turn on but struggle to deliver enough heat to warm your home. A dirty filter or burner can be the culprit for this problem. A loose blower belt or a clogged blower can also lead to insufficient heat production. Start by checking the filter in case you experience low heat production by the burner. Replace the filter in case light rays cannot penetrate through it once you hold it up. Clean the burner if it is dirty. You may need to call for technical support from a furnace technician in Sacramento in case these two remedies don’t fix the problem.

My Furnace Won’t Turn On

Check and confirm that that furnace switch is on if the furnace isn’t working. Go to the breaker panel and find out whether the breaker has tripped. You should also pay attention to the thermostat. Replace the batteries or adjust the settings in case any of those issues were preventing the furnace from turning on. The safety switch on the door of the furnace can also prevent the furnace from working. That switch is designed to pop out in case the door of the furnace is removed in order to access the hidden components of the furnace. Close this door so that the switch doesn’t prevent the furnace from activating.

Altered Flame Color

The flame from the burner should be blue. A yellow or reddish flame is an indicator of incomplete combustion due to the presence of contaminants. Those contaminants (dust, for example) are usually in the thermo-coupler or on the burner. Clean these components after switching the furnace off. A soft brush or a vacuum cleaner may suffice for this cleaning exercise.

Blower Not Stopping

The blower can work nonstop in case its limiting switch develops a defect. A blower that runs nonstop should only be repaired by a licensed professional since it is very risky for a layperson to tamper with such a complex electrical system. The technician from Fox Family Heating and Air will check and replace this limit switch in case it is found to be worn. This will prevent the blower from failing prematurely due to excessive wear.

Unusual Noises Coming From My Furnace

The furnace should not emit any loud noises, such as scraping, rumbling, rattling, or popping sounds. Such sounds could indicate that a mechanical component, such as the blower belt, has slipped or failed. Lack of lubrication can also cause friction between moving parts. The best thing that you can do in such a case is to turn the unit off and call a professional from a Sacramento heating and air conditioning company to fix the defective component before other parts are affected by that malfunction.

Some furnace problems can be repaired by the homeowner while others require expert intervention. Avoid taking on any furnace repairs which you aren’t comfortable with. Let the professionals at Fox Family Heating and Air take care of those problems so that heating can be restored to your home quickly.

5 Simple Furnace Fixes You Can Perform

5 Simple Furnace Fixes You Can Perform

5 Simple Furnace Fixes A Sacramento HVAC Company Says You Can Perform 

You may not need to wait for a professional to perform each repair needed to get your furnace working again when it breaks down. Here are some simple repairs that you can perform on your own if you are handy with tools and have a basic understanding of how furnaces work. Call a Sacramento HVAC technician from Fox Heating and Air if you aren’t familiar with the components of your furnace so that you avoid exposing yourself to needless risks or damaging the furnace further.

  • Check the Thermostat

A furnace that fails to work may have a simple fault in its thermostat. Start your DIY repair by confirming that the switch is set to heat rather than cool the home. Check the temperature setting and be certain that it is appropriate for the general conditions at that time of the year. For example, try setting the thermostat to a higher temperature than the ambient temperature and see if the furnace kicks in. Make sure that the day and time settings are accurate (the thermostat isn’t reading p.m. during morning hours, for example). Contact a Sacramento furnace repair technician in case you suspect that the thermostat has failed due to electrical issues.

  • Shutoff Breakers and Switches

Find the switch on or close to your furnace and confirm that it is turned on in case your furnace isn’t working. Fox Family Heating and Air technicians often respond to calls and find that someone accidentally turned the furnace off. Check the breaker too in the breaker panel. Get professional help from a Sacramento heating and air company in case the breaker keeps tripping each time you reset it.

  • Check the Filter

The heat exchanger of your furnace will shut off fast in case the filter is clogged and air can’t flow freely through it. Change the filter in case you hold it up and light doesn’t travel through its filter media/pleats. Ask a Sacramento furnace repair expert to demonstrate the correct way to install a new filter so that you start performing that basic task yourself. Remember that the filter change interval will depend on the type of filter and the conditions in your home. For instance, homes with pets may need to change the furnace filter more frequently than the change interval for homes with no pets.

