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uncle_bob · 11-14-2019, 06:45 AM

Hi

The heat pump goes through some interesting "rock and roll" when you first fire it up in the cold. Ours seems to take forever to get out of the mode ( ...maybe it's 2 minutes, but ... I'm cold ....).

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Our normal practice is to never run more than one tank at a time. When the first one goes dry, we switch to the other one. We then start shopping for a fill up on the empty tank. Right now, the trailer is in storage with one tank empty. I'll fill the other in the spring.

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If I can find a $9 a night site with 50A electric ( = COE campground outside Hannibal Missouri) this time of year, I'm going for that over a "free" site with no power. Propane is cheaper, but the hassle factor just isn't worth it. Toss in maybe running the generator and it's doubly not worth it.

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How much moisture you get inside the trailer is very dependent on how many are in the trailer (two people and three big dogs ... hmmm.....). It also depends a bit on just how cold it actually gets. If the windows get well below freezing, they will frost up (on the inside) at night. They will then melt and drip the next morning. Indeed humidity / rain is a big deal. Taking daily showers also will get things pretty damp ....

Lots of fun !!!

Bob

Bill M. · 11-14-2019, 07:26 AM

Questions: Can you run both the heat pump and the propane furnace at the same time? Do they have separate thermostats? Or does the system switch automatically at some outside temperature?
My old, simple system is to set the propane heat to about 45 or 50 degrees to keep the pipes from freezing and use an electric heater on top of that to make it more comfortable for humans and the dog.

gypsydad · 11-14-2019, 09:08 AM

Quote:

Originally Posted by Bill M.

Questions: Can you run both the heat pump and the propane furnace at the same time? Do they have separate thermostats? Or does the system switch automatically at some outside temperature?
My old, simple system is to set the propane heat to about 45 or 50 degrees to keep the pipes from freezing and use an electric heater on top of that to make it more comfortable for humans and the dog.

Yes, you can set both with same thermostate; heatpump and furnace have separate controls, as does the AC "Cool". The heat pump extracts "heat" from the air outside. The heat pump in your AC unit is not a good source of heat below 40 typically....I know, some folks may disagree, but that's a fact. You can just feel the difference in temperature coming out the AC /Heat pump vents when it gets really cold out... We use the furnace below 40 and down blankets at night. I set the furnace to lowest setting, 40, to insure pipes won't freeze up.

As for moisture...we just purchased a dehumidifier while on our trip last few weeks in Florida...what a difference it made! Have not tried it while using the heater yet, but folks I spoke with at Alumalina said they used it with the heater and works great. Remember, "baby, it's cold outside"!

Bill M. · 11-14-2019, 11:42 AM

We had a heat pump in the house for years. Best thing we ever did was switch to gas. We are now warm and the heat bills are half of the heat pump bills. And with the new air conditioner the cooling bills are less too.

But... I see the reason for a heat pump in a trailer. It is the only way to get enough heat from electricity to warm the trailer. 110 volt heaters are very limited in capacity to keep them from overloading the circuit. The heat pump will put out a lot more BTU's and it does not cost much to add the capability to the AC.

lsbrodsky · 11-14-2019, 01:17 PM

There was something wrong with your heat pump. They are very efficient and in almost every case, the cheapest way to heat your home, unless your electric rates are very high. I have a ground source heat pump and even as low as gas prices are now, my heat pump is about 20% cheaper to operate. But it just never feels as warm with a heat pump because the air coming out of the vents just does not feel very warm, certainly compared with a gas furnace. You can heat your trailer with an electric resistance heater that is rated below the 18 amps or so of your heat pump, but you are right, the heat pump will give you more BTU's. Seems like the units we have on our trailers lose their efficiency at cold temperatures outside at a higher temp than modern units installed in a home.
Larry

kscherzi · 11-14-2019, 01:49 PM

I owned a house with a heat pump, hated it. Below 50 it ran nonstop. It always felt drafty and uncomfortable inside because it was running nonstop. Also loud, hard to sleep. Below 40 it's helper resistance heat strips kicked in and shot our electric bills sky high. Our whole neighborhood had the same thing and everybody hated them. I'll never own a house with a heat pump again.

**jcanavera** · 11-14-2019, 02:43 PM

I don't know how the modern heat pumps work on the newer Airstreams but mine has a defrost cycle that occurs after a certain amount of run time. That's because that outside coil that is usually hot in the summer when cooling, is cold when you are in heat pump mode. It can condense moisture which turns to ice. Unless you have some kind of air flow sensor it is possible when it is damp outside to freeze that outside coil up if the timed defrost cycle is too short. So in damp or rainy weather, even though it's above freezing outside, be a little more aggressive on using the furnace rather than depending on the heat pump. Once that outside coil turns to a block of ice, you get no heat from the heat pump!

Also as noted by others, the heat pump will not send warm air down to the areas with water lines like the furnace does, so if you are going to get down below freezing, and even though the heat pump can keep the trailer warm, don't forget that those pipes behind closed compartments will not see much benefit from the heat pump and it gets pretty cold there.

