Problem with cold radiators

[mclard]

Hi
The problem ive got is that the first three radiators after the boiler are working great but EVERY other one in the house is stone cold. The boiler is situated upstairs. What ive noticed is that the feed to the radiator is roasting hot but the feed out is cold. Ive bled the radiator and even gone so far as to drain the whole system..... Could anyone give me any advice...
Cheers

 

[zidane]

have you tried turning the TRV's down on the ones that are hot, have you checked if the valves are open on the cold rads?

 

[mclard]

Ive checked the controlable valves and there ok, none of them are sticking, by you saying the TRVs are they the ( lockshield )valves on the other side, do i need to turn them clockwise until the others start to heat up??? Thanks for the response

 

[zidane]

yes mate!! they are on the opposite side, they should turn usually have a plus & minus sign on it. Try turning these but dont fully open them just enough to get them hot. The system works when balanced, if you turn one fully on, this one will take all the hot water & give a little to the others and the one on the end will get nothing ie will be cold. Try this if this doesnt work then try flicking up the pump switch which will be near your boiler on one of the pipes!!

 

[JohnD]

TRV is Thermostatic Radiator Valve.

Not the same as Lockshield Valve which is used for balancing

(spindle is covered with a plastic cover and has no knob)

 

[zidane]

His right!! sorry but most of you knew what I meant!! I'm still learning myself SORRY!! try turning the lockshield!!

 

[mclard]

So far it looks like its workin but its struggling not giving a great deal of heat out, but its getting there. What does this pump switch you mentioned look like, is it actually on the pipes or is it on the boiler itself ( its a Baxi by the way ).. Thanks

 

[JohnD]

pumps usually have three operating speeds, you can turn up the speed if circulation is poor, with a small control knob on the pump housing. However if the cause of poor circulation is sludge clogging it, you should clean the sludge out.

Warning: I am not a plumber, but I understand that if if you have a sealed system, like a combi, with no feed and expansion tank in the loft, you should not alter the pump speed.

No doubt one of the pros can say more about this.

Example: you can see the speed control knob on the side of this one

Look for "How to balance" in //www.diynot.com/forums/viewtopic.php?t=37170

 

[mclard]

What i dont understand is why this has happened. It was running fine then 1 by 1 the rads started to drop off. I have flushed the system, bled the radiators, swore at it, swore at it again and now thanks to to you both im getting somewhere . Could there be another cause of the problem or am i best taking the approach suggested and balance the system anyway...

 

[JohnD]

Did you use a sludge remover before? If not, you might just have disturbed the stuff without removing much of it.

Did you add a corrosion inhibitor before? If not it will have been generating more sludge.

Did you bale out the F&E tank before? If not the extra sludge will have been washed down into the system on refilling

Did you add a Magnaclean before? If not, any disturbed black sediment will have circulated round until it found somewhere to accumulate.

Also, have a look for any sign that your system is "pumping over" into the F&E from the vent pipe (the one curved over the top of it).

There is also the possibility that your pump is wearing out. The presence of corrosion products in the circulating water will not help.

I am not a pro, just a sensible householder.