Radiator not working

Hi,

About 8 years ago my late father (was more knowledgeable on plumbing than me) and I fitted central heating into my house. I used old cast radiators throughout which I spent many hours sourcing and cleaning out etc.

All was fine until this winter when a large ground floor radiator is failing to warm up. The vertical pipe up to the lock valve does eventually gets hot and the rad may get the very slightest bit of warmth in it (radiant heat?). The pipe leading away from the thermostat remains cold.

I have followed previous threads advice and have ended up replacing the thermostat, checking operation of the lock valve which is ok and taking the rad outside and flushing it through. When draining the rad the water is very clear and there was no muck at all inside. I have also switched off all the other rads and just left this one going for a few hours with no luck.

I'm guessing some form of blockage / air lock after the thermostat but have my doubts as I accidentally turned the thermostat on when removing the rad and water poured out.

Any ideas please?

Thanks, Andy.

Blocked return pipe

The whole system is probably full of crap.

That was quick!

What do you think is the best way to clean the system out?

Thanks, Andy

The best way to clean a system is rip it out and repipe it.

The other option is chemical clean, flush and inhibit.

Fernox F3 is pretty good, or Kamco Hyperflush which can be left in for about a month.

Just managed to get an almost completely blocked microbore system going after leaving hyperlflush in for a good four weeks

I will do that tomorrow. A big thankyou in advance if it's the problem. Will let you know.

Andy

Hi,

Drained the system this morning (water very clean and no muck at all) and after refilling, put in some Fernox F5. The system has been running all day with that in and still no difference with the radiator.

The cans instructions were on the vague side. It said to be left in the system at least one hour. How long should I give it before I move onto the next option and start pulling up pipes?

Thanks, Andy