Thermostat fan setting (auto vs circ)?

[steelyman]

I’ve replaced my 2007 Honeywell thermostats with a newer model - T6 Pro programmables.

Step up for me because the originals weren’t programmable. The T6 is not wi-fi connected (my choice, I don’t “do” the smart home stuff).

They seem to be working well so far and have several options that weren’t on the thermostats that were replaced. One is a new fan setting: CIRC, in addition to AUTO and ON. Apparently this tells the thermostat to run the fan for ~1/3 of the time when not controlled by the heat/cool setting, in order to provide improved circulation.

This seems like a good option, especially during the “shoulder seasons”, spring and fall. I have a dual-zone setup (first and second floor).

I’m trying this out on the second floor to see how it goes and if it makes any difference. It’s getting chillier here in central NC.

Any thoughts/experiences with this?

Here’s the link for the new gadget, which appears to be manufactured by Residio under the brand HoneywellHome:

https://www.honeywellhome.com/us/en...thermostat-up-to-2-heat-1-cool-th6210u2001-u/

 

[Aerides]

Ours AC thermostat does something similar. Basically it runs to cool, then it's set to dehumidify, usually runs that for about 5-10 minutes after the temp goal is met. In FL, there's a big difference between 78f at 55% humidity, and 78f at 45%h.

I don't have any similar setting on the heat side, but we only run the heat a handful of days each year.

 

[camfused]

^^^ I don't know much about this either, but it seems like a bad idea for NC, due to our humidity. If humidity is allowed to build up on the coils, it could cause them to freeze and block up. But, I could be totally wrong.

 

[steelyman]

^^^ I don't know much about this either, but it seems like a bad idea for NC, due to our humidity. If humidity is allowed to build up on the coils, it could cause them to freeze and block up. But, I could be totally wrong.

That’s something to consider. The motivation for the new thermostat was caused by too-frequent cycling which was in turn caused by blocked coils and resulting poor airflow (due to dirt buildup from lack of maintenance, since corrected/washed). I’ll monitor as I go.

 

[target2019]

I don't think my Echonet thermostats have this feature. Seems to be just FAN On or Auto.

For about a month in transition from Cool to Heat, I turn the fan ON for a few hours, on the lowest speed.

 

[latexman]

We just bought a condo in Bradenton, FL that has Honeywell's color wifi programmable. It has "Circulate", but the previous owner used "Automatic", and I've never changed it. I'm interested in other's experience. I do find it handy to adjust the temperature when we are enroute to the condo so it's our usual 72 F when we get there.

If coils are freezing up, better have the A/C looked at. Normally, the coil runs about 40 F so freezing is a non-issue.

 

[steelyman]

We just bought a condo in Bradenton, FL that has Honeywell's color wifi programmable. It has "Circulate", but the previous owner used "Automatic", and I've never changed it. I'm interested in other's experience. I do find it handy to adjust the temperature when we are enroute to the condo so it's our usual 72 F when we get there.

If coils are freezing up, better have the A/C looked at.

I agree. I’m thinking this may warrant more frequent filter changes which is not a bad thing but seems unrelated to freezing up.

 

[Al in Ohio]

I’ve replaced my 2007 Honeywell thermostats with a newer model - T6 Pro programmables.

Step up for me because the originals weren’t programmable. The T6 is not wi-fi connected (my choice, I don’t “do” the smart home stuff).

They seem to be working well so far and have several options that weren’t on the thermostats that were replaced. One is a new fan setting: CIRC, in addition to AUTO and ON. Apparently this tells the thermostat to run the fan for ~1/3 of the time when not controlled by the heat/cool setting, in order to provide improved circulation.

This seems like a good option, especially during the “shoulder seasons”, spring and fall. I have a dual-zone setup (first and second floor).

I’m trying this out on the second floor to see how it goes and if it makes any difference. It’s getting chillier here in central NC.

Any thoughts/experiences with this?

