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Safari Tim · 01-30-2007, 04:58 PM

I'm trying to decide on an AC for the Ambassador.

I could either go with the heatpump that is also a 13.5kbtu air conditioner. The heatpump will provide heating to around 40 degrees outside.

Or I can go with the 15kbtu with a heatstrip.

Is the extra 1500btu worth it over not having the heatpump? Or should I go with the heatpump so I can save on propane when we have full hookups?

silverback · 01-30-2007, 06:01 PM

Tim,
We went with the 15K BTU unit in the 28' because we live in AZ. I believe ours also has the heatpump as we have the digital wall thermostat with different modes. We do a lot of winter camping and have not used the heatpump (yet). If you're planning on visiting the southwest in the summer you may want the 15K unit for the 28'.
-KL

jdalrymple · 01-30-2007, 06:04 PM

I have the heat pump. It works great until you really need heat, then it just blows cold air. I would say get the electric strips. The other side of the coin is you need to run the furnace some to keep plumbing and tanks from freezing in the belly pan. I have made that mistake too. Live and learn.

str8strm · 01-30-2007, 06:06 PM

the heat strip on our AC does not do much, I think you feel cooler with all the air circulation!! We have furnaces in the MoHo and ran them almost non stop (for the first time) at the 29 palms rally earlier this month---it got down to 18 degrees. We would not have done well with only the heat strips. Of course we were on full hookups and could have used a small space heater to augment the heat strips. As noted above the furnaces kept all the internal plumbing from freezing, our outside hoses froze the first night so we went to using tank water.

Pick · 01-30-2007, 06:15 PM

I have a Carrier heat pump for our house, (60,000 BTU) It kept our house warm last night down to 25*F. It has a built in 5 KW heat strip, but we seldom use it.

The heat strip in our Coleman really doesn't provide much heat at all.

SafariSS · 01-30-2007, 06:24 PM

I have a DuoTherm(Dometic) 15k AC w/heat pump. I have found the heat pump to work ok down to about 45F. My main thing is I dont like the condensation that it produces when running in heat pump mode as I like to keep the outside of the trailer clean! During AC mode the condensate runs out the little tube in the wheel well.

Does anyone know if running the Heat Pump down really cold will cause icing on the condensor?

Pick · 01-30-2007, 07:01 PM

Quote:

Does anyone know if running the Heat Pump down really cold will cause icing on the condensor?

Yep! It does! My home unit has a "defrost mode". Actually all it does is go back to normal air conditioning mode for a few minutes to clear the ice off.

Silvertwinkie · 01-30-2007, 07:04 PM

I also have the 15k A/C with heat pump. I use both and for a 28' Airstream, heat pump issue aside, 15k is the smallest you want to go with. I know some folks will disagree, but back when it was not common, I special ordered our unit with it. Today, many of the 27' footers commonly have it. It does cool very well, even in direct sunlight, or at least it does on my 25' Safari.

I recall several folks trying to talk me out of it, even some folks at the dealer. They said:

"It's only 25' and it's not a standard option for the Safari."

I said "I know and if it's an option for the 25' Classic which has the same specs, then it's good enough for the Safari."

One of the best additions to my Airstream I made, right next to getting the second Fantastic Vent.

Dry heat, humid heat, it doesn't cycle as much as folks said it would and cools perfectly....those who see me at the Midwest Rally know I can get it cold enough to hang meat inside.

lewster · 01-30-2007, 08:26 PM

That's how heat pumps work. There is a reversing valve in the suction line that reverses the flow of refrigerant to turn the evaporator into the condensor, and the condensor into the evaporator. This causes the usually warm air that gets discharged from the condensor to the outside to flow across the evaporator and then into the trailer.

They are not very efficient below 50* and just don't seem to throw much heat at that temp or below. Neither will a heat strip. The furnace is noisey, but it will surely give you the most bang for the buck, considering the much larger transfer of BTUs that they will produce.

That said, the heat pump WILL take the chill out of a cool-ish morning without running the furnace and it's associated noise....and they are only about another $100 or so over the standard A/C unit.

Safari Tim · 01-30-2007, 09:18 PM

Cool. For some reason I thought the heatpumps only went up to 13.5kbtu.

So it looks like the 15kbtu with heatpump is the way to go then. No downside to the heatpump?

Silvertwinkie · 01-30-2007, 09:20 PM

Quote:

Originally Posted by Safari Tim

Cool. For some reason I thought the heatpumps only went up to 13.5kbtu.

So it looks like the 15kbtu with heatpump is the way to go then. No downside to the heatpump?

Not unless it gets under 50 degrees outside. Like Airstreams and tow vehicles, few downgrade.

2toomany · 01-31-2007, 05:29 AM

Only from my past experience with a carrier 15kbtu mounted on a 73 safari camping in the southeast, winters are very mild but offer great camping weather. The carrier will keep you warm to about 38 degrees and will still work below that but, the temp in the trailer will also start to decrease, this is where your furnace or alternate heat source is helpful. Very rarely do we ever camp for extended amounts of time below 38 degrees, but there again it rarely gets below 38 on a continious basis in the southeast. Hope this is helpful

Pahaska · 01-31-2007, 07:05 AM

I keep hearing that heat pumps don't work under all kinds of temperatures; 40, 45, etc., even 50 degrees according to Silvertwinkie.

