COLD HALL RAD:

[RONCHAM]

Hi all -
I’m asking this question for my son as he’s working past midnight most days on his new (old) house which is a small 3-bed semi.

All his rads heat up except the hall rad (there is no kitchen rad). His boiler is wall-mounted in the loft as is the F/E tank. The vent pipe rises a few inches above water level in F/E tank and apparently there is occasional but not excessive overpumping. His pump is new. The drain off cock tees off inlet or outlet to hall rad (not sure which) and passes through an outside wall. He has since replaced both valves on this rad (but kept old drain-cock in place) and these valves also have integral drain-cocks. He has repeatedly refilled and bled the system.

It was suggested he closes off every rad except the hall rad, switch on the CH, connect a hose to the drain-cock on outlet side of hall rad, drain until hot water comes out then close off. But this hasn’t solved the problem. I would appreciate any further suggestions?

 

[seco services]

shut the other rads and leave hall one open fully and turn on heating.
is any of the pipes to the rad warm at all ?

 

[RONCHAM]

Thanks for very fast reply, I'll have to check on that one. But my son advised the following... I closed off all rads including the problem rad. I then opened the outlet drain on the problem rad and water trickled out (I assume from the system, not the rad which should have been isolated). When I re-opened the valves I could hear what sounded like water running though and the rad went luke warm. The boiler overheated so I couldn’t properly test, but I still don’t think it was flowing correctly.

If I have both valves open and then drain the outlet, water rushes out (obviously pumped) and the rad fills up with hot water. When I close the drain, the rad slowly cools down as the water in it doesn’t move anywhere.

 

[seco services]

one of the pipes is more likely airlocked.
with both valves open the water is fast flowing cause its coming from the pipe thats clear thats why you just have that rad open and run system it will push airlock out.
with draincock open it won't.

or stick a hose on the draincock and force the airlock backwards with mains pressure.

 

[RONCHAM]

Thanks again - I'll pass that info on. I'm not sure if the old drain-cock is a tee off one of the vertical legs into the hall rad or off a horizontal leg but I thought an air-lock might be there?? If so, would it likely shift with the method you advised?? I suggested to my son that he could cut it out if it's not too difficult since he's now fitted new valves with integral drain-cocks.

 

[seco services]

would it likely shift with the method you advised??

useally yes.
has the rad ever worked or how long has it not worked ?

I suggested to my son that he could cut it out if it's not too difficult since he's now fitted new valves with integral drain-cocks.

you can but if it's not leaking leave it.

 

[RONCHAM]

Hi - I did ask him if it had ever worked but he's not actually sure as he only noticed during this recent very cold spell, especially as there's no rad in the kitchen either!

The reason I suggested he might cut out the old drain-cock was that if it was the source of the air-lock it might recur. I'll update when he's tried your earlier suggestion.

Thanks again.

 

[RONCHAM]

Hi - here's the promised update on this problem.... a mains hose was fitted onto the draincock to hopefully shift any airlock. Unfortunately it didn't do the trick . It's either a very tenacious airlock or one that quickly recurs? I can't believe the repeated drainings and fillings to the system have created an airlock every time?? About the only untried course of action is a new radiator although I can't think how the old one might have failed. It would be nice to have some transparent pipelines to observe what's going on !!