Here’s the link for the new gadget, which appears to be manufactured by Residio under the brand HoneywellHome:

https://www.honeywellhome.com/us/en...thermostat-up-to-2-heat-1-cool-th6210u2001-u/

Retired HVAC Engineer here. Circ is the recommended setting for two story houses to help even out temperature variations between 1st and 2nd floors. I have a nest thermostat and I run circ for 1/3 each hour plus I installed an extra temp sensor upstairs to control in the evening thru morning.

 

[steelyman]

Retired HVAC Engineer here. Circ is the recommended setting for two story houses to help even out temperature variations between 1st and 2nd floors. I have a nest thermostat and I run circ for 1/3 each hour plus I installed an extra temp sensor upstairs to control in the evening thru morning.

Fantastic - thanks! Good to hear from a pro. All during morning coffee.

Is e-r.org a great resource or what?

 

[Dash man]

I have a Honeywell T5 thermostat that has that feature, but I’ve never tried it. Thanks for the info! I just changed the setting.

 

[latexman]

Retired HVAC Engineer here. Circ is the recommended setting for two story houses to help even out temperature variations between 1st and 2nd floors.

Thanks, and great news. My 2BR/2BA condo is 1 level and < 1300 sq. ft. so no need for me to experiment with Circulate!

 

[braumeister]

We have a ceiling fan in the living room and keep it on a low setting most of the time for the same reason.

 

[Al in Ohio]

^^^ I don't know much about this either, but it seems like a bad idea for NC, due to our humidity. If humidity is allowed to build up on the coils, it could cause them to freeze and block up. But, I could be totally wrong.

Running circ would reduce that as it continues to run warmer return air through the coil for another 20 mins to melt any frosting.

 

[Al in Ohio]

We have a ceiling fan in the living room and keep it on a low setting most of the time for the same reason.

Ceiling fans are another tool in your toolbelt to both help even out space temperatures and make you feel cooler without quite needing the AC yet due to increased skin evaporation. Especially good for upper level master bedrooms.

 

[bltkmt]

Retired HVAC Engineer here. Circ is the recommended setting for two story houses to help even out temperature variations between 1st and 2nd floors. I have a nest thermostat and I run circ for 1/3 each hour plus I installed an extra temp sensor upstairs to control in the evening thru morning.

Good info. We have four zones - three upstairs and one down. Would you suggest circ on all?

 

[Time2]

Ours AC thermostat does something similar. Basically it runs to cool, then it's set to dehumidify, usually runs that for about 5-10 minutes after the temp goal is met. In FL, there's a big difference between 78f at 55% humidity, and 78f at 45%h.

I don't have any similar setting on the heat side, but we only run the heat a handful of days each year.

"there's a big difference between 78f at 55% humidity, and 78f at 45%h."
I agree 100% with this, I have experimented with a dehumidifier and found if I can get the Humidity down to 40%, I'm still comfortable with the temp 4* higher. The problem with the dehumidifier is that it produces a lot of heat, so wherever I put it, that area got quite warm. I quit using the dehumidifier when it was recalled for starting fires. Kenmore paid $75 to send in the cutoff power cord. That wasn't enough, but I also didn't want to risk a fire.

 

[OldShooter]

An ounce of data trumps a pound of theory. Buy three or four very simple cheap mechanical thermometers, calibrate them together to make sure they all read about the same, then scatter them in the rooms where you're interested in seeing differences. If the temperature differences are minimal you don't need to pay the electricity bill to circulate the air, conversely if they are significant then the circulating air is probably a good investment.

For example: https://www.amazon.com/Taylor-EMW0063562-1-Pack-White/dp/B0063K9IHM

 

[RunningBum]

It seems like it'd make sense for cooling, especially if you have multiple levels are an area that is hotter or cooler than others for whatever reason. For heating, it might work, but if you happen to be near the vent it seems like the forced air flow would be cooling on your skin, which you don't want in cold weather.

 

[Time2]

Some may get a benefit from more filtering of the air in the house when the fan is on more.

 

[HenryD]

We have a fully occupied basement and two stories above. Several pets. Fan on constantly and frequent filter changes help to normalize the humidity and temp somewhat. I keep temp/humidity meters on the upper floor and in the basement. The indoor/outdoor air exchanger gets used spring-fall.

