Auto switch - Heat Pump to Propane Furnace not happening

dboliek · 12-18-2012, 03:29 PM

We have a 2000 Winnie Chieftain 35-U. It has a Suburban SF-42 propane furnace and an RVP 6535 series Heat Pump with a 6535-3451 Thermostat.

I've noticed several folks mentioning that when it got chilly, their heat pump auto switched to the propane furnace. Indeed the instructions for the thermostat say if the heat pump cannot maintain above 45 degrees, furnace will engage.

We were out several weeks ago, plugged into 30 amp shore power, when the temperature went down, the heat pump couldn't keep up, but the furnace didn't automatically switch on. When I got cold enough I got up and turned it on and it came on as it should.

Any thoughts as to why the auto switch didn't occur?

Navy Flier · 12-18-2012, 04:46 PM

You might want to contact Winnebago and make sure that your system will indeed work as you state. I do have that capability in my 08 Horizon but I did not in my 2003 Horizon.

zippo · 12-18-2012, 05:02 PM

My 2008 is suppose to auto switch. Sometimes it will and sometimes it won't. When it was within warranty no one could fix it. So out of warranty I live with it. If I wake up freezing I have to get up and switch to the furnace.

Tom N · 12-18-2012, 05:06 PM

Are you the original owner?

I have read of some disabling this feature to save LP.

I would pull the thermostat and look for a disconnected wire.

-Tom

Sammie · 12-18-2012, 05:43 PM

Quote:

Originally Posted by dboliek

We have a 2000 Winnie Chieftain 35-U. It has a Suburban SF-42 propane furnace and an RVP 6535 series Heat Pump with a 6535-3451 Thermostat.

I've noticed several folks mentioning that when it got chilly, their heat pump auto switched to the propane furnace. Indeed the instructions for the thermostat say if the heat pump cannot maintain above 45 degrees, furnace will engage.

We were out several weeks ago, plugged into 30 amp shore power, when the temperature went down, the heat pump couldn't keep up, but the furnace didn't automatically switch on. When I got cold enough I got up and turned it on and it came on as it should.

Any thoughts as to why the auto switch didn't occur?

Dave,

You might try moving the switch back and forth on the thermostat a few times to clean the contacts inside. I have heard that others have had similar problems with this thermostat and this has helped cure the problem.

Sammie

mikf · 12-18-2012, 06:06 PM

mine does not automaticly switch at 45 degrees. only when it cannot keep up, and then switches over to propane and after 2 hours it will try the heat pump again. or if I turn my thermostat up more then 4 degrees above the inside temp the propane kicks on. have you tied turning your thermostat up? I have warmed my rv up with just the heatpump by just turning the thermostat up 3 degrees at time when the outside temps have been in the 30's. I always hear about heatpumps not working when the temp drops, but my heatpump in my home runs and puts out heat when the temps get well below zero. same principle as the rv, when heatpump cannot keep up aux. heat kicks in to bring up to temp, but the heatpump never shuts off. as a side note I just installed a hot water tank in my home that heats the water with a heatpump mounted on top of the tank with electric heating elements to back up the heat pump if it can not keep up. supposed to save $300 a year on my electric bill.

sellhomz · 12-18-2012, 06:23 PM

Your heat pump in your house will have something like electric strips back up that will cut on under 35 degrees to assist. Go check your power meter it will be spinning and you can cut that on any time if you turn it up more than about four degrees at a time. Some systems have a light marked emergency heat to go directly to the strip heat if the heat pump compressor were to malfunction and you need heat

mikf · 12-19-2012, 05:55 AM

Quote:

Originally Posted by sellhomz

Your heat pump in your house will have something like electric strips back up that will cut on under 35 degrees to assist. Go check your power meter it will be spinning and you can cut that on any time if you turn it up more than about four degrees at a time. Some systems have a light marked emergency heat to go directly to the strip heat if the heat pump compressor were to malfunction and you need heat

My heat pump has no heat strips, if it can not keep up the electric furnace inside my home kicks in and a light comes on my thermostat to let me know. That does not happen very often. We used the electric furnace as the only source of heat for A couple of years before we got the heat pump

Doug Sage · 12-19-2012, 07:29 AM

Quote:

Originally Posted by zippo

My 2008 is suppose to auto switch. Sometimes it will and sometimes it won't. When it was within warranty no one could fix it. So out of warranty I live with it. If I wake up freezing I have to get up and switch to the furnace.

Times 2.

Patrol 65 · 12-19-2012, 07:22 PM

My thermostat has a switch for selecting electric or gas. I too have read on this forum about the auto switching feature but mine doesn't switch. The heat pump just stops coming on when the temperature drops too low and I have to move the selector from electric to gas for the furnace to come on. I am not the original owner so I just figured that the thermostat works like the one on my stick and brick house.

Tom N · 12-23-2012, 10:19 PM

Below is a quote from my RVP manual.

"If the Heat Pump is unable to maintain the coach
temperature, the thermostat will automatically cycle the
furnace on. The new True-Air Thermostats (Electric
Heat Mode) will call for second stage (Furnace)
heating operation anytime the temperature inside the
coach is more than 5 degrees cooler than the customers
chosen setpoint temperature. It is entirely possible the
furnace and the heat pump may both operate at the
same time to satisfy the thermostat."

-Tom

DancinCampers · 12-24-2012, 05:58 AM

If the heat pump shut down due to the outdoor coil thermister opening, then the following would apply:

The second way is when the outdoor freeze sensor opens & shuts down the heat pump. Under this condition, the gas furnace will operate. BUT, according to the manual, in this case it will come on when the indoor temp reaches 45 deg F & turn off when the indoor temp reaches 60 deg F. At this time the thermostat should be changed over to gas.

I did have this happen to me once. Took me awhile to figure out. Once you change the tstat to gas the thermostat will operate as you have set it.

dboliek · 01-02-2013, 06:22 PM

Thanks for the responses. It's not really major to us as we don't do a lot of cold weather camping... I was just wondering since we had been out when the temps dropped into the 30's and the switchover never happened.

It also sounds as if the heat pump gets over its head at about 45-degrees outside, but doesn't switch to gas until it gets to 45-degrees inside... which could be a considerable difference.

My solution is right there with most of yours. It's not but about 6 feet from the bed to the thermostat and it really isn't that hard to get up, flip the switch and climb back into bed.

Again thanks for the responses and the research. I apologize for my slow response, but the holidays were here and I just didn't want to turn my computer on.

Happy New Year...

Dave and Missy