  • Turn the Gas On

Someone in your home could have turned the gas valve off accidentally thereby stopping the furnace from working. Check the gas line from the furnace back to the gas meter. Locate the valve (handle) and turn it so that it is now parallel to the gas line. Check the pilot light in case you have an older furnace. That pilot light has to be lit in order for the furnace to generate heat.

  • Flush the Drain Lines

Greg Fox from Fox Family Heating and Air advises that homeowners should check the furnace drain lines frequently in order to confirm that they aren’t blocked. The furnace will shut down in case the flow of water through the drain lines is hindered by a clog or when the line is constricted by a heavy object. Biological matter can also grow in the lines and limit the flow of water. Flush such lines with a mixture of bleach and water so that any bacteria or other microorganisms can be flushed out.

It is important that you restrict your DIY repair efforts to the most basic fixes when your furnace develops a fault. Take all the necessary precautions, such as turning the power off, before you attempt any repair (if you must). The safest option is to find an affordable Sacramento furnace repair technician, such as those from Fox Family Heating and Air so that the professional can inspect the entire system before fixing any defects found. The money that you pay the technician will be much less than what you will spend in case you make a mistake and cause irreparable damage to the furnace unit.

Average Cost of Furnace Repair

Average Cost of Furnace Repair

Average Cost of Furnace Repair in Sacramento

Nothing could be as bad as your furnace breaking in the evening just as temperatures are dropping rapidly in winter. The first thing that is likely to occupy your mind is the cost of fixing that furnace or heat source since a replacement is often very expensive. Sacramento furnace repair experts explain that the repair cost will depend on the type and model of furnace you have as discussed below.

Repairing an Electric Furnace

Electric furnaces move air over coils in order to heat that air. The heated air is then distributed to the different rooms in your home by a network of ducts. Electric furnace units tend to be small, so the cost of repairing them also tends to be lower than the cost of repairing the other types of furnaces. Sacramento furnace repair experts estimate that it requires a maximum of $300 for repairs but the cost varies depending on the particular make/model of the electric furnace.

Propane Gas Furnaces

Propane gas furnaces run on liquefied propane. The gas burns in order to push heated air around your home. A pilot light sets off the operation of the furnace by igniting the burners located inside a combustion chamber. Heat travels from the combustion chamber to the heat exchanger from where it continues to the rest of the home. Propane furnaces are more expensive to repair and the cost will range from $300 to about $1,200 depending on the specific component affected. The heat exchanger is the most expensive component to repair (about $1,200 to replace it).

Natural Gas Furnaces

Fox Family Heating and Air technicians explain that natural gas furnaces only differ from propane gas furnaces due to the fuel used. The rest of the components and mode of operation are identical. Consequently, the repair cost for natural gas furnaces is similar to the cost you are likely to incur if you had a broken propane gas furnace.


Some homes are heated by hot water. This water starts out in the boiler where it is heated before a network of pipes moves it around the home. Radiators amply the effect of the hot water so that each room feels cozy and warm.

Hot water systems rarely develop major problems suddenly. Instead, minor issues build up until the system malfunctions. For example, mineral deposits can slowly accumulate inside the water tank until they finally cause it to spring a major leak. Honest furnace repair experts will tell you that the repairs will cost from $180 to nearly $600 depending on the exact defect found.

Heat Pumps

Heat pumps work by transferring heat from outside to the interior of your home during winter. The pump then reverses and channels indoor heat outside during the hot months of the year. The heat pump is usually linked to your air conditioning system. Some heat pumps rely on geothermal energy while others rely on heated water to operate. Repairing a heat pump costs more than repairing an electric furnace. For example, the thermostat alone will cost you about $300 to replace while a damaged defrost control board will cost you double what the thermostat costs.

How to Limit Furnace Defects

As you can see from the estimates above, you will spend a lot of money on furnace repairs if you don’t take steps to preserve the condition of your furnace. Greg Fox recommends two key measures to avert most furnace issues.

