Humidity Control On Thermostat Not Working - HVAC - DIY Chatroom Home Improvement Forum
Advertisement


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Like Tree2Likes
Reply
 
Thread Tools Search this Thread
Display Modes
Old 08-31-2020, 08:42 AM   #1
Newbie
 
Join Date: Apr 2018
Posts: 8
Rewards Points: 16
Default

Humidity control on thermostat not working


Hi folks,
The thermostat (Trane XL824) allows you to enter a target humidity level. Unfortunately, it's not getting there.

Right now (early morning here in NC), here's the info from the thermostat:
"Cooling target" = 55%
"Indoor Humidity" = 65%
"Cool to 74F"
"System Idle at 73F"
Outdoor Temp = 71F
Outdoor Humidity = 90%

Is it because the set point of 74F is too high? The problem with lowering the setpoint this past summer is that is got seriously freezing inside. We've had to go outside to warm up

There are no obvious air leaks from the outside to inside the house.

This is a fairly new HVAC system (put in 3 years ago)
I contacted Trane online more than a month ago (twice) but no response.
The obvious solution would be to get the HVAC technician to come on over but with this virus raging that maybe not a good idea right now.

Cheers
Epictetus is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 08-31-2020, 09:10 AM   #2
Member
 
Join Date: Sep 2012
Posts: 13,514
Rewards Points: 318
Default

Re: Humidity control on thermostat not working


Raise the set point to 77 and see if the humidity goes down.
SeniorSitizen is online now   Reply With Quote
The Following User Says Thank You to SeniorSitizen For This Useful Post:
Epictetus (08-31-2020)
Sponsored Links
Advertisement
 
Old 08-31-2020, 11:17 AM   #3
Member
 
Join Date: Jul 2018
Posts: 771
Rewards Points: 1,542
Default

Re: Humidity control on thermostat not working


Sounds like it's set up with "overcooling" enabled for dehumidifying. basically it'll keep running to pull the humidity out, even if you reached the set point. this can work, but it's not the best method. if it's cooler outside than inside, there likely isn't enough thermal load in your house to allow the coil to get cold, get saturated, and start draining out water by the time it cools down the house.

many of those thermostats have the option to control a whole house dehumidifier. if where you are in NC is very humid even when it's not hot out most of the time, this is the direction I would steer you.
u3b3rg33k is offline   Reply With Quote
The Following User Says Thank You to u3b3rg33k For This Useful Post:
Epictetus (08-31-2020)
Sponsored Links
Advertisement
 
Old 08-31-2020, 12:34 PM   #4
Newbie
 
Join Date: Apr 2018
Posts: 8
Rewards Points: 16
Default

Re: Humidity control on thermostat not working


Thanks for the replies!

Quote:
Originally Posted by SeniorSitizen View Post
Raise the set point to 77 and see if the humidity goes down.
Wow. That's interesting. Not sure where you are coming from but I'll give it a try! Is this just a test?

Quote:
Originally Posted by u3b3rg33k View Post
...it'll keep running to pull the humidity out, even if you reached the set point....
OK, I'll contact the HVAC company because the humidity set point is obviously not over-riding the temp set point, as it should.
Never even thought about a dehumidfier!

Many thanks!
Epictetus is offline   Reply With Quote
Old 08-31-2020, 01:30 PM   #5
Newbie
 
Join Date: Apr 2018
Posts: 8
Rewards Points: 16
Default

Re: Humidity control on thermostat not working


I must be losing it.

My wife just pointed out that we tried a dehumidifier a couple of years back. It pumped out such an incredible amount of heat as to be not an option.

Works great in the crawl space though.
Epictetus is offline   Reply With Quote
Old 08-31-2020, 01:39 PM   #6
Member
 
user_12345a's Avatar
 
Join Date: Nov 2014
Location: Canada
Posts: 12,450
Rewards Points: 58
Default

Re: Humidity control on thermostat not working


Your t-stat either over-cools a couple of degrees below the temp setpoint to reach humidity setpoint, slows the blower down to improve dehumidification, or both.

This is assuming it was set up properly.

Your unit can not dehumidify without cooling. When it's mild, even with overcooling enabled, it won't run long enough to dehumidify to 50% on it's own. Only a dehumidifier can do that.

Run exhaust fans when cooking and showering - that helps.
__________________
I am not in the business of any trade I give advice on. I have non-professional hvac experience + good knowledge of theory. Attempt repairs at your own risk. Never jump out safeties - especially pressure switches - on a furnace for testing with fuel supply on; use a meter. Do not troubleshoot with live line voltage present unless there's no alternative.
user_12345a is offline   Reply With Quote
The Following User Says Thank You to user_12345a For This Useful Post:
Epictetus (09-01-2020)
Old 08-31-2020, 02:51 PM   #7
Member
 
Join Date: Sep 2012
Posts: 13,514
Rewards Points: 318
Default

Re: Humidity control on thermostat not working


Quote:
Originally Posted by Epictetus View Post
Thanks for the replies!


