How Does Comfort-R Work?

Home / Learning Center  

How Does Comfort-R Work?

Comfort-R is the HVAC manufacturer Trane and American Standard’s dehumidification mode on variable speed air handlers.  So, if you live in an area affected by high humidity levels, Comfort-R mode is a great way to automatically adjust how that humidity translates inside your home. It’s an added feature that separates Trane’s premium models from their standard models. The premium units with variable speed motors (…not ECM motors) are the S9V2 and XC95 gas furnaces, the XL16c packaged units, and the TAM9, TEM6, and TEM 8 air handlers. 

If this is your first time watching our channel, please click subscribe down here on the bottom right, and if you click that little bell on the right, you can let YouTube know you want to be notified of all of our videos as they come out.

A quick refresher:

The two main functions of an air conditioner are to (1.) remove heat and (2.) remove humidity.  When the AC is turned on, the moisture (or humidity) in your home is brought to the evaporator coil (the cold coil.)  The warm air from the house comes into contact with the cold evaporator coil and condenses to make water on the coil. That condensate then drains out to the side of the house and onto the ground.

Check out my video  and blog  regarding condensation drainage if you’d like to know more about that side of the air conditioning system. It’s an important part of your system.

Now, evaporator coils only have so much room for air to pass through when the AC is on.  They have very thin blades for air to pass through. If the coil gets too wet, the blower is getting a lot of resistance when it’s trying to push the air, so the dehumidification process becomes more difficult, cooling the house takes longer, which increases the electric bill for your home!  Whew! 

How does Comfort-R work?

In the most basic sense, Comfort-R Mode regulates airspeed at start-up to carefully control humidity levels.  Lower humidity can lead to savings by reducing moisture levels in the air so you can keep the thermostat at a higher setting and still feel comfortable.  Comfort-R mode also offers a warmer start-up with an all-electric heat pump during the heating season, so you don’t feel that blast of cool air when you turn on the heater when you’re looking for warm and cozy air.

Now I’m going to get a little technical here, but I’ll try and keep most of you with me.  I always try to talk in basic terms, so everyone understands. Let’s learn about this with a simple single-stage system.

  • On a call for cooling, a single-stage air conditioner and its indoor blower motor both turn on and begin cooling immediately at 100% speed or capacity.  (And yes, people do buy upgraded variable speed furnaces like the S9V2 furnace to match their standard single-stage outdoor condenser.)
    • So when the AC starts, the outdoor unit comes on at normal speed.  100%.  But, the indoor blower with Comfort-R enhancement will slowly ramp up to 50% speed over the first minute. This will allow the indoor evaporator coil to get cold quicker – because you don’t have as much room temperature air going across the coil to compete with the coil, allowing it to get colder, faster.
      If you have a heat pump match-up, this 50% ramp-up during the first minute will let your indoor coil get hot, quicker.
    • Over the next minute or two and up to about 8 minutes, the fan will run at 80% capacity to help further dehumidify in cooling mode or enhance warm air heating for heat pumps.
    • If necessary, after 8 or 9 minutes of the AC being on (or heat pump), the fan will increase to 100% capacity boosting its function until the thermostat is satisfied.
    • Now, normally when the temperature is satisfied, the outdoor compressor shuts off, AND the indoor blower turns off. There’s no delay.  In Comfort-R mode, the outdoor compressor shuts off, but the indoor fan will ramp down to 50% capacity.
      For 3 minutes.  This is for efficiency because the indoor coil will still be cold for a bit, so why not utilize the cold coil and run some air across it and have it sent into the house’s rooms?
  • In a general sense, everything works the same. Two-stage systems operate at a 70% speed and 100% speed or capacity. It’s a slow ramp-up to 50% of whatever stage it’s in (1st or 2nd stage.) Up to 80% for a few more minutes, even if it’s in the same stage, and then up to 100% fan speed for that stage if needed until the setpoint is reached.  Back down to 50% blower speed after the compressor shuts off and the temperature in the room is reached. That last three minutes for efficiency; and then shuts down entirely.
  • Fully-modulating systems can fluctuate widely – usually 25% to 100% in very small increments.  And these will always come with a variable-speed blower to match the outdoor condenser.  The ramping up and down happens accordingly.
ECM Fan Control
Enhanced Mode

Two things to know:

  1. Your HVAC company has to set this up for you at the time of installation.
  2. You have to use the 824, 850, or 1050 thermostats for the system to interpret the humidity levels (and that’s in 2021 at the time of this video.)