It's on my list to buy a spare fan motor since I am sure we are wearing it out prematurely and I don't want to get caught out needing one in a hurry at an inopportune time of year.

 

[MichaelB]

Is there any mechanical risk to running the fan for extended periods without the A/C , such as premature wear or overloading the fam?

 

[ERD50]

Retired HVAC Engineer here. Circ is the recommended setting for two story houses to help even out temperature variations between 1st and 2nd floors. I have a nest thermostat and I run circ for 1/3 each hour plus I installed an extra temp sensor upstairs to control in the evening thru morning.

I was about to post the same thing, based on personal experience.

Since OP said they are on separate zones on each story, I don't think the CIRC setting (runs the fan ~ 1/3rd of the time, regardless if the heat or AC has run that long) would make a big difference.

In our previous home, we had one zone and two stories. When we got the new HVAC/thermostat, I found the CIRC feature to really help keep the upstairs bedroom from getting hot overnight.

Without CIRC, the thermostat was on the 1st floor, and on a not-so-hot night, A/C would not run much, and the heat would keep building up on the 2nd floor, while the 'cool' stayed on the 1st floor and kept the A/C from running. CIRC really helped to keep it even.

But two zones ought to pretty much do the same thing.

-ERD50

 

[Time2]

Is there any mechanical risk to running the fan for extended periods without the A/C , such as premature wear or overloading the fam?

I'm sure there is wear from the additional time the motor runs, but I don't think there is any additional load, unless you want to get nitpicky and say colder (air conditioned) air is more dense and harder for the fan to push, in that case less load when just Fan. It is just more time on the motor. Depending on the motor type, you may want a capacitor in stock also. Newer units, probably have the ESM motor vs the older (less troublesome/more repairable) PSC motor.

 

[Qs Laptop]

They seem to be working well so far and have several options that weren’t on the thermostats that were replaced. One is a new fan setting: CIRC, in addition to AUTO and ON. Apparently this tells the thermostat to run the fan for ~1/3 of the time when not controlled by the heat/cool setting, in order to provide improved circulation.

Any thoughts/experiences with this?

I have a 2-story walkout in Minnesota. In the winter I see about a 5 degree difference from finished basement (with carpeting) to main floor. So when it's 72 on the main floor it's 67 in the basement. (Don't judge me for setting my thermostat at 72, it's freakin' Minnesota!)

I tried the circulation option to smooth out the temperature gradient. With my thermostat it's not truly "circulation mode" that is, the fan doesn't automatically shut off after 1/3 of the time without a heat cycle. Instead it runs the fan continuously at the lowest speed setting. When the thermostat calls for heat the furnace kicks on and heated air is dispensed.

Using this method, it reduced the temperature gradient about 1 degree.

I found greater success by changing the default fan speed on my furnace control board for the heat cycle. The default setting on heat cycle is to run the fan at it's lowest speed. Instead, I set the fan speed to the 2nd slowest speed. This is done by adjusting DIP switches on the control board. So the fan speed was bumped up just a bit. I also shut off the fan running continuously between cycles.

Using this method I reduced the temperature gradient about 2 degrees. Bonus--the furnace doesn't seem to cycle as many times as it did on slowest fan speed. And the early morning start-up heating cycle is pushed back about half an hour because the higher fan speed heats the house faster than the lowest fan speed.

I'd follow OldShooter's advice and get some thermometers and actually measure and record the results. I did this at my house. Only way to know for sure.

 

[OldShooter]

Is there any mechanical risk to running the fan for extended periods without the A/C , such as premature wear or overloading the fam?

I wouldn't worry about it. But never say never. Any motor will wear more when running than when not, but any furnace providing a continuous run option should have been designed to suit the need. These have been in the market/tested for a long time.

It's kind of like the new auto stop/start car engines. The older car starters will not have been designed for this kind of duty, but the new ones have. Now we just have to wait to see how the new designs work out.