Adding heat strip kit to Coleman Mach 15

[sportcoupe]

I am adding a heat strip kit to the Coleman Mach 15 roof air conditioner in my 2022 Vegas. The Thor wire diagrams provided in Owners Resource are lacking completeness.

I compared them to my RV and visually inspected the wiring in preparation for the heat strip addition. I am missing information on the White wire and the unused Orange wire to the roof AC Airxcel Mach 15 control box. If I knew where the White and Orange wires go, I would be in business. They are not at the RV Master multiplex box under the bed. The Black, Green and Yellow wires are at RV Master.

I attached picture of the roof AC control box for reference, it gets replaced to a heat ready control box. I also attached the known wiring diagram I created based on visual inspection of the RV.

Having a touchscreen, I was surprised to see wiring for thermostat. I don't have a standard thermostat. I wonder where those White/Black wires go?

[ducksface]

My roof ac and my propane floor heater share the same thermostat.
How will adding the heat strip work with the floor heat? Simultaneously?
Can you select either?

[sportcoupe]

I have no thermostat that I can find. I have a touchscreen and a multiplex unit under the bed. The touchscreen is an Android tablet and is wireless to the multiplex unit.

The multiplex has a gas furnace 12v output to engage the gas furnace as indicated in my diagram. I will split this signal to be selectable for electric heat strip or gas furnace. It could be wired so both run simultaneously.

[ducksface]

I've thought about adding a heat strip because it's a mod, and I do mods.
I'd have to add a selector switch with off, floor, strip, both.
Or
add a seperate thermostat.

I've also thought about just putting a 1500w heater in line with the propane and use the same ducts. There's a company which charges about $700 for a milkhouse $15 1500w that goes in line. Ridiculous.

I'll follow your heat strip install. I've been wanting to do it, heat from top and bottom.

[abjbrtd]

Sounds like a very rewarding project, research has begun on adding a heat strip to our Dometic

[taylorbob1]

We carry a portable space heater for winter months when we have shore power available.
Here’s a video of a permanent electric wall heater install in a Vegas.

https://www.youtube.com/watch?v=wwPSW89Umfg

[sportcoupe]

I have a portable space heater. It does ok but temp varies through the rv. Same as if it was permanent mount. They both take up space too. Something that is important to me.

Adding a heat strip to the roof AC allows the heat to be evenly distributed through the roof ducts for more overall comfort. Is it required? No, or course not. I like to mod and the price isn't too bad.

Now, if I can just find our what the White wire goes to and same for the unused Orange wire. I need to use the Orange wire or I have to run a new wire.

[sportcoupe]

For my Coleman Mach 15 in 2022 Vegas 24.1, the Airxcel rep (Coleman) stated these were the parts needed for my unit. The heat strip is a new item of course. The control box replaces the existing control in the roof AC unit. The new control is heat ready, the heat strip plugs into this new control box.

The control box is highly dependent on what thermostat you have. You will also need to add the new heat control wire from thermostat to roof AC control box.

Part numbers I am using. Your application may vary.
Heat Strip p/n 9233A4551
Control Box p/n 9330C755

[Judge]

Originally Posted by sportcoupe

Having a touchscreen, I was surprised to see wiring for thermostat. I don't have a standard thermostat. I wonder where those White/Black wires go?

You do have a thermostat.... it is a digital thermostat controlled by the FireFly / Multiplex Touch Display.

First, there is a temperature sensor for each A/C unit. The temp sensor is usually under an overhead cabinet. The temperature is reported to the multiplex system and then based on the thermostat settings at the display (Off / On, Temperature Setting, Fan Setting - Auto / Hi / Lo), the thermostat in the multiplex system will call for cooling and fire up the A/C unit accordingly.

The furnace circuit is separate. I don't think you will be able easily tie the heat strip into the furnace circuitry. You would likely need a multiplex software upgrade as well to enable that capability. You might just have to wire a separate thermostat or On /Off Switch to use the heat strip.

I have thought about adding the heat strip to my two units but have decided against it so far. From what I read they really don't put out much heat and my FireFly multiplex system requires a software upgrade and configuration change to make it a seamless installation so the touch display can be used.

I have also thought about going to one of the 15K A/C units that is also a heat pump if one would of my A/C's would fail... but that would be a similar challenge because the FireFly software would need to be upgraded and if it requires any additional wiring compared to the standard A/C models, that would be a challenge getting the wiring run to the multiplex main control board.

[sportcoupe]

Originally Posted by Judge

You do have a thermostat.... it is a digital thermostat controlled by the FireFly / Multiplex Touch Display.

First, there is a temperature sensor for each A/C unit. The temp sensor is usually under an overhead cabinet. The temperature is reported to the multiplex system and then based on the thermostat settings at the display (Off / On, Temperature Setting, Fan Setting - Auto / Hi / Lo), the thermostat in the multiplex system will call for cooling and fire up the A/C unit accordingly.

The furnace circuit is separate. I don't think you will be able easily tie the heat strip into the furnace circuitry. You would likely need a multiplex software upgrade as well to enable that capability. You might just have to wire a separate thermostat or On /Off Switch to use the heat strip.

I have thought about adding the heat strip to my two units but have decided against it so far. From what I read they really don't put out much heat and my FireFly multiplex system requires a software upgrade and configuration change to make it a seamless installation so the touch display can be used.