  • Annual Inspections. Ask technicians from Fox Family Heating and Air to inspect and service your furnace once each year. So, that any developing problem is detected and fixed early before it causes more costly damage to your unit. For example, a faulty seal can be replaced before it causes the blower motor to fail.
  • Furnace Filter Replacement. The Sacramento furnace repair professional should also change the furnace filter during the annual service visit. You can also learn how to perform this simple maintenance task to save time and money.

Talk to Fox Family Heating and Air, a professional Sacramento HVAC company, before you have any repairs done. You will be given advice regarding the suitability of repair or replacement of the furnace unit based on several factors.


How Does a Gas Furnace Work?

Easy Guide to gas furnace troubleshooting


Understanding How a Gas Furnace Works and the Sequence of Operation

Hey guys, how are you doing?  Today I’m going to describe for you the sequence of events that needs to happen for your furnace to start blowing warm air into your house. We’ll start at the thermostat and go all the way to the blower turning on, forcing air into the rooms of your home. Furnace troubleshooting is the topic coming up today on Fox Family Heating and Air.

Furnace Troubleshooting Safety

First, I want to give fair warning to anyone watching this that isn’t already an experienced technician in the HVAC industry.  This furnace troubleshooting video is for educational purposes only.  Fox Family Heating and Air does not recommend anyone other than a professional start opening up the furnace to try to diagnose the failure going on with your system.

There are high and low voltages that can shock a person.  There are also lots of moving parts that can damage body parts—namely, hands and fingers.  The furnace also produces hot surfaces within the furnace compartments and around the housing, potentially causing severe burns.  An actual flame produced by the ignition and startup of a gas furnace can cause severe burns and damage to a person or property.

When your house reaches a point where the heat needs to come on to keep you comfortable, a series of components work in a specific order to produce that heat.

The Thermostat

The thermostat is the first part of the sequence that engages, making the furnace work. There’s 24-volt power at the R terminal of the stat already.  Within the workings of the thermostat, 24 volts closes a switch at the W terminal.  That signal is sent to the control board back at the furnace.

The Furnace Control Board

The control board is a printed circuit board with various switches, resistors, and terminals that act as the quarterback of the heating system.  It calls the plays as they need to happen.

Low Voltage Wires

The control board has a terminal block with screws on it, with a set of thin low voltage wires coming from the thermostat.  Typically, the colors of these wires are red, yellow, white, green, and blue.  The wires are going to R (red), Y (cooling), white (heat), green (blower motor), and blue (common).

Note: the wire colors don’t matter here. They’re still copper on the inside of the sheathing.  So if we use a brown wire for R at the control board, brown needs to be hooked up to R at the thermostat.

The Inducer Motor

Once the control board receives the thermostat signal to turn the heat on, it tells the inducer motor to come on.  The inducer motor is a major component that removes the carbon monoxide from the flame of the gas furnace.  It draws the spent gasses into the metal or PVC flue pipe, which transfers those fumes from the furnace to the atmosphere through the roofline.  You may have seen the metal pipe sticking out of the roof of your house in the winter, exhausting steam into the air. That’s the exhaust we’re talking about here.

The Pressure Switch

This safety device proves that the inducer motor is on and doing its job properly.  If it’s not, the sequence shuts down and retries again.  This pressure switch is actually measuring the suction the inducer motor is producing and sends a signal back to the board, letting it know that startup is working so far.

Roll Out and High Limit and Pressure Switches

Meanwhile, other low voltage safety switches are sending a signal of all-clear back to the board.  There are a couple of “roll-out” switches and a high-temperature limit switch that must confirm to the control board all is well there, too.  The wires leading to the roll-out, high limit, and pressure switches are usually all wired in the same series circuit with each other as a safety control.  If any of these safety switches sense anything wrong with the heating system’s startup, the sequence stops, and retries.

