Upstairs hot water

[Simonj1]

Hi

Im after some help please.

The hot water in my shower started going intermittent hot and cold and did not really get that hot. Its not electric, it runs from the boiler with the hot and cold going into a thermostat that you control. I thought the cartridge in the thermostat had gone so ordered a new one but I still have the same issue. I might be unlucky and the cartridge I ordered may be faulty.

Im trying to work out if its a boiler issue or an issue with the pipes. It looks like the same hot feed pipe from the boiler feeds all the hot taps, both up and down stairs. So far I have done the below tests

1) Ran the hot taps in the kitchen and downstairs sink. They work fine. I watched the boiler as they run and it sits at around 65 degrees and gets hot. The pipe that feeds these from the boiler are hot to touch, so looks like no issues

2) The same pipe feeds the shower from the boiler. This gets luke warm when I run it and does not get as hot as above. However the boiler temp display is higher and goes up and down between 75-85 degrees when I run it.

3)The same pipe from the boiler feeds the bath. when they are turned open more the water does not get piping hot, I have to turn it lower and it gets very not but it has to be on a slower water flow but does stay consistently hot

Has anyone please get any ideas on what the issues could be, is it the boiler or something wrong with the pipes to the taps/shower?

I really appreciate your help
Thanks,
Simon

 

[oldbutnotdead]

Combi boiler? Modern hpuse/flat? There may be (should be) a mixing valve feeding the bath to prevent scalding, that might be causing your warm water issue.
The shower isn't drawing enough water through to cool the boiler heat exchanger properly. How clean is the shower head, how kinked/old is the flexi to the head (if there is one).
EDIT To test the above, run the hot tap in the bathroom sink while the shower is on, see if that stabilises the temperature.

 

[Simonj1]

Hi it’s an old house but we had a new combi heating system installed 6.5 years ago and new bathroom installed 5 years ago The shower head is clean and the flex cord was replaced after this started happening. It’s both a shower on a cord and above is a fixed head showe as well... if that makes sense!! Both dont have the issue.

I tried your suggestion with both hot and cold water in the upstairs sink and bath. It still went cold apart from when I left the cold tap on in the bath and it stayed hotter for longer and was the hottest it’s been like back to normal, but then the water pressure was lower as I had the cold tap on. Any ideas what this may mean?

I really appreciate your help
Thanks
Simon

 

[oldbutnotdead]

Hmm. It sounds as if the hot water feed to the shower is being restricted somewhere, thus reducing the hot water pressure at the shower enough so the cold is overpowering the hot, pushing it back down the pipe, reducing flow & causing boiler to run too hot & cycle. Are there non-return valves in your mixer bar? Or in the pipes supplying the bar?