Uneven Shower Pressure

[Drumnut]

Hi, we were getting uneven shower pressure and fluctuating temperature from the shower. A plumber advised that we replace the shower which we did. The temperature is now good but the water pressure is still uneven. We get mains pressure for about 2 minutes and then the pressure drops right away but the temperature remains even. At this point there is a noise from the pipes- a whining, vibration- reasonably quiet. After a few more minutes the pressure briefly returns and this then continues in a cycle. The temperature remains even throughout although when the pressure does return sometimes it goes full cold before evening out again. We have checked the pressure from the boiler and the mains water supply and both seem good. There's no evidence of a leak from the pipes. We also tried lowering the mains pressure to the shower incase it was too high for the unit. But still no difference. Any ideas appreciated? Thanks.

 

[Deleted member 120897]

I would start by testing the pressure at the shower feeds, see how they compare to the other tests. By lowering the mains pressure, do you mean fitting a pressure reducing valve, or closing the stopcock? If the latter, then you haven’t done anything to the pressure, just the flow rate.

 

[Ben-gee]

What type of shower is it? Electric or mixer?
If mixer, what is your hot water source?

 

[Drumnut]

What type of shower is it? Electric or mixer?
If mixer, what is your hot water source?

Thanks for your reply. It is a mixer shower. Hot water source is a 30kw Combi boiler.

 

[Drumnut]

I would start by testing the pressure at the shower feeds, see how they compare to the other tests. By lowering the mains pressure, do you mean fitting a pressure reducing valve, or closing the stopcock? If the latter, then you haven’t done anything to the pressure, just the flow rate.

Thanks for your reply. Yes, we only reduced the flow rate. We're going to try fitting yet another shower unit (that we've tested somewhere else) and will test the pressure at the shower feeds at the same time.