[RE-wrenches] Water system with Grundfos SQFlex

[Jay]

Hi Brad

With 2 check valves leaking I’d look for a broken pipe or a corroded fitting. 

If there is anyway to isolate between the 2 check valves then you could measure the pressure drop on both sides which should point to the direction of the leak. 

Jay

> On May 25, 2024, at 7:41 PM, Bradley Bassett via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
> 
> 
> I have a water system with a Grundfos SQFlex SQF3-2 pump. I'm getting water flow in reverse either through the pump or a leak up to the pump. My question is if the check valve on the top of the pump is not sealing, will the progressive cavity pump allow water to flow through the pump in reverse? I'd think that with a positive displacement pump it would not, except very slowly or if it turned the motor backwards which I think would be very unlikely. There is about 100 psi head on  the pump. 
> 
> I think it's most likely I have a leak somewhere in the plumbing, and of course another failed check valve farther up in the plumbing. It's possible to get failures even with redundant protection if you have two concurrent failures, which I must have here. 
> 
> Brad Bassett 
> Old time solar guy who used to do solar pumping back in the '80's and '90's. Mostly retired now.
> 
> 
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