I have also thought about going to one of the 15K A/C units that is also a heat pump if one would of my A/C's would fail... but that would be a similar challenge because the FireFly software would need to be upgraded and if it requires any additional wiring compared to the standard A/C models, that would be a challenge getting the wiring run to the multiplex main control board.

Understood that the thermostat is the multiplex unit but....

The multiplex unit has two black/white wires labeled thermostat. The wires are there, I saw them. See my diagram in post 1. I wonder where they go to? Thor diagrams don't show the other end.

I found the temp sensor. It just reports temp to the multiplex unit.

The gas furnace output from the multiplex unit can just be manually switched for gas heat only, electric heat strip only or even both at the same time. No software changes required when using a basic manual switch.

Yes, I have to add additional wiring. No big deal.

[Judge]

First... you can't alwaya trust Thor wiring / labeling / schematics at face value. There are many examples of errors documented on the Forum.

Second.... There are plenty of example of Thor running wires that go to nowhere because some coaches use them and some don't.

The BMPro system is different than the FireFly Multiplex I have in my Magnitude.

It is possible those wires run to the display panel. Have you pulled it to check the wiring behind it?

Black and White wires not typically used with a basic thermostat in a coach. In a residential system the black wire is typically 24V. Normally there is only Yellow (cooling), White (heat), Green (fan) and Red (power) in a coach or typical home HVAC thermostat.

[sportcoupe]

I didn't trust Thor diagrams. That's why I inspected the wiring on the coach myself. I made the diagram in post 1 of my findings.

If the Thor black/white wires are installed, and they are because I touched them. They go somewhere, not nowhere.

The orange wire is capped at the roof AC control. This orange wire goes somewhere but it's not documented on the diagrams they provide.

BMPro RV Master is a multiplex unit. It communicates to the touchscreen wirelessly.

Thor isn't using industry standard wire colors or even wire type for the thermostat to AC wiring.

[Judge]

Originally Posted by sportcoupe

If the Thor black/white wires are installed, and they are because I touched them. They go somewhere, not nowhere.


BMPro RV Master is a multiplex unit. It communicates to the touchscreen wirelessly.

Ask some owners about wires they found running through the walls or ceilings with the ends hanging loose under cabinets, access spaces, etc. In many cases they have even been wires with voltage.


My FireFly MultiPlex system also has a display that wireless controls the light switches, etc. and also the Bluetooth for the app. However, it has a wiring harness plugged into the back of it. That wiring hardness runs to the main control board. Yours may not work that way.

[sportcoupe]

Originally Posted by Judge

Ask some owners about wires they found running through the walls or ceilings with the ends hanging loose under cabinets, access spaces, etc. In many cases they have even been wires with voltage.

I am asking Thor owners about where the wires at the roof AC control go to. There is a bundle taped together with black, green, yellow, white and orange. I traced some to the multiplex unit. The others go somewhere else.

It's a long shot as most don't mod their coaches. I have asked Thor, awaiting reply. My bet is I have to find them myself.

[16ACE27]

Originally Posted by sportcoupe

I have a portable space heater. It does ok but temp varies through the rv. Same as if it was permanent mount. They both take up space too. Something that is important to me.

Adding a heat strip to the roof AC allows the heat to be evenly distributed through the roof ducts for more overall comfort. Is it required? No, or course not. I like to mod and the price isn't too bad.

Now, if I can just find our what the White wire goes to and same for the unused Orange wire. I need to use the Orange wire or I have to run a new wire.

Probably too late for you as you've gone down the heat strip path, but when using a portable space heater just run the A/C fan on low (no cooling) to distribute the heat at the ceiling throughout the coach. We usually run the space heater just below the main A/C return for this very reason.

[ducksface]

I can pull my wall thermostat so you can see colors and inputs if you think it might help you trace those wires.
It's a manual, but it might supply a clue about maybe the wires are for a manual thermostat since the ac isn't Thor, it's universal.

[sportcoupe]

I think the unused orange wire is for coaches with a roof AC with heat pump. If that's true, I wonder where the other end would be? Like I stated, I didn't see it at the multiplex unit under the bed.

I get there was ways to run a portable heater better, I prefer the heat strip inside the roof AC method. It's out of sight and clean.

[16ACE27]

Originally Posted by sportcoupe

I think the unused orange wire is for coaches with a roof AC with heat pump. If that's true, I wonder where the other end would be? Like I stated, I didn't see it at the multiplex unit under the bed.

I get there was ways to run a portable heater better, I prefer the heat strip inside the roof AC method. It's out of sight and clean.

Look at the furnace wiring.

[sportcoupe]

There was an orange at my furnace. There are orange wires everywhere. I did a continuity check of the furnace orange wire to my AC unused orange wire. It's not the same wire.

I wish Thor owners resource would give us complete 12v coach wiring diagrams.

[Jimbo56]

I bought a small ceramic heater at Aldi for 19.95. And have used a small fan for years. I open the passenger tray. Plug the heater in. Set it. Let the fan circulate it (use fan for AC as well. Have used this set up in WV when camping at Babcock SP. Dropped down to 20’s several nights. Kept my little 28’ A at 68 overnight even back in the BR. Both take up very little storage in the wardrobe.