Analog Coleman Mach Thermostat - Page 2

Witch Doctor · 12-02-2014, 06:28 AM

Buy it from Amazon, it will work. Dealers BS only.

WFD · 12-09-2014, 09:52 PM

For anybody who has changed to the digital Coleman Mach stat...do you recall if the wires are soldered to the terminals in the old slider one or simply screwed terminals? If so are the wires long enough to simply cut them to attach to the new stat, and do they need to be soldered into the new stat?

TakeItEasy · 12-09-2014, 11:11 PM

Quote:

Originally Posted by WFD

For anybody who has changed to the digital Coleman Mach stat...do you recall if the wires are soldered to the terminals in the old slider one or simply screwed terminals? If so are the wires long enough to simply cut them to attach to the new stat, and do they need to be soldered into the new stat?

Mine had wires leads with crimp connectors attaching them to the rv wires. I just cut the wires before the crimp connectors and crimped the new thermostat to the trailer wires.

LandJ · 09-09-2015, 11:55 AM

Sorry to revive such an old thread, but I'm wanting to replace the analog Coleman Mach thermostat in my trailer to a digital to minimize temp swings. I have an additional desire that was mentioned in the thread, but i didn't see the resolution. I want to be able to run the A/C fan while the furnace is running.

Any help would be appreciated.... I'm looking at the 8330-3862 thermostat, but it's not clear if that will allow the fan to run while heat is on.

DaveSchwartz · 09-09-2015, 01:26 PM

I don't think it will do that. I think the system switch makes it work with only one unit at a time. I'm also given to believe that the fan switch controls only the A/C fan in A/C mode (the furnace fan is controlled automatically internal to the furnace unless an external switch is added).

I could be wrong, however I've got one coming in the next day or two to do exactly the swap you're talking about and I'll let you know for sure.

If not, it may be possible to turn on the A/C fan at any time by putting an SPST switch between one of the fan control wires any something else but I have no direct knowledge of that and will disavow any damage.

LandJ · 09-09-2015, 01:59 PM

Thanks, Dave, looking forward to hearing how you make out.

Looking closer, it seems the furnace requires a 24V supply for the relay, while the A/C requires a 12V supply. That must be why the thermostat uses +12V and -12V taps, to provide 24V across them. I have a vendor supposed to get back with me after they hear from Coleman to see if what I'm looking for can be done with any of their thermostats.

I've seen some people cob this to together on youtube, but I don't want to compromise systems on my trailer while it's still new, lol. I'll post up once I hear back.

Witch Doctor · 09-09-2015, 02:27 PM

Quote:

Originally Posted by LandJ

Sorry to revive such an old thread, but I'm wanting to replace the analog Coleman Mach thermostat in my trailer to a digital to minimize temp swings. I have an additional desire that was mentioned in the thread, but i didn't see the resolution. I want to be able to run the A/C fan while the furnace is running.

Any help would be appreciated.... I'm looking at the 8330-3862 thermostat, but it's not clear if that will allow the fan to run while heat is on.

It will not work without installing a fan center at the furnace. They do sell fan centers but you will need to add wires to and from. this would not be DYI project unless you have a HVAC background, and then it still would be very hard to do. Only other thing I can think of is to add a simple stat with a jumper for heat only then use your original stat for the A/C fan control. you would remove the white wire from the stat and put it on the heat stat with a jumpered red wire for power.

DaveSchwartz · 09-09-2015, 03:10 PM

Quote:

Originally Posted by LandJ

Looking closer, it seems the furnace requires a 24V supply for the relay, while the A/C requires a 12V supply. That must be why the thermostat uses +12V and -12V taps, to provide 24V across them. I have a vendor supposed to get back with me after they hear from Coleman to see if what I'm looking for can be done with any of their thermostats.

