Coleman Mach Stat Upgrade

[Mavarick]

So I was going to do an upgrade from my Coleman Mach stat to the Ritetemp 8085C as poster here: http://www.rvforum.net/SMF_forum/index.php/topic,30343.msg288196.html#msg288196 . I had a few questions on the wiring but before I could figure out what was needed I realized that the Ritetemp stat 8085C is not sold at Home Depot anymore. Does anyone have a model number from Home Depot or similar stores that I could use to do the upgrade to a programmable stat? I know there are newer models of Ritetemp stats but I?m not much of an HVAC guy so not sure if they will work on a heat pump system in the Rv.
From what I understand the stat has to run on internal battery power (AA or similar, not just for backup), I want it to switch automatically from heating to cooling as needed and also from elect to gas heat with an app 4-5 degree delta as needed.
Thanks for any suggestions.

 

[Jeff]

If you find one that handles the electric heat and two compressor delta for cooling please let us know.

 

[Alfa38User]

If you find one that handles the electric heat and two compressor delta for cooling please let us know.

Have you tried to find a Hunter Thermostat (see attachment). Don't know where they are sold in USA but...

 

[Jeff]

Have you tried to find a Hunter Thermostat (see attachment). Don't know where they are sold in USA but...

I had seen this but could not see anywhere that it referenced the 3 degree bias for the heat pump/gas furnace heat.

 

[Mavarick]

Thx Alfa, I did look at that Hunter install sheet also. The way the Ritetemp was laid out by Duner seemed to be the simplest so that is why I went that way. After looking online it seems that there are many choices that would probably work but I?m not educated enough in HVAC to make that determination by looking at specs. I can probably go to Home Depot etc and check with one of the guys there but figured someone here has already been through this. I do want to upgrade so if needed I guess a little trial and error might be in my future.

 

[Alfa38User]

Jeff,

If you are referring to the calling in of the furnace should the heat pump fail to be able to make the grade under colder conditions, I think that might be one of the things that will fall by the wayside in changing out a Coleman unit, (IF that portion is not taken care of by the ac/heat pump unit itself). The other thing lost is the two speed fan stuff. I have not delved into this change out more than that.

I have not had to do this myself but I have changed out 3 different Coleman units, the original and 2 replacement units which, thankfully, were all under warranty by Coleman. The last one was a keeper and it has now been 6 years.

 

[Jeff]

Ours is working fine but it would be nice to be able to program it but not at the expense of losing the heat pump with automatic gas heat backup.

 

[Mavarick]

Guys, I hear what you are saying in regards to the gas furnace coming on but I really don?t think that will be an issue. I use a heat pump at home with a gas furnace as a secondary and it works fine, I can even adjust the delta. Most of the stats list out that they are for heat pumps with or without an emergency backup source. What I need to make sure of is that the stat is run by it?s own battery, not external power and, a wiring layout that will match up to our Coleman stat. The one I use at home needs an external power source and is app $200 so that?s not an option. If no one on the forum has done this maybe I?ll go to one of the appliance parts warehouse where they really know these things and I?ll talk with them. Either way I?ll follow up with what I do.

 

[Mavarick]

So after calling numerous places I?m finding this is way more of an issue than I thought. The mfr that I spoke with said it?s all about cost of the unit. It?s simple to accomplish with another board, about a $20 increase, but they can't pass along the cost so they don?t do it.
First off, all of the stats listed in previous articles such as Hunter 42999b or Ritetemp 8085 or 6080, have been discontinued. The only ones I could find are used so I passed.
The requirements were to work with a 2 stage HP, switch to heat or cool automatically as needed by the room temp, switch to backup (or emergency) heat such as gas furnace with a 4 or 5 degree delta in temp.
The home stats that run on 24v or 110v ac seem to accomplish this ok, but not when the 12v dc comes into play. None of the mfr above have anything right now that I can find so I?m kind of at a loss until I figure out something else.
If anyone knows of any other options or sources let me know. If I do discover something that works I will post an update, thx.

 

[Jeff]

An option for the gas heat is to simply separate it and run the funace off a separate thermostat that is set 4-5 degrees cooler than the Coleman and to simply run both compressors all the time.

I decided the Coleman stat was the best option at the moment and left it alone.