Heatpump vs. Standard AC

[Cracker]

I had to replace the Penguin heat pump on my 2000 AS. Apparently the PO had tried to run it on low voltage and burned it up. It's a great unit - but awfully expensive for the "heat pump" convenience and auto "switch-over function. Its' cost was over 2.5 times the cost for a standard 13.5 rooftop Dometic - which I replaced on my previous motorhome. For the record, the MH A/C had the heat strips and I would judge them as being equally effective. Some of the cost differential may have been the result of replacing the heat pump at Jackson Center vs replacing the standard A/C at a local RV dealer.

[Safari Tim]

Thanks guys.

Dometic sent me the Quick Cool ceiling package like this. I did tell them it was for a non ducted trailer.

But I could not find that pdf Don found. Thanks. That shows the airbox I thought I needed which looks just like the one you pictured with the vents on the ends and the return on the bottom.

I'll call them Monday and double check. They need a chart on their website so you can see this stuff more easily.

[lewster]

Mark,

Perhaps you misunderstood my post (or maybe I did). The ADB (air distribution box) sends that cooled (or heated) air forward and back thru the horizontal vents and has mechanical controls.

The ducted Quick Cool ceiling package that's used with the Comfort Control digital T/stat will send the air in only one direction......DOWN thru the only vent that it has (Dometic calls it an air shower.....oops, that's Carrier that calls it an air shower anyway, you get the picture! ) if there are no other ducts to distribute the air and will not send it forward and aft like the ADB will. It is located directly under the evaporator's blower and puts out quite a bit of air, but it will only blow in the downward direction or slightly to either side. Just a matter of choice as to how you want the air distributed in your trailer .

Tim, I hope they told you that you need a remote temperature sensor with the CCC. It should come in your electrical package and there should be instructions as to it's placement for best operation.

[markdoane]

Originally Posted by lewster

Mark,

The ducted Quick Cool ceiling package that's used with the Comfort Control digital T/stat will send the air in only one direction......DOWN thru the only vent that it has

Lew,

What I'm saying is that you can get the Comfort Control Center electronic digital thermosat with the ADB also. That's the only point we dispute, I think.

The CCC thermostat will work by itself, without the remote temp sensor. You do need to have a 'good' location for mounting, on a interior partition, away from windows, out of direct airflow, near the return, etc. I think it might be easier to use the remote sensor.

[Safari Tim]

My question was pretty convilouted (sp?).

What I wanted to know is if Dometic sent me the wrong part. They sent the Quick Cool celiing peice and I was pretty sure I needed an Air Duct Box (ADB) since my trailer is NOT ducted.

I just could not find the ADB for the Heatpump model until Don sent that PDF.

[lewster]

Ok, Dometic pulled a fast one on me and never notified me in my regular dealer correspondence and tech updates about the 'NEW' ADB that is compatible with the CCC (they blanked out the 2 sections where the old manual controls go!). In the past (like last year) this was not a possible combination and could not be ordered as such.

I see that you can now get the same combination as an option on your NEW Airstream....direct from the factory as a mid-year upgrade.

NICE!!!!!!!

[Phil Gobie]

I am looking at gen sets and wondering about efficiencies of the heat pump compared to reg AC any comments? I am considering the Yamaha 2400. it is rated at 2000 continuous and 2400 for 20 minuets and will handle 6000 for a few seconds. I may be able to get away with putting a hard start capacitor on my existing AC but I am thinking that a more efficient AC may be better than spending more for a larger Gen set?

[thecatsandi]

Tim,
I have the Combo Heat Pump/AC with heatstrip. I like it. At campground where I have Electric it saves on Propane for those chilly but not cold days.

[Safari Tim]

Great. I look forward to getting it installed.

Regarding the posts above, which ceiling package do you have?

Do you have the 15k btu model?

-Tim

Originally Posted by thecatsandi

Tim,
I have the Combo Heat Pump/AC with heatstrip. I like it. At campground where I have Electric it saves on Propane for those chilly but not cold days.

[jcanavera]

One thing I would venture to guess. I would assume that the AC/Heat Pump unit will probably have a shorter life, just on the assumption that it will be run more frequently. My neighbor's home heat pump wore out after year 10 while most of us got 15 years out of our AC only units.

