Thermostat for Suburban Furnance

[perryg114]

Has anyone found a decent aftermarket thermostat for the Suburbans? A standard home HVAC thermostat won't work because the unit is powered in most cases by the 25VAC coming from the HVAC unit. A baseboard heater thermostat would work but that is way overkill. I would prefer something digital or at least with numbers on the control so you know about what temperature it will maintain. The OEM thermostat is crappy and has no numbers on it. It is trial and error.

Perry

[TG Twinkie]

What is wrong with a simple Honeywell mercury bulb thermostat? Only 2 wires connected directly to the furnace. Easy to read dial setting and ambient temp.


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[idroba]

Mercury bulb thermostats are no longer made, and never worked in RVs because they are very sensitive to level.

However, you can use any of the household thermostats which use a battery for power. They are almost universal in application and can be used with the 12 volt DC supply in an RV, the milivolt systems and regular 24 volt AC systems.

Just look for a thermostat which needs batteries. They are pretty common. Your thermostat wires from the wall will connect to the Red and White connections on the new thermostat. The Heat-Off-Cool switch will be moved to heat when you want it, Off when you store the rig, and the cool will do nothing. The Fan switch on the new thermostat will also be inoperative.

[Skater]

Originally Posted by idroba

Just look for a thermostat which needs batteries. They are pretty common. Your thermostat wires from the wall will connect to the Red and White connections on the new thermostat. The Heat-Off-Cool switch will be moved to heat when you want it, Off when you store the rig, and the cool will do nothing. The Fan switch on the new thermostat will also be inoperative.

This is exactly what we did, and it was one of the best upgrades we've done. The original thermostat was hard to read and inaccurate according to my wife, so we spent a bit of money on a digital model. Bonus: It allows me to set temperatures as low as 40 degrees (as opposed to the original's 50 minimum), which is good when I need to heat the trailer to keep it from freezing, but I'm not using it.

[perryg114]

You have model information? It was my understanding that even the battery powered ones used the 25VAC to save the batteries.

Perry

[idroba]

The battery ones are all electronic and use the batteries for power exclusively. They use a relay to actually make the connection between the thermostat wires. Modern electronics take so little power that a pair of AA batteries lasts about 2 years.

I have no specific model information, the ones I have used simply have been ones which show up at Goodwill. Specific model numbers change so often that it is hard to find current ones. Again, just look for a thermostat, usually digital these days, which has batteries, usually a pair of AA's and it will most likely be just fine.

[TG Twinkie]

The Honeywell thermostat in my Argosy still works just fine.
No programming, no error messages, no batteries required. No failures on the road because of some cheap electronic circuit board.
I set it where we are comfortable. It maintains that temperature. I don't really care if. When it is set at 70 degrees, the room gets to 72 or 68.
If I get cold I turn it up. If I am hot I turn it down. Usually just set it and forget it.
It only controls the furnace. Which I like. The A/C has a separate built in unit. None of those crazy interaction problems I read about here on the forum.
As for energy efficiency. Is there an RV that is really energy efficient when it comes to heating or cooling?


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[perryg114]

The suburban thermostat has no numbers on it. Trailer may double as a mother in law cottage so I need something idiot proof.

Perry

[Piggy Bank]

Perry,
When in MIL mode, will your space have wi-fi?

If so, you "might as well" consider a wi-fi enabled stat. This would allow a user with phone app to read and change the settings. (As well as being to change at the wall.)

In this way, MIL calls you at work and says it's cold in here, furnace isn't working right. You pull up the app, log in, and say, well, right now the temp is 69, but I will bump it up to 71 if you want me to.

Might be overkill, but the ability for you to actually see the temp on you phone app when away from home might be worth it to you.

[perryg114]

It won't have WiFi but I might have a CAT5 Ethernet connection to it. I expect the WiFi enabled version will be a little above my price range. Last year I made up a CAT5 cable to go out there and I store it under the house inside one of the crawl space vents. Which reminds me that I need to order an external CAT5 connector. At the end of last year I just cut the connector off the CAT5 cable. I at least need a female end that I can leave inside the fridge vent door.

Perry

[perryg114]

Here is what I got and it works fine.

Shop Honeywell 1-Week/Everyday Programmable Thermostat at Lowes.com

I will never use the programmable stuff most likely. There is a common R and Rc which are shorted together. The other wire goes to W on the terminal strip. It seems to work great. The wires coming from the wall could be any color so don't rely on that. It does not matter which goes where. All you are doing is completing a circuit. This one is also not vibration sensitive like the old bi metal spring one.

Leaving the fan going on low on the AC really helps keep the temperature more even. There is not enough flow to the bedroom in the back so it is colder there unless the AC fan is running to mix the air. Also it keeps you from hearing the furnace kick on and off.


Perry