I doubt that the furnace needs 24V - 12V is the only thing I see on the rvcomfort.com surburban furnace site. An RV has only a 12V system and I don't think the thermostat has a voltage doubler. Home systems do run on 24VAC and that's why its sometimes hard to adapt a home t-stat to an RV.

I don't think he wants to switch on the furnace fan without the heat (there's another thread which includes that concept for distributing heat from a space heater without using propane), but the A/C fan when the t-stat is in heat mode. Like I said, this is likely to be easier because an A/C with a wall t-stat has accessible fan relay connections already conveniently brought down to the t-stat by wires (unlike an RV furnace which more than likely doesn't have an externally accessible fan relay). Usually its only the t-stat in charge of putting 12V to one of the A/C fan relay lines but you may be able to rig up a switch to do it too.

Witch Doctor · 09-09-2015, 03:21 PM

Quote:

Originally Posted by DaveSchwartz

I doubt that the furnace needs 24V - 12V is the only thing I see on the rvcomfort.com surburban furnace site. An RV has only a 12V system and I don't think the thermostat has a voltage doubler. Home systems do run on 24VAC and that's why its sometimes hard to adapt a home t-stat to an RV.

I don't think he wants to switch on the furnace fan without the heat (there's another thread which includes that concept for distributing heat from a space heater without using propane), but the A/C fan when the t-stat is in heat mode. Like I said, this is likely to be easier because an A/C with a wall t-stat has accessible fan relay connections already conveniently brought down to the t-stat by wires (unlike an RV furnace which more than likely doesn't have an externally accessible fan relay). Usually its only the t-stat in charge of putting 12V to one of the A/C fan relay lines but you may be able to rig up a switch to do it too.

you run a 24 volt stat off of the batteries that's why they work but the OP will not beable to run his A/C fan only with the heat these units are not built that way. You need a fan center or a relay tied in or a by pass switch to the motor only to bring on the fan for the A/C. No other way....

Witch Doctor · 09-09-2015, 07:44 PM

I have been thinking about what you want to do, Probably the easiest way would be to add a jumper from the red wire at the stat and splice the fan wire to in between a SPST switch. What would happen then is that you could call for heat which would energize the white wire to the furnace for heat. Then turn on the switch that would send voltage to the fan wire at the A/C. Then your blower would come on when you call for heat if you wanted to circulate the air through your duct work. So the switch would feed the fan on. That might work. without using any relays. just a SPST switch. I hope I didn't confuse you. I guess I could draw you a little diagram on how to do it. Most people want there furnace fan to run with there space heaters. You are wanting to run your A/C blower when the furnace is on if I understand your question correctly.

Timex · 09-10-2015, 03:29 PM

Quote:

Originally Posted by gljurczyk

I have been thinking about what you want to do, Probably the easiest way would be to add a jumper from the red wire at the stat and splice the fan wire to in between a SPST switch. What would happen then is that you could call for heat which would energize the white wire to the furnace for heat. Then turn on the switch that would send voltage to the fan wire at the A/C. Then your blower would come on when you call for heat if you wanted to circulate the air through your duct work. So the switch would feed the fan on. That might work. without using any relays. just a SPST switch. I hope I didn't confuse you. I guess I could draw you a little diagram on how to do it. Most people want there furnace fan to run with there space heaters. You are wanting to run your A/C blower when the furnace is on if I understand your question correctly.

If he wanted circulation, wouldn't a small oscillating fan do the trick? I doubt the air blowing out of the AC ducts would be warm enough to do any good. Our furnace does good in circulating the air. And with the fireplace or a space heater, we're plenty warm.

Witch Doctor · 09-10-2015, 03:56 PM

Quote:

Originally Posted by Timex

If he wanted circulation, wouldn't a small oscillating fan do the trick? I doubt the air blowing out of the AC ducts would be warm enough to do any good. Our furnace does good in circulating the air. And with the fireplace or a space heater, we're plenty warm.

