Dometic 10-button Thermostat

[waterskier_1]

Hello all.  I'm having a curious problem.  I'm getting ready to head to AZ and have had the front area on Aqua-hot to maintain a min of 50F degrees.  Today, I was starting to do the major loading, and went to the rear thermostat (both thermostats are Dometic 10-button units), and selected FURN (Aqua-hot) and the Heat Pump came on.  I'ts only 33F degress here, so I know it won't work on heat pump.  But no matter if I select Heat Pump or Furnace, only the Heat Pump starts.  I know last winter the Aqua-hot worked fine, so even though the PO replaced the old thermostats (and A/C's) with 10-button t-stats, I know they worked.  So, what would cause this?  I'm headed out now to reset the t-stat, and then see if the dip switches are in the correct places, but I can't imagine how they could have changed.

My current set-up may not be standard.  The front t-stat controls the front A/C and also Aqua-hot.  The rear t-stat controls the rear A/C and also Aqua hot.  Each only have one zone.  The center is controlled (best I can tell) by the basement t-stat in the bay, which also controls the bath heat.  There is no separate bath temp control, only an on/off switch for the bath cozy register.  

Anyone have any ideas or experience something like this before?  I hate to tear everything apart - plus I don't really have the time, I'm planning on leaving Sunday.

  -Rick N.

2005 Exec, DD Series 60

2014 JGC Overland Diesel

Colorado Springs, CO

[waterskier_1]

Upon further checking, I found that when I select Aqua-hot, BOTH the Aqua-hot and the the Heat Pump come on.   For now, I think I can temporarily fix this by simply throwing the A/C breaker for the rear A/C.  I haven't tried yet, because I was trying to warm things up a bit before I extend the bedroom slide, and then can get to the closet to load, but also the Breaker Panel.  

Still curious if anyone has experienced something like this.  It may not be unique to the 10-button remote, since both are coming on, it could happen with the older remotes too.  Not sure if it's a wiring problem or thermostat problem.  When I get settled, I can try switching out the thermostats, front to rear, and see if the problem remains or if it transfer to the front...might lead to some additional info.

  -Rick N.

[Dr4Film]

Rick, I am not much help with your problem but will be following it to see what the outcome will be.

However, I am assuming that the front thermostat controls the front AC and the front Zone #1 Heat Ex changer of the Aqua-Hot system. The the rear thermostat controls the rear AC and Zone #3 Heat Ex-changer of the Aqua-Hot system. What is surprising to me is that you don't have a thermostat inside the coach for Zone #2 which is your bath area.

I have one 10 Button Thermostat in my bedroom which controls both front & rear AC's & HP's only. Then I have three separate Aqua-Hot thermostats which control the three different heat ex-changers zones, #1 Kitchen and Salon area, #2 Bathrooms and #3 Bedroom.

Hopefully by doing a reboot on the thermostat it will return to normal operation.

After reading the instruction manual for the 10 Button Thermostat, it states that the primary heat source will be the HP if the outside temp sensor is 35F or above. If the outside temp sensor is 30F or below the thermostat will select the AUX Heat source which would be your Aqua-Hot. Hope this helps a little.

[waterskier_1]

Richard, 

Thanks for your insight.  You have it correct.  I noticed that I didn't have a Aqua-hot Zone 2 on either thermostat (each just has zone 1 - only 2 total A/C's) last fall.  I was in the basement just forward of the Aqua-hot installing another solar controller, and I hear the circulation pump running on the Aqua-hot.  I saw that zone 2 was enabled on the control panel.  I went inside to turn it off, and couldn't find any way to do so.  Ultimately, to keep the pump from running all the time (I didn't have the Aqua-hot turned on so there was no how antifreeze) I turned the thermostat in the bay to max temp.  That shut it off, at least for that day.  I haven't returned that thermostat to normal position, since I'm still winterized - I won't unwinterize until I get to Arizona.  

