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Our coach can’t hold its water …
Left Indianapolis this morning and headed north towards home after four plus days of early winter camping with 50amp shore power.
About an hour into the trip we pulled into a rest area. As we were rolling down the ramp into the rest area I thought I heard “something” (a motor) start running in the back of the coach and thought that to be “odd” as I couldn’t think of anything that should “start” while we’re slowing to an eventual stop.
Cathie got out to check ride height and said, “Even though I shut the “grey water dump” valve, there is water running out of the coach!” I thought … for grey water to be running out of the coach water had to be running in the shower or sink and it shouldn’t be. Did she turn on the macerator by mistake? I didn’t want to look.
Went to the back of the coach, I could quickly see nothing was coming from the macerator (whew!) but there was water coming from the underside of the coach. I knew we were low on water (I filled at home on Tuesday before I left, water turned off at Indy campground so I was rationing it), so it wasn’t overflow. Whatever water was running out of the coach was warm or hot as there was steam coming off of it. I could hear that same motor I mentioned two paragraphs earlier. Opened curbside water bay door, the water pump was running, and the water was coming from the water heater overflow. I pulled the plug, pump stopped, and water flow diminished to almost nothing. I could see that the water pump was working very hard to pump whatever water was left in the fresh water tank out of the water heater overflow.
I played with the pressure relief valve thinking there might be some calcium build up (ETLC put the water heater in last year and we put soft water in the coach; so I really don’t think that is the problem). But it never really closed and the water would come out with the pump energized.
So … has the pressure relief valve failed? Or is there another problem? Is it possible for the pressure relief value to fail? Do I need to replace that? With the well discussed 75# version? Probably call Raritan in the morning to get a replacement for a year old water heater?
I hope I don’t have to pull the fresh water tank out to replace that valve like Dana had to replace his water heater! Its too cold to do that right now.
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24 Replies
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Maybe the pump is creating more than 75psi of pressure and the relief valve is protecting other plumbing by releasing it.
Maybe the pump didn’t just start to run when you slowed, but you could start to hear it when you slowed.
Maybe introducing heat to the hot water heater via engine coolant circulation created too much heat/expansion.
We haven’t had this one, but we’re putting in a new one next year, with no symptoms from the old one.
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Usually is that the engine hot coolant, which is too hot to have uncontrolled flow through the water heater, causes the pressure relief valve to partially open, thus causing the water to go out under the coach. Above the water heater is two manual valves from the engine coolant loop to the water heater. Close those valves all the way and then open each 1/2 turn. The other option is to add a control system that only allows hot coolant through as the water heater would need it to heat the water…
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I partially agree with Jeff about partially closing the coolant valves to the Raritan.
Unless you are restricting coolant flow to the exact amount that equals heat loss from the HW tank the only thing restricting the flow will do is delay the time it takes for the HW tank water temps to reach engine operating temps. Engine temps of 200 are way too hot and will open the relief valve and will cause a serious burn from scalding.
Apart from installing a thermostat and solenoid valve to shut off coolant flow once the tank water temps reach the set point of the electric heater there is one other possibility.
If the coach has an accumulator tank make sure it is functioning. If you can turn off the pump and when you open a faucet the water runs for a minute or more the accumulator tank is OK. If water doesn’t run there is no air cushion to absorb the expansion of water as it heats in the HW tank so it forces the pressure relief valve open.
The only other detail is if you ever replaced the check valve on the CW supply to the tank that might be an issue because that valve needs a very tiny relief hole to allow the expanding water to escape back into the CW side and into the accumulator tank.
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Shut the valves to the coolant loop at the heater and forget them, you have electric to heat water. FYI, if you turn it off at the water heater, the Webasto will not heat your water.
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Even if you had to replace the valve, the only thing that may be in your way would be the filters. No big deal!
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Water in use ; PUMP ON
Water not in use ; PUPM OFF
That does not help the overheat Issue from the engine loop. But it will protect your water pump !
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I cannot disagree with Rocky but the reality in my world is if I have to start keeping track of what switches need to be on that’s when the bus is heading downward in terms of convenience.
