Too smart a thermostat?

[Monkeyman_and_L]

Freeze warning in our area tonight, and they ain't kidding. Hadn't dumped fresh tank and needed to purge lines. So much easier on the class A.

Then I decide to keep coach warm so I can follow up tomorrow with final winterizing stuff. Air purge and pink stuff into drains and tanks.

Set thermostat for both zones to 60, dial to heat pump. Notice the furnace kicked on. Hmmm, not what I wanted, so I remove the furnace fuse.

Come out later to do a couple more quick items, notice coach interior at 37 degrees, both zones. Started troubleshooting. Notice that after I reset the power on the thermostat and set up temperature demand, the unit flashed between heat pump and furnace.

Reinstalled furnace fuse, opened propane tank, cycled twice because of air in the line and timeout. Furnace now heating.

So, is it just smart enough to know it can't jump the temp 23 degrees to insist on the furnace being active?

This heating system has me baffled. Gotta sort it out.

Anyone else?

[gutfelt]

GREGORYJ wrote:
Our residential Heat Pump operates in lower outside temperatures than the our RV's Heat Pump because the residential unit has a Defrost Mode. When the outside humidity is higher and with cool outdoor temps, the outside heat ex changer can frost over. The residential unit periodically goes into defrost mode to melt the frost off, then continues to operate in lower outside temps like 20 degrees. Our RV Heat Pump does not have this feature, so when the outside heat ex changer frosts over, it stops and the gas furnace cuts in. If I go outside and look, the heat ex changer is covered with white frost. With low outside humidity it can work in colder temps which could vary from above or below freezing outside temps.
Also in Electric Heat mode, if I turn up the RV thermostat more the 4 degrees above the room temperature, the thermostat will run the gas furnace instead, by design, because the furnace will heat the RV faster. If I want to use electric Heat Pump heating only, I will up the thermostat setting 4 degree at a time till the desired temp is reached. This may not be how your system works, but this is common for basement Coleman Heat Pumps.

yes we know as Doug already explained this several posts back !!

That is a design feature of RVP (Coleman) AC/HP systems. Coleman believes that it will take too long to heat up an RV by HP ONLY with a greater than 5 degree split. Once the RV gets below the 5 degree split, the furnace shuts off and the HP will continue the final complete heat cycle. Doug

[GREGORYJ]

Our residential Heat Pump operates in lower outside temperatures than the our RV's Heat Pump because the residential unit has a Defrost Mode. When the outside humidity is higher and with cool outdoor temps, the outside heat ex changer can frost over. The residential unit periodically goes into defrost mode to melt the frost off, then continues to operate in lower outside temps like 20 degrees. Our RV Heat Pump does not have this feature, so when the outside heat ex changer frosts over, it stops and the gas furnace cuts in. If I go outside and look, the heat ex changer is covered with white frost. With low outside humidity it can work in colder temps which could vary from above or below freezing outside temps.
Also in Electric Heat mode, if I turn up the RV thermostat more the 4 degrees above the room temperature, the thermostat will run the gas furnace instead, by design, because the furnace will heat the RV faster. If I want to use electric Heat Pump heating only, I will up the thermostat setting 4 degree at a time till the desired temp is reached. This may not be how your system works, but this is common for basement Coleman Heat Pumps.

[vjstangelo]

We have used our Coleman Heat Pumps in temps of low 30's with no issues.

I have noticed that if the Delta T between the setpoint on the tstat and room temp is too high, the system will automatically engage the propane heat as well.

[YC_1]

Bill.Satellite wrote:
I may have missed someone mentioning this but if these are roof mounted A/C / Heat Pump units they will not keep the wet bay warm anyway. You must run propane heat to get warm air down there.

These RV's are so different.

My Propane heaters do NOT heat the basement. Past Rv's of mine did.

My basement is heated by 12VDC.

[time2roll]

Sounds like all is operating correctly. Nothing to be baffled about. Just let the system operate.

[Bill_Satellite]

I may have missed someone mentioning this but if these are roof mounted A/C / Heat Pump units they will not keep the wet bay warm anyway. You must run propane heat to get warm air down there.

[Mile_High]

When it got cold enough for the heat pumps to shut down on our 5er they would go into a bit of a vibrating mode enough to wake me up. That 5er had two separate Comfort.RV thermostats but only one had the furnace on it. The furnace would come on and that heat pump would shut down, but the other heat pump would continue to blow unheated air until you shut if off.

