This month I've asked my friend and excellent RV service technician in his own right, Chris Dougherty, to chip in with a response. (Chris, by the way, just may be coming out with a must-read book for all RVers in the coming months! Keep your eye here in the RV Doc Newsletter and on RVdoctor.com for information about its release date.)
I have a 1977 Winnebago Elandan motorhome. Right now it has a Coleman thermostat and I was wondering if I could put in one of the commercially available, (for your house), digital thermostats? Are they compatible? Charlie W. (Townsend, MT)
Charlie, it may be a bit complicated, but IF the stock system has not been modified (for example, the thermostat in the coach is heat only (bi-metal), and hasn’t been upgraded for some reason to heat and cooling), then yes, you can upgrade the thermostat to a battery operated thermostat. The key is that it must have an equivalent anticipator value of .2-amps.
Most residential systems, I believe, run 24 VAC through the thermostat, so the programmable thermostat would have to be self-powered. White-Rogers has several different thermostats that fit this bill. They are designed for 24 VAC and millivolt systems. There is no anticipator setting on these, however, and in their manual for the Model 1F78 they state:
"Digital thermostats normally provide precise temperature control and may cycle faster than some older mechanical models. A faster cycle rate means the unit turns on and off more frequently but runs for a shorter time so there is no increase in energy use. If you would like to increase the cycle time, clip Jumper W-905 as mentioned in the instructions for Hydronic Heating Systems. It is not possible to shorten the cycle time.”
This can be a concern, especially in winter conditions, because of the relative lack of insulation, the RV interior temperatures may drop precipitously, resulting in a lot of cycling and wear/tear on heating components. If used for milder conditions, though, it would likely be acceptable.
