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srx-6 · 02-23-2010, 08:09 AM

MH is a 2009 Monaco Camelot 42PDQ, Aqua Hot is AHE-450-DEI. The problem occurs when in furnace mode. Zone 3 controls the heat exchanger in the rear bedroom, zone 2 controls the 2 heat exchangers in the bathroom. Monaco tech says all of these operate on the #2 circulation pump on the Aqua hot. Zone 3 will blow warm air, and zone 2 blows only cold air. The tech seems to think there is an obstruction in the zone 2 fluid lines. I thought the fluid lines went through all heat exchangers before returning to the aqua hot. Any ideas where to look for obstructions or maybe a valve that is closed? Thanks in advance for any help.

BigSkyBob · 02-23-2010, 08:26 AM

There are no valves in your circulation circuits. I would check to make sure there aren't three circulation pumps for the three zones, the techs have been known to be wrong. My coach has two pumps but being 40 feet I have but two zones. My understanding is the pump circulates hot solution through the assigned circuit then returns to the boiler to be reheated. Could possibly be air locked or low on solution in that section that is blowing cold air.

srx-6 · 02-23-2010, 08:34 AM

I have checked the unit and there are only 2 pumps. I thought the fluid goes thru all heat exchangers before returning and, the warm air blows only when the fan is on a particular unit. I can't figure why cold air from 2 units and warm from the 3rd one.

BigSkyBob · 02-23-2010, 08:34 AM

I just thought of something else you might check. The panel that covers the Aqua-Hot unit has a wiring diagram on the back side of it, so check to see if it shows 12 VDC going to two pumps or three. I checked my wiring diagram for 42 foot coaches and it doesn't show the circulation pumps for some reason.

BigSkyBob · 02-23-2010, 08:38 AM

I posted too late. You only have two pumps. Then I'd check the lines by taking out drawers or the front register grill to see if the lines are carrying hot solution. You're correct in your assumption that the solution circulates through all the registers before returning to the boiler.

Roger Berke · 02-23-2010, 08:57 AM

You will probably want Monaco to check this out the next time you are there for service.

The first thing that I would check is to see where the wiring for the middle zone is connected to the Aqua-Hot control board. The Aqua-Hot recomended connection is Zone 2 on the control board. A drawing showing the upper left portion of the control board is attached.

Could also be bad control board not commanding the #2 (right side) pump to start.

- Roger Berke -
Moderator - HydronicRVHeating : Hydronic-RV-Heating

srx-6 · 02-23-2010, 09:20 AM

Thanks Bob and Roger
The pump should be working if I am getting warm air out of one heat exchanger. Is that correct?

Roger Berke · 02-23-2010, 10:06 AM

When zone 2 is calling for heat you should see the right pump turning under the plastic cover.

If you turn on all heating zones do you get heat out if zone 2?

- Roger Berke -

srx-6 · 02-23-2010, 10:23 AM

Roger Do not get heat from zone 2 at all. I think the pump is working because Monaco tech said pump #2 operates zone 2&3 and, zone 3 works properly.

BigSkyBob · 02-23-2010, 11:02 AM

SRX, can you gain access to either of the lines feeding the #2 registers? It could be, but a long shot, that the #2 registers got by passed during construction.

srx-6 · 02-23-2010, 11:06 AM

Thats what I am thinking

BigSkyBob · 02-23-2010, 09:52 PM

srx, did you ever get the problem solved with the #2 heat registers in your coach?

RV Wizard · 02-24-2010, 02:54 AM

I believe you are going to have to look for a possible kink in the hose going to zone #2 heat exchangers. If the pump is running and there is a complete circuit, you should have heat in the exchanger.

Tom Hill · 02-26-2010, 04:54 PM

One more thing to check. Down by the pumps there are check valves on each line thgat go out of the aqua hot. They can stick. Mine did. I just tapped on them with a wrench while the pumps were running and they freed themselves. all works fine now