Wow. That's interesting. Not sure where you are coming from but I'll give it a try! Is this just a test?
*********************************************
Not a test, just a fact.and this 8 % reduction in R H is without any moisture removal.


http://dpcalc.org/




Edit: Edit:
Attached Images
   

Last edited by SeniorSitizen; 08-31-2020 at 03:00 PM.
SeniorSitizen is online now   Reply With Quote
The Following User Says Thank You to SeniorSitizen For This Useful Post:
Epictetus (09-01-2020)
Old 08-31-2020, 05:35 PM   #8
An old Tradesmen
 
Join Date: Oct 2008
Location: Somewhere
Posts: 39,259
Rewards Points: 86
Default

Re: Humidity control on thermostat not working


Quote:
Originally Posted by SeniorSitizen View Post
*********************************************
Not a test, just a fact.and this 8 % reduction in R H is without any moisture removal.


http://dpcalc.org/




Edit: Edit:

Of course, thats presuming that there also is no moisture gain from the longer off cycle.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is online now   Reply With Quote
The Following User Says Thank You to beenthere For This Useful Post:
Epictetus (09-01-2020)
Old 08-31-2020, 05:51 PM   #9
Member
 
Join Date: Sep 2012
Posts: 13,514
Rewards Points: 318
Default

Re: Humidity control on thermostat not working


Quote:
Originally Posted by beenthere View Post
Of course, thats presuming that there also is no moisture gain from the longer off cycle.
That should be perfect being everyone here seems to want a longer run cycle and moisture needs to be removed before the temperature will make a significant change.
SeniorSitizen is online now   Reply With Quote
The Following User Says Thank You to SeniorSitizen For This Useful Post:
Epictetus (09-01-2020)
Old 08-31-2020, 06:01 PM   #10
An old Tradesmen
 
Join Date: Oct 2008
Location: Somewhere
Posts: 39,259
Rewards Points: 86
Default

Re: Humidity control on thermostat not working


Quote:
Originally Posted by SeniorSitizen View Post
That should be perfect being everyone here seems to want a longer run cycle and moisture needs to be removed before the temperature will make a significant change.

But raising the thermostat set temp, shortens run time.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is online now   Reply With Quote
The Following User Says Thank You to beenthere For This Useful Post:
Epictetus (09-01-2020)
Old 08-31-2020, 06:05 PM   #11
Member
 
Join Date: Sep 2012
Posts: 13,514
Rewards Points: 318
Default

Re: Humidity control on thermostat not working


Quote:
Originally Posted by beenthere View Post
But raising the thermostat set temp, shortens run time.
Not if there is moisture increase. Moisture has to be removed to reduce temperature equals more run time.
SeniorSitizen is online now   Reply With Quote
The Following User Says Thank You to SeniorSitizen For This Useful Post:
Epictetus (09-04-2020)
Old 08-31-2020, 07:19 PM   #12
An old Tradesmen
 
Join Date: Oct 2008
Location: Somewhere
Posts: 39,259
Rewards Points: 86
Default

Re: Humidity control on thermostat not working


Quote:
Originally Posted by SeniorSitizen View Post
Not if there is moisture increase. Moisture has to be removed to reduce temperature equals more run time.

Actually, moisture doesn't have to be removed to lower temp.


Many systems only remove a small amount of moisture, leaving the home with a high RH. Specially as outdoor temp decreases.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is online now   Reply With Quote
The Following User Says Thank You to beenthere For This Useful Post:
Epictetus (09-01-2020)
Old 09-01-2020, 01:15 PM   #13
Newbie
 
Join Date: Apr 2018
Posts: 8
Rewards Points: 16
Default

Re: Humidity control on thermostat not working


OK, folks.

Many thanks for the replies.
Lots to think about.

Maybe, because we are getting to be a bit elderly, my wife and I are more susceptible to slightly colder conditions. For example, right now, at 1pm:
From thermostat readout:

System is idle
Setpoint 71F
Humidity 66%
Humidity Setpoint 60%
Outside Temp 75F
Outside Humidity 90%

In one room with an Accurite thermometer:
68F
64%

For us, it's unpleasantly cold in this room, especially when the AC starts to kick in.

Is using a small ceramic heater too stupid.

Cheers
Epictetus is offline   Reply With Quote
Old 09-01-2020, 02:09 PM   #14
Member
 
Join Date: Jun 2018
Location: Colorado
Posts: 524
Rewards Points: 904
Default

Re: Humidity control on thermostat not working


Quote:
Originally Posted by Epictetus View Post
Is using a small ceramic heater too stupid

Take your dehumidifier out of the crawl space and run the hell out it. Removes moisture, adds heat and you get longer run cycles from the a/c.
57TinkerMan is offline   Reply With Quote
The Following User Says Thank You to 57TinkerMan For This Useful Post:
Epictetus (09-04-2020)
Old 09-01-2020, 02:29 PM   #15
Member
 
user_12345a's Avatar
 
Join Date: Nov 2014
Location: Canada
Posts: 12,450
Rewards Points: 58
Default

Re: Humidity control on thermostat not working


i don't think it's set up properly.
__________________
I am not in the business of any trade I give advice on. I have non-professional hvac experience + good knowledge of theory. Attempt repairs at your own risk. Never jump out safeties - especially pressure switches - on a furnace for testing with fuel supply on; use a meter. Do not troubleshoot with live line voltage present unless there's no alternative.
user_12345a is offline   Reply With Quote
The Following User Says Thank You to user_12345a For This Useful Post:
Epictetus (09-04-2020)
Sponsored Links
Advertisement
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Top of Page | View New Posts