Radiator comes on when hot water on

[Jl1010joanne]

Hi all,

Looking for some advice...i have noticed that when our hot water is running, three radiators upstairs come on. Can anyone give some advice on what this could be? And if I get someone to fix it, how much would it cost?
It' literally three radiators coming on. The rest of the radiators are cold.
Thanks in advance

 

[JohnD]

have you got a hot water cylinder?

Look for one of these, probably near the pump and cylinder, might be near the boiler

https://www.screwfix.com/search?search=port+valve

for the moment, turn off the radiators (just finger tight, no great force)

 

[Jl1010joanne]

Thank you for your help. It's a combi boiler...just thought it's so strange that only 3 radiators come on

 

[45yearsagasman]

The make/model of your combi would help.

 

[Combicert]

Get your boiler manual (or download it..)... check which the ‘flow’ pipe is - coming out your boiler. Turn it off using the isolator. Try and recreate the issue.

Sounds like a diverter valve to me - probably worn over the years. It may be servicable but good chance its just a replacement... which may/may not require the system draining.


Cost - probably £80 or so labour and the cost of the valve - depends on boiler type and ease of replacement.