But you bring up another question.  From what I understand, you have two thermostats on Aqua-hot Zone 2?  One inside for the bath, and one outside in the bay?  Or don't you have a thermostat in the bay to turn on heat for the water pump/manifold, etc.?

  -Rick N.

[Dr4Film]

2 hours ago, waterskier_1 said:

Richard, 

But you bring up another question.  From what I understand, you have two thermostats on Aqua-hot Zone 2?  One inside for the bath, and one outside in the bay?  Or don't you have a thermostat in the bay to turn on heat for the water pump/manifold, etc.?

  -Rick N.

Rick,

I do have a separate thermostat in my tank bay where there is a separate heat ex-changer. I am assuming that it is part of the Zone #2 system. Plus I know that Zone #2 pump is used for stirring the boiler fluid too. I have four pumps, one for each zone, #1-#2-#3, and one for the Engine Pre-Heat Loop.

My Aqua-Hot is model 431/12 which is the same as AH-100-01 & 02 I believe.

[waterskier_1]

Interesting.  If you have two thermostats on the same zone, which one has priority?  I honestly thought I should have a zone 2 on a thermostat inside too, but then convinced myself that there would only be one on a zone.  I have the larger 600D, but it's was replaced by a PO.  Therefore, I'm not sure if the replacement is correct or not.  I really think I should have a way to kill the zone 2 circ pump without having to pull the fuse for the aqua-hot to kill everything.  

>>>I just performed a reset, and I now have Aqua-Hot without the Heat Pump.  I'm not sure if all else is working, since it's now 23F degrees out and way to cold to have either A/C or the HP work.  But, I'm hopeful!  

[Dr4Film]

Rick,

Glad that the reboot worked. How do you activate the HP when you want to if the thermostat always uses the Aqu-Hot for heat?

In regards to my Zone #2, when the thermostat in my bathroom calls for heat it turns on the heat ex-changer in the bathroom but not the one in the tank bay. When the thermostat in the tank bay calls for heat it then turns on the heat ex-changer in the tank bay but not the one in the bathroom. Yes, hot boiler fluid is running through the loop because the pump is running but the fans are not active in the area where it is not calling for heat. That is also true with the stir pump which is Zone #2 also I believe.

[waterskier_1]

Richard, 

I think I understand what you said regarding zone 2 of the AH.  I'm going to re-phrase to make sure I got it.  It sounds like the zone 2 Circ Pump is always running, acting as the stir pump, and also at ready for when the bay thermostat call for heat and also for when the bath thermostat calls for heat.  If correct, I think my system is similar.  I just don't have the bath thermostat, but instead a switch to turn on the fan for the heat exchanger.  It's kinda manual, but I have rarely used bath heat.  In my floor plan, it is in the toilet room with the sink.  The shower is across the hall where I would think you'd more likely want additional heat.  If all this is correct, then it seems like the AH Zone 2 pump is always running.  Can you shut it off with the bath zone t-stat?  I don't see a way to turn mine off other than to pull the fuse to the Aquahot itself.

Regarding the Heat Pump, I'm not quite sure what I said, but what I meant was when I put the t-stat in Aquahot Mode, it no longer also engages the roof HeatPump.  That was the original problem - both ran at the same time.  I can select with the Mode switch HP or Cool or Fan only or Auto (never used that).  I have read that if you select Heat Pump and it gets too cold, it will automatically switch to aquahot (or furnace).  I have never tried this.  In fact, I just don't use the Heat Pump at all....too noisy and I have the larger AquaHot with two heat elements, so as long as I have 50Amp I can get by on heat with aquahot (if not too cold...in which case I switch to diesel).  

I thank you so much for helping me better understand how zone2 of the Aquahot works.  I wonder how hard it would be to connect that to Zone 2 of my thermostat so I could Kill the pump when it's winterized and sitting in storage.

