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Pops 06-04-2005 03:28 PM

Heatpump experience
 
Anyone have experience with the LS option (particularly with the 13500 heat pump)?

PWRSTRK 06-04-2005 06:48 PM

Yes, we've used it extensively and have been very happy about it. It does not distribute air very efficiently throughout the cabin, but given what it is it works great. As to the a/c -- we love it. Tom

jcanavera 06-04-2005 07:08 PM

Quote:

Originally Posted by Pops
Anyone have experience with the LS option (particularly with the 13500 heat pump)?

Are you having problems or are you just curious?

Jack

05ModPod 06-04-2005 07:33 PM

We have one of those fancy units in the Excella - the other day it was so hot and I was clearing some bush right beside the unit - I thought I wonder if that unit blows cold - so I grabed a beer and a chair (as we took out the couch already) and fired her up.

Although she took a while - the fan operates for an extended time then you hear the A/C kick in and after about 5 minutes she started to blow cold - not sure if this was because she had not been used for a year or so??? but the second and third breaks - she blew cold right away. We tested the heat a few days earlier and she worked fine too. Fairly quiet and on the 28' the cold air did make it to the back as well as the front - but if you are standing at the sink no such luck - so a small fan might be in order to better circulate the cool air around the kitchen area. :D

Tinsel Loaf 06-04-2005 08:48 PM

It is interesting that when we use the heatpump the unit draws a wee bit more current than when used in the ac mode. It must be the power used in the reversing valve while heating. The reversing valve default is off for Cooling using no current.

flyfisher 06-05-2005 03:48 AM

Quote:

Originally Posted by Pops
Anyone have experience with the LS option (particularly with the 13500 heat pump)?

THe heatpump in our trailer may be different, but this is something to think about:

I was surprised to learn last fall, after experiencing some freezing nights in our trailer, that the heatpump in our 2004 Classic is designed to shut off well above freezing (at something like 37 degrees), and the furnace is designed to not automatically turn on until the temperature gets to freezing or somewhat below.

Don't quote me on the exact temperatures, but as I recall there is a 5-7 degree range just above freezing where we can get mighty cold in the trailer if we expect to keep warm using just the heatpump.

There is something explaining this in our owners manual, but it is as clear as mud. I thought our heatpump was defective at first, so when we were in Jackson Center in early October, I asked about it. Several of the service people knew something about it, but they had to call Dometic or Duo Therm to get the detailed explanation, and later called me at home with the specifics (the exact details of which I've now forgotten!).


John

Pops 06-05-2005 06:27 AM

No, I am just about to purchase one and was making some last minute checks.

Thanks to all for the help.

jcanavera 06-05-2005 07:12 AM

Heatpumps also have a defrost cycle that comes into play once temps dip below 35 degrees and your run time exceeds 30 minutes. When that occurs the inside fan will shut down and the compressor cycle will go into A/C mode. This heats up the outside coils and defrosts any ice on them. Unfortunately its not a perfect solution. Here is a picture of my heat pump on an October day in which it froze up. Problem was temps were in the lower 40's but we had very heavy humidity due to an all day rain. Run time of the compressor was less than 30 minutes but cycle time was fast enough to not allow the outside coils to lose the ice that had formed. I'll let the picture speak for itself.

Frozen Heat Pump

Obviously we switched over to the furnace at this point.

Jack

flyfisher 06-05-2005 08:52 AM

Quote:

Originally Posted by jcanavera
Heatpumps also have a defrost cycle that comes into play once temps dip below 35 degrees and your run time exceeds 30 minutes. When that occurs the inside fan will shut down and the compressor cycle will go into A/C mode. This heats up the outside coils and defrosts any ice on them. Unfortunately its not a perfect solution. Here is a picture of my heat pump on an October day in which it froze up. Problem was temps were in the lower 40's but we had very heavy humidity due to an all day rain. Run time of the compressor was less than 30 minutes but cycle time was fast enough to not allow the outside coils to lose the ice that had formed. I'll let the picture speak for itself.

Frozen Heat Pump

Obviously we switched over to the furnace at this point.

Jack

I'm still confused as to exactly what is intended to happen, but all I know for sure is our heatpump didn't provide any heat during several nights when the outside air temperature was approximately in a range of 26 - 40 degrees. Our furnace did not automatically turn on, and if I undestood the Airsteam people correctly at Jackson Center (which I am now wondering if I did), they said what I experienced was normal.