The Ignition Sequence

Next, three components engage in lighting the flame and proving that it is lit. When the pressure switches and other safeties tell the control board all is well, the board starts the ignition sequence.  First, the board sends a signal to the ignitor.  This could be a hot surface ignitor that glows orange or a spark ignitor, which produces an arc between two metal forks lasting for several seconds.  (My blog post and video discussing why hot surface ignitors fail might be of use for you, too.)

Whether the ignitor glows or sparks or not, the next component, 24 volts, is sent to the gas valve, which opens the diaphragm inside of it. It opens, allowing natural or propane gas to flow on to through the metal burner assembly.

The Heat Exchanger

The gas now flowing through multiple orifices in the burner assembly reaches the ignitor, causing a flame to ignite and burn in a controlled fashion straight into the firebox or heat exchanger.  For the purposes of this post, we’ll call it the heat exchanger.

Crossover channels within the burner assembly allow the gas to flow from the first burner to the last one, where the flame pours over a thin metal safety rod called the flame sensor.  The flame meeting the rod creates a millivolt DC signal to the control board that allows the gas valve to remain open.  No flame being sensed means gas is flowing uncontrolled throughout the furnace cabinet, which is not good.

At this point, we have power, a good thermostat, a functioning inducer motor, ignition, flame, and flame sensor to verify it.

A delay now occurs to allow the heat exchanger to warm up so cold air isn’t sent through the ducts and into the air.  The heat exchanger is a hollow metal box with individual chambers.  The flame pours into each chamber, warming the metal to an extreme temperature.

Once hot enough, the air that flows over and around the metal box warms quickly from room temperature to about 100 to 140 degrees.  The temperature is set by the manufacturer and must be closely adhered to.  This will keep the system operating safely and to proper specs.

The Blower Startup

After this delay completes, the blower starts up, sending forced room temperature air over the correct speed of the metal heat exchanger.  If the air is sent over too fast, the air entering the room won’t be warm enough.  Too slow of air or not enough air and the system gets too hot.  Too hot means the high-temperature limit we discussed earlier will open, telling the control board something’s not right. So, this blower motor has to be dialed in just right.

Furnace Troubleshooting Tips

Here are some things that can happen when the furnace isn’t starting up correctly.  The following troubleshooting tips are not all-inclusive and are not to be taken as scripture that what is going with the furnace you’re working on is the problem.  These are general problems only.

No power to the board – If the unit is plugged in correctly and the breaker at the main panel is in the on position, there should be power to the furnace control board.  A transformer can fail between the outlet and the control board, and they can and do regularly.  The board with proper power can send the high and low voltage signals it needs to be the quarterback and run the plays.

Power, thermostat, no inducer motor – Low voltage power is sent from the control board to the R terminal at the thermostat.  Assuming you have 24 volts there, the thermostat closes the W switch, which now has 24 volts applied to it.  If the 24-volt signal is getting back to the control board’s W terminal, the control board will send the high voltage signal to the inducer motor.  If voltage is getting to the inducer motor but it doesn’t run, you likely have a bad inducer motor or capacitor for the inducer motor if it has one.  If you’re not getting voltage to the inducer motor from the board, you have a bad board or faulty wiring connection between the two.

Power, thermostat, inducer, no ignition – If the inducer motor is running, the ignitor should start glowing or sparking.  The gas valve should open, allowing the gas to flow, the gas flame should crossover to the other burners in line, and a signal should be received at the flame sensor telling the board everything is good to go.

As with many components in furnace troubleshooting, if the part is getting power but not operating, it’s likely failed.  If it’s not getting power from the control board, it’s likely a bad board.  I have a great video on why control boards fail for more information.

Power, thermostat, inducer, ignition, flame, sensor, but no blower – If everything works as it’s supposed to, except the blower motor hasn’t turned on after the flame ignited after about a minute or so, something is going on there.  If the motor is getting power but not working, the motor or its capacitor may have failed.  If the motor is not receiving power from the board, the board is likely bad.  Not all blower motors have capacitors, either.  This is especially true for systems made in 2020 or later.

