Heat Pump/Air Con Thermostat

The thermostat on my 2005 Itasca Horizon 40 AD went to Heaven and I have been trying to replace it.  Seems that Coleman no longer makes them so have been provided with new model numbers and so far different websites have conflicting numbers.  So----has anyone recently replaced their thermostat and if so which model did you get?  Where you got it would also be nice to know.

Don, WIT 70041

Suggest you replace the thermostat with an aftermarket off-the-shelf model.  Here's Duner's post about replacing the original with one from Home Depot.

I just installed a Honeywell Focus PRO TH 5320U-1001 3H/2C Thermostat (No set back clock). Ordered it at Amazon for $58.00. If you want the same thermostat with setback timers the model # is Honeywell Focus PRO TH 6320U-1001 3H/2C Thermostat. Home Depot or Lowes carry these models. They are for use with 3 heat sources and two cooling sources hence the 3H/2C which is the key to getting a replacement thermostat

You can use Duner's wirng instructions to connect it. Thermostat will work off of both 12volts and 2x AA batteries even though specs say 24V AC

Temperature control like Duner mentioned is much better as well than the original thermostat.

I think I'm getting inspired to replace mine even though the Coleman  thermostat is working.  I recently installed a Honeywell  RTH8500 series thermostat in the house for the auto-changeover feature between heat and cool - it will change from heat to cool or vice-versa with only a 3 degree difference from heat to cool setpoint (and it's programmable and very accurate at holding a set temp.)  This would be a huge benefit for the coach where we're on heat at night and AC during the day.

My previous post should have said Home depot nor Lowes carry these models. So they DON'T have them.  :-[

John, both of these two thermostats have the automatic switch over between cooling and heating, so there is your excuse to do the replacement 

Harry - do you have your notes on the wiring?  Honeywell doesn' t show a connection for the "C" wire and Duner does.  I just noticed before your post those thermostats are auto-changeover  ;D !!

John,

Connect the two blue wires (blue and blue/white) together and that is all you need to do. No connection to C terminal needed. You can hear a relay pick in the AC unit in the back when you connect them together. Must be an interlock.

Inside the existing RVP thermostat it is wired the same way (2 blues connected together on the circuit board).

As Duner stated these are ground wires. The C terminal connection is only needed in order to power the thermostat via 12 volts. AA batteries and relays inside the Honeywell thermostat take over this function.


edit:
After taking a closer look at Duner's wiring I see additional differences in terminal labeling. I'll make a chart like Duner's that shows the correct labeling and also the programming instructions for the Honeywell thermostats in case others want to make this change.

Harry B said:

After taking a closer look at Duner's wiring I see additional differences in terminal labeling. I'll make a chart like Duner's that shows the correct labeling and also the programming instructions for the Honeywell thermostats in case others want to make this change.

Click to expand...

Most excellent!  When you get that done, I'll add that and Duner's mod to the forum library.

John Canfield said:

Most excellent!  When you get that done, I'll add that and Duner's mod to the forum library.

Click to expand...

Has this been added to the library?  I couldn't find it.

Darryl

I did a bit of looking into this, and it appears that the Honeywell thermostats only have a single fan speed.  I don't think that is a huge issue, but I was curious if other people had found a thermostat that did have multiple fan speed settings.

Darryl

The Atwood Comfort Control System

Has two speeds for both the furnace (if the furnace can do that) and the a/c's and it supports 4 zones.

dvleemin said:

Has this been added to the library?  I couldn't find it.

Click to expand...

I guess this fell off of Harry's to-do list  .

The only issue with having a high and a low blower speed is when the Energy Management system is having to shed loads - one of the loads it can shed is the high blower.  It would take a little cogitating to see if that Attwood thermostat (great find Gary!) would work similarly.

John Canfield said:

I guess this fell off of Harry's to-do list  .

The only issue with having a high and a low blower speed is when the Energy Management system is having to shed loads - one of the loads it can shed is the high blower.  It would take a little cogitating to see if that Attwood thermostat (great find Gary!) would work similarly.

Click to expand...

True.

I guess another option would be to wire an external switch between the two fan wires to flip it back and forth.

Attwood thermostat (great find Gary!)

Click to expand...

I cheated - I have the ACCS t-stat in my rig, so already knew about it.

The ACCS t-stat uses a separate controller for each zone, so you have to add (or replace) the zone controllers as well as replace the t-stat. Not an inexpensive changeover.

I guess this fell off of Harry's to-do list  .

Click to expand...

Yep, you are right John, it did.  Dealing with some health issues, shifting my focus. I'll get on it again soon.

The ACCS thermostat looked good until I noticed that it does not support two compressors on the same zone. RVP A/C has two compressors. This thermostat is designed to control multiple single compressor roof A/C units.

I did get a Honeywell thermostat to work properly including the delayed compressor start up but it also only has a single fan speed control. I have modify the wire connections at the thermostat some, so it requires some wiring/soldering skills. I have added a relay and two diodes external to the output of the Honeywell thermostat. So it is not a plug and play mod but temperature control works great this far. It only varies by one degree. (programable).

I am still not happy with it (high and low fan switching) so I will try to remedy this in the future.

The RVP thermostat is very much different from house thermostats if you want the compressor delayed start up to work. In other words if you shut the compressors down you don't want them to restart for several minutes which allows the compressor head pressure to bleed off. Without the head pressure gone, the compressor will likely trip breakers when trying to start.

Thanks Harry - standing by to see if you can mod the Honeywell thermostat to get two fan speeds working.  If ever there was a need for a programmable t-stat it is in the coach.  Heat in the morning, AC in the afternoon when we're in Colorado or higher elevations.

Harry, "The RVP thermostat is very much different from house thermostats if you want the compressor delayed start up to work. In other words if you shut the compressors down you don't want them to restart for several minutes which allows the compressor head pressure to bleed off. Without the head pressure gone, the compressor will likely blow fuses when trying to start."

It's a simple thing to do...since all you need to do is add TDR's [time delay relays]to the wiring of the compresses.. They are relative cheap and are done both factory and aftermarket all the time.
I always add one to the compressor starter coil or low voltage control to prevent tripping breakers or blowing fuses..
Prevented tones of call-backs from customers playing w/thermostats..

George

Icemaker said:

Harry, "The RVP thermostat is very much different from house thermostats if you want the compressor delayed start up to work. In other words if you shut the compressors down you don't want them to restart for several minutes which allows the compressor head pressure to bleed off. Without the head pressure gone, the compressor will likely blow fuses when trying to start."

It's a simple thing to do...since all you need to do is add TDR's [time delay relays]to the wiring of the compresses.. They are relative cheap and are done both factory and aftermarket all the time.
I always add one to the compressor starter coil or low voltage control to prevent tripping breakers or blowing fuses..
Prevented tones of call-backs from customers playing w/thermostats..

George

Click to expand...

Some of the Honeywell thermostats are made for heat pumps - although for residential ones - not RV ones.  However, is there really a difference?  Wouldn't thermostats made for heat pumps handle the delay automatically?

Darryl

I think the major difference is the operating voltage. The RV thermostat uses 12V DC whereas many household thermostats use 24V AC (through a transformer or directly off the furnace / A/C supply. However, household thermostats can come in a variety of forms.

Alfa38User said:

I think the major difference is the operating voltage. The RV thermostat uses 12V DC whereas many household thermostats use 24V AC (through a transformer or directly off the furnace / A/C supply. However, household thermostats can come in a variety of forms.

Click to expand...

My understanding is that the thermostats will work with 12V as well as 24V (just not 110V).  Is that not the case?