Here's a partial statement from my Dou-Therm operating instructions:

"DEFROST CYCLE
This cycle is active during HEAT PUMP operation and allows the heat pump to operate down to 30 degrees F. When the outside ambient temperature is less than 42 degrees F and greater than 30 degrees F, a defrost timing cycle will begin. The defrost timing cycle will allow operation of the heat pump for 25 minutes. The fan will then be shut off, the refrigerant flow reversed and run for 4 1/2 minutes, this is the DEFROST CYCLE. The refrigerant flow will then return to normal and, after a 30 second delay will continue until the temperature is greater than 42 degrees F or until the temperature becomes less than 30 degrees F, at which time the furnace will activate." (which should happen, per the instructions, if the furnace is hooked up to automatically kick in, as described in the prior Section "AUX.HEAT")

I interpreted this to mean that the Heat Pump should pump out warm air down to 30 degrees F, except for going through a 4 1/2 minute defrost cycle, followed by a 30 second rest :rolleyes: , every half hour. However, that's not what happens in this temperature range on my heat pump - the fan just continuously blows cool air - when I asked the service guys at Airstream they told me mine was normal.

John

TomW 06-05-2005 09:03 AM

Quote:

Originally Posted by flyfisher
I interpreted this to mean that the Heat Pump should pump out warm air ... However, that's not what happens in this temperature range on my heat pump - the fan just continuously blows cool air ...

Keep in mind that "warm" is a relative term when it comes to heat pumps. A heat pump, in winter time operation, works by taking heat from the outside air. So, the cooler the outside air temperature is, the less heat the unit will be able to extract from it. The point where the heat pump is not able to efficiently extract heat from the outside air is where the heat strips or furnace should come on.

To me, the heated air produced by a heat pump is never very warm. In your case, you might want to quantify your "cool air" by measuring the temperature of the air before the filter, and the temperature of the air when it leaves the unit. Your dealer's service department should have a spec on what the lowest allowable difference should be.

Tom

dmac 06-05-2005 09:50 AM

We have the heat pump and it works fine. We used it in April when it ws 35-45 degrees outside at night and it kept the trailer warm. Because the air is not ducted the heat does not reach the bathroom. However, it saves propane when at a site with hookups.

I read somewhere that the heat pump is supposed to function above a certain temperature, and the fiurnace kicks in below that temperature - all automatically. However, our electronic thermostat has a manual setting for heat pump and another for furnace, and there does not appear to be any automatic switchover capability.

Overall the LS package provides some value, if you can get it for the right price.

Janets Husband 06-05-2005 11:08 AM

Quote:

Originally Posted by dmac
We have the heat pump and it works fine. We used it in April when it ws 35-45 degrees outside at night and it kept the trailer warm. Because the air is not ducted the heat does not reach the bathroom. However, it saves propane when at a site with hookups.

I read somewhere that the heat pump is supposed to function above a certain temperature, and the fiurnace kicks in below that temperature - all automatically. However, our electronic thermostat has a manual setting for heat pump and another for furnace, and there does not appear to be any automatic switchover capability.

Overall the LS package provides some value, if you can get it for the right price.



Dan

This question is kinda off topic but how much current does your Heat Pump pull? Can you run it off of a 20amp plug?

flyfisher 06-05-2005 01:15 PM

Quote:

Originally Posted by TomW
Keep in mind that "warm" is a relative term when it comes to heat pumps. A heat pump, in winter time operation, works by taking heat from the outside air. So, the cooler the outside air temperature is, the less heat the unit will be able to extract from it. The point where the heat pump is not able to efficiently extract heat from the outside air is where the heat strips or furnace should come on.

To me, the heated air produced by a heat pump is never very warm. In your case, you might want to quantify your "cool air" by measuring the temperature of the air before the filter, and the temperature of the air when it leaves the unit. Your dealer's service department should have a spec on what the lowest allowable difference should be.

Tom

Tom - I generally understand how the heat pump works in our home - we've had several of them and used them continuously since 1979, so I wasn't expecting warm or hot air from my trailer's heat pump, but just warm enough to keep the trailer more or less comfortable when the temperature was above freezing outside - with no wind and no rain to overburden the heatpump's operation. But, that's not what we experienced - all it did was blow COLD air - so cold in fact that I had to get out of bed, turn the heat pump off and turn on the furnace - and I'm a guy who ordinarily likes temperatures that are colder, rather than warmer. I probably had the thermostat set for the mid-60's, but the temperature inside our trailer was more like mid-30's when I turned on the furnace.

Of course, the service people at Airstream don’t give me a lot of confidence with they’re explanations either. Here’s a picture of how my outside condenser fins looked when I bought my new trailer last year:

https://www.myfishingpictures.com/img/019311.JPG

When I spoke to 2 of Airstream service and production directors about that specific problem in May last year right after I bought this trailer, they professed to not understand what the term “fins” meant, and although I have asked them for a new air conditioner during 2 separate trips to Jackson Center last year, they declined to replace this smashed one, and told me that these smashed fins will not effect the unit’s performance (they did straighten them partially.)