Jack

[lewster]

Originally Posted by jcanavera

One thing I would venture to guess. I would assume that the AC/Heat Pump unit will probably have a shorter life, just on the assumption that it will be run more frequently. My neighbor's home heat pump wore out after year 10 while most of us got 15 years out of our AC only units.

Jack

Quite possible, considering that the compressor willl be running any time the unit is on, and with the heat pump working when the unit would otherwise be off and the furnace operating..........doing double duty.

But in reality, I've seen these units need replacing after 1 week, month, year, or not at all...................sort of depends on who built it and what you get. I believe that they are assembled in Mexico now (or that's what the last one that I installed said on the box), so as the old saying goes................
"ya pays yer money and ya takes yer chance"

[thecatsandi]

since I have the 31 I believe it is the 15K unit. I have not checked but it is adequate.

[flyfisher]

I don't know whether or not the factory installed heat pump that I have in my 2004 Classic works like others or not, but my heat pump is factory set to only operate down to about 38 degrees, after which it only blows cold air. The furnace does not automatically switch on at that temperature and you have to manually turn it on at that temperature - as I recall it does go on when the outside temperature falls to about 28 degrees. We about froze to death a couple nights until we learned how it worked (didn't work).

My poorly written owner's manual aludes to this pecular operation, but it took a couple guys at the factory service center to clarify this issue for me, and even they weren't completely sure how it worked while I was there for service and they had to call Dometic to make sure.

That certainly isn't how my Trane heat pump works in my home. You'd think that the one in our trailer would be set to automatically switch from the heat pump to the furnace when the temperature falls below some cut-off point.

John

[Cracker]

Originally Posted by flyfisher

I don't know whether or not the factory installed heat pump that I have in my 2004 Classic works like others or not, but my heat pump is factory set to only operate down to about 38 degrees, after which it only blows cold air. The furnace does not automatically switch on at that temperature and you have to manually turn it on at that temperature - as I recall it does go on when the outside temperature falls to about 28 degrees. We about froze to death a couple nights until we learned how it worked (didn't work).

My poorly written owner's manual aludes to this pecular operation, but it took a couple guys at the factory service center to clarify this issue for me, and even they weren't completely sure how it worked while I was there for service and they had to call Dometic to make sure.

That certainly isn't how my Trane heat pump works in my home. You'd think that the one in our trailer would be set to automatically switch from the heat pump to the furnace when the temperature falls below some cut-off point.

John

Wow - that's news! Like John, I was under the impression that the furnace would kick in when the temperature (outside or inside) dropped below what the heat pump could handle (---i.e. - when the heat pump shut down.) My system was totally replaced in 2005 - including the "latest bells & whistles" thermostat. Has anyone else had "hands-on" experience with these units under the "dropping temps" scenario we're talking about? I can't believe the factory gurus didn't have the answers - and it makes me wonder if they really got it straight from Dometic! Like John pointed out, the way this has been explained means that, we either get up at 2 a.m. and switch to the furnace - or we freeze our butts off until it drops to 28 deg outside and the furnace kicks in! Further, if the temperature drops down to just below freezing and hangs there - and we don't get out of bed - the tanks freeze, the pipes break, and we're unhappy campers!

[flyfisher]

Originally Posted by Cracker

Wow - that's news! Like John, I was under the impression that the furnace would kick in when the temperature (outside or inside) dropped below what the heat pump could handle (---i.e. - when the heat pump shut down.) My system was totally replaced in 2005 - including the "latest bells & whistles" thermostat. Has anyone else had "hands-on" experience with these units under the "dropping temps" scenario we're talking about? I can't believe the factory gurus didn't have the answers - and it makes me wonder if they really got it straight from Dometic! Like John pointed out, the way this has been explained means that, we either get up at 2 a.m. and switch to the furnace - or we freeze our butts off until it drops to 28 deg outside and the furnace kicks in! Further, if the temperature drops down to just below freezing and hangs there - and we don't get out of bed - the tanks freeze, the pipes break, and we're unhappy campers!

I talked to several guys at the plant, and although they each understood the concept that I described, none knew the exact ambient temperature at which the heat pump went off and the furnace went on. The temperatures I stated above may be off by a degree or two, I don't remember them exactly either, but those are pretty close.

