Install water Pressure Regulator Before or After Pump

[objecttothis]

From 6-9am and 6-9pm we have very high water pressure but the rest of the day and night we have very low water pressure. I have installed a pump that we can turn on when the water pressure is low. I have purchased a pressure regulator but I need to know if I should install it at the inlet to the house (before the pump) or after the pump. The pump increases the water pressure to 50psi. I'm concerned that if I install it inlet > pump > regulator, that it will properly limit the pressure but that it will put wear and tear on the pump by providing resistance. But if I install it inlet > regulator > pump the regulator will be negated if the water pressure is high and the pump is on since the "pulling" force of the pump will reduce the pressure at the regulator artificially. The pump has an automatic shutoff when it reaches 50psi, so perhaps the pressure is more a measurement when water isn't flowing than when it is. I just know that now when the pressure is too high it's breaking shower heads.

 

[Valveman]

With a 30/50 pressure switch and pressure tank on the pump, I would install the pressure regulator on the inlet side of the pump and set it at 50 PSI. That way if the city can keep the pressure at 50 or at least above 30 PSI the pump will never come on. Water will just flow through the pump. But if city pressure gets below 30 PSI the pump will come on. It will normally keep cycling on off at 50 and on at 30 for as long as you are using water unless you have a Cycle Stop Valve set to hold a steady 40 PSI from the pump. Sometimes people will plumb the city water to a small cistern with a float valve like in a toilet, and use the booster pump to draw from the cistern,

 

[objecttothis]

Thank you for your advice on this.

Unfortunately we don't have space for even a small cistern with where the pump and regulator are at, though I have seen people do that here. The regulator I purchased is here (Amazon.com). If I understand your description properly, I would install that at point C in your diagram above. This regulator is also advertised as a backflow prevention valve. I think that's the same as a check valve.