Increasing Water Pressure

MuddyDog

I have a Grundfos MQ water pump installed at home. Wondering how I increase the water pressure we get from it. Recently we had some plumbing done and I mentioned that the pressure in the sink was too much and I think he turned it down based on that but now the pressure in the shower isn't what we'd like. See pic attached. Is it an easy job or do I need to get him back in to increase the pressure?

MuddyDog

Anyone got any ideas?! ;-)

John.G

MuddyDog wrote: »

Anyone got any ideas?! ;-)

Its difficult to tell from the picture but the item with the white "cap" may be a pressure reducing valve for the pump, however there is a item with a red cap adjacent to it with a pressure gauge showing 1.0 bar, is this a separate circuit to the pump discharge?, it may be a PRV (pressure relief valve) for a heating system. I wouldn't touch anything until you can establish if they are in fact two entirely different systems, you might post a few more pictures.

Edit: Just looking at it again there, it looks like you may have a pressure reducing valve (with pressure gauge) and then a PRV installed after that, the PRV should have the pressure setpoint stamped on it, possibly 6 bar.

MuddyDog

Yeah John I believe what you said is spot on from what I remember the plumber saying! How would I increase the pressure on this system?

John.G

MuddyDog wrote: »

Yeah John I believe what you said is spot on from what I remember the plumber saying! How would I increase the pressure on this system?

I don't know if you have a 3.5 bar (35 meter) or a 4.5 bar (45 meter) pump, you should see something like MQ3-35 or MQ3-45 or something like that on the pump casing. You havn't said if that pressure gauge is fitted on the pump discharge line, if it is then I would just put on the shower and see what pressure it is showing while the pump is running, the pump should start if the pressure is < 2.0 Bar or if the flow rate is > 1.4 LPM and it stops when the flow rate is < 1.4 LPM. IF you are quite happy yourself that you have a pressure reducing valve and if you feel competent/confident to do so then IF the white piece is a cap on the pressure reducing valve; remove it and you should find a adjusting screw beneath it, you can then adjust this slowly to give you the required pressure but again I must emphasize that you are happy to do this as you don't want to flood your house with cold water.

MuddyDog

Assume that if I adjust the screw a little too much that the pressure would be such that water would spew everywhere and I may be unable to go back to the way it was?

Edit - If I turn the water off at the mains and drain the tank and let the taps run dry before doing it would that be safer? How much of a turn of the screw are we talking? Say 12 to 3 on a clock or much more or less or does it differ from system to system?

John.G

MuddyDog wrote: »

Assume that if I adjust the screw a little too much that the pressure would be such that water would spew everywhere and I may be unable to go back to the way it was?

Edit - If I turn the water off at the mains and drain the tank and let the taps run dry before doing it would that be safer? How much of a turn of the screw are we talking? Say 12 to 3 on a clock or much more or less or does it differ from system to system?

The maximum pressure that you can get is either 4.1 bar (MQ3-45) or 3.2 Bar (Mq3-35) according to the pump curves, I'd say a lot of these installations don't have any pressure reducing valves so I wouldn't be too worried. Have you taken the cover off the PRV yet?, if you have then, just run the shower and adjust the pressure to suit, I don't know if the adjusting screw goes clockwise or anti clock to increase the pressure but I wouldn't expect them to be too sensitive, 1/2 a turn one way or the other shouldn't make a huge difference....the main thing is to identify the PRV and establish if it has a cover, if you think the white piece is the cover then just slacken it slowly, it should then unscrew easily by hand, it is possible that this is the adjustment knob but I don't think so.

K.Flyer

That particular pressure reducing valve does not have a cover. The adjustment screw is on the top of the grey plastic cover, usually concealed under a small "3 Bar" sticker.
The top of the cover will indicate - / + direction, but as far as I can remember, clockwise is for increasing the pressure.
If you are increasing the pressure do it in cgecked stages until you reach the point you are happy with. There usually should be no need to increase beyond 3 bar.