Heat Pump question now that cold season has arrived

[JoePa77]

Again, I want to thank this forum for all the advice I have received and all the information I have found searching since I have just started to learn about motorhomes. I have searched the forum and found out a lot about the use of heat pumps vs furnace. My question seems to be specific to my unit. It is a 2020 FR Forester 2861DS. I am trying to run the heat pump (and my 15,000 BTU AC does have one) and when I turn it on it seems to run for a minute or so then turn off, then on for a minute or so, then turn off, .. repeat...

So the first time I tried this last week it was about 45 degrees here in Ohio, both those nights it did not seem to bump the temp inside very much running like that (stat was set to 65, heat, and auto). I ran the furnace briefly just because it was never run before. It ran, tripped the smoke detector, even though I saw no smoke but did smell the new furnace. Opened the windows and ran the fan and everything was fine. Move forward a little to yesterday, temperatures in the 60s, set the stat to 75 turn on the heat pump. I could definitely feel more heat coming out of the vents on the ceiling, the inside temp went from 68 to 71 while it was running for about an hour (still running very briefly and stopping for a longer time, repeat). I was working on getting packed to use this weekend in Michigan but the Heat Pump was not running consistently - Maybe this is how it is supposed to work? That is why I am asking. I have not read in this forum about anyone saying this was normal operating procedure. It seems running this way would never heat up the motorhome even on a warmer day let alone in the 40s.

Any help on what I am doing wrong, or is this a warranty issue would be appreciated.

[nayther]

Your temps certainly should be high enough for the HP to work. When the ambient gets down below 30 their efficiency falls off pretty good. Does the HP have a heat strip?

[SlowrideHD]

Almost sounds as if it is cycling off and on due to a low refrigerant level. Was it working OK when on the cooling function?

[JoePa77]

It did work in August while in Florida 95+ degree days. We survived. But had it back at the dealership for 6 weeks and have not run anything for a while. They should not have done anything to AC but maybe tonight I try the AC to see if your suggestion to troubleshoot can help diagnose issue. Seems like it should run heat pump similarly to AC.

[JoePa77]

Nayther, not sure if it truly does have a heat strip. I believe it does not but will check the manuals tonight and reply. If that might be a cause it is something more for me to be aware. Thanks.

[TowPro]

on other posts I hear where every minute the heat pump comes on for a couple seconds so it can move air across a temp sensor that is built into the device.


I also hear our Heat pumps don't ever shut all the way off when on AC, they just go to low speed fan when temps are at set point.


I also read here that the unit does not use the temp input from the thermostat, instead it uses an internal sensor one for temp sampling, and the one on thermostat is only for Propane heat use. Something about hold a button (forget which one) down for 10 seconds and it shows you what this internal temp sensor sees.


I also read where people were trying to relocate this internal temp sensor to affect a more constant temp range.

[G Hollingsworth]

Given the choice, I prefer to use my heat pumps over the furnaces as the heat is more evenly distributed thought the coach, and I don't have to get propane as often. That said, at 45 degrees F you are getting close to the temperature when heat pumps can no longer make heat. On Auto, the system should kick on the furnace, heat pump or both as needed. On my last motorhome, if i set the thermostat more than a few degrees (say from 60 to 70F) if would kick in the propane furnace no matter the temperature outside. So, to keep it on heat pump as much as I could, I would set it up a few degrees at a time, let it reach that temperature then a few more degrees.

On my new motorhome, I've had a lot of trouble with the control system (Precision Plex) so I can't say for sure how it works. The dealer tells me they have found the problem but I haven't got the rig back to confirm.

[cariboo camper]

Originally Posted by JoePa77

Again, I want to thank this forum for all the advice I have received and all the information I have found searching since I have just started to learn about motorhomes. I have searched the forum and found out a lot about the use of heat pumps vs furnace. My question seems to be specific to my unit. It is a 2020 FR Forester 2861DS. I am trying to run the heat pump (and my 15,000 BTU AC does have one) and when I turn it on it seems to run for a minute or so then turn off, then on for a minute or so, then turn off, .. repeat...

So the first time I tried this last week it was about 45 degrees here in Ohio, both those nights it did not seem to bump the temp inside very much running like that (stat was set to 65, heat, and auto). I ran the furnace briefly just because it was never run before. It ran, tripped the smoke detector, even though I saw no smoke but did smell the new furnace. Opened the windows and ran the fan and everything was fine. Move forward a little to yesterday, temperatures in the 60s, set the stat to 75 turn on the heat pump. I could definitely feel more heat coming out of the vents on the ceiling, the inside temp went from 68 to 71 while it was running for about an hour (still running very briefly and stopping for a longer time, repeat). I was working on getting packed to use this weekend in Michigan but the Heat Pump was not running consistently - Maybe this is how it is supposed to work? That is why I am asking. I have not read in this forum about anyone saying this was normal operating procedure. It seems running this way would never heat up the motorhome even on a warmer day let alone in the 40s.

