Drained Sytem Now Central Heating Not Working

[FatPunk]

Ayup

We recently had a leak from one of the rad valves so I had to drain the system to replace this. Because of the location of the H+E tank it's nigh on impossible to prop the arm of the ballcock so I turned off the hot water valve and main water stop cock to bled the system.

I fitted the new valve, closed all the rad bleed valves and turned the mains back on to fill the system. All seemed fine but when turning the CH on I get a loud whooshing noise and banging from the pip between the boiler on the ground foolr and the pump above it on the first floor.

I blead all the rads and the pump and this has failed to resolve. Boiler works but heats for a couple of minutes then cuts out which isn't surprising as whilst all the pipes and rads are cold the pipe between the boiler and the pump is red hot.

read all the posts and tried everything except draining and refilling or backfilling from the drain point - HELP!

I have the floowing CH system;
Baxi Bermuda LFE 3 Super
Grundfos Pump
Open system
3 rads ground floor, 3 rads first floor, 1 rad dormer
H+E tank in dormer

Sorry for the long post but wanted to try and give all the info first time

 

[bab]

Try bleeding the pump .large chrome disk with slot in the middle of motor, Do this with all off, then try hotwater only to start. is there any air vents near the cylinder on the coil.

 

[FatPunk]

Bled the pump already. Gave it a quarter turn and you could here the air escaping and the header tank filling the system up. Unfortunately this did not fix it. Can you explain a little more on the vents near the coil - I'm not with you on that (sorry, new to this!)

 

[corgiman]

try turning the pump around the other way for a bit

Its worked for me before (when I am tearing what little hair I have left)

 

[FatPunk]

Could do but it looks like a bugger of a job! Are they valves on the great big brass bits that connect it to the pipe? They have screws on em! turned the one on the opposite side to the boiler a quarter turn and a load of black water came out...

 

[Gasguru]

Yes - you should have read your plumbing bible "Thou shalt never turn a quarter turn pump valve or thou shalt be in the s**t".

Sometimes there are airvents on the heating pipes to the cylinder. Since you didn't mention any zone valves the cylinder may be heated by a gravity circuit in which case there may not be any additional vents.

 

[FatPunk]

Aha - no zone valves, no vents (no heating)!

 

[FatPunk]

Replaced the valve and cleared the crap out, refilled and all ok. Now running some cleaner through before redraining for the inhibitor - wish me luck!!