Thermostat will not work, too cold???

[CKS1955]

Good evening,
I have a 30,000 Beacon Morris garage heater that is controlled by a Honeywell programmable thermostat (RTH221B). Went to use the unit today and the heater would not turn-on. I could control the fan, but when I placed it in heat mode nothing would happen. So I took the thermostat from inside the house and used it in the garage to see if it was the heater unit or a thermostat issue. The unit fired right up.

Well then I started to wonder maybe one of the wire came loose, so I reinsalled the Honeywell thermostat and the unit fired right up (I had left the Honeywell in the house while I was using the other thermostat to test the unit). I started to wonder if the air temperature could be too cold for the thermostat to function properly. So I let the garage adjust to the outside temperature (current temperature around 0 degrees fahrenheit). I set the thermostat to call for heat and nothing. I then warmed the thermostat with my hands/breath and then it would work when put into heat mode.

Could the air temperature be to cold for the thermostat to work or is it defective?

Thanks for any insight,
Jay

 

[dw1]

Does that T Stat have aaa batteries in it? do they need to be changed out?

 

[CKS1955]

Checked the batteries and they were fine.

Jay

 

[brewchief]

I've seen a few that wouldn't work when very cold, sometimes an old-fashioned mechanical stat is hard to beat.

Sent from my SM-G900V using Tapatalk

 

[dfiler2]

Define cold.

 

[CKS1955]

Define cold.

Temperature around 0 degrees fahrenheit.

Jay

 

[gregtwojeeps]

Good evening,
I have a 30,000 Beacon Morris garage heater that is controlled by a Honeywell programmable thermostat (RTH221B). Went to use the unit today and the heater would not turn-on. I could control the fan, but when I placed it in heat mode nothing would happen. So I took the thermostat from inside the house and used it in the garage to see if it was the heater unit or a thermostat issue. The unit fired right up.

Well then I started to wonder maybe one of the wire came loose, so I reinsalled the Honeywell thermostat and the unit fired right up (I had left the Honeywell in the house while I was using the other thermostat to test the unit). I started to wonder if the air temperature could be too cold for the thermostat to function properly. So I let the garage adjust to the outside temperature (current temperature around 0 degrees fahrenheit). I set the thermostat to call for heat and nothing. I then warmed the thermostat with my hands/breath and then it would work when put into heat mode.

Could the air temperature be to cold for the thermostat to work or is it defective?

Thanks for any insight,

Jay

Sounds like you are on the right track. If you still have the T-stat box that it came in, look at the stats temperature operating range posted on it. The range may be posted on the back of the stat also. Good luck. jmo

 

[beakie]

I have a honeywell "heat only" t-stat in the garage.
below 35*F (could be 32*) it turns off... just displays "Lo" and won't turn on until temp gets about 35*F

I use the hot air gun aimed near the t-stat for a few minutes to bring the ambient temp around the t-stat up to a temp it will read, then activate the heater.

batteries fine, I can control the fan np (via separate switch) but the t-stat just won't work below 35*F

 

[JCByrd24]

Same as beakie, Honeywell is retarded, mine stops working below 40F. Thought lo meant low battery, nope. I pop mine off the plate and use alligator clips to jumper until t stat reads again.

 

[CKS1955]

I agree, I don't think the t-stat is defective, just not designed to operate in this type of environment. Here is a link discussing t-stats: http://www.garagejournal.com/forum/showthread.php?t=146776

Jay

 

[CKS1955]

Good afternoon,
Has anyone used the Honeywell Thermostat CT87N.

http://www.honeywellstore.com/store...1006-the-round-heatcool-manual-thermostat.htm

I have not been able to locate anything on why it would not work with starting temperature as cold as 0 degrees fahrenheit.

Thanks,
Jay

 

[Milton Shaw]

It's probably a software issue on those thermostats. They probably are looking for a resistance range in the thermister and if it is out of that range they don't know to what to do. Designers at there worst.

 

[CKS1955]

The response from Honeywell for the Honeywell RTH221B Basic 1 Week Programmable Thermostat:

Jay,

Thank you for contacting Honeywell.

This thermostat is not recommended to be used in a garage or unconditioned space. Operating ambient temperatures are 32°F-120°F for this thermostat.

Sincerely,
Honeywell ECC Customer Care

 

[CKS1955]

The response from SupplyHouse.com for the Honeywell CT87N Thermostat:

Q:"Can you use the Honeywell CT87N in a garage? The thermostat will only be used when the garage is in use. The starting temperature could be as low as 0 degrees fahrenheit. Thanks."

