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12 volt water pump running all the time
Heard a noise in the curbside water bay while doing a take-off check, and noted the 12 volt sureflow water pump was running continuously, even though 120v pump was turned off and water pressure was 40 psi. Turned 120 volt pump on and off, ran water, etc, and 12v pump kept running. The 12v pump (which I hadn’t even noticed before) was connected to an unlableled rocker switch in the bay, which I switched off. I presume this pump is there to give you some pressure when off city water and when 120v pump is off, inverters off, etc. Should the rocker switch always be on, or only used when you need it? Is there a pressure sensor malfunctioning that has it on when system is pressurized? I have all the Marathon documentation for the coach and it does not mention anything about this 12v pump.
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7 Replies
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Not sure which way the rocker switch should be but with our Marathon, when the key is turned on, the 12v pump is energized for use when going down the road. We also have a 12v pump switch inside to turn on 12v when say you are dry camping.
Maybe pressure switch on pump is shot?
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Where is your interior switch located?
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I don’t have a Marathon so don’t put too much credibility in what I say.
The feelings are the pump pressure switch might be the cause of the continuous running pump, but do not rule out a constant, but unknown water flow. I believe all conversions will have some form of check valve to prevent pressurized water from back flowing into the water tank. If the coach does have a check valve it it is leaking a small pump may in fact keep running to make up for the ongoing pressure loss.
Easy to rule out. Pressurize the system to the extent possible and turn off both pumps. If the system loses pressure you have a problem with something other than the pressure switch.
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Thanks for the advice. System actually holds pressure well – even overnight with pumps off. I suspect the pump needs to be replaced or else a sensor if not located in the pump. Headed to Marathon in a couple weeks anyway so I will get it resolved. Disappointed there is no documentation on this extra pump and no labeled switch for it.
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I believe Shurflo has an internal pressure switch and as a demand pump it likely closes the circuit at the slightest pressure drop. You might consider going to the web site of the pump manufacturer and seeing if they have any specs or listing of service parts. Marathon probably can deal with it, but it is probable you may also find all you need is a single part to fix it.
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I think the addition of a 12V water pump was for redundancy more than anything else. The 12VDC pump is normally turned off at the switch in the street side water bay and normally only used if the 120VAC water pump is inoperable. The 120VAC water pump is wired to run off the inverters and controlled by the Techlink system. So either water pump can be turned on/off with the Water Pump switch on the panel. At least that’s how they work on my coach but others may be not be set up the same way.
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Our 12v switch is located in the DC panel located in the bedroom, right next to the 12v water heater switch and 12v heat switch.
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