Any help on what I am doing wrong, or is this a warranty issue would be appreciated.

That's the way mine works. Sounds like yours is working as it should. Fan will come on and "sniff" the air to determine room temp and then if heat required you will hear compressor cycle and warm air will come out of vents. If no heat required fan will shut off until next cycle. If outside temp drops below 45? Heat pump will shut off and furnace will take over. Does on mine anyway.

The smell from running furnace first time is normal and you will find if you are travelling n dusty conditions furnace will also smell kind of weird.

[jvalich]

At 45 you are getting to the point when efficiency starts dropping quickly. Also if the shrouds are black the unit is actually cooler than the surrounding air at night due to black body radiation. That phenomenon will transfer energy from the black sky which is colder. An example is a solar hot water system. The freeze function will kick in at an air temp of 37 because black body radiation will cause the panel to freeze above 32.

[Luke Moseley]

I've used my heat pump in some pretty cold weather (<20) . What I've found is the HP does ok in moderately cold conditions but, when it gets COLD, the furnace does a better job. As long as I'm in a campground and on their power, I just use a simple electric ceramic heater and it does great. I can't answer your HP cycling issue but others on this forum probably can. Good luck.

[NXR]

My Airxcel air conditioner/heat pump do cycle like that when on Heat. Mine run for nine seconds and then are off for 60 seconds. Once it sees the need to heat then they run continuously. The cycling is so annoying when trying to sleep that I'm considering the Wacko silencer for $200 for the bedroom unit.

My Airxcel heat pumps also automatically shut down when the outside air temp hits approximately 45 degrees. "Approximately" is the manual wording and I've seen them go off at 49 degrees. I know they shut off because that annoying cycling just stops entirely and the propane furnace starts the heating.

Ray

[CaptnJohn]

OP does not have a heat strip, old technology. The HP works on the same principle as a home unit. I run mine to 38, it switches at 35. Dometic 15k I think the HP is 16k.

[karykatz]

Joepa77

My name is Kary Katzenberger and I am the Product Manager for the Forest River Class C Division. I have been in contact with Dometic regarding your heat pump because it isn't operating the way its designed. It sounds like the control board needs to be replaced. If you go to your local dealer they should be able to help. The Dometic part number for the replacement board is #15080. Thank you for purchasing a Forest River product.

[5picker]

Originally Posted by karykatz

Joepa77

My name is Kary Katzenberger and I am the Product Manager for the Forest River Class C Division. I have been in contact with Dometic regarding your heat pump because it isn't operating the way its designed. It sounds like the control board needs to be replaced. If you go to your local dealer they should be able to help. The Dometic part number for the replacement board is #15080. Thank you for purchasing a Forest River product.

Kary,
Welcome!
I see it is your 1st post!

Thank you for participating in these forum discussions.

With your presence and those from a few folks in other divisions, it is a good sign Forest River is moving in the right direction when it comes to customer service.

[emm-dee]

My Atwood heat pump works just fine if I fool it with the temp setting. Apparently the previous info about different temp sensors is correct, but the sensor in the unit (not the one in the wall mounted control box) sees things differently.

For example, if the actual indoor temperature is 72 degrees and I select a desired temp of 75 the heat pump will do its normal procedure of “sniffing” the air temp for about 5-6 seconds every couple minutes. Apparently the HP sensor is seeing a temp higher than what the panel selection is set for because the compressor does not activate. However, when I select 77 degrees I’ll hear the compressor come on and hot air flows. So for now I just set the panel temp at 77 or 78 and the heat pump works great and coach temp stays 72-73 degrees.

Maybe it should work differently but as far as I’m concerned the coach is warm and I’m not gonna mess with it.

[NXR]

Originally Posted by emm-dee

My Atwood heat pump works just fine if I fool it with the temp setting. Apparently the previous info about different temp sensors is correct, but the sensor in the unit (not the one in the wall mounted control box) sees things differently.

For example, if the actual indoor temperature is 72 degrees and I select a desired temp of 75 the heat pump will do its normal procedure of “sniffing” the air temp for about 5-6 seconds every couple minutes. Apparently the HP sensor is seeing a temp higher than what the panel selection is set for because the compressor does not activate. However, when I select 77 degrees I’ll hear the compressor come on and hot air flows. So for now I just set the panel temp at 77 or 78 and the heat pump works great and coach temp stays 72-73 degrees.

