Bullet Premier replacing Digital Thermostat with Programmable thermostat

[Rocky65]

I have a question about replacing the Dometic thermostat with a programmable one. I researched what's out there now and seen about alot of people using Hunter Brand etc. and saw Virtual Garage's use of a Rona. However I think I have run into a new situation with my Premier 19FBS that I just got a few weeks ago. I have Dometic Thermostat but it is the new Digital LCD type and I brought the Honeywell RTH230B that has the standard 5 slots for wires RC/RH/Y/W/G that I wanted to use to replace the Dometic. But the trailer wiring to the Dometic only has 3 wires blue/orange/red and hook to terminals marked 12- comms 12+.The wire coming out of the wall has other colored wires with it yellow/white/green/brown but they are cut off right at the wire and are unstripped and not used. So my question is can I use a programmable thermostat in this setup or am I stuck with the Dometic one. Hopefully I am making sense and hoping someone up there has the answer for me. Thanks.Here is the link to some photos that will help clarify things.

https://picasaweb.google.com/markrock65/BulletPremier?feat=directlink

[rlevitt]

Hi Rocky65
try the link that I have supplied and see if that helps at all.
Ron
http://www.modmyrv.com/2008/07/14/rv-digital-thermostat

[Rocky65]

Thanks but it doesn't address my unique situation as all the other scenarios have multiple coloured wires coming out of the wall and its just a matter of which wire goes where however mine only has the two 12v. wires red & blue and an orange wire that's labelled comms which I assume is short for common ? I have a feeling that these wires go back to the Duo-therm AC. unit and from there go through some switching unit and then another set of wires goes from there to the furnace?

[Rocky65]

I opened up the hatch inside the trailer to the AC last night and traced the 3 wires going back into the Electronic control box and then wires coming out of it that appear to go the furnace. What I have so far found online is this is Dometic's new electronic control box that replaces the old analog one that you and alot of people have in their units that is why I have a different thermostat and only 3 wires so I am thinking my next step is to maybe phone Dometic to see if there is anyway to make this work with a programmable thermostat but I have a feeling they are going to say I would have to revert back to the old controller box and go from there.I will let everyone know what I find out and I hope it doesn't mean it is going to be problematic down the road for people to add their ownn programmable thermostat. I don't understand why RV maunfacturers do this kind of things and call them an upgrade but don't go all the way and make it a fully programmble thermostat.

[Rocky65]

An update, I did contact Dometic and they were no help at all, they say they will not comment on installing any after market thermostat with their AC systems, very disappointing to say the least.So needless to say I am hoping someone out there will be of some assitance as I am not sure I want to be brave and start experimenting myself and risk damaging the AC unit or furnace and then be out the $$ to get it repaired.For now I will have to satisfied with the Dometic one.

[Inherentwired1]

Dometic systems are different now. The thermostat wire goes to a circuit board hidden near the furnace and is a "trunk" or communication wire. The circuit board then tells the heater or air conditioner to turn on or off. Dometic has full instructions available on line for your model. In order to replace the dometic thermostat with another, you have to also remove the circuit board and use the extra wires that were not used.....It's alot easier to just use the Dometic thermostats (they're pretty good), rather than changing to another brand. A new one costs about $60.00 Canadian. The biggest problem with Dometic stats is their lack of guidance on how to use them.