Furnace vs. heat pump

[SGR]

We have a 2015 Forester 2861DS.

Our thermostat has a setting for Furnace and another setting for Heat Pump.

When we are not connected to shore power (which is usually) we use the furnace setting for our heat. When shore power is connected and we try to use the furnace setting it automatically turns on the heat pump and not the furnace.

First of all, is this correct?

Secondly is there any way to use the furnace instead of the heat pump while connected to shore power?

We don't like running the heat pump late at night (during quiet hours) because it is very loud. Just as loud as the air conditioner on the inside of the rig!

[BehindBars]

While it doesn’t answer your question, here is a suggestion. When on shore power and you need some heat overnight, set up a small space heater. It would be generally much quieter than the furnace or heat pump, and it won’t use up your propane like the furnace would. That’s what we have done for the last 20 years.

[CHICKDOE]

what you describe is not correct! heat pump is a function within the air conditioner and can only be used when connected to 120 vac provided by shore power (or generator) furnace only uses 12vdc and should be usable at any time.

many people get confused when they try to run the furnace and they think the air conditioner (hear pump) comes on. what is actually happening is that the a/c blower motor comes on (this requires 120vac). the a/c compressor is not supposed to come on. this is by design but can be altered. go to your thermostat and under the fan setting are three speed options (hi, low, auto). if the fan is set to hi or lo it will come on when the furnace comes on. the intent is to allow the a/c blower motor to distribute the hot air coming out of the furnace. if you do no want this set the fan speed to auto.

i would try setting the fan speed to auto and then try your furnace again and see if it works. it only uses your 12 vdc power supply.

[BehindBars]

Originally Posted by SGR

We have a 2015 Forester 2861DS.

Our thermostat has a setting for Furnace and another setting for Heat Pump.

When we are not connected to shore power (which is usually) we use the furnace setting for our heat. When shore power is connected and we try to use the furnace setting it automatically turns on the heat pump and not the furnace.

First of all, is this correct?

Secondly is there any way to use the furnace instead of the heat pump while connected to shore power?

We don't like running the heat pump late at night (during quiet hours) because it is very loud. Just as loud as the air conditioner on the inside of the rig!

On our Sunseeker thermostat, I can force it to go to furnace only and not run the heat pump. Post a photo of your thermostat. Directions for operating the thermostat can be found on the Forest River manuals web site.

[5picker]

Please let us know what thermostat you have.

As mentioned, some of them allow furnace only, heat pump only or a combination of the furnace and the blower only in the A/C unit.

Also when on heat pump, most thermostats will default to furnace if the outside temperature gets too low for the heat pump to be efficient or if the setpoint is too high for the heat pump to overcome or satisfy.

Also take note... there are true heat pump options and then there are also heat STRIP options in A/C units. It is important to know which you have.

[ActionJackson]

Originally Posted by CHICKDOE

what you describe is not correct! heat pump is a function within the air conditioner and can only be used when connected to 120 vac provided by shore power (or generator) furnace only uses 12vdc and should be usable at any time.

many people get confused when they try to run the furnace and they think the air conditioner (hear pump) comes on. what is actually happening is that the a/c blower motor comes on (this requires 120vac). the a/c compressor is not supposed to come on. this is by design but can be altered. go to your thermostat and under the fan setting are three speed options (hi, low, auto). if the fan is set to hi or lo it will come on when the furnace comes on. the intent is to allow the a/c blower motor to distribute the hot air coming out of the furnace. if you do no want this set the fan speed to auto.

i would try setting the fan speed to auto and then try your furnace again and see if it works. it only uses your 12 vdc power supply.

Yes, all very correct info. ^^

[ActionJackson]

Originally Posted by BehindBars

While it doesn’t answer your question, here is a suggestion. When on shore power and you need some heat overnight, set up a small space heater. It would be generally much quieter than the furnace or heat pump, and it won’t use up your propane like the furnace would. That’s what we have done for the last 20 years.

Yes, that's what we do also. Quiet, safe (small ceramic heater) and gas-saving.

[jkoenig24]

I second the recommendation for a SMALL electric heater with ONE CAVEAT. Do NOT run a 110VAC electric heater at its' HIGH setting. 110VAC circuits, when used continuously, should only be used at 80% MAXIMUM of their rated capacity (ie a 20A breaker should NOT draw over 16A continuously; a 15A breaker should NOT pull more than 12A continuously). Running a circuit CONTINUALLY at its' rated capacity is very likely to overheat wires / outlets and circuit breakers.

Remember, OTHER devices WILL be drawing 110VAC current which will be CUMULATIVE with the draw of an electric heater. If, for instance, you run the microwave or hair dryer for 5 or 10 minutes while the electric heater is running, you'll really strain the onboard circuit breaker AND the circuit breaker(s) on the power pedestal. Such a condition is a fire just waiting to happen. IF the circuit breakers are properly installed and of good quality, they should do their job and shut down an overloaded circuit BEFORE damage occurs. I for one, would rather err on the side of safety and consciously work to keep demand BELOW the rated capacity. The rig (and lives) you save may be your own.