Maybe it should work differently but as far as I’m concerned the coach is warm and I’m not gonna mess with it.

Mine works the same way. Holding the Sleep button for five seconds is supposed to show you the temp as the thermostat sees it, for example 72.

If I want the real temp at 74 I have to set the thermostat about 5 degrees higher or 79.

It's like the thermostat temp sensor only works for the air conditioner part. Or it doesn't do anything at all except when you press the Sleep button for five seconds. Heat rises and cold sinks, so maybe it really doesn't have anything to do with the temperature sensing.

Ray

[nomad297]

Originally Posted by 5picker

it is a good sign Forest River is moving in the right direction when it comes to customer service.

It is my opinion that Forest River is ALWAYS moving in the right direction when it comes to customer service.

Bruce

[wtroyer01]

Hi everyone, my name is Will Troyer and I am the Account manager for Dometic (Atwood) that handles this Forest River Facility. I inadvertently gave Kary the wrong part number below and I would like to clarify that it should be part number 15092 (Not 15080). The previous number I provided is for a Non-Ducted system and wont be the correct part for your 15K ducted Air Command.

I would also like to provide a little background to this subject.

This condition does not always present itself, but it could potentially happen for some people. It really depends on what the temperature is outside Vs what the set-point temp is in the coach.

The way the existing “heat pump mode” software was written was that the fan would shut off when the set-point was satisfied. With the Thermistor located in the air-box, and the air not blowing across it, the software will think that it needs to start again when the air cools off in the AC. Once the fan starts and pulls in the room air, it satisfies the thermistor again and the cycle starts over. This seems to present itself more often where the set-point temperature is easily (or quickly) achieved by the heat pump.
To fix this, we updated the software in the replacement control board so that when the heat pump set-point is satisfied, it will put the fan on its lowest setting so that air will continue to be pulled across the room thermistor. Once the room temp is calling for heat again, the compressor will engage and potentially raise the fan speed (depending on set-point Vs actual). This eliminates all of the “Short cycling” or Off/On nuisance issues, if they are having them. Also this is the same logic that is used on the "Cool" function in the software.

Hopefully this helps you all, and I will pass this post along to our Tech service group!

Originally Posted by karykatz

Joepa77

My name is Kary Katzenberger and I am the Product Manager for the Forest River Class C Division. I have been in contact with Dometic regarding your heat pump because it isn't operating the way its designed. It sounds like the control board needs to be replaced. If you go to your local dealer they should be able to help. The Dometic part number for the replacement board is #15080. Thank you for purchasing a Forest River product.

[NXR]

Originally Posted by wtroyer01

Hi everyone, my name is Will Troyer and I am the Account manager for Dometic (Atwood) that handles this Forest River Facility. I inadvertently gave Kary the wrong part number below and I would like to clarify that it should be part number 15092 (Not 15080). The previous number I provided is for a Non-Ducted system and wont be the correct part for your 15K ducted Air Command.

Wow, thank you for being here and providing this info, Will!

I have a five-month old Georgetown motorhome with two AC-1511 AirCommand ducted systems. Is 15092 board part number for use in the AC-1511? Will the board replacement be covered under the Dometic warranty?

On a related note, when you press the Sleep button on the thermostat for five seconds it shows you the current temperature. Is the thermistor providing that information located in the wall-mounted thermostat or is it the same one you just mentioned at the Dometic unit itself?

I need to set both of my thermostats about five degrees higher than a thermometer placed just below the thermostat to get the desired temperature. So if the Sleep button shows 70 and I want the temp at 70 I need to crank the thermostats to 75 to get there.

Again, thank you VERY MUCH for being here.

Ray

[wtroyer01]

Hey Ray,

I would say if you are experiencing this issue with a coach under warranty, we should defiantly get this taken care of for you! And, yes this board will work on both of your AC's as long as they are the Atwood units.

As to your question about the Temperature reading difference, In heat pump and AC mode, the themistor in the return air up by the coils is doing the work. When you hit the sleep button, this is reference thermistor.

I believe that your issue of set point to actual may also be a result of the same problem where the fan is shutting off when the temp is achieved. My guess is that after the boards are changed, this will be much improved.


Now, There is a thermistor on the actual T-stat. However, it is only active when in "Furnace Mode", and while you have no shore power or generator. This was done for the dry campers out there that don't use 110v. Without the 110V, the Ac couldn't run the fan and pull air across the thermistor, thus not letting the system sense the room temp properly.