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Webasto water heating –
Hi All,
Our Marathon has a webasto and 2 10.6 gallon Atwood water heaters stacked together. I was working on them (the lower thermostat burnt up) and was testing out the 12V heating since the electric is OOO while I wait for the thermostat part.
Thursday, I turned on the 12V Heat, and 12V Water Heater. After about an hour I checked the water and it was fairly hot. I went down the the bay and touched the hoses going into the water heaters. The upper ones were hot, and the lower ones were much cooler.
Today, tuned on the 12V water heater and the 12V heat. I went back to the bus after almost 3 hours and the interior was nice and warm, but the water was cold. I went down to the bay and touched the hoses. The upper heater, both hoses are cold. The lower heater, the top hose is slightly warm and the bottom hose is cold.
Nothing else has changed – I didn’t touch any valves. And to my knowledge, the are all open.
My question is, is there an electro-magnetic valve somewhere that is part of this system that is not working reliably? OR. Am I doing it wrong? Am I supposed to only turn on one of the buttons? “12V Heat” or “12V Water Heater” only? Or, am I supposed to do it in a certain order? Like, press water heater first, then heater?
Any help is greatly appreciated!
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10 Replies
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Walt,
You don’t have to have both 12v heat on if you just want the 12v water heater. You said you’re working on the thermostat. The Webasto is thermostat controlled, but I don’t know if it uses the same thermostat your working on.
Mine is an H, but there is a manual ball valve near the Webasto, normally open, that controls the water heater loop. The water heater loop also has shut off valves at the water heaters. I would make sure those valves are open.
There are some solenoids as well on mine, but they do not apply to the water heater. Your circulation pump is working, otherwise you wouldn’t have any cabin heat with the 12v heat button and the Webasto would have shut down due to high temp.
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This is the thermostat I’m replacing – the bottom water heater electrical thermostat. It got burnt up. Don’t know why… the element registers 10 ohms… same as the top one. And it’s not grounded out either. Maybe the thermostat just got tired…
On our bus – above the webasto are 2 valves. One electric and one manual. The manual one is for the water heater? And the electric one?
I’ve also sent some photos to Marathon – I’ll post what I hear back from them too.
And, I plan a visit to OR soon too – if I can’t figure it out over the phone or email… I’ll be there soon.
Thanks!!
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The electric one may be for bay heat.
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Most of the time 110 volt components burn up are connections, Either loose wire nuts or spade connectors get loose. I always tape my wire nuts and if the spade doesn’t slide on tight pinch it so it slides on tight. I did mobile RV service for 8 years and I’m also an Aqua Hot dealer and that’s to most common for that.
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something got hot there lookiing at the yellow connector.
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I replaced my thermostat, but it was located on top WH. I set the temp at 135 degrees.
I believe the bottom one I’m looking at does not control the temp, but reads the temp from the programmable one on top.
It does look like some type of electrical short occurred.
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How many valves effect the Webasto systems water heating function. There are 2 or 3 don’t exactly remember at the electric water heater and they are open. With the electric water heater circuit breaker off and the Webasto on I don’t get hot water. Engine coolant temp and heater get heated but not the water.
What am I missing?
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Following , I have the same problem after having the water heater replaced. No engine loop heat or webasto for hot water. But heat in front of coach works.
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HI WALT. i had a problem like yours. 1999 marathon . im third owner. no hot water on the engine or boiler. prior owner said never good. i fought it for a month, all valves open everything correct just no hot water . warm. i disconected all the hoses on the side and the loop hoses on the two water heaters. found big blockage in the nipples of the water heaters. dont know what it was probally there from day one. hope this helps. i have found posts on this site to really be helpfull to me. thanks to all.
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Thanks! I will check that sometime. I’ve found that we are “mostly” plugged in or just run the generator… so it hasn’t really come up much since I discovered the problem. But… I do find I have to work on the electric part of the water heaters quit often so one day I’ll check that out.
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