Need help, upgrading Dometic Analog Thermostat to Digital

[out_west1]

I've tried upgrading my Dometic Analog thermostat model number 3107610-002 to a Digital thermostat with no luck. My AC model number is a Dometic Duo-Therm 59516.331.

I've tried three different Digital Thermostats listed below with no luck (and wiring per instructions found in many different references online).

Tried:
1. Honeywell RTH2300B
2. LUX DMH110
3. Coleman Airxcel 8330-3362

My current wiring setup on my analog is:
1. Red wire +7.5 volts
2. Yellow Wire to Cool
3. White Wire to Furnace
4. Blue Wire to Hi Fan
5. Orange Wire to Low Fan
6. Black Wire to Ground

In wiring the two different "Home Style" thermostats I've wired my Red +7.5 volts to the positive red wire RC/RH which is jumpered on thermostat, Yellow wire to AC wire, White wire to furnace, and I wired just my Hi fan wire and capped off the Low wire and the ground wire (since not being used since powered by battery from thermostat). Nothing worked at all.

So I tried the Coleman Digital thermostat which was almost an exact wire for wire match (minus a couple different colors), but I matched my wires to the matching wire uses on the thermostat, and again nothing would turn on at all.

Has anybody dealt with this? Does anybody have recommendations? I sent off an email to Dometic wondering if I need some sort of different control board, but it doesn't sound like I should have to go to that extreme to upgrade to a Digital thermostat when so many other RV users do it all the time.

Any help appreciated........

[time2roll]

Dometic does make a single zone digital thermostat and requires a new control box in the ceiling. Hi/Lo fan is selectable or automatic. Not programmable.

https://www.rvpartscountry.com/Dometic-3316230000-LCD-Touch-Thermostat-with-Control-Kit-Polar-White

[out_west1]

Just wanted to thank everyone for their help. I installed a Hunter model 44157 digital thermostat and wired it up like you guys stated with the ground being the power wire, and both the Low and High wires plugged into the G (Fan) connection on the thermostat. Both the AC and heater work just fine. May at some point wire in the switch to have both Low and High fan speeds, but it isn't a big deal to me right now.

[Chris_Bryant]

I don’t think it will work, as I believe Coleman internally jumpers the +12 vac to what should be the RC and RW terminals, which need to be ground.
Not 100% though- it might me able to be modified. You can get thermostats with 2 stage capability, though I’ve never hooked one up.

[out_west1]

I have one more question if anybody might know the answer. I tried the Coleman Airxcel 8330-3362 digital thermostat (before knowing about the ground) which is for RV's (it is not a home thermostat). The Coleman does not run off batteries (like the home ones), and connects using 6 wires just like my Analog does. The plus about the Coleman is it already has a fan low and high setting.

Do you guys know if the Coleman would work in my setup if I swapped the red hot wire, and ground wire positions? Or is that going to piss off the thermostat itself?

[out_west1]

Chris Bryant wrote:

out_west wrote:

Chris Bryant wrote:

Old-Biscuit wrote:
My current wiring setup on my analog is:
1. Red wire +7.5 volts ------NOT USED (Cap/tape off)
2. Yellow Wire to Cool -----to A/C ("Y")
3. White Wire to Furnace ---to Furnace ("W")
4. Blue Wire to Hi Fan ---High Fan ("G")
5. Orange Wire to Low Fan ---Low Fan (Cap/Tape off)
6. Black Wire to Ground ----TO 'RC/RH' jumpered terminal

This, with the exception that you need to connect both high and low fan- the Dometic analog system switches grounds to energize the relays (not +12 vac), and the fan is two relays, low fan relay energizes the blower, hi fan relay switches between hi and low, so both must be grounded.

Chris, just trying to get clarification on this since I have to purchase another digital thermostat to try now that I'm finally getting somewhere with using the ground instead of the +7.5 red wire.

1. So if I jumper both Low and High wires together, the fan will work in high mode?

Yes

2. If I were just to connect to the High wire, the fan will not blow without also jumpering to the Low)?

Correct

3. What if I were just to connect to the Low, the fan would work in Low?

Yes- the low turns the fan on, the high just switches between high and low. They did this so there is no way both high and low can be energized at the same time

4. I wasn't planning too initially, but can I run a switch like others have done to still get Low and High speed fan control?

Yes- it will be a simple spst switch just connecting the high and low together.

Thanks for any clarification....

No problem 🙂

Thanks for the response Chris. Very helpful......

[Chris_Bryant]

out_west wrote:

Chris Bryant wrote:

Old-Biscuit wrote:
My current wiring setup on my analog is:
1. Red wire +7.5 volts ------NOT USED (Cap/tape off)
2. Yellow Wire to Cool -----to A/C ("Y")
3. White Wire to Furnace ---to Furnace ("W")
4. Blue Wire to Hi Fan ---High Fan ("G")
5. Orange Wire to Low Fan ---Low Fan (Cap/Tape off)
6. Black Wire to Ground ----TO 'RC/RH' jumpered terminal

This, with the exception that you need to connect both high and low fan- the Dometic analog system switches grounds to energize the relays (not +12 vac), and the fan is two relays, low fan relay energizes the blower, hi fan relay switches between hi and low, so both must be grounded.

Chris, just trying to get clarification on this since I have to purchase another digital thermostat to try now that I'm finally getting somewhere with using the ground instead of the +7.5 red wire.

