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Old 10-31-2020, 07:54 AM   #1
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2013 30' International
SAN ANTONIO , TX
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Need advice on heat pump/furnace for a newbie

We recently purchased a new to us 2013 International Serenity 30rb. This is our first ever Airstream and only the 2nd time camping in it. Last night was going to be in the low 40s so we decided to use some heat. We have 2 A/C units on the rig so I turned on the furnace which was on zone 2. Everything was working and the trailer was warming up but all of the sudden the smoke alarm started going off. I know a home heater will smell bad the first time you use it for the winter but this was a little weird so we shut it off and had to open the door to try and get the smell out and it did actually seem a little smokey inside.

Next option was to use the heat pump so I turned both zones on and set the heat pump to low. This worked great and the trailer got nice and warm. To sleep we decided to turn off zone 1 (rear bedroom) and just leave on zone 2 (living room area). This worked but unfortunately the heat pump kept shutting off and then starting up several minutes later all night. Is this normal for a heat pump? I could understand it doing that if I had it set to auto but not sure why it's doing that when I have it set to low.

I'm wondering if I can get any heat if I just turn both fans on instead of the heat pump. Really trying to see how we get it to stay on the entire night and not cycle on and off because it wakes us up each time it does that. Appreciate any help and advice you can give me on this. Really love our Airstream and mainly do a lot of camping in the spring and summer but definitely have a few winter trips planned so want to figure out the best way to do this especially if the furnace is not an option.
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Old 10-31-2020, 07:58 AM   #2
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I have one heat pump, one zone. When the temp is in the 40's the heat pump just won't put out any heat and will cycle as you suggest. Get your gas furnace working; it is the choice in the 40's and below, despite the fact that home heat pumps will work fine in the 40's. What many of us do is use small ceramic electric heaters plugged in to an outlet. Quieter and works better. My 25 ft trailer only needs one.
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Old 10-31-2020, 09:20 AM   #3
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A bit more on the heat pump:

If the relative humidity is high (close or at dew point). The heat pump outside coils will condense quite a bit of water from the air which drops onto the roof and runs off. If the temperature drops below 43 the condensation will freeze and the unit will cycle into "freeze" mode reversing to warm the outer coils then returning to heat mode. When cycling like this, it won't generate a lot of heat.

If the dew point is well below freezing, then you can run the heat pump down to about 25 before it gets so inefficient it also won't generate much heat.

So, if you have shore power, get a little portable electric heater (750-1200 watts so you don't trip breakers) and use it when outside temperatures are below 45. Use the furnace as well when it is below 25 so the tanks don't start to freeze.

On the furnace, you can access it via a trap door usually under a cushion above the intake.
You can get into the plenum and clean out the hair and dust which is likely what was smoking. Or you can just burn it away with the windows open (not recommended) if you are sure that is the issue. You can also inspect it for some other trash in there that is burning. Access the air chambers from the inside. The outside area is to access the burner and controls.
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Old 10-31-2020, 09:31 AM   #4
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Had the same thing happen with our furnace on our first camping trip. I'd only be concerned if it sets off the smoke detector the next time you use it. We haven't had it go off again after the first use. The furnace will be key as temps get low. The furnace will help keep your tanks from freezing, the heat pump will not. As others have mentioned, the heat pump isn't going to be effective in the temps you mentioned.
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Old 10-31-2020, 10:20 AM   #5
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Whatever your source of heat, keep a couple of windows cracked open so that condensation on walls/windows doesn't build up while you sleep.
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Old 10-31-2020, 10:35 AM   #6
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Carlisle , Pennsylvania
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Hi

If your RV has been in storage for a while, "interesting" things may take up residence here or there. Spiders / bees / wasps / mice .... all might decide this or that is a great place to live. If you get a bee hive in your furnace (or hot water heater or fridge) "chimney" it's going to be a bit of a mess. If they decide to make a home in the burner, you may have a hard time getting it to light.

As noted above, heat pumps get a bit weird as you go below about 40 degrees. They *may* do ok, they may not. The freeze / thaw cycle is very normal. If you watch it, there generally is a lot of steam coming off the device as it goes through the cycle. That may re-condense on the outside of the RV and you get water or (worst case) ice as a result.

Fun !!

Bob
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Old 10-31-2020, 10:46 AM   #7
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I don't know how the defrost cycle has changed over the years but on my heat pump on the Classic it seems to be tied to continuous run time. So if it really is cold out and the heat pump is running constantly (I use auto), the fan will shut off but the compressor flow is reversed which makes the outside coils warm which will defrost any ice that has accumulated. Once that timed function completes, the fan will come back on and the compressor flow is reversed again an the heat pump goes back into heating mode.

