Parts for Grundfos MQ 3-35

[semipro]

Does anyone know of a good domestic source for parts for this thing? The Grundfos part number is 96526653.

More: My Grundfos MQ 3-35 booster pump has started to act up. Its short short cycling, staying on only 10 sec. regardless of water demand. It then restarts after about 20 sec. I've checked a few things and believe that the spring in the pressure switch may have broken. I removed the pressure switch to check it our and the adjustment screw seems too easy to adjust. I adjust it in clockwise (in) to increase the pressure threshold and the operation of the pump improved quite a bit. The pump operates nearly continuously now under demand.

BTW, if I'm on the wrong track I'd be glad to know it.

 

[Reach4]

I would think looking at the pressure gauge could tell you if the pressure switch is operating at the right pressure.

 

[Sponsor]

 

[Valveman]

MQ pumps are not known for lasting. They look cool and work without a tank, but unfortunately they are made to be replaced on a regular basis. Working on them is a lesson in futility. Get a regular jet pump with a regular pressure tank/pressure switch and you won't have to worry about yout water system for decades.

 

[semipro]

The MQ is being used as a 2nd stage booster in a two pressure level system that includes an open-loop ground (well) source heat pump. The HP operates a low pressure as determined by deep submersible pump and domestic water is supplied at a higher pressure by the MQ. I plan to provide more info in a future post where I'll be asking about the potential incorporation of a CSV.

 

[Valveman]

We do the same thing with standard, reliable, and long lasting jet pump using a CSV. Electronic devices are great until all of a sudden they are not. If you want a dependable supply of water coming out of the faucets, keep the system as simple as possible, which means using regular mechanical pumps, pressure switches, and CSV's.