1. So if I jumper both Low and High wires together, the fan will work in high mode?

Yes

2. If I were just to connect to the High wire, the fan will not blow without also jumpering to the Low)?

Correct

3. What if I were just to connect to the Low, the fan would work in Low?

Yes- the low turns the fan on, the high just switches between high and low. They did this so there is no way both high and low can be energized at the same time

4. I wasn't planning too initially, but can I run a switch like others have done to still get Low and High speed fan control?

Yes- it will be a simple spst switch just connecting the high and low together.

Thanks for any clarification....

No problem 🙂

[out_west1]

DrewE wrote:
What Old-Biscuit and Chris said should work for you. The main problem you're having is using the +7.5 rather than ground as the common. It's a very understandable blunder as the Dometic system is somewhat unusual (certainly compared to normal domestic thermostats) in switching to ground/common.

***Link Removed*** describes what I did to update my thermostat; it's the same thing, but a couple of wire colors were a bit different.

Thanks Drew for the link. I must have been typing my messages the same time you were. I didn't see your original post. And thanks to old biscuit and Chris for their information as well. It has been very helpful. Wish this information would have shown up when I was doing my google searches, but nothing this helpful showed up. I just wish I would have signed up for this forum and found this information before I already returned my thermostats. So I have another one on order.....

I did finally hear back from Dometic, and they just told me I need this thermostat and control kit 3316230.000 which as I understand it would require rewiring the setup. So I'm glad I found out about this ground wire from the forum members here before wasting time and money with that setup.....

[out_west1]

Chris Bryant wrote:

Old-Biscuit wrote:
My current wiring setup on my analog is:
1. Red wire +7.5 volts ------NOT USED (Cap/tape off)
2. Yellow Wire to Cool -----to A/C ("Y")
3. White Wire to Furnace ---to Furnace ("W")
4. Blue Wire to Hi Fan ---High Fan ("G")
5. Orange Wire to Low Fan ---Low Fan (Cap/Tape off)
6. Black Wire to Ground ----TO 'RC/RH' jumpered terminal

This, with the exception that you need to connect both high and low fan- the Dometic analog system switches grounds to energize the relays (not +12 vac), and the fan is two relays, low fan relay energizes the blower, hi fan relay switches between hi and low, so both must be grounded.

Chris, just trying to get clarification on this since I have to purchase another digital thermostat to try now that I'm finally getting somewhere with using the ground instead of the +7.5 red wire.

1. So if I jumper both Low and High wires together, the fan will work in high mode?

2. If I were just to connect to the High wire, the fan will not blow without also jumpering to the Low)?

3. What if I were just to connect to the Low, the fan would work in Low?

4. I wasn't planning too initially, but can I run a switch like others have done to still get Low and High speed fan control?

Thanks for any clarification....

[out_west1]

Thank you guys for the replies. I was digging around and ran into this post by Wishbone51 who stated the ground wire worked as his power, which is basically what both old biscuit and Chris just posted.

So thank you guys for that information. I did jumper my black ground wire to the white furnace wire and the furnace did turn on. So at least now I was getting somewhere. I tried the same thing to my Yellow AC wire, and it appeared like it was going to work, but couldn't be sure. I can't run my AC on shore power at my house yet. So I can only run it if I run my generator. When I did this it seemed like the generator noticed a load if I jumpered the wires, but I didn't really hear anything running. I already returned the digital thermostats that I tried before. So now I have to pick up another one to try. But it seems like this is the ticket so far.

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29890468/gotomsg/29891848.cfm#29891848

http://www.modmyrv.com/2012/01/03/mod-100-honeywell-digital-thermostat


I'm happy to finally be getting somewhere, but also frustrated at the same time. I was searching online for days and couldn't find anything that was helping. So I signed into this forum, and now I'm finding some good information. So happy to find something online that is finally helping.....

[DrewE]

What Old-Biscuit and Chris said should work for you. The main problem you're having is using the +7.5 rather than ground as the common. It's a very understandable blunder as the Dometic system is somewhat unusual (certainly compared to normal domestic thermostats) in switching to ground/common.

This thread describes what I did to update my thermostat; it's the same thing, but a couple of wire colors were a bit different.

[Chris_Bryant]

Old-Biscuit wrote:
My current wiring setup on my analog is:
1. Red wire +7.5 volts ------NOT USED (Cap/tape off)
2. Yellow Wire to Cool -----to A/C ("Y")
3. White Wire to Furnace ---to Furnace ("W")
4. Blue Wire to Hi Fan ---High Fan ("G")
5. Orange Wire to Low Fan ---Low Fan (Cap/Tape off)
6. Black Wire to Ground ----TO 'RC/RH' jumpered terminal

This, with the exception that you need to connect both high and low fan- the Dometic analog system switches grounds to energize the relays (not +12 vac), and the fan is two relays, low fan relay energizes the blower, hi fan relay switches between hi and low, so both must be grounded.

[Old-Biscuit]

My current wiring setup on my analog is:
1. Red wire +7.5 volts ------NOT USED (Cap/tape off)
2. Yellow Wire to Cool -----to A/C ("Y")
3. White Wire to Furnace ---to Furnace ("W")
4. Blue Wire to Hi Fan ---High Fan ("G")
5. Orange Wire to Low Fan ---Low Fan (Cap/Tape off)
6. Black Wire to Ground ----TO 'RC/RH' jumpered terminal

[CA_Traveler]

Flute Man wrote:
Contacting Dometic is the proper way to go. They can tell you which digital thermostat is compatible with their system .....if any.

X2 Additional equipment may also be required.

[Flute_Man]

Contacting Dometic is the proper way to go. They can tell you which digital thermostat is compatible with their system .....if any.

Jerry Parr