Now whether there is an actual sensor for air flow is a trigger to defrost for the newer units is unknown to me. I do know that outside humidity plays havoc with mine and on extremely damp situations and temperatures in the lower 40's, my heat pump will not run long enough in defrost mode to melt heavy accumulations of ice.

I've learned over the years to recognize those outdoor conditions and I'll switch over to use the furnace rather than rely on the heat pump. I would say that the heat pump works well for me and I'll use it 90% of the time when I feel that heat is required.

Here's a picture taken many years ago of my heat pump freeze up on a lower 40 degree day. We had been out of the trailer most of the day and came back to this. Trailer was very cool inside, heat pump mode running but the air blowing out of the unit inside was very cool with little heat. Note the outside coils all coated with ice. You get very little heat in this situation. This was taken in 2004 and my trailer was new. I'm running the same heat pump unit today.

Jack
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Old 10-31-2020, 12:10 PM   #8
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I think the defrost cycle is controlled by a compressor head pressure switch. When the outside coil freezes up, the head pressure rises. When the switch closes, the unit goes into defrost mode.
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Old 10-31-2020, 01:04 PM   #9
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The modern units use compressor suction pressure (proxy for refrigerant temperature), outside ambient air temperature and coil temperature to detect coil freezing. It will adjust defrost time based on temperature differentials.
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Old 10-31-2020, 01:44 PM   #10
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Quote:
Originally Posted by BayouBiker View Post
The modern units use compressor suction pressure (proxy for refrigerant temperature), outside ambient air temperature and coil temperature to detect coil freezing. It will adjust defrost time based on temperature differentials.
That's pretty cool and high tech. Wouldn't you think that they could build these units with connectors for refrigerant charging if they can build them with that kind of technology?

Larry
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Old 10-31-2020, 04:18 PM   #11
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Well apparently I guess I should have probably addressed this as a warranty item when the trailer was new. I have heard mine go into defrost mode before but as you can see by my picture, something didn't work right. The only thing I could put my finger on was that we had rain and high humidity outside and it was in the mid to low 40's. I've never seen this condition in the 16 years after that picture was taken. I've never been in that situation with the heat pump since then. It's been cold but no high humidity situation.

I also was told that the unit would switch to furnace automatically once the temperatures got below a certain level. Never have seen that happen. What I have seen is the heat provided starts to get cooler as the outside temperatures drop. I was in Michigan a couple of weeks ago and the temps at night got into mid 30's. Heat pump was doing fine until the middle of the night. I woke up noticing it was uncomfortably cool in the trailer and the heat pump and fan were running. I had the thermostat set for 65 F. I got out of bed and put my hand up to the air blowing out the unit and it was temped at best. Not warm enough to overcome the coldness in the trailer. I set the control to furnace and the furnace immediately turned on. I've never been in a situation where I saw any kind of automatic change over to furnace from heat pump. It's always been a situation where I've manually had to make the change because I'd notice that the unit was no longer producing the hot air necessary to keep the trailer comfortable. That usually occurs when temps fall to 40 degrees or below.

Jack
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Old 10-31-2020, 04:50 PM   #12
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Jack, I don't know that they have always had a temperature sensor on the coils or one for ambient air. I only know that the newer models do.
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Old 10-31-2020, 06:22 PM   #13
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Jack, I assume you have the ccc1. Are you aware of the learning function which has to be done everytime 12v is removed from the thermostat in order for the auto switching to furnace to occur?
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Old 10-31-2020, 07:44 PM   #14
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Quote:
Originally Posted by dznf0g View Post
Jack, I assume you have the ccc1. Are you aware of the learning function which has to be done everytime 12v is removed from the thermostat in order for the auto switching to furnace to occur?
Tell me more, I may not know about this. I turn the master control switch to off every time I am not using the trailer. In addition I pull the batteries after the end of the season. I know back in late 2003 when I bought the trailer no one talked about any type of learning function.
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Old 10-31-2020, 10:18 PM   #15
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I have a 2013 trailer with the Penguin II AC. Low on my thermostat relates to the fan speed setting. So I think think when your AC cycled it was normal operation, just the fan ran on the low setting.

What's concerning is the burning smell when running the propane furnace. Maybe its just dust, but maybe.........
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Old 11-01-2020, 12:13 AM   #16
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Originally Posted by jcanavera View Post
Tell me more, I may not know about this. I turn the master control switch to off every time I am not using the trailer. In addition I pull the batteries after the end of the season. I know back in late 2003 when I bought the trailer no one talked about any type of learning function.
So, in order for the furnace switch over to occur, turn off the thermostat slide switch on the bottom of the unit. Depress the top and bottom buttons on the face. While holding them down, slide the bottom switch on. "FF" will appear on the screen. The auto switching to furnace will now occur at approximately 35*f. This must be done every time 12v is removed from the thermostat.
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Old 11-01-2020, 12:16 AM   #17
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Thanks Iíll do this in the future...

Jack
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