Hardside A-Frame and thermostat upgrade

rawlus · 05-23-2012, 07:16 AM

Has anyone here attempted or successfully changed out the analog thermostat in our A fames with a digital model?

I know many writeups on the web exist for this and know the Hunter digital model is a popular replacement, but most of these writeups dont address a unique difference we have in our A Frames, namely the choice of heat source, from the furnace or the heat pump/cool cat.

Maybe there is a dual-zone digital thermostat that would work in this application?

Any ideas you guys have would be helpful. I can live with the analog, but would prefer a digital for its ease of use and accuracy, hopefully reducing unnecessary recycling.

thehamguy1 · 05-23-2012, 07:36 AM

There was some discussion of this last Fall but I'm not sure if it's been done yet. Evidently Dometic has a digital thermostat that's been showing up in some new FR models. I think it can accommodate having two sources of heat. I've lost any links I might have had to the website and I don't recall who first posted about the new thermo. Maybe you've already checked it out, tho...

rawlus · 05-23-2012, 07:43 AM

Yeah. I think it's this one, I may have even posted about it before and forgot... Dometic Single Zone Digital Thermostat

I see that I can get the version with Heat Pump in either black or white from RV Wholesalers for $28 without the control kit. I dont know if I need the control kit if I am just replacing their analog Thermo with the digital one.
RV Parts Wholesalers

Jeep4Two · 05-23-2012, 09:27 AM

Rawlus:

I think you and I both talked a little about this. I hate the wide range of swing in temp with the analog thermostat. Running the heat pump set on say 65 lets the temp swing as much as 4 degrees on either side of the set point at 'sleeping level' which is about the same level in the camper as the thermostat.

$28 is super affordable for such an upgrade. My question is also about this 'control kit'. Not sure what that would be either. Might have to dig out my manual when I get home.

DGrissom · 05-23-2012, 10:15 AM

Quote:

Originally Posted by rawlus

Yeah. I think it's this one, I may have even posted about it before and forgot... Dometic Single Zone Digital Thermostat

I see that I can get the version with Heat Pump in either black or white from RV Wholesalers for $28 without the control kit. I dont know if I need the control kit if I am just replacing their analog Thermo with the digital one.
RV Parts Wholesalers

We have that in our A128S. I currently have the microwave out for repair or exchange and will check the wiring to see if any kit or box is attached in the back of or near the controller.

So far, it has worked well for us. We used it in the fan only, cool, and heat pump modes.

Jeep4Two · 05-23-2012, 01:07 PM

I think the ck triller will be on the ax unit itself. No room for a controller that size behind the thermostat based in what I saw on that site linked above.

I had my radio out a while back and it's tight in there and I saw no large silver box like the controller.

I suspect the controller is the same between the two thermostats, keyword 'suspect'.

rawlus · 05-23-2012, 05:11 PM

The "control kit" for the Analog one looks very similar to the control kit for the LCD one.

Jeep4Two · 05-23-2012, 05:57 PM

I agree, they look similar. On the Dometic site all I can find is thermostat with control kit part numbers.

If a control kit is needed then its more cost and work than it would be worth IMO. Looks to be ~$100 or slightly more for both. I have no idea where the control kit goes, likely on the main Unit which means figuring out exactly where and how to get to it.

rawlus · 05-23-2012, 09:20 PM

I have an email in to Dometic to see what's up. I'll let you know what I here back.

Jeep4Two · 05-23-2012, 09:47 PM

Thanks Rawlus. I'm super interested and was going to try a call tomorrow. I'll wait to see what you hear.

rawlus · 05-24-2012, 08:16 PM

Heard back from dometic.

Quote:

If you are operating your unit from an analog thermostat and want to change it over to the single zone LCD you would have to purchase a complete control kit. *Thank you *

We appreciate this opportunity to address your situation, and hope all your future travels are trouble free. Please do not hesitate to contact us any time, to order parts or if *we can be of assistance. *

Customer Support Center
800 544 4881
RV.Com / DometicUSA.com
Dometic LLC

It seems the digital control box uses network type cable connectors among other differences. The faceplate and control box is about $99 from the online retailers so that pushes it down my priority list considerably. Sorry for the bad news folks.

Jeep4Two · 05-24-2012, 09:00 PM

Bummer to hear that. I was stoked. I guess I will live with the wild temp swings. Not worth $100.

Jeep4Two · 05-25-2012, 09:47 AM

Ok - I had to know first hand - not that I don't trust Rawlus

I called Dometic and got some additional information from a very helpful Erin at their customer support line. In order to use the digital thermostat with our A-Frame models that shipped with the analog thermostat, you would have to REPLACE THE ENTIRE COOL CAT UNIT! Wow! There's an expensive upgrade. Here's what I learned.

She was able share the installation document for the latest dometic cool cat heat pump / ac units (series 441004). The manual was for the 441004.701 system. On the last page they show the installation of the thermostat (SZLCD Thermostat) and it is only a 3 wire install (+12, -12, COMMS). So basically instead of having connections for all the various functions (HP/HS, +12, Cool, Furn, HIfan, Fan, Grnd) this digital thermostat has only power and communications. I haven't confirmed the analog connections on my thermostat, but that seems reasonably accurate.

SO, even IF you bought the LCD WITH Control Kit I don't think the Dometic conversion would work in our AFrame units.

Jeep4Two · 05-25-2012, 10:15 AM

This has gotten me thinking.

Many RV'ers with Dometic Duotherm thermostats have replaced their units with standard digital thermostats (the Hunter el cheapo seems popular).

They make one mod to that thermostat for a typical AC / Furnace installation, adding a toggle switch for the HIFan / Fan setting (since there is only one fan setting on a 'normal' residential thermostat.

Another problem (other than fan speed) with our AFrames is the fact that we have AC, Heatpump, Furnace (3 conditioning choices) and the typical residential thermostat of course would only have Heat and Cool.

Got me to wondering - would it work the same with the heat source as the fan speed? Could you just tie the wires that connect to Furnace and HeatPump from the analog thermostat to a toggle switch to select the heat source you wish to use and then connect the output of the toggle to the residential thermostat just as is done with the HIFan and Fan wires?

Here's a writeup from ModMyRV on the Hunter install: RV Digital Thermostat Upgrade | ModMyRV

rawlus · 05-26-2012, 09:41 AM

Did someone in this thread remark that their a frame had the digital controls? Maybe a newer model?

Jeep4Two · 05-26-2012, 12:50 PM

The 2012's and up have the LCD thermostat.

rawlus · 05-27-2012, 02:43 PM

Darn it.

backpacker3 · 05-27-2012, 04:57 PM

I have the digital stat in my unit. Last week when camping we actually used the heat pump one night to see how it would work and it preformed very well. One thing I did notice was that there was about a 2 to 4 degree swing in the stat. I can live with that. The manual for the stat states it has a 2 degree swing but I am going to have to run the heat pump/ac a few times before I really see what type of temp. diff. there is.

You may also like: