Atwood Heat Pump

to Bob Vaughn: I can double check, but I am fairly certain that the book does not say that the furnace will not operate until 45 degrees. The furnace will operate if the heat pump does not satisfy the heat needed within some timeout. It is very short. So the furnace kicks in and begins to heat. When the heat pump is ready, it will begin to operate and the heat pump's thermostat will take control away from the furnace so that it will shut off again (it has an automatic run time requirement in the furnace) so they will both be running at the same time for awhile. But if you don't feel significant heat - like 80 to 90 degrees coming out of the unit, it isn't working right. At least that is what my atwood puts out. What the book is saying is that the furnace is operated under 45 degrees - the heat pump is shut off. But my experience is that it will operate between the furnace and the heat pump to under 40 degrees, but then it has to deice itself quite often. There are two 'furnace' operations - one in conjunction with the heat pump similar to aux heat on a hvac system and one that is separate where you actually do not use the a/c at all, but it turns over operation to the furnace when you switch the 'furnace' to on.

Don't worry about the fan running, let it run. If it doesn't shut off, then there is something wrong. If it continues to heat until you are baked out, then your system is either set up wrong or you switched the 'Furnace' switch on - it must be off. Use 'Furnace' only if you want the Atwood to not run the furnace temp.

to blofgren and Bob Vaughn: the heat pump should put out plenty of heat if it turns on. The girl was referring to the fact that the heat pump code uses the sensor temperatures to decide how to respond and they are inside the heat pump using inside air. The outside air temp only comes into play if the heat pump cannot supply heat. You can read the temperatures on the various thermistors using the Information setting hold temp down and fan at the same time and then use temp up to select between the thermistors.

The heat pump is supposed to have a feature for setting the operating parameters so that you can lower the temp of shut off down to 32 degrees, but I could not get mine to go into that mode.

I use my heat pump on my house down to 25 degrees. It works fine, just as good as electric heat when it gets into that range below 35 degrees. My propane backup furnace heat for my home was too expensive and electric has been quite cheap so I have been using the lower numbers without trouble. I have 2600 sq ft and one 6T high SEER (14, I think) heat pump with propane gas furnace for aux heat. Nice set up - furnace and power in the house can be run on a 3000 watt genset.

To Bob Vaughn - I don't think that you made an error. All you need is to find out why it is not operating as it should. My units kick out HOT air at high fan speed.

You are right about the person who answers your questions. That is ridiculous. Of course it is not due to the temperature being too high. It is supposed to function and it isn't. I recently had a young tech tell me that pulling the plug on my router at the box was different than unplugging it from the wall outlet. When I said no it wasn't, she argued with me that it works differently. Sorry, when I disconnect the power - there is no power in that router and the POR works the same way in both cases. She was not convinced and said that they have it happen all of the time, describing how sometimes people unplug from a power strip - again she was all wet. What she meant was that a person might have a bad switch on the power strip and the power does not go off. Mine had gone off and the problem was something that required service at the input side of the router. I told her that she was confused about how the thing works and that I have an electrical engineering degree and knew better than what she was trying to feed me. I used to design that kind of equipment, for pete's sake!

Well, in my experience with this unit, you guys are all correct and all wrong!!

First you are absolutely correct about the BIMBO. She told me the same thing about the temperature being to warm in the room. Good heavens, are people really that stupid? Well, maybe so.

I originally installed and tested its operation in both heating and cooling in early September. But didn't really use it other than to test it. Mine do operate though. I installed two of them (Atwood 15033 black version of the 15028) in place of one Coleman 13.5K and a Coleman 11K BTU a/c. I have an Intellitec system that compounds the issue. I rewired everything in order to get it to work and the first time out my daughter used it and suffered by setting the system to 60 degrees and never called me to help them get it running even though I had provided them with a step-by-step on how to use it.

The second time out, I was there. The symptoms are that the air conditioners operate like a champ, but the heat pump fans turn on, run for 5 seconds, turn off, wait thirty seconds, turn fan on, turn off after 5 seconds and then immediately turn on the heat pump compressor - kicking out huge amounts of very warm air. But then it goes back to the same cycling BS again. All night long the same constant cycling - enough to drive someone crazy.

The second night, the temperature dipped a little colder and the unit refused to come on at first - ran the furnace instead. Not realizing what was happening, I shut it off and set the temperature to 60 degrees and operated the air conditioner for a minute or so. (I had apparently waited until it got too cold to turn the heat pump on.) As soon as I discovered that the heat pump could be made to function doing that, I ran each a/c until it was definitely cooling and for about 30 seconds to one minute, then switched it to heat pump using the setting of whatever the room temperature was plus 1 degree. I was able to increase the temperature slowly, moving it up to the 'room temperature' reading.

Still, every once-in-awhile, the unit that operates the furnace would kick in. So I would start over. That night after I finally got things set up, the units would operate continuously as they should - that is, the thermostat called for heat, the fan started on low, the compressor started (the fan kept running on low) soon the fan ran faster (when the heat pump was outputting heat) and as the temperature increased, the fan speed increased. When the temperature limit was reached, the compressor shut off, the fan continues to run until a timeout is reached. That, oddly enough, is how it is intended to operate, I think.

The furnace is set to operate from only the front unit. When the other unit goes into reverse mode to clear the coils, the furnace does not run so it never comes out of that function. So the second night, the a/c unit w/o the furnace did not run much. It shut off leaving the furnace and the second heat pump to heat the coach. But at least that incessant 5 second run, 30 sec off, 5 sec run, 30 sec off of the fan did not happen.

However, the next night it was warmer and what little heat was needed, the heat pumps provided, but with that 5-, 30-sec cycling BS.

If your system is set up correctly, the furnace is designed to be backup for the heat pump and should not be set to 'Furnace', ie, do not switch the furnace button on the thermostat to on. That expects the furnace to operate as a normal furnace and bypasses the sensors. Mine just turned on and heated the place up to 80-90 degrees.

I think that I am going to modify mine so that the second thermostat also operates the furnace (I only have one furnace) somehow. Right now, the furnace feature is disabled on the rear heat pump, so the heat pump stops and cannot start again because of their idiotic coding, I suspect. If I tell it to go into furnace mode automatically, it should work like the other one and start up again once it stops to defrost itself. In fact, I might not have to do anything to the unit except change the jumpers to allow furnace even though it doesn't actually operate the furnace.
Update: the jumpers were already set to S2 2-3 jumpered which means that it is the same as the other that has the furnace. All I did was wire the Atwood relay in series with the other shutoffs. The power comes to the furnace as 12 vdc red wire, goes through some fuses and then out on a blue wire to the a/c through the relays and back to the furnace on another blue wire through the butterfly switch to ground.

I found that the temperature on the control set at 75 got the walls to 68 about halfway up the wall, but so did one set at 75 and the other at 72.

My setup is a ducted system in a 2004 Fleetwood Flair 33R. It uses 30 amps and I have modified it so that I can operate as 50 amp or 30 amp. The Intellitec unit controls the shedding of the a/cs when the load on the 30 amp side gets too high. I figured out a way to keep using that feature by using an additional 30 amp ATS (total of three) and two Solid State Relays (SSR) to allow the Intellitec system to intercept the unit to be 'shed'. Both units can be 'shed' when using 30 amps only. One is shed when using the genset or 50 amp service, but it took a third 30 amp Automatic Transfer Switch to do it (cheaper by a long shot than one 50 amp ATS).

The thermostat for the bedroom rear unit is located in the bedroom proper. The front unit's thermostat is on the wall in the center of the coach. Each of the units pushes air into center of the coach and to the nearest end - ie, rear units feeds the bedroom and center of the coach, while the front unit feeds the center of the coach and the front of the coach. There are two separate ducts to provide this capability and it nets out fairly evenly across the coach.

I am very impressed by the Atwood AirCommander. It is a reworked version of the Cormorand built by AirCommander in Australia. The Dometic company apparently is attempting to get rid of a very good product by making it look bad.

It is very well designed and except for their poor engineering of the control board, has pretty good state-of-the-art features. It runs on less current to produce the equivalent of 18K btu per hour and the heat pump puts out like gang busters. It does it with less current than my smaller Coleman units and cost a bunch less. Plus it has a good looking digital thermostat and may be used ducted or ductless, not to mention the much superior filter design.

The main objection that people mentioned was that it uses reverse air flow so although that is better for driving along, it is not so good for situations where the outside unit has to be cleaned. The Coleman requires climbing onto the roof-top to clear the crud off the coils where the Atwood requires the cover and the plenum to be removed to get at the coils. This is not a big issue for me, but if it is, I would rather use a fine mesh screen on the low speed input side rather than take it apart a lot.

I garantee if the thermostat does not at least start and run the furnace, there is something wrong with a sensor, the thermostat or the installer missed something. Mine seems to control the temperature while on the furnace, however I have to play with it to find the comfortable temp. Can't trust to set it and get it. I'm still working with people to get it operating like it should. The factory guy told me how it is designed to work and mine does exactly as he said except it will not heat my coach or get it too the set temperature with the heat pump. The outlet temp is hot enough, but it will not run long enough to get to set trmp. Not sure it will ever happen and may have to junk it and eat the cost.

imgoin4it wrote:
I have the same acnd unit and I'm here to tell you when it comes to the heat pump it is absolutely terrible. It has 4 sensors. One of them is for the outside temperature and in the instructions it tell you that the heat pump does not run when the outside temp is below "about" 45 degrees. It will not heat the coach even when it "works". It will heat until the outlet temp gets to about 100 degrees then it shuts off. Doesn't make any difference that inside temp is still 60 degrees. As for a company. Dometic bought atwood from the Australian company. They haven't changed it to work differently. This info was from an domestic representative total knowledgeable with the whole situtation. The unit is a fantastic airconditioning unit. It's quiet,the 15,000 BTU unit is more like 18,000, it Puts out more air than any other unit I have seen. As a heat pump it is a disaster. My installer is still working with the company trying to get it to work in some acceptable manner, but in the mean time and after a year it is still a piece of **** when it comessage to heat.

This seems to sum up my issues, except the control panel will not allow me to turn on the gas furnace. I wonder if I could have the tech install a separate thermostat to run the gas furnace?

I have the same acnd unit and I'm here to tell you when it comes to the heat pump it is absolutely terrible. It has 4 sensors. One of them is for the outside temperature and in the instructions it tell you that the heat pump does not run when the outside temp is below "about" 45 degrees. It will not heat the coach even when it "works". It will heat until the outlet temp gets to about 100 degrees then it shuts off. Doesn't make any difference that inside temp is still 60 degrees. As for a company. Dometic bought atwood from the Australian company. They haven't changed it to work differently. This info was from an domestic representative total knowledgeable with the whole situtation. The unit is a fantastic airconditioning unit. It's quiet,the 15,000 BTU unit is more like 18,000, it Puts out more air than any other unit I have seen. As a heat pump it is a disaster. My installer is still working with the company trying to get it to work in some acceptable manner, but in the mean time and after a year it is still a piece of **** when it comessage to heat.

AC1511

Bob Vaughn wrote:

JaxDad wrote:
I’d be surprised that a company the size of Atwood produces a product that doesn’t work.

First off though, as Blofgren mentioned, a heat pump doesn’t really work with air temperatures below about 42 deg. F.

While I do not have that brand, mine are Coleman, the thermostats have settings for gas heat, A/C, heat pump, and fan continuous or automatic.

What does the operation manual for yours say about this? Is there a trouble-shooting section?

It sounds like the installer messed up some wiring or something. I would suggest you get someone to look at your setup.

The pump never satisfies the thermostat setting.....out put temp only reaches 70 degrees....it only runs a couple of minutes then shuts off....the control panel will not let me turn on the gas heater.....Dometic bought out Atwood so there is confusion as to who does what there. The instruction manual needs to be re written because it clearly states that the gas heat will not come on until it gets down to 45 degrees ......

In your first post you said it was in the high 40’s, that’s close to the point where a heat pump doesn’t do much.

At marginal temps it will be difficult for the heat pump to satisfy the stat before the unit overheats and shuts down.

If the gas heat doesn’t come on until it’s 45 deg outside and you were in the ‘high 40’sk then the gas heat would not come on.

What is the model number of your unit?

ksg5000 wrote:
If it's new take it back and ask for replacement or refund - your credentials are enough to convince me. Any chance it's just a problem with the thermostat?

It is a strong possibility that the switch that turns on the gas furnace in the auto mode is also disabling the gas furnace in the manual mode. There may also be a design flaw which prevents the gas furnace from being used when there is no 110 volts.....thus not being able to get heat when just on battery power....