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Plumbing

Bath mixer tap to shower head runs cold after 2 minutes of use? But stays hot running a bath?

Anonymous user 09/03/2024 - 3.08 PM

Hi Hoping a Pro can help me pinpoint the problem please. So i have a bath mixer tap that has a hose that connects to a shower head, if i pull the centre leaver to the right the water gets directed to the shower head and i can get it to the perfect temp using both hot and cold tap ends, which it will stay at for about 2 minutes but then goes stone cold. When this happens i turn off the cold tap fully but the hot tap will continue running cold water until i turn off for 20 seconds then turn back on and its hot again. This only happens when i use the shower head connected to the mixer tap. If i run a bath i have the centre leaver to the left so the water is directed through the tap, and if i just use the hot tap open and leave it to fill the bath it stays piping hot the whole time well over 5 minutes. Also other taps in the house run hot water without problems. Had a plumber come out and he replaced the the Plate Heat Exchanger but this did not fix the problem which i thought it would not otherwise i would have the same problem with all the hot water taps in the house. Im guessing there is a problem with the mixer tap or some sort of back flow when using the cold water with the hot? Any help on how to fix this would be appreciated and also give my ears a rest from the Mrs. Cheers Update **All fixed, thanks for all the comments, fixed by buying a bigger shower head which i think has helped solve the flow problem as posted. :) **

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5 Answers

Martin Leicester

Rating: 5 out of 5

Milton Keynes

This sounds like a difference in pressure between the hot and cold feeds to the tap. When you move the lever to use the shower then the cold and hot mix and the pressure of the cold if greater than the hot can push back the hot the reduced flow turns the boiler off and you get 2 mins as you use up the hot in pipe. Try this 1. Hold shower head at same height of tap and see if it stays warm. (ie hot pressure will be higher as it isn't pumping up hill) 2. return head to holder and try turning on the cold tap of the basin on, this will reduce pressure of the cold feed. See if you can get the shower working at a good temperature. If you can then at least you know what the problem is. If this is the problem adding an inline ball valve to cold feed may help as you can restrict the water flow in the cold feed. Good luck I hope I have helped!

Answered31 March 2020

Alan McCreadie Plumbing & Heating

Rating: 5 out of 5

Ayr

Should never have changed the heat plate exchanger if hot water ok at all other taps. Either a problem with divertor on mixer or dirt in a filter.if it isa shower head on a hose try changing it. Try running it without the shower head Shower head might be dirty.

Answered31 March 2020

Mario Bathroom installer LTD

Rating: 5 out of 5

Taunton

Cold and hot water is wrong fix, cold shuld be on the right and hot and left.

Answered21 March 2020

Dave Roberts plumbing

Rating: 5 out of 5

Penrhyndeudraeth

If there is a mixer cartridge in the shower head, that might be the problem. It certainly sounds like something is overheating though if the hot comes and goes so I can see why the previous guy thought it might be that...but, I agree, the (combi boiler?) plate exchanger would not be the problem if you can get consistent hot water from other outlets and the problem only occurs with the shower. See if you can remove the cartridge as they are notoriously hard to replace but certainly not impossible. There is a website that deals with replacements and you need the dimensions to get a match unless you are lucky enough to get one from the original manufacturer. Hope that helps.

Answered31 March 2020

Anonymous user

1# wrong fixing hot and cold connection. 2# it is depend on the size of the pipe and hose as well ,it seem to be cold water goes into hot water connection due to insufficient size of shower hose and when turn off the tap pressure goes to normal because of balance pipe size ,if you install one way isolation value on the hot water connection or buy good quality big bore hose of the shower .

Answered31 March 2020