It's odd that this morning, in the mid-30s, I had to turn the thermostat down a bit because it was too hot in the trailer. I had it set at 72 and it was cycling, so I turned it down to 69.

In 4 years of owning heat pump-equipped Airstreams, I have only had the furnace switchover occur about three times and, those times, I also had frozen water hoses.

The output from a heat pump is not very hot, but it is warmer than the intake air and will keep the trailer plenty warm. While I use a ceramic heater to help initially warm the cold-soaked trailer, the heat pump keeps the trailer warm to near freezing.

**moosetags** · 01-31-2007, 07:21 AM

Our 13.5k heat pump works great for us. We use it almost exclusively to heat Lucy. We have camped in Lucy with nights in the 30's for about 30 nights, and have found that the heat pump is all we need.

silverback · 01-31-2007, 07:59 AM

I was just about to respond that I would have to give the heatpump mode a try at the FCU rally and then I woke up and realized we won't be plugged in. Don't think I'll try it on the Honda 2000i. -KL

Loren · 02-03-2007, 11:11 AM

No one has yet mentioned the issue of who pays for your heat.

If you are running the furnace you are burning the LP that you paid for. If you are running the heat pump you are using the campground's electricity. I realize that you are paying for the campground's electricity, but they are not going to give you a rebate if you don't use it.

I also have used a heat pump at low temperatures. In our trailer, the furnace will automatically start to provide supplemental heat when the heat pump senses the need for it. Generally this is a good thing, since at those temperatures there is a possibility that your pipes and tanks may freeze.

Always remember that the heat pump will NOT provide any freeze protection to your pipes and tanks. The furnace will.

I think you'll be happy with a heat pump.

Loren

Pahaska · 02-03-2007, 03:26 PM

I think that folks think that heat pumps are not working because they feel the outlet air and it isn't real hot like a ceramic heater.

Heat pumps, both residential (I have owned one) and RV, put out a whole lot of air at just a few degrees hotter than the input air. However, because of the large amount of air moved, there are a lot of BTUs added.

This morning there was ice on my windshield, but my heat pump kept the trailer cozy all night and I only heard (and smelled) the furnace come on once in the very early morniing.

I did use the ceramic heater in the bathroom for my shower last night rather than boost the temperature in the entire trailer. Other than that and initial warm-up from cold-soaked trailer, we use the heat pump exclusively.

In a lot of ways, outside of the bathroom, the steady heat from the pump at just above room temperature is more comfortable than the furnace cycling.

Safari Tim · 02-04-2007, 12:37 AM

OK guys, I'm putting together a system with a 15k BTU Penqiun heatpump with the Comfort Control Center that will switch over to the furnace automatically.

Since my trailer is NOT ducted, I'm trying to figure out the ceiling package. I assumed it would look similar to this without the knobs.

However their website shows this one toward the center of the page. But I think that is the same as this which reads like its for ducted systems.

So, anyone who has a heatpump with the CCC package, what does your ceiling peice look like?

lewster · 02-04-2007, 06:11 AM

Hi Tim,

Your links show 2 different lower units which have 2 different install modes. The one from the Dometic web site is strictly for ducted applications and uses the Comfort Control Center which is attached via a 4 conductor phone cable to the PC control board in the upper unit. While it will spill out conitioned air from the adjustable grill at the rear of the unit (the return is just in front), it does not distribute the air horizontally like the non-ducted version.

The other lower is for non-ducted applications andd is not compatible with the CCC, as it has it's own thermostat with a rotary temp control (mechanical with no degree settings) on one side and a selector switch for mode and fan speed on the other side.

AFAIK, the 2 are not compatible, but you can use either unit with your upper 15K heat pump. You could modify the ducted version with a forward and rearward facing set of outlets that drop out of the ceiling, but that would be a lot of work......though not impossible. It might require a dropped plenum on the ceiling as there isn't much depth to an A/S ceiling, but you could make it decorative and use........ALUMINUM (what a concept!)

Let me know if you have any other questions about this, I work on these ducted units on a daily basis and have seen lots of install methods from the MoHo OEMs..............

markdoane · 02-04-2007, 08:23 AM

Tim,

I hate to disagree with my friend Lew, but I will.

The Model number for a 15k Heat Pump should be 630516, and it is useable with an 3106615 airbox. Here's the Installation Instructions http://www.dometicusa.com/pdf/3109529.069.pdf

If you read the text next under 'Interchangeable Fit" in your Dometic link, it says it can use either the ducted method or the airbox.

I don't have the heat pump feature on mine, but the installation instructions (link above) doesn't distinguish between the two.

Here is a picture of my airbox installed. I want you to make one IMPORTANT change when you install the airbox.

In the second picture you will see that I added two foam strips just inside the metal ribs in the ceiling template. If you don't do this, air will short circuit between the supply plenum and the return plenum. This is because of the curvature of the roof not matching the flat airbox. The ribs in the airbox seal against the inside of the ribs when it is flat, but there is about a 1/4" gap the full length if the roof is curved.

I don't know if Airstream does this when they retrofit Penguins to vintage units, but if they don't it could explain some of the poor performance issues that have been reported .