My new SHURflo standard water pump was running non-stop, plenty of water, no leaks on the output side (and no faucets open). SHURflo manual says, "Check for air trapped...in water heater", but water heater manual suggests that there's supposed to be an air pocket in the water heater to help prevent the Pressure Relief Valve from weeping when the water heats up and expands; it even explains how to "replenish the air pocket".
Seems like contradictory information, no?!
Don B.
1987 Toyota/Dolphin Mini 22'
4-cylinder can't tow anything
No stove/oven
Solid-state fridge
Pure sine wave inverter
Full-timer (no rent/mortgage for me)
Shurflo may be saying that with traped air the system can't be purged. I've seen this corrected just by opening all cold and hot valves and letting the system purge the extra air.
But since you have good water flow then check the shut off switch (probably located on the pump) that tells the pump it's reached the maximum pressure and should stop pumping. Usually it's one switch that controls both starting and stoping the pump.
Live'n, You may have a valve open between your pump and the water tank. I have 3 valves on mine, one drains the tank, one the system (pipes and such) and one to open when I want to fill off of the camp ground water system. Hope this helps. Enjoy, Mike
As you can see there are several possible answers to the pump problem.
But your question is about trapped air?
Anyway, one more thing, that might happen is, that pump wear-out, or got defect and will not build enough pressure to activate pressure switch.
Try the trick with all faucets open and if that doesn't help measure the pressure in the system. It suppose to go up to 40 psi in most of the systems.
Pessimist sees dark tunnel, optimist sees a light at the end, realist sees lights of coming train.Engineer sees 3 idiots on the tracks.
With an 87, I doubt that you have a single water connection with a tank fill valve, but rather you pobably have a seperate tank fill that is not the same as the city water connection? If you do have a single connection for both city water and for filling the tank, then leaving the fill valve open would cause the pump to run forever. But you porbably do not have that so I would suspect that the pump has not primed like it should. Do you get any water from the faucets if you open them? If you do, then you need to check to see what the pressure is and where the pressure switch on the pump is set. It will usually slow down if there is pressure building up but the switch is set too high. Also, is it safe to assume that your water tank is at least 1/4 full?
Don, it is contradictory. The water heater does need an air pocket at the top for the pressure relief valve to operate correctly.
What I think they actually meant when talking about trapped air in the water heater is not opening a hot water source so the water heater will fill up.
That's a common problem with small RV water systems. If there's no place for the air to go the water pump has to compress the entire amount of air up to the set pressure and that can take over an hour.
If you've got an outside shower that has hot water it makes a good place to let the air out. No splashing in the sink or other inside fixture from the air sputtering out.
If that doesn't fix the problem of constant running, there's a good chance the pressure switch inside the pump isn't reacting and need looking at.
I've checked them by just using a foot or so of hose off the pump outlet with a plug. That way the pressure should come up almost immediately.
The times my pump has failed to shut down are usually when the water tank runs dry. It will shut off when there is a little air in the output side but not if there is a lot. It will not shut off at all while drawing air in the input side...
The reason the pump won't shut off when it runs out of water is because the pump is designed to be "self-priming". It can't tell the difference between a fresh water tanks that has run dry and one that is full, but the water has not been "pulled" up through the lines by the "self-priming" pump. When the water runs out, you have to manually turn off the pump at the pump switch.
Thanks to all for your comments. Thanks Mike, I understand now what SHURflo meant.
The water tank was 3/4 full, and I had run plenty of water through both faucets after installing the pump. I've tightened and sealed the short piece of hose on the input side of the pump. The pump must be pulling air in through itself. I'm returning this (new) pump and getting a FloJet VSD because I want unchanging temperature while showering.
I chose the FloJet because I hear that the motor speed is infinitely variable, and the SHURflo offering is a three speed motor.
Now, do I choose the 3.7GPM or the 4.5GPM? I dry-camp only, I'm single, and my fresh water tank is 17 gallons. But the VSD pump gives me 3.7 GPM @ 25 PSI, and my standard pump is 3.0 GPM @ 45 PSI?
Bottom line: Will the toilet flush any different between 3.7@25 and 3.0@45? (Gimme unchanging shower temp and a powerful flush and I'm happy.)
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