Power thermostat, inducer, ignition, flame, sensor, blower, shuts down on high limit or roll-out – Lastly, if the blower motor comes on and the system starts heating, but after a few minutes or even several minutes the system shuts down, the high-temperature limit switch may have opened causing the system to retry again, after the heat exchanger cools off.  If the chamber that houses the heat exchanger gets too hot, this high limit switch will shut down the system.

So What Causes a Shutdown?

First, we have to check that the blower speed settings are correct.  Next, the air filter could be dirty, ductwork could be too small or even collapsed, or the evaporator could be clogged with dirt. (Check out one of my most popular videos that shows what kind of problems a dirty evaporator coil can create.)

All of these items have one thing in common:  not enough air flowing over the heat exchanger.  This causes the inside temperature of the furnace to go over the recommended setting established by the manufacturer.

Although many things can go wrong with the gas furnace, sometimes in combination with each other.  Not much else can go wrong unless something in this sequence goes wrong.  I sure hope this answers some questions you have about troubleshooting a gas furnace.  Be safe and use your head out there. Don’t get in over your head if you don’t know what you’re doing.

Thanks so much for stopping by, and we’ll see you next time!

Don’t miss our videos related to this topic:


Troubleshooting a Furnace Gas Valve

Troubleshooting A Furnace Gas Value

10 Easy Things to Check When Troubleshooting a Furnace Gas Valve

Hey guys, today we’re going to talk about troubleshooting a furnace gas valve.   I wanted to expand on our recent gas furnace troubleshooting series by going into each part of a furnace sequence of operation.  I’ll describe what the gas valve does and why it’s important.  And towards the end, I’ll give you ten things to check when you’re troubleshooting a furnace gas valve.  That’s coming up here on Fox Family Heating & Air.

The Furnace Sequence of Events

First, as a technician, you have to know the sequence of events that occurs for a gas furnace to start up properly. It’s straightforward, and you should have this memorized before you can even consider being qualified for troubleshooting a furnace gas valve.

  1. Power to the furnace control board
  2. Thermostat signals the call for heat
  3. Inducer motor kicks on
  4. Pressure switch proves the inducer operates correctly
  5. Ignitor activates
  6. Gas valve energizes
  7. Flame pours across burners
  8. Flame sensor proves all burners are lit
  9. The blower forces air through the ducts

First, the Inducer Motor Starts

When a furnace begins a new cycle, the inducer motor is the first thing you should see kick on.  One hundred twenty volts are applied through the wires coming from the control board.  This starts the inducer motor for up to 60 seconds before anything else even happens.

Next, a safety device called a pressure switch activates when the diaphragm inside it recognizes the inducer motor’s suction or purging action. 

When the “all clear” signal arrives at the control board, high voltage is sent to the ignitor – be it a hot surface ignitor or a spark ignitor.  The hot or sparking ignitor stands in the way of the gas that is getting ready to pour over it. 

This is Where the Gas Valve Comes Into Play

Modern gas valves typically have a printed circuit board in them that receive a 24-volt signal to activate the valve inside of it.  Remember the video I did on printed circuit boards?  If not, I’ll attach it below so you can brush up on what they are and the things that can go wrong with them.

This sequence will happen in three stages – and even if one step of this doesn’t perform, each part is still going to do its thing sequentially once the board gives the signal.

So, after the board senses the pressure switch and inducer motor are working:

  1. 120 volts is given to the ignitor (on some package units, it’s 240 volts.)
  2. 24 volts is given to the gas valve.
  3. The flame sensor starts detecting if there is a flame or not.

The ignitor is supposed to come on for a set amount of time: 30 to 60 seconds. (See our video on ignitors for an in-depth explanation of this topic.)

Next, the gas valve opens.  The gas coming from the utility company or the propane tank in the back yard is free to flow on to the ignitor.  That gas valve is what’s regulating the flow of the gas.

The flame sensor senses whether the flame is correctly burning.  At the opposite end of the burner assembly, the flame sensor also stands in the way of the flame.  The rod, which should be cleaned annually, by the way, will heat up and send a millivolt signal down to its ceramic base and on to the control board.

