Aqua Hot Operation Question

[Dick Simonis]

I'm still learning the Aqua Hot and, while familiar with a Hurricane, I'm not certain precisly how some of the AH features work.

The system is our Marquis has a two switch control panel for the diesel burner and preheat.  The electric element is simply turned off and on by the breaker in the AC panel.  I has two zones and, I think, a heater in the bay.  What I don't understand is the bay heat control.

I assume that as long as either (or both) the electric heat and diesel burner is on, the bay heat will function based on it's own thermostatic switch.  The question is how the bay heat knows if there is heat available?  At least the Hurricane had a defined ON/OFF switch where the AH does not.

Now that the MH is home and in the barn, I will not have the heat sources turned on until the temp forecast suggests I would need freeze protection but yet the bay temps can easily fall below the switch operation threshold.  What prevents the bay heater from calling for heat and having the associated reticulation pump start running and never shut off?

Thanks for any input.

[David T. Richelderfer]

A couple comments on what I know and what I think is correct.

My coach is similar to yours.  My coach has three heating/cooling zones "upstairs" and a 4th heating zone in the basement.  Upstairs the zones are living room/kitchen, bathroom, and bedroom.  The living room/kitchen has a single-zone thermostat.  The bathroom and bedroom operate from a two-zone thermostat located in the bedroom.  This two-zone thermostat operates both zones independently by selection - select either zone 2 or zone 3.  I have not looked much for a basement thermostat - zone 4.  I think it is automatic and likely heats when needed.  I suspect the basement heater will operate any time the temperature makes the thermostat call for heat, but I do not know that.  Others here - perhaps Mr. Claxton - will know.

Also in the basement there is a two-receptacle wall plug with switches to make the plug live or dead.  I have two heat tapes plugged into that receptacle, but I have never had the switches on to power the two heat tapes.

The electric element is turned off and on by a breaker - mine is labeled "hydronic heater" - in the main 110v breaker panel in the bedroom.  I think the electric element requires either shore power or the generator on to supply its power.  The diesel burner has a switch over the kitchen sink, facing forward, with the engine pre-heat switch towards the window and the zone 1 thermostat and one of three Aladdin joysticks towards the center of the room.  I think the diesel burner and other Aqua Hot functions will operate without shore power or the generator on.

If you have the heat tapes in your coach's basement, then you could operate them using a 110v cord from a wall receptacle in your barn.  In my case, I had a line ran from my house's main breaker panel for plugging in my coach.  The receptacle I had installed has 50a, 30a, and 20a plug-ins.  This way I have power at the far exterior corner of my garage for any electrical device - blower, trouble light,... up to powering my coach on 50a, if needed.

[Edward Buker]

Dick and David,

I  believe what you both have written up is correct as to how the wiring and controls work. The basement zone is within the tank area and there is a button thermostat that controls if the basement zone is heated. In the case of the coach living area zones when you turn off the thermostats the heating is disabled regardless of the temperature as far as the living area thermostats are concerned. My understanding of the basement zone is that there is no such on off control beyond the thermostat. The house battery switch would probably disable it. One could mount a SPST standard switch in the bay in series with the button thermostat (either wire) that is in the bay that controls that zone. I went to the 100 series manual and I noticed that the bathroom zone pump actually has two heat exchangers on it so when the basement calls for heat or the bathroom calls for heat the pump will run. You could also put a switch in series with the black or orange wire that goes to the B zone relay (bath/basement zone) at the Aqua Hot and with wire mount it outside of the Aqua Hot for access. These are wires that come from the basement button thermostat. From the wiring diagram I see no reason to believe that the zone pump feeding the bathroom and basement would not cause the pump to run when no heat is present. I have not looked at how the thermostat wires are fed into the Aqua Hot but the orange wire within the Aqua Hot that I am referring to is indicated as being fed by a blue wire from the basement button thermostat. You may have access to that wire to mount a switch outside of the Aqua Hot cabinet as it comes in. Not sure if this wire color code is correct for all models of Aqua Hot or if Beaver followed the Aqua Hot color code to the button thermostat. I would take a panel off and look at the button thermostat wiring color and decide what option is best if I was to add a switch.

Later Ed

[Orman Claxton]

The basement heat will only operate  IF heat is available and T Stat calls for it.