A:Supplyhouse Staff from SupplyHouse said:
"yes but you can not set it that low."

 

[rburke65]

Why would you sell stat for a furnace/heated that won't function when when you most need the heat? Dah........

 

[LS6 Tommy]

If I have an old yoyo (HONEYWELL T87) I'll send it to you. Those old mercury stats run pretty flawlessly as long as the anticipator is set right and it's mounted level.

Tommy

 

[CKS1955]

If I have an old yoyo (HONEYWELL T87) I'll send it to you. Those old mercury stats run pretty flawlessly as long as the anticipator is set right and it's mounted level.

Tommy

Thanks for the offer Tommy. I had already ordered one via eBay and it showed up in the mail today. Wish I would have waited for the older ones that operate with mercury, the new ones no longer use it.

Jay

 

[GMBracing]

why not just add a switch to "jump start" the thermostat when you want to heat up mthe area. turn on switch it will start the boiler and when it gets above 35 deg turn the switch off and let the tstat do its job
it you want it could be a spring type timer that you turn on for the start, them it will auto shut off and let tstat work

 

[CKS1955]

Installed the Honeywell CT87N this weekend and the unit ran great, cycled on and & off like it should. The only thing I noticed is the thermometer on this thermostat was under about 4 degrees (common occurrence with these). The CT87N's thermostat would be set to 60 degrees, but the CT87N's thermometer would read 56 degrees. Simple adjustment, remove the face and adjust the thermometer with an allen wrench. It took a few tries to get it exact (used a digital thermometer as a guide for the temperature), but working as it should now. Heat shuts off at the thermostats setting of 60 degrees and thermometer reads 60 degrees.

Jay

 

[darcyh]

Reviving an old thread here. I'm thankful to the OP for posting his experience.

I had the same problem with a Honeywell RTH2510 programmable thermostat on a typical forced air gas fired furnace. Here's how it went.
1) Power went off for several hours during a snow storm causing the temperature inside to drop below 32 degrees F.
2) Below 32 degrees the thermostat ceases to display the temperature and now displays LO it its place. This is not a low battery warning. There is a separate low battery warning as part of the display.
3) Power comes back on and the stupid thermostat does not activate the furnace because while it is displaying LO it no longer functions.
4) At first I though the unit was defective, so I removed it and jumped the red and white wires. The the furnace activated and heated the house. I replaced the Honeywell with a old school mechanical unit. At the time I did not know that this appears to be the normal behavior of this thermostat.
5) Once the temperature rose to 32F the unit came back to life and I could hear the relay click and Heat On was displayed.
6) I was able to replicate this behavior by placing the thermostat in the freezer and sure enough, 32 degrees was the threshold. Below that the display goes to LO and the thermostat fails to function. In my opinion this is a significant design flaw.

Fortunately we discovered this and took action before anything froze. If we had not, pipes may have been damaged.

This information is not widely available. It's only through Jay's post I discovered this.

We have a different model of Honeywell thermostat in our house. I am going to freeze it and see if the same thing occurs. I am wondering if this is endemic of all digital thermostats.

 

[CoogarXR]

My garage thermostat loses its mind when it gets too cold. It just randomly closes the heat contacts, even when the mode is set to "off". Sometimes briefly, sometimes for several minutes. But when it's set for heat, it turns on the heat no matter the temp. It's the turning-off part that doesn't work in extreme cold.

I remember the first time I found out. I had the heat off, but when I went out in the garage, it was warm in there, and the electric heat was turning on and off, over and over. Pissed me off, not only for the wasted electric, but for the wear on my heater kicking on and off for who-knows-how-long.

So now, in the winter, I just shut the breaker off when I leave.

Sure, I could get a new thermostat, but like I said in another thread, it's a unique old thermostat with wired ethernet and a web server built in. It's nice to be able to turn on the AC before I go out there in the summer. The cold-side of the thermostat works perfectly, lol.

 

[darcyh]

Reviving an old thread here. I'm thankful to the OP for posting his experience.