My understanding is that heat PUMPS become less effective once the outside temperature drops below ~ 50ºF. The colder it gets, the more efficiency decreases until about 40ºF where it just doesn't work at all.

For anyone doing EXTENDED cold weather use of their RV, I'd recommend that they consult a QUALIFIED PROPANE SPECIALIST and discuss the PROPER installation of a propane fired catalytic heater. LOTS can go wrong if the installation in not done properly and, it's imperative that such a system is ALWAYS USED PROPERLY.

[cariboo camper]

On my thermostat there is an on/off switch, also a button for Mode and a button for furnace on/off, and a few others for other different stuff , the mode button has four functions. cool, heat, fan and dry. First off I push the on/off switch to on, cycle the mode button to heat, if it is cold enough to call for heat the heat pump will do its thing unless it too cold for it to work which is just above freezing, in that case the furnace will cycle on.

To stop the heat pump from cycling push the on/off button to on, select heat from the mode settings, and push furnace button to on, then set temp. Heat pump should not function at all.

Hope this helps.

[SGR]

I have attached a picture of our Dometic thermostat. It has only 3 buttons: 1. On/Off Mode 2. (+) 3. (-)

Pressing the mode button once turns on the fan, while the fan is on the (+) and (-) buttons allow you to choose Hi or Low

Pressing the mode button a second time turns on the Air Conditioner, if connected to shore power or running the generator.

Pressing the mode button a third time turns on the Furnace as long as shore power is not connected. If shore power is connected, the heat pump turns on or at least air starts blowing from the AC unit and eventually the air turns warm.

Pressing the mode button a fourth time turns on the Heat Pump, if connected to shore power or running the generator.

On all three of the cool/heat options the (+) and (-) buttons control the temperature.

I bought this motorhome new and have all of the documentation (I believe) and find nothing about operating the thermostat.

I do think that the small electric heater would work for me but we don't often use shore power and I would like to not carry a heater around!

[JLeising]

Fan actually has three choices - Hi, Lo and Au (automatic). If you set to Au, it won’t come on with the furnace (as noted by CHICKDOE above. Believe CHICKDOE likely correctly analyzed your problem.

[kcmusa]

What if you turned off the breaker for the AC?

[CHICKDOE]

what happens if you turn the furnace on when not connected to shore power?
go to the fan mode and then use the +- buttons to set the fan speed to auto. then try to turn on the furnace when connected to shore power. what happens?

when you say the a/c comes on when you select the furnace is it just the a/c blower motor or is the actual a/c compressor coming on?

the furnace and the furnace blower motor are powered by 12 volts. (battery)
the a/c compressor and the a/c blower motor are powered by 120 volts. (shore power)

[BehindBars]

Originally Posted by SGR

I have attached a picture of our Dometic thermostat.
I bought this motorhome new and have all of the documentation (I believe) and find nothing about operating the thermostat.

Quite often, new owners are not supplied all the documentation that should have come with the RV. For some appliances, you have to get the manuals yourself. From the Forest River Interactive Manuals web site, here is a link to a thermostat manual for a 2015 Forester, that appears to match what you pictured.

https://s3.amazonaws.com/cd-content....94a347a499.pdf

Heat Pump mode seems to be a separate selectable mode from Furnace mode. I’ll let you read the manual and interpret it.

The following is quoted from the manual:
“ “Furnace” - Furnace Mode
In this mode there are 3 fan speed selections:
Lo - (LOW): The fan operates continuously at low speed.
Hi - (HIGH): The fan operates continuously at high speed.
Au - (AUTO): The fan will be OFF.
Note: If additional indoor air circulation provided by the air condi- tioner is not desired during Furnace Mode of operation, select Au (AUTO) in the Fan Mode to shut the air conditioner fan off. If Lo (LOW) or Hi (HIGH) is selected the air conditioner fan will continue to operate on the selected speed.”

[SGR]

First of all, thank you to all who have replied to my posts!

So I went out to the motorhome this morning while it was still cool enough to be able to get the heater to come on.

As for replies by CHICKDOE & JLeising, you were absolutely correct!

I have never used the fan function until playing with it yesterday for my post.
I was unaware of the Hi/Low functions of the (+) & (-) buttons. I thought that they were only for the temperature of the air con and the heater! I still had no idea that pushing them once more would give me AUTO.

Even if I had known about the AUTO, I not sure that I would have made the connection in my brain about the heat pump coming on with the furnace. I'm still not sure that the heat pump actually comes on or if it is just the fan but it really doesn't matter as now I know how to stop it!

BehindBars, I'll check out the manuals website!

Thanks again to all!

SGR
2015 Forest River Forester
2010 Honda CRV
SoCal

[CHICKDOE]

Glad it is now resolved. Almost guaranteed that only the a/c fan was running, not the compressor. Now go have fun.