No heat in new cast iron radiator

[Ballbag]

I have purchased and fitted a new cast iron radiator in the same location as the previous radiator, with some minor piping alterations.

The existing central heating system uses a gas boiler heating a hot water tank upstairs.

My Problem :

When I turn the heating on this is the only radiator that does not get hot (I know cast iron rads take a while to heat up). The feed pipe going into the radiator is also not getting hot. The radiator is full of water as I have bled it.

I have tried turning all other rads off + hot water. NO JOY! (pipes don't get hot either)

The only way I can get hot water into the radiator is to remove the bleed screw. BINGO! this work, not very practicable. So I thought there was an air block in the return pipe.

So I closed the feed valve, opened the return valve, and removed the bleed screw. DISCO! this work, water comes flying out.

I give up !!! Can anyone help !

 

[htgeng]

What alterations did you make to the pipework. Is your system vented or sealed?

 

[Ballbag]

Thanks for quick response.

The old radiator was longer than the new cast iron one. So basically I extended the original pipework. I also renewed the return pipework at the joint for aesthetic reasons.

The heating system is vented.

 

[htgeng]

water coming out the bleed screw doesn't necessarily mean you'll get a flow through the radiator. It could be an airlock in the pipe, which can be a real problem with vented systems.

Had a similar case a few weeks back when I fitted a replacement radiator. I recommend upgrading to a sealed system and no doubt I will get called back before winter to do the job.

A heating engineer would charge less than 200 quid to do the necessary work. Also use fernox MB1 when refilling system.

 

[ChrisR]

Might be worth checking the valves are opening properly. Remove rad, add hose to valve and you should get v good flow - both sides. May even clear an air lock, especially if valves don't open much.

 

[Ballbag]

Problem Solved.
I took the radiator off to check the valves and the ends of the radiator were bunged up with silicone.
I had put plumbers silicone seal on the threads for extra sealing.
Obviously when I screwed the valves in, all the silicone travelled to the end of the thread and bunged up the holes.
How stupid do I feel!

Thanks you your replies.
I think this forum is one of the best I have used.

 

[ChrisR]

NO need to feel stupid at all. That sort of thing can always surprise anyone - I bet you didn't hink you had anything like enough silicone on it. Its also easy to stretch ptfe across the end of a rad fitting!


Thanks for letting us know.