John

2airishuman 06-05-2005 02:15 PM

the heat pump feature is of limited value
 
hi folks

i too have the heat pump feature and it sure sounds like a cool....i mean hot.....feature.

having used it now for several weeks...i think it has limited value and in no way performs as well has a house hold heat pump system.

when outside temps are 50 and up it can provide some quick warm air inside the coach but below 50 it just doesn't put out enough heat to warm up anything but the circulating air. the trailer will still seem cold because everything that makes the trailer is still cold....skin, walls, cabinets, floors and so on.

the heat pump is not ducted so only the air inside the coach will warm and then only above waist level.

the trailer unit itself will still be cool/cold as will the sofa, dinette, bed and toilet. conduction of this coolness to the human body makes us feel cold unless we insulate ourselves from touching anything trailer related....i for one don't want to wear a hat and gloves and woolies all of the time inside the trailer just to save propane.

the holding tanks will all slowly drop in temp too and this becomes a significant source of cold depot for the rest of the trailer and occupants.

for me the heat pump is a nice little feature but of limited value....i wouldn't pay extra for it. and it can provide a little warm air when electricity is your only energy source and temps are not lower than 50 or daytime sunlight is warming the trailer itself.

most would be better served by just using the furnace and buying larger lp tanks or adding a super efficient lp catalytic heater. these are amazing little inventions and provide a much better heat to humans. if electricity is plentyful then plug in an electric cat unit near the sleeping area or toilet, and just run the ac fan to circulate the air as needed.

just like the ac, using the furnace early on to keep the trailer baseline temp higher means heating up the living space takes less effort later in the evening and night.

of course someone could try installing a heated floor setup during an extreme remodel...

cheers
2air'

pienjim 06-05-2005 03:40 PM

Our heat pump has worked fine...up until two nights ago. When I awoke I realized it was blowing cold air. Outside temp was no lower than 42 degrees. I tested it the next day (Outside air a bit warmer, 55 maybe) and it would not blow warm air at all. Something has gone awry, but it may take a trip to a Dometic repair person to figure it out. Anybody know of one in Anchorage?

Paula

jcanavera 06-05-2005 09:03 PM

Based on what we have seen, the threshold for the heat pump to furnace cut over is way too low. Once the heat pump runs for a bit, the inside discharge air is about 90 degrees on mine when outside temps are in the mid to upper 40's. It however does fall off as the outside temps continue to slide. Once you get into temps around 35 or so, the output becomes marginal.

I never did think about it but just as in cooling mode, the BTU rating of a unit probably affects the heat output also. Mine being a 15K unit, probably has a little more punch than the 13.5K unit.

jcanavera 06-05-2005 09:10 PM

Quote:

Originally Posted by flyfisher
Of course, the service people at Airstream don’t give me a lot of confidence with they’re explanations either. Here’s a picture of how my outside condenser fins looked when I bought my new trailer last year:

they declined to replace this smashed one, and told me that these smashed fins will not effect the unit’s performance (they did straighten them partially.)

John

Keep in mind that if those outside coils get a coating of ice on them, the heat produced will be minimal or almost non existant. A lot depends upon the outside humidity and run times.

Personally I have never owned an A/C unit on any RV that didn't have some minor coil damage on them. Personally I think its sloppy assembly by the A/C manufacturer. From what I see on your picture there should be little if any affect on the performance of your unit. They are shipped and installed with the covers in place so the damage you see didn't come from Airstream.

Jack

Tinsel Loaf 06-05-2005 11:52 PM

Gary
Our heat pump will trip a 20 amp breaker after a period of time, about 15 to 20 minutes. However, it will not trip the same breaker the ac mode.

Silvertwinkie 06-06-2005 06:57 AM

Pops, if you are buying a new 28', then I would highly suggest you look at the 15k unit with the heat pump and comfort control system. I found that the 11k unit was not really all that good with our 19' unit and there were some folks here that had 25's or 27's and the 13.5k unit was also a bit overtaxed. In our 25' we have the 15k unit and love it....in full, exposed sun with 90 degree temps I can get the inside of our Safari to be in the low 70s. Additionally the heat pump is a great feature and with LP prices being what they are, if I get take the edge out with the heat pump, I do and in the long run, it saves me a little bit of $$$ in propane costs compared to the fossil fuel thirsty 25k BTU furnace. The neat thing about the heat pump units is that they actually shut off (in both A/C and heat pump modes), where the heat tape units run all the time making any progress in managing the interior temps a bit more difficult as I found with our manual 11k unit with heat strip.

dmac 06-06-2005 07:31 AM

The heat pump should draw about the same amperage as the air conditioner - rated at 14.6 amps while running, but the starting amps will be higher. Dometic's web site does not list starting amps, but does show a minimum 3500 watt generator.

The Dometic web site states that the heat pump will provide 13,000 btu of heat, and function down to 40 degrees F.


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