I can't argue your point, but this is what the OP wanted so I only offer to help him do what he wanted. More then likely it will cause more of a draft, but I just answered how it could be done. He might be at 110 degrees at his registers but will only be about 60 out of the A/C duct work.... But I will try to help anyone, never said that it would help what he wants to do.....

I remember the 70's crunch, people were putting in wood burning stoves, they wanted a R/A installed above to circulatre the heat in the house. It never worked to what people thought. The faster you move air the cooler it gets.....

Timex · 09-10-2015, 04:08 PM

Quote:

Originally Posted by gljurczyk

I can't argue your point, but this is what the OP wanted so I only offer to help him do what he wanted. More then likely it will cause more of a draft, but I just answered how it could be done. He might be at 110 degrees at his registers but will only be about 60 out of the A/C duct work.... But I will try to help anyone, never said that it would help what he wants to do.....

I remember the 70's crunch, people were putting in wood burning stoves, they wanted a R/A installed above to circulatre the heat in the house. It never worked to what people thought. The faster you move air the cooler it gets.....

Glenn, I knew what you were saying was trying to help. Crazy thing, when I was installing my thermostat, I had to trial and error which wire controlled what. Actually had the furnace and AC going at the same time! I knew that wouldn't ever work. Probably start raining inside!

I had a free standing wood burning stove in our first house. It would radiate the heat but the back rooms never heated well.

LandJ · 09-10-2015, 04:38 PM

Quote:

Originally Posted by gljurczyk

I can't argue your point, but this is what the OP wanted so I only offer to help him do what he wanted. More then likely it will cause more of a draft, but I just answered how it could be done. He might be at 110 degrees at his registers but will only be about 60 out of the A/C duct work.... But I will try to help anyone, never said that it would help what he wants to do.....

I remember the 70's crunch, people were putting in wood burning stoves, they wanted a R/A installed above to circulatre the heat in the house. It never worked to what people thought. The faster you move air the cooler it gets.....

Thanks for taking the time to think of how to accomplish what i asked, i probably won't do it. I had seen someone do the same thing on youtube, but, frankly, I'm not that interested in cobbing things together -- I hoped there was a ready made solution.

LandJ · 09-10-2015, 04:45 PM

Quote:

Originally Posted by Timex

If he wanted circulation, wouldn't a small oscillating fan do the trick? I doubt the air blowing out of the AC ducts would be warm enough to do any good. Our furnace does good in circulating the air. And with the fireplace or a space heater, we're plenty warm.

I have used a fan, it does the trick, but I really like the noise and "breeze" from the A/C blower. So far we have been doing as you suggested, using a small electric heater and the blower together and it works great. Once it gets a little colder, though, I'm not sure that I can get away without running the furnace, and then I can't run the blower.... hence the reason for my query.

Another couple issue that I'm working through; I can't run the blower on low, unless the thermostat is set to cool. No biggie, I just turn up the stat so the compressor won't engage. And, I'm also having an issue with the huge temperature range that the analog/stock thermostat swings. Plus and minus 5 degrees is what I read, and i believe that is probably accurate in my trailer.

I'm just looking for answers to get things set up the way I would like.... thanks for taking the time to respond!

John

Timex · 09-10-2015, 05:28 PM

By all means change out the analog. I don't know why they put them in RV's anyway. The price difference can't be much during manufacture.

You'll never regret getting a digital thermostat.

DaveSchwartz · 09-15-2015, 03:50 PM

8330-3862 thermostat arrived in the mail today... direct wire-for-wire swap, 10 minutes start to finish.

Fan operation is as described in the chart (below) on the single-sheet manual that came with it. The A/C fan does not operate in the HEAT mode. I do think if you added an SPDT center-off switch with center red, gray/green on either end (in parallel with the thermostat on those wires) it would do what you wanted (that would also work on the analog thermostat).

I wasn't sure if my A/C fan had two speeds until I paid close attention when testing out the new one... LO is just slightly quieter than HI.

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