[Doug Musick]

My coach has a dedicated electric heater for the bathroom with it's own thermostat.  Turned it on last night by turning the thermostat up.  It kicked in just fine, but won't shut off now when hitting the set temp or when turning the thermostat all the way down.  I dismantled the thermostat and made sure the circuit was broke, heater continues to run.  The heater itself is buried under the bathroom closet and has the blower for the dometic unit sitting on top of it.  It also appears if I throw the breaker I will be shutting off power to several of the heaters in the coach.

Any ideas how to shut it off?

[Tf175]

I am not sure,  but there must be a relay that is energized by the thermostat.  Is the heater a 110 v unit , 1500 watt ?

[encantotom]

just a silly question. do you have an aquahot in your coach?

or is it electric kick heaters and propane furnaces?

tom

[Doug Musick]

After more dismantling in the closet it is a hot water radiator with a blower. It is an aqauhot unit.

[Richard]

Pull the three clear cube relays on the AH control board. If that turns it off, replace all three while you are are at it.

[Doug Musick]

Pulled the cube to the pump which was running. That got it shut off and the other heaters still work.

Any recommendations on where to order the relays from

[encantotom]

yes, i ordered them from grainger.

https://www.grainger.com/product/1A486?c...728ac5bc90

grainger part number 1A486 ten bucks apiece

tom

[Doug Musick]

Thank you. I'll get the new relays and see if that solves the problem.

[Doug Musick]

Got the relay and same problem, the heater runs constantly. Changed out the thermostat, same thing.

I disconnected the thermostat and connected the two wires, heater ran constantly, disconnected the two wires, the heater continued to run constantly. I removed the new relay for now and am just leaving the water closet door open to keep it comfortable.

Does the thermostat circuit operate by open = heater on and closed = heater off? If so I could have a broken wire in the loop somewhere causing the heater to run constantly. I think my next step is to test the continuity of the wires.

[Richard]

A ha ! Aquahot uses a close to ground signal to turn the zone on. But the the thermostat puts out a 12 POS signal. The secret is that AH feeds the 12 POS into a standard cube relay to close the circuit to ground. Made no sense at all the first time I looked at it.

The signal from the tstat triggers the cube relay. When the relay is activated, it closes a circuit to ground. The ground circuit activates the clear cube relay for the zone.

Look around in the same area for one or two standard Bosch cube relays. Replace them and check the spade
connections.

One more thing. My coach has TWO thermostats that will turn on that zone. One is the bedroom heat Tstat, the other is a simple twist knob tstat in the bathroom.