Hi,

I have just replaced a single panel rad in the living room with a double panel...

Problem is that the not all of the downstairs radiators get hot now. I suspected an air lock... All of the pipework for the downstair rads comes from the ceiling void, so I shut all of the rads off and then put a hose on each of the return side lockshield valves then opened the lockshield (return side) and drained each rad until no more spluttering could be heard and the water ran freely.

One of the radiators (in the downstairs cloakroom) wouldn't drain off, no water would come out of the lockshield drain... I tried sucking on my hose but nothing - it wasn't having any of it. Felt as if I was sucking on a capped pipe?! A one-way valve?

Anyway, turned the rads on one at a time and now there are two that aren't getting hot - The downstairs bog and the dining room.

Any ideas? Do I need to drain it a bit more? Should the pump be off when I drain? There is a vertical pipe near the pump with a bleed valve on the end - This always has air in... Can you tell me what oder I should do things in?!

Thanks,

fM

PS This site has helped me out no end - Is there a way to donate?

You need to get all the air out to start with then re-balance the system.

Pump must be off when bleeding the rads.

Do you know how to balance a central heating system?

Also, the vertical pipe by the pump must also be bled of all air.  If this is always collecting air I would advise having a self bleed valve (auto vent) fitted here, that will immediately cure that problem. (see link below)

http://www.plumbworld.co.uk/229-49

Another thought, on your new rad I bet you have opened the lockshield valve fully but it probably needs restricting back a fair bit to how it was on the old rad.

So, as a test, completely close off this lockshied on the new rad and see if the others now get hot, then (assuming they do get hot) slightly open this lockshield the MINIMIM amount needed to get hot water flowing through it (do all this with the normal rad valve fully open).

Don't forget to have the room stat turned up to max to ensure the boiler and pump are running all the time while you do all this

Ok, I have all rads working now... Got to balance the system next...

Air in the pipe collects over time, accelerated due to air in system.

If you direct your attention to my next problem, topic entitled "Balancing!"

Cheers!

fM