[georgelesley]

dougrainer wrote:

georgelesley wrote:
Our furnace will also come on to help the HP if you select a temp increase of 5 deg or more from ambient. HP shuts off completely at 36 deg and furnace from there.

That is a design feature of RVP (Coleman) AC/HP systems. Coleman believes that it will take too long to heat up an RV by HP ONLY with a greater than 5 degree split. Once the RV gets below the 5 degree split, the furnace shuts off and the HP will continue the final complete heat cycle. Doug

Thanks Doug. I finally figured that out fiddling with it and ultimately reading the book. It is not a feature I like. I also do not like.that I can have the fan on continuously in cool mode and the hp cycles as needed, but on heat mode the fan only cycles on and off with the compressor. OK, I am a control freak.

[Bumpyroad]

dougrainer wrote:
BUMPYROAD.

THIS IS AN RV FORUM. IT IS RIDICOLOUS TO BRING UP TOPICS AND SYSTEMS THAT ARE NOT RV RELATED. WHO CARES WHAT YOU HAVE DONE ON YOUR HOME SYSTEMS????? Doug

PS I was 22 forty years ago. 33 years ago in Texas I HAD a HP system in my new house and since there was NO Natural gas in my new Neighborhood, I had the 220 electric back up system and until the outside temps were below 28 degrees that HP kept my 2000 sq ft house very comfortable. Yes we had sub 35 degree temps all the time in winter. Also, I doubt anyone on this forum has 20 years of repairing, installing and troubleshooting and fixing RV HP's as me. I KNOW the parameters and what they can do on RV's.

i mentioned wishing I had natural gas in my initial post, most folks can figure out that I was not talking about having a 2,000 mile long gas line back to my home from a campground. and just voicing my general dislike of heat pumps, they suck.
if my posts offend you, PLEASE block me.
thanks,
bumpy

[YC_1]

My Duotherm heat pump works down to 32 degrees. It does a decent job but they are noisy. I have made the gas heaters very quiet so prefer them.

[dougrainer]

georgelesley wrote:
Our furnace will also come on to help the HP if you select a temp increase of 5 deg or more from ambient. HP shuts off completely at 36 deg and furnace from there.

That is a design feature of RVP (Coleman) AC/HP systems. Coleman believes that it will take too long to heat up an RV by HP ONLY with a greater than 5 degree split. Once the RV gets below the 5 degree split, the furnace shuts off and the HP will continue the final complete heat cycle. Doug

[dougrainer]

BUMPYROAD.

THIS IS AN RV FORUM. IT IS RIDICOLOUS TO BRING UP TOPICS AND SYSTEMS THAT ARE NOT RV RELATED. WHO CARES WHAT YOU HAVE DONE ON YOUR HOME SYSTEMS????? Doug

PS I was 22 forty years ago. 33 years ago in Texas I HAD a HP system in my new house and since there was NO Natural gas in my new Neighborhood, I had the 220 electric back up system and until the outside temps were below 28 degrees that HP kept my 2000 sq ft house very comfortable. Yes we had sub 35 degree temps all the time in winter. Also, I doubt anyone on this forum has 20 years of repairing, installing and troubleshooting and fixing RV HP's as me. I KNOW the parameters and what they can do on RV's.

[dougrainer]

Monkeyman_and_Lady wrote:

dougrainer wrote:

4. LAST, IF people would READ the Dometic operating instructions that come with the RV, this would be explained in detail.Doug

I've been reading. Believe me. The amount of data that came with the new coach had me wondering if I was trying to digest an encyclopedia.

Thanks for the data, though. It all makes more sense now. Espc why the bedroom gets very warm when the furnace is running. The only return for the furnace is in the bedroom, so it naturally gets more air. Will discuss that particular design flaw with Newmar on Monday. Maybe I missed some return in the main living area.

There is only 1 return. Do you have 2 furnaces? There is NO return like in a HOUSE. The only return is the actual location of the furnace in the cabinet it is in. You can discuss it, but there is no fix to that. Doug

[Monkeyman_and_L]

dougrainer wrote:

4. LAST, IF people would READ the Dometic operating instructions that come with the RV, this would be explained in detail.Doug

I've been reading. Believe me. The amount of data that came with the new coach had me wondering if I was trying to digest an encyclopedia.

Thanks for the data, though. It all makes more sense now. Espc why the bedroom gets very warm when the furnace is running. The only return for the furnace is in the bedroom, so it naturally gets more air. Will discuss that particular design flaw with Newmar on Monday. Maybe I missed some return in the main living area.