RV A/C Wall T'stat Wiring

[BradW]

Do RV manufacturers normally run the heat wire to the wall thermostat even if the A/C unit does not have heat?

I'm asking because I may order a new rv which has a Coleman A/C unit without the electric heating element and it is controlled by a wall t'stat. The t'stat has the heat setting on it.

I want to add the electric heat element and I'm wondering if I will have to add another control wire from the unit to the t'stat.

Thanks for any help,
BradW

[3_tons]

FWIW, our Eagle Cap came with only 4 wires to the t-stat... When replacing the power wasting 30k btu Suburban furnace with very power thrifty a two speed 15/22 btu Atwood (with t-stat - a big savings for our batteries), I had to run one additional wire to the t-stat...

3 tons

[Hornnumb2]

I already had a wall thermostat for a/c and to add the heat strip just had to swap control box in ceiling and different wall thermostat. Its a Dometic but no new wiring required.

[BradW]

Depends on which coleman a.c. you get. The 9k has controls on unit. The 11k has wall tstat which controls a.c. and propane heat.

[dougrainer]

BradW wrote:
I spoke with a very helpful Lance rep today. He told me that the only reasonable way to get electric strip heat in the A/C unit was to order the camper without any A/C and buy the unit I wanted separately and have the dealer or myself install it.

He also confirmed the camper has the pre-cut hole for the A/C and it is pre wired with 120V.

That works for me and that is what we will do.

Thanks for the responses,
BradW

So, I guess since it is a truck camper, they do not install a wall tstat and they use ceiling controls. Doug

[BradW]

I spoke with a very helpful Lance rep today. He told me that the only reasonable way to get electric strip heat in the A/C unit was to order the camper without any A/C and buy the unit I wanted separately and have the dealer or myself install it.

He also confirmed the camper has the pre-cut hole for the A/C and it is pre wired with 120V.

That works for me and that is what we will do.

Thanks for the responses,
BradW

[dougrainer]

The upper unit has no bearing on the controls. As I stated, RVP makes about 20 tstats for various applications. Rarely will a OEM install a Tstat that has upgrade features like a Heat Pump or Heat Strip. It saves them a few dollars. As to others, There is a BIG difference between DOMETIC systems and RVP systems in wiring. Apples and Oranges. Doug

[BradW]

dougrainer wrote:
They run a standard 7 to 8 wire harness from the Roof AC to the wall tstat. They only use 5/6 of those wires. So if you add the Heat Strip, you have the extra wire to connect. The NORMAL wall RVP tstat will NOT have the Heat Strip on it. They install the model tstat that has GAS heat. You would have to purchase the wall tstat that has the dual switch--Gas and electric(HS). Doug

PS, you understand that the optional Heat Strip does NOT heat the RV. It just takes the chill out. It is only a 5600 BTU heater.

That's what I'm hoping, that they run more conductors than they need for just a/c so I can control the strip heat I add.

Yes, its very low wattage. We've had one on our current Lance camper for many years and we use it a lot. It will keep our camper above 70 until the outside temp gets into the low 20s. Free heat when we have hook ups and it saves a lot of propane.

I believe the Coleman t'stat is set up to control the strip heat, but if the camper manufacturer (Lance) does run the extra wires for heat, that will be a problem. I also don't know if I can pull new t'stat wire in there if they didn't run 18/7 or 18/8.

I think this is the Coleman unit Lance provides: A/C Unit

Thanks for your response,
Brad

[time2roll]

BradW wrote:
Do RV manufacturers normally run the heat wire to the wall thermostat even if the A/C unit does not have heat?

Normal? What make and model air conditioner and heat do you have?

My Dometic uses a relay control box up in the ceiling for the thermostat to control the air, furnace, heat strip, heat pump etc.
(mine only has air conditioner and a furnace)

[ScottG]

TO answer your question, sadly the answer is no, they don't run that little extra wire in case you want to add heat.
Or at least they didn't in our AF.

[DrewE]

It probably depends on a combination of the thermostat model required and possibly the installation. If it's a digital thermostat with a proprietary communications/control interface back to the air conditioner, then I would guess that heat is automatically included without needing additional wires. If it's a generic thermostat interface, such that you could install most any old generic thermostat (or at least those that don't require 24VAC for the thermostat operation), then it's anybody's guess as to what wires are run. You may be able to tell by opening the thermostat and seeing what all is connected.

Sometimes the wall thermostat controls the RV furnace via the air conditioner, with the air conditioner control module acting to pass the control signal along from the thermostat to the furnace. Mine works this way; when the thermostat turns on for heat, there's clearly a relay clacking on in the air conditioner unit.

[dougrainer]

They run a standard 7 to 8 wire harness from the Roof AC to the wall tstat. They only use 5/6 of those wires. So if you add the Heat Strip, you have the extra wire to connect. The NORMAL wall RVP tstat will NOT have the Heat Strip on it. They install the model tstat that has GAS heat. You would have to purchase the wall tstat that has the dual switch--Gas and electric(HS). Doug

PS, you understand that the optional Heat Strip does NOT heat the RV. It just takes the chill out. It is only a 5600 BTU heater.

[agesilaus]

The heat setting on the thermostat controls the RV furnace doesn't it? Not the a/c