Mitsubishi WP-255 Water Pump

[Mattd]

I recently sold my property and have moved in to a rental house for the time being, pretty much ever since I moved in I have been having issues with the water pump.

The pump is fed from an underground tank, with the suction being roughly 2m.

When I first moved in I noticed that the pump was dragging a lot of air along with the water and didn't sound like it was working properly, as a test, I removed the check valve and spring from the suction side (items 3 & 4 in the drawing, thanks to Banana 7 for that, as I 'borrowed' it from his recent post, not the same pump, but believe they all are very similar in the design).

The pump worked flawlessly for about 6 weeks, with no air and sounded like it was working as it should do, then, for no apparent reason, it lost suction, the only way I could get it to get suction again was to put the check valve and spring back in, yesterday I tried to wash my car and the outside hose was just pulsating between water and air, so once again I removed the check valve, which immediately solved the air problem, all was fine until this evening, when it lost suction again, so back in with the check valve..........

Does anybody know whether this check valve should be in or out given the setup and suction distance? (in my old house it was out and worked perfectly for years, however, that was fed by a 2,000L above ground tank)

 

I do suspect that there maybe an issue with the foot valve in the tank, which should be checked out, the tank entrance is tiny, so not sure how yet, to be honest, I do not know if there is even a foot valve on the suction pipe!

 

There is also no non-return valve on the suction pipe, toying with the idea of fitting one, can't see any reason why it would not work? (to clarify, I mean a NRV just prior to the suction pipe flange on the water pump tank)

Can the NRV be fitted both horizontally and vertically?

 

Any advice would be appreciated.

 

Edited August 24, 2020 by Mattd

[Artisi]

Use a spring assisted NRV, works vertical or horizontal. 

[worgeordie]

Fixing stuff yourself...wish I had tenants like you 

regards worgeordie