Jack

uncle_bob · 11-15-2019, 06:22 AM

Hi

If you turn on both the furnace and the heat pump, they each have a temperature sensor somewhere. They also likely have "offsets" in their control circuits. The result often is that one will do all the work while the other just sits there doing near nothing.

Bob

PatLee · 11-15-2019, 06:44 AM

Bill M - I like your 'old' approach and think I'll try that next time I need to protect my pipes.

gypsydad · 11-15-2019, 03:06 PM

To my point about efficiency of a heat pump below 40 or so... There are several articles on this subject, including this YouTube video on a Dometic AC unit. Enjoy...

https://www.youtube.com/watch?v=Tnn5cAO3eMI

uncle_bob · 11-16-2019, 05:08 AM

Hi

If you are looking to cool the trailer to 70 degrees when it is 110 outside, you will be disappointed in the heat pump's performance as an A/C unit. They simply aren't sized to do the job of a 40 degree delta. Even at 30 degrees they are working very hard.

In heat pump mode they are a bit less efficient than as an A/C unit. Somewhere in the same 30 to 40 degree range, they are no longer up to the task. That's independent of all their other issues.

Units in a home are often sized the same way. Turns out that the builder gets a kick back from the government if the home has an "energy efficient" design. To big an A/C, to much heat, or to much electric feed for that number of square feet and he looses the "incentive payment".

Lots of strange stuff out there ......

Bob

jimfa440 · 11-20-2019, 11:10 AM

With only one morning at 32, I wouldn't worry about a thing, not even the water hose. It won't freeze until you have a sustained temp under 30. When you get up to do that bathroom thing in the wee (no pun intended) hours, run a bit of water. You'll be fine.
Opinions from #23456, happy camping.

bartzstream2 · 11-20-2019, 05:01 PM

Quote:

Originally Posted by uncle_bob

Hi

Fill the fresh water tank and run off of it. Disconnect the water hose and drain it. Disconnect the sewer hose and store it away. Ideally, hook up to shore power and run the furnace on electricity (if that's an option). If not, start researching propane resources nearby

. In any case, you do want to keep the trailer warm to prevent freezing issues (and also to protect the pipes

).

Bob

Open all the lower cupboard doors (all night) which will allow the areas where the water lines reside in the trailer to stay above freezing. Do not forget the are where the pump resides. I would not fill the fresh tank all the way. Depending upon where your furnace is located, its operation will bring room temperature air into those cabinets to be circulated through the heat exchanger before it is discharged into the living space. Condensation is one of the big problems in colder weather. The window frame channels may get completely full of it over an extended period. Just soak it up with towels, and crack the windows to help exhaust high humidity during the day when temps are likely higher than during the night. I would say that the dump valves freezing up are the most serious issue. Plan to pare back your water needs when possible and use the public facilities wherever you are. Hope this helps.

Granitefines · 11-21-2019, 08:15 AM

I always end up skirting cold weather with Thanksgiving in Baltimore and a stop by Busch Gardens in Williamsburg as I head south. I got tired of fighting condensation and a loud heater blower motor, So I made custom fitting window insulation for every window.

I sandwiched 2 layers of Mylar wrap around 1” green foam. I sewed it up in between a layer of “warm windows” fabric from Joanns. They fit over the screen windows with some Velcro or held in place with the curtains. They are stored in the shower and when you want to shower, I just set them on the bed. You will probably want a heavy duty sewing machine and it cost ~$300 for materials. It is now so comfortable and my heaters are not running constantly. In the morning, I just unlock the windows and walk around the outside, open the windows and squeegee off the built up condensation.

The project took about two weeks.

Mhphhoward · 11-21-2019, 08:43 AM

any doubt about freezing temps, disconnect city water. Better yet, use an electric hose, expensive but worth it.

Mhphhoward · 11-21-2019, 08:51 AM

Forgot to add; since it takes more energy to freeze a full tank than one a third full, when there's danger of a hard freeze best to keep fresh and gray tanks pretty full.

gypsydad · 11-21-2019, 09:17 AM

Quote:

Originally Posted by bartzstream2

Open all the lower cupboard doors (all night) which will allow the areas where the water lines reside in the trailer to stay above freezing. Do not forget the are where the pump resides. I would not fill the fresh tank all the way. Depending upon where your furnace is located, its operation will bring room temperature air into those cabinets to be circulated through the heat exchanger before it is discharged into the living space. Condensation is one of the big problems in colder weather. The window frame channels may get completely full of it over an extended period. Just soak it up with towels, and crack the windows to help exhaust high humidity during the day when temps are likely higher than during the night. I would say that the dump valves freezing up are the most serious issue. Plan to pare back your water needs when possible and use the public facilities wherever you are. Hope this helps.

Why not get a dehumidifier, assuming you have electric, and avoid leaving a vent open letting out the heat, your using to keep your trailer from freezing? We got one at Home Depot, while traveling last month to NC and FL for several weeks. Got tired of wiping off condensation from the windows, and leaving open a vent at night, which still did not eliminate the moisture...just caused the heater to run more.

Night and day difference inside now. We were surprised how much water is collected overnight with this unit, but no more condensation issues.