Only a certain amount of gas can be allowed to pass through the manifold and on to the burners.  The manufacturer of the furnace determines what that will be.  It is pretty standard, though—about 3.5″ water columns (wc).  The natural gas pressure coming from the street is somewhere around 7″-10″ wc, but the gas valve itself specifically allows that 3.5″ wc onto the burners. 

There are some situations and equipment where I’ve been told to bring the outlet pressure down to 3.25″ wc.  But I only did it on the advice from the technical support rep from that equipment.  Specifically, it was Ruud equipment.  The rollouts were getting too hot because the hood covering the flame would trap the heat and make the safety open.  Modifying the hood and adjusting the gas pressures were recommended to us, which seemed to fix it.

Furnaces differ, so please check your furnace installation and service guide for your system’s specifics.  This is something you don’t want to get wrong.

The gas valve is adjustable.  And usually, the installer of the equipment will dial in the outlet pressures on start-up.  Because the gas valve manufacturer – Emerson, White-Rodgers, Honeywell, and other valves makers will usually have it pre-set to that 3.5″ wc, some installers forget to do this.  We can’t assume the valve is correctly adjusted each time. That’s why you can have issues with your furnace related to your gas valve – because it wasn’t set up right by the installer during its first use.

Troubleshooting a Furnace Gas Valve

If 24 volts is coming from the board to the gas valve terminals and you don’t hear that little clicking noise the internal valve makes, you could have a bad gas valve.  To double-check, take the leads off to the gas valve and check there.  Got 24 volts?  Then something downstream of that 24 volts is not working. 

What’s the next thing that’s supposed to be working?  The printed circuit board or electric solenoid attached to the gas valve isn’t telling the valve to open, OR that gas valve board IS telling it to open, but the valve is stuck somehow.

If something is wrong with the internal components of the gas valve, it should be replaced. The gas valve cannot be repaired in the field. Only the gas valve manufacturer or someone certified by the gas valve manufacturer can make these repairs.

Some people will literally take a wrench and bang on the gas valve to get it to open up.  This is extremely dangerous.  Gas is nothing to toy with.  If you decide to try this and it kicks on, please replace the gas valve now rather than later. 

If we try to fix these ourselves and something goes wrong with the gas valve, and it somehow caught the house on fire, the investigation could come back to the furnace.  If they wanted to know who last worked on it and what was done to it, the gas valve manufacturer could claim innocence, and the homeowner’s insurance could deny the customer’s claim.  I know that sounds a little drastic, but it could happen.  Why put yourself in that situation?

I see people try to fix control boards, ignitors, and such, but we shouldn’t try to fix gas valves ourselves with such a sensitive instrument.

Here are ten things we can check when we think we have a bad gas valve before condemning it:

  1. Check the wires to the gas valve.  Are they cracked or frayed?  That could mean a couple of things.  You have a REALY old furnace, or something could have scorched the wires—things like that.  Replace the wire and continue your diagnostic.
  2. Check the coil at the gas valve.  If you check the coil’s resistance by putting your two-meter leads on each terminal and you get a reading of OL, you have a bad coil. There are more complicated things here but let’s keep this straightforward. 
  3. The gas coming into the valve should be at utility line standards.  It’s around 7″-10″ wc for natural gas in my neck of the world. There’s a port on the inlet side to check it.
  4. You may have plugged burner orifices.  A furnace that’s been off all summer can be the victim of a spider spinning a web inside the burner orifices.  Now, that’s a tiny spider, I know, but I promise, it happens!  Take a small piece of thermostat wire and gently poke inside the holes of the orifices attached to the manifold and try to fire up the system again.
  5. The flame might be coming on for a few seconds but then shutting off.  Is there a dropout of voltage or gas pressure to the gas valve?  That’s something to check for sure.  And you can do that by putting a “T” fitting in line with the hose to connect to your manometer.  Check the inlet and the outlet side to see if the pressure is dropping on either side of the valve. 
  6. Another reason the flame could drop out after only a few seconds of burning is the flame sensor.  If the sensor doesn’t detect the flame, the control board will signal the gas valve to shut down.
  7. If the flame does anything but shoot directly into the hollow metal heat exchanger, a safety can trip.  One safety trip is the rollout switch.  Sometimes you’ll get a little part of the flame that drifts off to the left or right, sending the switch off.  That doesn’t mean you should remove the switch.  It means you need to fix the problem.  Clean the end of the burner assembly nearest the heat exchanger.  Rust will sometimes build up on the crossover channels.  Use a wire brush to clean and see if that solves it.  Then place the burner correctly into the channel.
  8. The other safety trip that can cause the system to cut the gas off to the valve is the high limit switch.  If the furnace runs for a few minutes, then shuts off, something could be causing the inside of the furnace to get too hot. The first thing I would check is to see is if the evaporator coil is dirty.   I have a great video that shows what a dirty evaporator coil looks like and what it takes to clean it.
  9. The other reason the high limit could open is the blower motor speed could be set too low.  Check your installation guide as a reference for where the settings should be.
  10. Check the ductwork too.  These last three have all dealt with airflow.  If the return duct is crushed, then we’ll have low airflow again.  Visually check the return duct and feel around it if it looks questionable.  If the duct is not perfectly round, then this could be the problem. The furnace is suffocating.

