Grundfos CM Booster Self-Priming

Grundfos CM Booster Self-Priming Questions & Answers

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Tom
Tom

Hello, I have a new Grundfos CMB 5-46 installed on a new house. Every 10 minutes or so, the pump comes on without any taps being turned on. I cannot find any leaks. Could it be the pump settings need to be adjusted?

Grundfos
Grundfos   DM   

Hi Tom - the cut-in pressure can be adjusted in the PM2 Pressure Manager settings, however, under normal circumstances the pump will not power up (cycle) without some sort of pressure drop, usually created by an open tap or in this case maybe a very slow leak. If you have already looked for leaks and have found nothing, I would suggest checking the toilet/s, as these are very hard to detect a leak in unless it is constantly running. I suggest turning off isolation valve behind the toilet and checking if the pump still cycles. Do this for each toilet in turn to see if this may be the issue. If with toilet/s isolated the pump still cycles - we would recommend a plumber check your piping system. They may also be able to check the cut-in pressure of the pump as well. The included instructions for the PM2 do instruct how to set (lower) the cut-in pressure, but we would always recommend a plumber look at the system first. Regards Simon Tynski Grundfos Marketing.

Tom
Tom  

Thank you, great advice.

Adam W.
Adam W.

Hello, we've recently run out of water in our rain water tanks the pump was attached to and ever since they have refilled the pump the water pressure has dropped significantly. Any help would be greatly appreciated.

Grundfos
Grundfos   DM   

Hi Adam, thanks for your question. The CMB-SP is a self Priming model, so it should have evacuated any air in the pump after the tank ran out of water , so I can only suggest that some debris from the bottom of the tank may have entered the pump after it ‘ran dry’. If any pump impellers are blocked , it will certainly cause a decrease in pressure, so I suggest the pump is removed and taken to an Authorised Grundfos Dealer for inspection. Kind Regards, Aaron

Adam W.
Adam W.  

Excellent, thank you for your reply.

Adam W.
Adam W.  

Would the fact that we get a quick burst of good pressure which quickly turns into low pressure when we use any taps the pump is connected to change anything?

Grundfos
Grundfos   DM   

Hi Adam, I would suggest it is linked to the same issue. After the initial small burst of high pressure water, the pump will not be able to provide additional performance due to blocked pump impellers. Again, I suggest the pump is removed and taken to an Authorised Grundfos Dealer for inspection. Kind Regards, Aaron

djuro l.
djuro l.

prise

Grundfos
Grundfos   DM   

Hi Djuro I., thanks for your enquiry. How can we be of assistance?

Nat
Nat

Currently have a Davies HS50-06 pump plus Rainbank attachment. It is failing. what would the equivalent Grundfos product /products be?

Grundfos
Grundfos   DM   

Hi Nat - Replacing model for model across brands is not as easy as this reply might sound. We really need to know the location of the tank (Below Ground/Above Ground), satisfaction with your current pressure, satisfaction with current noise levels, etc. Having said that, assuming you are connected to an above ground water source, we have a number of options. If you'd like to stick with a Jet Pump, we have a JP 5-48; if you want something quieter and built to last then we have the CM Booster 5-46. To replace the Rainbank attachment Grundfos offers an Acquasaver device, which does the same job, working as a changeover device between mains and rainwater. Our advice would always be to seek out a reputable Pump specialist in your area and explain to them your particular requirements, size of house, number of taps, etc. This is advisable because we are assuming that the Davey pump you have now is the right one for your house and situation. Hope this helps. Regards Grundfos Marketing Team

Nat
Nat  

Thank you

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