Pump or balancing problem?

[missfriday]

Hi,

Have been scouring the forum and have made some progress - but now I've got stuck!

We have two radiators downstairs that barely heat up. If we turn off ALL the other radiators in the house, the 2 problem rads will get very hot, but the minute we turn the others back on - even at a very low setting - the 2 lose all their heat again.

We've bled, checked for airlocks etc. We've checked the pump, which appears to be working fine (mechanism rotating easily manually). Have also tried balancing the system, but this only makes a small difference to the 2 rads.

We've had radiator problems for a months but the other day our gas boiler stopped working (it had shut down twice before over the holidays and we reset it to get it going again). The engineer has serviced the boiler and fixed the pressure problems. Not sure if this could be connected.

Any ideas much appreciated!

 

[gassafeengineer]

definately a balancing problem, do you know how to do this?

 

[missfriday]

Thanks very much for your reply.

This is something I'm trying to figure out but I'm clearly doing it wrong!

I don't have a thermometer or anything, so I've just been playing with the trvs, turning the ones nearest the boiler way down, ending with the cold radiators trvs fully open. I'm sure there is a better way to do it - have looked through the faqs here and older posts, but i obviously haven't cracked it.

 

[gassafeengineer]

ignore the TRV this has nothing to do with it whatsoever. on the opposite end of the rad you have what they call a lockshield valve it is this you need to adjust. will prob have a white cap over it take this off and with a spanner adjust it

adjusting it:
starting with the rad nearest the boiler
shut it down (clockwise) and then open it half a turn
working away from the boiler open it more each time furthest radiator should be about 2 full turns

now see if your rads are heating up

what you are trying to do is restrict the amount of water going through the radiators as it will take the least resistive path (valve which is open fully)

hope this makes sense as you can tell im not an instruction manual writer lol

 

[missfriday]

Ah on the opposite side. I'm clearly an idiot!
I'll go and try this out now. Thanks a million!

 

[missfriday]

Just to say I followed your instructions and now have decent heat in the hall radiator. Thanks! The other one is a three parter below a bay window and the first of three is now reasonably hot too, although the last one is still pretty much cold.

I've been tweaking away, and some of the upstairs radiators are now down to about a quarter turn. The downstairs ones are between three quarters and one turn. Is it ok to keep tweaking them down further, or should I be thinking about other things? maybe sludge? now that all the radiators are slightly less hot, i would say that in nearly all the bottom half is not as warm as the top half....

thanks again for all your help.