I had the same problem with a Honeywell RTH2510 programmable thermostat on a typical forced air gas fired furnace. Here's how it went.
1) Power went off for several hours during a snow storm causing the temperature inside to drop below 32 degrees F.
2) Below 32 degrees the thermostat ceases to display the temperature and now displays LO it its place. This is not a low battery warning. There is a separate low battery warning as part of the display.
3) Power comes back on and the stupid thermostat does not activate the furnace because while it is displaying LO it no longer functions.
4) At first I though the unit was defective, so I removed it and jumped the red and white wires. The the furnace activated and heated the house. I replaced the Honeywell with a old school mechanical unit. At the time I did not know that this appears to be the normal behavior of this thermostat.
5) Once the temperature rose to 32F the unit came back to life and I could hear the relay click and Heat On was displayed.
6) I was able to replicate this behavior by placing the thermostat in the freezer and sure enough, 32 degrees was the threshold. Below that the display goes to LO and the thermostat fails to function. In my opinion this is a significant design flaw.

Fortunately we discovered this and took action before anything froze. If we had not, pipes may have been damaged.

This information is not widely available. It's only through Jay's post I discovered this.

We have a different model of Honeywell thermostat in our house. I am going to freeze it and see if the same thing occurs. I am wondering if this is endemic of all digital thermostats.

I was interested to see whether this problem showed up on other models. I placed our Honeywell RTH8500D thermostat in the freezer for half an hour. This was their top line unit several years ago. When removed it displayed 6 degrees and had the "Heat On" indicator. Pushing it into its wall mount plate, the furnace immediately switched on. This suggests to me the problem above does not apply to all Honeywell thermostats.

Thanks again OP for bringing this problem forward.

​

 

[PoorUB]

Many electronic thermostats "die" when they get too cold. The temperature sensor goes out of range and the thermostat goes to sleep. I would go set up temporary heat on a construction site and had to jumper out the heat terminals for a while until the space temp came up. Some times the thermostat was in the back of my truck and cold so it wouldn't run. A few minutes on the defroster would warm it up so it would work.
In my garage I have a cheap mercury stat set at 45F. I never set the electronic that low so the cheap 'stat will pick up if the electronic stops working, and it has a couple times when the garage door got left open.

 

[strutaeng]

You can't just jump the leads for the initial start-up to get the heater going and warm up the place?

 

[darcyh]

You can't just jump the leads for the initial start-up to get the heater going and warm up the place?

Yes, you can do this if you are present, but if you're away from the premises the place will continue to freeze.

In my opinion any device that fails to activate the furnace even if the temperature is beyond its limit is unacceptable.

 

[Milton Shaw]

PTAC units in motel and hotel rooms have a freeze stat on them that even when off will turn the unit on to keep the room/water from freezing. Why would Honeywell not design that into thermostats to protect home were a freeze would damage a lot more than in a hotel room. If the unit was plugged in and hit below about 40 it would come on in heat mode regardless of what the controls were set on.

 

[bonneyman]

If I have an old yoyo (HONEYWELL T87) I'll send it to you. Those old mercury stats run pretty flawlessly as long as the anticipator is set right and it's mounted level.

Tommy

Just make sure you have some calibration wrenches!

 

[audiford]

I had this same issue with Honeywell hardware, preinstalled in the garage.

1. Heated up the thermostat with the indoor heater to remove LO sign (did not help)
2. I noticed that due to the extreme cold, the back plastic plate mounted to the wall had warped enough to prevent solid contact, as a quick fix I ended up taping it down to keep the contact between the pins and unit, that will work until I fix the mount.

Hope this helps.

 

[bonneyman]

I had this same issue with Honeywell hardware, preinstalled in the garage.

1. Heated up the thermostat with the indoor heater to remove LO sign (did not help)
2. I noticed that due to the extreme cold, the back plastic plate mounted to the wall had warped enough to prevent solid contact, as a quick fix I ended up taping it down to keep the contact between the pins and unit, that will work until I fix the mount.

Hope this helps.

Stat to sub base issues are a problem at times.

Some of the old Honeywell T874 heat pump stats had a problem like this. The stat was connected to the subbase thru these spring-loaded tabs on the stat. Discovered the residual flux left on the soldered connection during manufacture would - over time - accelerate corrosion of the contact points. Producing intermittent operation. Very frustrating till I accidentally discovered the issue. Had been out to a house several times on a no-heat call. Thing worked fine while I was there. On one visit it wasn't working, and I accidentally bumped the stat - and it came on. Discovered the tabs were all black and crusty. After that - whenever I saw a T874 - I'd check and clean the contacts. Most were bad, never had any more issues. I'm hoping that by now all these archaic stats have been replaced, but there might still be some stragglers out there.