Some advise for EVERYONE who has a Hydro-Hot / Aqua-Hot,
DO NOT try to winterize by using air to blow out the water lines.It will NOT work.
The ONLY way is to pump antifreeze,( available locally)theough ALL lines, including the A/H lines

[Edward Buker]

Ormand,

I looked at the wiring diagram 2.1 for the 100-02s (pdf version page 5) in the shop manual. I cannot find any thermostat control of the Aqua Hot that depowers the DC to the circulators and fans when the boiler is below some temp. I have gotten up on a colder than anticipated morning when using just the electric element in the boiler and have literally had no heat coming from the fan driven heat exchangers that had been running with the circulators on for some time. Nor can I find any low temp off temp control in the schematic.

From what I can see the button thermostat in the basement by the water tanks is in parallel with the B zone relay output (position 6) that drives the bathroom/basement circulator pump. The only confusing part of this diagram is fuse position B says open which is the +12V feed to the basement button thermostat. If that is truly open then the button thermostat would never work. I will look at this tomorrow and see if there is a fuse in there and if the schematic was in error.

In the main zones if you drop the DC with the off switch at the thermostat then that keeps the contacts in the thermostat from ever operating and therefor the Aqua Hot circulators are off. I see no over riding switch like that in the storage bay thermostat circuit unless I have missed something.

I am not saying that you are mistaken on the "heat being available and being called for" in order to have the circulator be operational, it is just that I do not see any circuitry that makes that happen.....I'm puzzled but that will not be the first time....

Later Ed

[Edward Buker]

This is a shop manual for the 100-2s if anyone needs it. In this manual Appendix A is the schematic. On the lower left it shows the button thermostat for the storage bay. There is a fuse position labeled B that shows open but I checked mine this morning and it has a 10 amp fuse in it. From that fuse the power is fed to the thermostat and from that thermostat through a diode up to position 6 on the relay and the bay heater fan motor. That position 6 feeds the bathroom/basement circulator. The bathroom heater fan is not powered although fluid circulation is taking place. There other diode and wiring that feeds position 6 comes from the burner so the bathroom zone circulator comes on with the burner as a stir pump. If the bathroom zone is triggered to come on by the bathroom thermostat the relay closes which also feeds position 6 along with position 4 that powers the blower fan in the bathroom. So the bathroom/basement circulator has 3 power sources of which only one of them runs the bathroom fan. I think this is how it all works and I'm pretty convinced that the bay thermostat can keep the bathroom/bay circulator running without any heat. Probably the best way to avoid that is to put the switch in series with the button thermostat in the water tank bay near the access panel which on my coach is on the passenger side or you could pull fuse B or put a switch in series with the wire coming out on the bottom of that position B fuse holder and mount the switch outside of the cabinet. Hope I did not miss anything. If someone sees a circuit that I overlooked that avoids this issue let us know.

http://www.aquahot.com/esource/ecom/esource/staticpages/documents/AHE-100-02S%20Service%20Manual%20Rev.%20B%209-27-2011.pdf

Later Ed

[Dick Simonis]

Ed,  Good write up and thanks for the PDF.  I looked it over this morning and tend to agree that there is no obvious way to disable the 12 VDC to the AH controls which would suggest that any thermosat, including the button, can energize the associated control loop.  This morning I looked at the 12 VDC breaker panel thinking there may be a breaker for the AH.....nope.

I'm not sure but I think the AH runs of the chassis batteries and the air handlers off the house batteries but won't swear to that.  Of course I don't have a wiring diagram for the coach so no easy way to tell where power comes from.

There may still be something in the logic that prevent operation of the basement heater but it's not obvious.  I'm not comfortable with anything that that do an uncommanded start and in this case it could be a lot of unnecessary hours on the heater motor and worse a circulation pump.

If this indeed is a problem I'm actually thinking about an additional aquastat in the 12 VDC supply....90 F or some such as long as it wouldn't interfere with the heat source operation.

[Orman Claxton]

Inside the Thermostat cover, located center front top of A/H there is ACV control T stat, also ACV high temp Cutout,
Use a continuaty tester check to make sure they are both good.
Refer to pages 15-16-17-18-19 in the manual
Might try contacting someone at Beaver Bend to locate the bay T stat wireing diagram