Stubborn radiator just won't heat up Drainage and wastage systems and plumbing help, advice and answers

[Davidgr0034]

We bought a house a few months ago and replaced a downstairs bathroom radiator BEFORE ever firing up the boiler. We then tee'd off another radiator for the kitchen. Neither radiator really gets warm. Directly above these radiators is the boiler in a bedroom. I can see the pipe work and the 2 x 22mm from the boiler are hot , the 2 x 15mm to all the other radiators are hot, and 1 of the 2 x 15mm to the new rads are hot. I've flushed the pipes and checked water flow through them, i've checked i dont have dodgy valves anywhere but still the heat is only spreading slowly through the pipes as though the water isnt flowing. An air lock seems the only answer yet I cant see where one can have formed. HELP PLEASE!!!

[stoneyboy]

Hi davidgr0034,
Turn off all working radiators while the CH is on and see if this sorts the problem. If it’s an air lock once clear you can turn on the rads again.
Regards S

[Davidgr0034]

Thanks Stoneyboy,
I tried this and the boiler quickly entered a max temp error state, so the water obviously isnt flowing around that loop. I rebooted the boiler a few times in case it then cleared an air lock but same result each time..... must be a blockage.

[stoneyboy]

Hi davidgr0034,
If you want to try pumping round the new circuit for longer you could turn down the temperature on the boiler, it doesn’t need to be firing.
You say in your post that water flows fine from all new pipe work and you have checked the valves so an air lock is still the most likely cause.
However have you checked the valves are two way flow? Also that none have a loose jumper which would shut off water flow if fitted on the wrong end of the radiator.
Regards S

[Davidgr0034]

So.... I decided to take the opportunity to replace all of this leg of the plumbing as it'd been adapted a number of times and was the oldest part of the system, then see if the problem persisted. On removing it, it turned out that an innocent looking compression joint in the ceiling void was actually a one way valve and was the wrong way around. So I'm glad that A. Its fixed and B. It wasnt my fault! Its probably been there since the early 90s when the bathroom extension was built and means the radiator has probably never worked! Thanks for your replies...

[stoneyboy]

Hi davidgr0034,
That’s good news and a relief for you to have identified the problem.
Regards S