[Dr4Film]

Rick,

The stir pump being pump #2 is only stirring when the Aqua-Hot diesel is running. That is so the boiler will not have any hot and cool spots in the 16 gallons of fluid. The pump does not run when the AH is off. So it doesn't run ALL the time. The other times it runs is when either Zone #2 or the Bay Heater is calling for it to run.

Don't know whether you can add a thermostat to the heat ex-changer in the toilet room or not. My thermostat is in the bath hallway wall and the heat ex-changer is under the main vanity. I have nothing in the toilet room so when it is really cold we just leave the door open to get the heat into that room.

Does the 10 Button Thermostat have a separate mode for the Aqua-Hot and the HP?

[georgecederholm]

Rick,

Sorry to come to this thread late. Here are a few thoughts:

Since (I think) you have an aftermarket system, some of the "what Monaco did" stuff may have been changed during the "upgrade". If I recall correctly, your 2005 Exec has been upgraded to an Aqua-Hot 600D with dual electric elements and two of the newer 10-button thermostats, which implies that your original roof units have been changed as well. Is that correct?

In general, everything I've read about how rigs with two roof units but three Aqua-Hot zones were accomplished was that a standalone Dometic control board was embedded in a cabinet somewhere to handle the lavatory/bath zone. If my assumptions (!!) are correct, that would mean that whoever upgraded your roof units and thermostats would have had to chase down that hidden control board and upgrade it as well. That board would be connected to one of the RJ-11 data cables from either the front or rear thermostat (original would likely have been the rear). So, if that middle zone board was never found/upgraded, then you'll not see that zone on either thermostat.

Monaco would not have left the middle zone uncontrolled, and the basement circuit would circulate for that area but not likely control the power to the heat exchanger fans. But that doesn't mean the upgrade installer would have carried that forward, especially if the Aqua-Hot 600D change and the roof unit/thermostat change were done at different times. I suspect that your best next move (other than getting to the relative warmth of Q) would be to try to locate a hidden control board. I never captured the threads on this from the old site because I have three roof units, but maybe someone recalls likely locations. I would think there should be a limited number of likely places, like behind false walls in the shower or water closet wall cabinets.

George C, 2005 Exec, with very similar upgrades

[OhReally]

On 1/16/2020 at 1:17 PM, georgecederholm said:

Rick,

Sorry to come to this thread late. Here are a few thoughts:

Since (I think) you have an aftermarket system, some of the "what Monaco did" stuff may have been changed during the "upgrade". If I recall correctly, your 2005 Exec has been upgraded to an Aqua-Hot 600D with dual electric elements and two of the newer 10-button thermostats, which implies that your original roof units have been changed as well. Is that correct?

In general, everything I've read about how rigs with two roof units but three Aqua-Hot zones were accomplished was that a standalone Dometic control board was embedded in a cabinet somewhere to handle the lavatory/bath zone. If my assumptions (!!) are correct, that would mean that whoever upgraded your roof units and thermostats would have had to chase down that hidden control board and upgrade it as well. That board would be connected to one of the RJ-11 data cables from either the front or rear thermostat (original would likely have been the rear). So, if that middle zone board was never found/upgraded, then you'll not see that zone on either thermostat.

Monaco would not have left the middle zone uncontrolled, and the basement circuit would circulate for that area but not likely control the power to the heat exchanger fans. But that doesn't mean the upgrade installer would have carried that forward, especially if the Aqua-Hot 600D change and the roof unit/thermostat change were done at different times. I suspect that your best next move (other than getting to the relative warmth of Q) would be to try to locate a hidden control board. I never captured the threads on this from the old site because I have three roof units, but maybe someone recalls likely locations. I would think there should be a limited number of likely places, like behind false walls in the shower or water closet wall cabinets.

George C, 2005 Exec, with very similar upgrades

Rick, I'm pretty sure George is on the right track here. If you had/have HPs in roof AC units the board George refers to would be in one of those.  

Good luck.

-Jamie