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Old 04-22-2014, 04:09 PM   #11
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Originally Posted by JBoyer View Post

Second question - we were hooked up to park water and had good pressure. I wanted to bleed our fresh water tank down some for our return trip so I turned on the pump and walked to the other side of the motorhome to turn off the park supply. In the meantime, my wife was using some water to do dishes. When I went back inside, she mentioned that for a few minutes, we had "awesome" water pressure. I was always under the impression that the pump was somehow separate from the city water feed. How "wrong" am I??? Does anyone use the city feed and pump regularly??

Thanks all!
Do you have a Pressure Reducer on your city water hose. If not, get one as you never know what kind of pressure these city lines have and you may end up blowing out your camper lines if the city pressure is too great.

Brother Les

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Old 04-22-2014, 04:28 PM   #12
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I am not a hydraulics guy so forgive me if I am off base.

As I understood it, the pressure source (pump or city water connection) providing the highest pressure will supply all the volume used.

So if the city water has a higher pressure, the shurflo pump will run in a "no flow" condition (as such it does NOT contribute - add- its pressure to the system.

However, as pressure fluctuations in the incoming city water occur (taps open/close or high volume use on the campground supply pipe, momentary pressure drops at the output side of the pump can cause FW tank water pressure to momentarily exceed pipe pressure and open the reverse flow check valve; thus allowing the returning city water pressure to be forced back into the pump potentially damaging the check valve and fill the fresh water tank even if the pump is subsequently turned off.

I have been told that for the above reason, he pump should not be powered when city water is connected to ensure the check valve remains solidly closed while the lines are pressurized with city water pressure.


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