It’s something your installers have to set up for you at the time of installation. They have to cut the BK jumper on the integrated control board for Comfort-R Enhancement to work.  Air handlers also may have dip switches to dial in for the indoor variable speed motor to match the airflow required for the outdoor unit size.
Field Wiring Diagramn For Two Stage Headting Thermostat,Two Stage Heat Pump You also have to have a Trane (or American Standard) 824 thermostat. The Comfort-R function doesn’t work with any thermostat except its 824 on the non-communicating systems and the 850 or 1050 thermostats on communicating systems. That’s because the thermostat senses the humidity in the house, not a sensor that one might think is located in the air handler itself. So, you can’t use Nest, Ecobee, Sensi, or other popular smart thermostats with Comfort-R technology.


Who needs Comfort-R Technology the most?

Alaska and Hawaii have some of the highest humidity levels every summer! Other than that, it’s the states in the Southeast, Midwest, and Northeast that have to deal with high relative humidity, like:

  • Florida
  • Louisiana
  • Mississippi
  • Iowa
  • Indiana
  • Michigan
  • Vermont
  • New Hampshire
  • Maine

You don’t have a lot of people west of the Rockies complaining about heavy, humid air in the summertime. The atmosphere is so dry in California that wildfires spark up and blaze on for weeks at a time because there’s very little moisture in the air to keep them at bay. 

Dehumidification is rarely discussed here in the Sacramento Valley. That’s why Comfort-R dehumidification may not necessarily be needed quite as much in the western states as in the eastern ones. But you’ll still find homeowners discussing it with their installer to try and keep precise tabs on the humidity level in their home. And, some people like to invest in the latest technology for their homes. So, let’s talk about it!

What Energy Star says about humidity:

Energy Star says anything above 50% indoor humidity in your house is considered high. It can not only cause added stress to your air conditioner but the human body as well. High humidity in a home can make people struggle to get a good breath because of all the moisture that comes into the lungs with the air they’re trying to breathe in. Energy Star says 30% to 50% humidity in a home is just about right. 

Modern thermostats have humidity levels readily available for you to view on your smartphone or the face of the thermostat itself. See how the thermostat below shows outdoor temperature and humidity as well as indoor temperature and humidity? That’s great information to have for someone trying to monitor humidity levels in their home.


The benefit of having a furnace, packaged unit, or heat pump air handler with a variable speed motor is that Comfort-R technology can be utilized. This allows for:

  1. Easier dehumidification of the home.
  2. The home to cool down faster.
  3. Keep your electric bills lower.
  4. Keep money in your pockets.
  5. 5(On heat pumps) Remove that cold blast of air that comes out when starting heating mode.

Hopefully, this gives a better idea of how Trane and American Standard Comfort-R mode works and what is needed to make it happen. We also discussed if Comfort-R mode is something that your home even needs depending on where in the country you live.

If this is your first time watching our channel, please click subscribe down here on the bottom right, and if you click that little bell on the right, you can let YouTube know you want to be notified of all of our videos as they come out.

Thanks so much for watching. We’ll see you on the next video.

Fox Family Heating & Air serves Sacramento, Rancho Cordova, and all of Northern California. If you’re looking to schedule HVAC service in these areas, give us a call!

Hours of Operation

Mon – Fri: 7:30 am – 5:00 pm
Sat – Sun: 8:00 AM – 4:00 PM

Rancho Cordova Chamber of Commerce
Nice Job Badge
IHACI Member Logo
HEE Certified Company

Previously Seen On

GoodDay Sacramento

HVAC Insider Logo
the News logo HVAC-Insider
HVAC Revealed Success Secrets HVAC-Overtime

HVAC Refer Guy