Nothing quite like getting soaped up in the shower and remembering I forgot to turn on the water pump. Or while I am driving hearing Di shout something’s wrong because we have no water because her memory is as bad as mine.
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Don’t know which pump Dick has. But if it has a failed pressure switch, could it produce > 75psi?
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The water pump in his coach will produce enough pressure to blow the plastic lines apart. I know from experience.
I was fortunate the line separated in the water bay and only flooded that bay before the water was drained from the tank and the pump destroyed itself. When I replaced the pump I added a back up pressure switch and then monitored the pump shut off pressure occasionally to make sure it was not turning off at the safety switch pressure.
I believe he has a Groco pump and those are very capable, but very expensive.
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Dana: During my first attempt at winterizing the coach I didn’t drain those filters and busted them apart. When Jeff Rowe replaced the water pump that had frozen and busted he eliminated those filters, so it doesn’t look too bad.
Jon: Have you thought about rigging up a three-way circuit with an air switch in the shower?
Jon: Now you’ve got me thinking more. I have a Headhunter Mach 5; Jeff installed in December of 2014.
1. Did the temperature of the Detroit/Webasto/water heater circuit get so high that the pressure in the water heater got to 75PSI and trigger the high pressure valve on the water heater to open pushing water out of the water heater? I suppose that if I had a pressure gauge in the water system (probably between the water pump and the water heater) I’d know what the pressure was when the water was coming out. I’ve have to fire up the coach to test this.
Maybe we’ve had this problem in the past and never realized it. Maybe the high pressure valve opened in the past and we lost a bunch of water when the coolant water got high. If the water pump was off, only a small to modest amount of water would get tossed out to release the pressure. With the water pump on there was some pressure and a steady flow of water to replace what was being discharged.
I like having the water in the water heater being 190* after stopping at the end of the day. It gives us a significant amount of hot water before we need to use the electric; both of us know that we have to mix cold (shower already has a temp mixing valve). I’ve seen Tom’s solution of putting a temperature controlled solenoid valve on the coolant line entering the water heater to hold the temp down to a reasonable level. I’ve thought about putting a temperature mixing valve near the outlet from the water heater to bring the temp down, but still have lots of BTUs in reserve.
2. Did the high pressure switch in the Headhunter Mach 5 stick or is it failed, and the water pump created more than 75psi pressure which opened the high pressure valve? I just went out to the coach and turned the water pump on. It ran for a few seconds, built up pressure, and stopped.
So now I’ve got three potential sources of the problem:
1. High coolant temp raised the temp in water heater, expanded the water, pressure went over 75psi and high pressure valve released water.
2. High pressure switch has a problem and is releasing water at low pressure.
3. High pressure switch on the Mach 5 pump has failed or has problems and the pressure in the water system exceeded 75# and water was released under the coach.
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My expansion valve was plugged up and did the same thing earlier this year. Jeff sent me a new one and all is well. Mine had all kinds of scale and lime deposits in it that kept it open just enough to pump out almost half a tank between Nashville and Paducah, KY.
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Mark: I was leaning in the that direction, but my water heater is only a year or 18 months old.
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I had (have) the same issue on my last trip after replacing my water htr last year. Did several trips this summer previously w/o problem. Never had a problem with previous water htr. Htr stopped leaking after pressure was bled down. I suspect it was build up of pressure due to heat. Can’t remember details on a one way inlet valve.
My water htr is off while bus is stored and I’m going to make it a point to use a little hot water as I begin trips to reduce pressure build up while driving. Could also be new water htr has a lower pressure relief valve? We’ll see.
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Jon, I have that same Groco pump. It looks like a typical starter motor for a car. But it is painted white, is 24 volts, and costs over one hundred dollars per volt.
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Sheesh Dick, I think the cheese has finally got the best of you.
I didn’t say any of this…
Tom: Have you thought about rigging up a three-way circuit with an air switch in the shower?
Tom: Now you’ve got me thinking more. I have a Headhunter Mach 5; Jeff installed in December of 2014.
I’ve seen Tom’s solution of putting a temperature controlled solenoid valve on the coolant line entering the water heater to hold the temp down to a reasonable level.
Jeff and Lindsay
91 Marathon XL
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