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SteveE
Recently, I installed a digital thermostat (Honeywell RTH-221, (< $20.00 at Home Depot) in my travel trailer and was very pleased at how much better it was at maintaining a consistent temperature in the trailer.
However, I have just discovered that when the interior of the trailer gets below freezing, the thermostat will not come on until it is warmed up to above 32 degrees F.
I suppose I could modify this one with a bypass switch....but why ....
Can anyone recommend a digital thermostat that, without modifications, will allow the RV furnace to come on when the thermostate is below freezing?
Thanks, Steve
mdcamping
yeah it could be the temperatures in your RV are out of the specifications of your digital T-stat, something that you would come across at a Home Depot. Try your local plumbing/A/C wholesaler, they usually have a wider range of digital t-stats...more reliable brands also...$20 is relatively cheap for a digital t-stat.

Mike
pianotuna
Hi Steve,

If you still have the old thermostat you could wire it in parallel with the Honeywell. Just set the old one high enough to allow the new one to cut in.

I chose to have a manual thermostat because of the likelihood of batteries freezing.
SteveE
Thank you for the feedback on my thermostat issue.

I stopped by a HVAC company yesterday and discussed the problem with them. They had never heard of this, but upon further research of several of the Honeywell thermostats they carry, they concluded that this seems to be the way Honeywell thermostats are designed (why????).
Anticipating I would return it, I stopped by ACE hardware and bought the ACE brand (no idea who makes it), non programmable digital thermostat.
Tests of this new thermostat in the garage freezer (~0 degrees F) were encouraging as, while the unit displayed "LO", it still seemed to activate when turned on. I installed it in the trailer yesterday evening and this morning, with the interior of the trailer at 23 degrees, the thermostat display said "LO" but readily turned on the furnace when it was switched on. Yea!
I further like the large display, easy to depress buttons, and large front panel mounted on/off switch of this thermostat. The ACE thermostat also has a hysteresis (heat anticipater) adjustment (two different settings) which may be helpful if I find the thermostat is coming on too frequently.
Guess I'll just have to take it out on a trip to see how well it really works smile.gif
I haven't had any issues (yet) with zinc carbon batterys freezing but then it dosn't get as cold here
in Central Oregon as many other places may get. A quick look at the Everyready site indicates that storage tempuratures of -20 degrees C (-4 degrees F) are acceptable for their batteries and we seldom have temps much colder than that....for long.
mdcamping
Glad to hear everything worked out okay!

Mike
pianotuna
Hi Steve,

Where I live it gets to -40. Even LI batteries don't tolerate that particularly well.
mikel3560915
QUOTE(SteveE @ Dec 6 2011, 10:33 AM) *

Thank you for the feedback on my thermostat issue.

I stopped by a HVAC company yesterday and discussed the problem with them. They had never heard of this, but upon further research of several of the Honeywell thermostats they carry, they concluded that this seems to be the way Honeywell thermostats are designed (why????).
Anticipating I would return it, I stopped by ACE hardware and bought the ACE brand (no idea who makes it), non programmable digital thermostat.
Tests of this new thermostat in the garage freezer (~0 degrees F) were encouraging as, while the unit displayed "LO", it still seemed to activate when turned on. I installed it in the trailer yesterday evening and this morning, with the interior of the trailer at 23 degrees, the thermostat display said "LO" but readily turned on the furnace when it was switched on. Yea!
I further like the large display, easy to depress buttons, and large front panel mounted on/off switch of this thermostat. The ACE thermostat also has a hysteresis (heat anticipater) adjustment (two different settings) which may be helpful if I find the thermostat is coming on too frequently.
Guess I'll just have to take it out on a trip to see how well it really works smile.gif
I haven't had any issues (yet) with zinc carbon batterys freezing but then it dosn't get as cold here
in Central Oregon as many other places may get. A quick look at the Everyready site indicates that storage tempuratures of -20 degrees C (-4 degrees F) are acceptable for their batteries and we seldom have temps much colder than that....for long.


So with the ace brand did you have to do any modifications????
SteveE
QUOTE(mikel3560915 @ Sep 21 2012, 07:48 PM) *

So with the ace brand did you have to do any modifications????

None at all. It works great.
I am only using it for heating (though it does have a cooling setting).

Steve
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