Now whenever we go to bed with the outside temperature in the low 40's we just turn off the heat pump (if it is on) and turn on the furnace. However, we also got a ceramic space heater this past year so we're using our heat pump less now than we did before anyway (ours is the 15k btu unit).

John

[Cracker]

In truth, the temperature change that would require the performance we're talking about from the thermostat - an overnight change from say 50 degrees to below 28 degrees - is not that common during most of our camping seasons. By the time we turn in at night I think most of us already know that the heat pump will, or won't, be up to the task. However, it would still be a neat arrangement if the furnace would kick in at the exact time the heat pump bows out - and vice versa. In my simple way of thinking, this doesn't seem like it would be an unusually difficult programming task for the thermostat??? The only thing that would be required is an optional setting that would make the decision on which unit runs dependent on the A/C's outside temperature sensor. As long as the outside temperature was in the operating range of the A/C the heat pump would function - and when it dropped below that range the furnace would kick in. The desired interior temperature setting would be common to either unit and the changeover would, indeed, be seamless in either direction. Does that make sense - or did I miss something???

[Pahaska]

I have owned two Classics with the heat pump and, in both trailers, the changeover is seamless.

I always wake up once when the furnace first kicks in. In every case, the trailer interior was still comfortable which indicates to me that the changeover was made while the heat pump was still capable of maintaining interior temperature.

In each case, it went seamlessly back to heat pump when the temperature rose in the morning. I have never placed the thermostat in furnace mode except to initially warm a cold-soaked trailer.

[Loren]

Originally Posted by Cracker

Has anyone else had "hands-on" experience with these units under the "dropping temps" scenario we're talking about? I can't believe the factory gurus didn't have the answers - and it makes me wonder if they really got it straight from Dometic!

Our unit also changes over automatically when the temperature gets too low. If the furnace doesn't light for any reason, the heat pump will pump cold air. This is a thermostat function, not the heat pump.

Last fall we had the heat pump/air conditioner in our 34 Front Kitchen replaced. The original one was dripping water into the living room when operating as a heat pump. As it turned out, the main frame (pan?) was broken. It was only a few hundred dollars more to get an entirely new unit.

Our first unit changed to furnace automatically, but the new unit didn't. I discovered this while sleeping in the trailer in 20* temperatures at Jackson Center waiting to see the service department the following morning. Thank goodness I brought the dog along. We both shivered through the night, but made it without permanent damage.

The Airstream service people didn't know too much about the heat pump. They referred me back to the Dometic dealer who installed it.

It eventually turned out to be a set-up issue with the new Comfort Control thermostat. The service person was supposed to punch in a secret code to have the thermostat search for installed equipment (air conditioner, heat pump, furnace) and set itself correctly. My service guy didn't do that and the thermostat didn't know that the trailer had a furnace, so it never started the furnace. To make matters worse, I couldn't turn the heat pump off and select furnace at the thermostat because the thermostat didn't recognize the furnace.

After re-programming the thermostat, the new heat pump also changes to the furnace when the temperature gets low enough.

To make a long story short (too late)... Be sure that your thermostat is set up correctly by whoever does the installation. This step is apparently not covered well in the installation instructions that came with the new unit.

Good luck,
Loren

[Safari Tim]

You guys are on top of things.

As I am preparing to install this unit myself I've been reading the manual a few times. (slow learner) .

To have the system auto switch over to furnace, you have to be wired for it first of all. So the furnace thermostat wires have to be run up into the air conditioner, not the thermostat.

There is also a dip swtich programming in the air conditioner to tell it if there is a furnace connected. This switch must be set correctly.

And lastly, the Comfort Control Center (thermostat) has to be reset after the above settings are made, to learn what is present.

So, if you have this setup and its not switching over these are some things you can check.

[jcanavera]

Originally Posted by thecatsandi

since I have the 31 I believe it is the 15K unit. I have not checked but it is adequate.

Well the 15K unit is not standard equipment for a 31. It's always an upgrade, but it's not hard to tell since the 15K unit should have some exterior graphics on the shroud that designate the 15K unit.

Jack