What else should folks check when troubleshooting a furnace gas valve?  Leave me a comment down below to share your expertise.

When you’re installing the new gas valve, there are few things to keep in mind. It’s a like-for-like change out, but gas leaks are a serious issue, so make sure to use some pipe dope or pipe tape to seal the fitting. 

Also, don’t bend the manifold when you’re trying to remove the gas valve or put the new one back on.  Use two wrenches to get a proper hold on the manifold and the gas valve.

I strongly recommend not over-tightening the gas valve to the manifold.  You could bend the manifold, but also remember, someone might have to get that thing off someday, and you’d be creating a challenging situation for a tech that has to come out and service it in a few months.  Some guys get a little over the top and really crank down on it.  Not necessary. 

Check for gas leaks with an electronic gas sniffer or soap bubbles.  This will assure you the fittings are snug and leak-free.  And don’t forget to check the outlet side when the gas valve is on.  It doesn’t help when the valve is off because no gas is flowing through it.

If it’s a natural gas set-up, the spring that comes inside the valve will already be the right one.  If you’re using LP gas, you’ll need to make sure you put the right spring in it. It’ll come in the box.  Check the manifold orifices to ensure they are the right ones for LP too. And put the sticker on the gas valve that says LP.  This will help future HVAC technicians when they service the furnace.

And lastly, check the gas pressure on the new valve after you’ve replaced it.  I can’t say it enough. It’s simple to do with the right tools, don’t just change the valve and not check the pressures.

When it comes to troubleshooting a furnace gas valve, there’s also a setting for low fire on two-stage units that needs to be checked.

If the gas pressure is too low, your furnace’s efficiency will go down.  More condensation than usual will build up because the air in the air-fuel mixture will be too high.  The condensation can cause corrosion, possibly creating the need for a heat exchanger replacement in the future.

High gas pressure can be just as bad for your furnace because it dramatically increases the furnace’s overheating risk. When this happens, high limit switches will start opening, causing intermittent operation.  It can also crack your heat exchanger since it’s only rated to handle a certain amount of heat.  And cracked heat exchangers can introduce the spent gasses inside the heat exchanger to be carried along with the heat blowing into the house.

So, to recap.  When a furnace begins a new cycle, the inducer motor is the first thing you should see kick on. A safety device called a pressure switch activates when the diaphragm inside it recognizes the suction or purging action of the inducer motor.   Next, the three parts of the ignition sequence begin.  The ignitor kicks on, the gas valve opens, and the flame sensor senses that the flame exists.  If this all goes well, you have heat blowing into the house about a minute later when the blower kicks on.

What else should folks check when troubleshooting a furnace gas valve?  Leave me a comment down below to share your expertise. Thanks so much for stopping by, and we’ll see you at the next blog post.

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