Duo Therm AC or Thermostat problem - Help?

[tkdmike]

I have the Duo Therm Penguin with a Duo Therm digital thermostat in the front bedroom of the BH. Something is not functioning properly and I'm not sure if its a thermostat or AC unit issue and the service department at my dealer is closed today.

The AC unit cycles strangely. It comes on and cools well for under a minute (about 50 seconds). Then it shuts off for five minutes and comes back on again for about the same duration. It does this repeatedly and the effect is that it does NOT cool the bedroom. I removed the thermostat with the idea I'd replace it with a Hunter unit like I did the LR thermostat but it is wired with four wire telephone cable. Any ideas? Suggestions? Thoughts?

 

[Rickhansen]

Had the same setup in our 3670, and the same issues. The majority of this problem is that the A/C airflow blows on the thermostat. If you redirect the vents away from the thermostat, or hang a towel over it, you'll find that the problem is reduced.

I did not like the Duo-Therm thermostat. I purchased a different interface for an "analog" thermostat and replaced the board in the A/C, and replaced the Thermostat with a Hunter programmable stat. That allowed me to adjust the cycle rate to suit the size of the bedroom and high airflow.

This turned out to be a fairly difficult (had to replace the flat cable with thermostat wire) and expensive mod, and it didn't totally solve the short cycling, but it helped and made operation consistent as I had replaced the Living Room thermostat with a Hunter earlier for the programmability.

 

[tkdmike]

Thanks Rick. I had redirected airflow away from the thermostat but that didn't do much. The cycling through the night woke me up. So far, in the past 25 minutes it has cycled on and off five times. On for about 2-3 minutes at a time. Off for 3-4 minutes, on again, etc. etc. etc. During the heat of the day it would stay on for a while and didn't cycle so quickly but at night, without the sun's radiant heating, it short cycles like nuts.

I'm going to turn the fan on low instead of auto tonight so at least I will have consistency and airflow rather than the start/stop. I was afraid there would be some issue with changing thermostats. I'll call the shop on Monday and see if they've come up with anything.

BTW - we're like you guys - fulltiming and working.

 

[Rickhansen]

Good Luck with this Mike. I think I have the old board and thermostat here somewhere. If I run across it I'll take a look to see if there are any identifiable jumpers or switches that might yield some result. That particular t-stat, as I recall, had some "networking" features that sounded good. I think it allowed you to stage or sequence multiple A/C's and limit them if you were running on generator power, or something. I thought it was odd that Heartland used that controller when they had a straight analog thermostat for the main living room A/C. I still have the old parts if you suspect a problem, and we could work something out, as I have no need for these now.

On the full-time subject; I left Michigan about 4 years ago for work, Jan stayed behind to get the house sold (almost 18 months) while I was in North Carolina in our Travel Trailer. I am a regional Project Manager for large projects, so the RV living provides the ability to "follow the work" without the liabilities of houses, leases, etc. Jan told me in no uncertain terms, that we wouldn't be doing that again.

We upgraded to the Bighorn 3670RL in late '07 and have been in Florida for the past 15 months. Looks like we'll be here through September at least. After that, who knows?

The irony is that my gas-engine 2500 HD isn't enough truck for the BH. We're in one place long enough that it has worked out well, though. I hired a guy from Florida to come to NC and haul the BH to Florida. Moving was a 12 hour, door to door effort. The total cost was $1000, while the company provided a $5000 "moving allowance". With a deal like that, why buy a bigger truck?

Catch you later.

 

[jimbo56]

x2

This short cycling is annoying. Would a cover over the thermostat help?

 

[twrailroad]

my brother had same problem he replaced the thermostat and works fine now...

 

[jackwittmann]

I had the same problem with my 3670. What I did was install a round louvered vent (same as the rest of the vents installed), I installed it in the center of the unit and directed it to flow towards the bed. I closed the discharge vent blowing towards the thermostat. It works great.

Jack Wittmann

 

[TXBobcat]

I don't have a wall thermostat on my Duo Therm Penguin. It is built in on the right side of the control panel. My Penguin does the same thing but it will cool the bed room down to about 63*. If I leave it at the lowest setting it will sometimes frost up, I think. The air will not blow through very much but if I turn it off for a while and restart it again with the thermostat turned up just a little bit. Then it seems to work just fine.

I don't know why it cycles on and off so often. It does not reach the temperature it is set at but will continue cooling and meet the thermostat setting.

If anyone finds out the answer I would like to know.

Thanks
BC