Rationale of using a variable frequency drive water pump

[Julian]

I am trying to understand how a VFD pump would be better than an on off pump in boosting water pressure in buildings. Does a VFD pump runs continuously but maintain a set pressure? How about if no one in the building uses the taps, say during sleeping times? will it run continuously? If so how does it suppose to lower power consumption?

 

[centralheatking]

I am trying to understand how a VFD pump would be better than an on off pump in boosting water pressure in buildings. Does a VFD pump runs continuously but maintain a set pressure? How about if no one in the building uses the taps, say during sleeping times? will it run continuously? If so how does it suppose to lower power consumption?

Julian we will struggle to help you unless you put up a schematic of this set up and who you are in the set up. A number of people are really very experienced on PF but on the principle of output quality depends on input I suggest expand on your post. We will enjoy assisting you no problem ....centralheatking

 

[Julian]

Thanks for the reply, pumps are installed in a 4 story building to supply water for tap, bathing and washing, It is not intended for central cooling or central heating. It does not fill a tank at the top of the building and fitted with inproportionate 21 gal pressure tank which is water lug. 1 pump runs continuously the other is turning reverse because NRV is broken. more info here Two pumps connected in parallel runs continuously - https://www.plumbersforums.net/threads/two-pumps-connected-in-parallel-runs-continuously.110296/
I am an alternative technician, a plumber and electrician in this case. The pumps and VSD's was originally installed by grundfos. One pump was replace with a new one by a contractor from grundfos after it broke. Motor is rated at 50hz and is running at 60hz, fix speed. driven by an ATV212. I have only experience with on off pumps. What is the rationale of installing a continuously running pump in a system that is use intermittently. How do I program this thing to start/stop at certain pressure. there is a pressure transducer installed.

 

[Julian]

This seems not the right section. Shall we move this to the appropriate section? OR maybe not the right forum.