New radiators don't heat up

[maxhat]

Hi

I have just fitted 7 new rads & all the pipe work. The system is a combi bolier with a 2 pipe sealed central heating system.

All the upsatairs radiators heat up fine and 2 of the downstairs also do. I have problems with 3 of the rads.

The problem seems to be where I have a tee junction to feed 1 rad in one direction and the other 2 rads in the other, the pipe is hot going into the tee but only 1 of the pipes coming out of it is hot.

I have bleed these rads to remove any trapped air but this has not made a difference.

Have I pipped it up wrong should I have not split the pipe and kept one long pipe with only tee's off to feed a rad?

please help!

Thanks

Max

 

[P.J.]

Maxhat,

Silly question: are you sure both valves on the new rads are open ? There seems to be some sort of back pressure from the new rads to stop the tee distributing hot water out of both ends.

Otherwise, all I can think of is that the water flow wants to go to the old rad, maybe cos thats in a straight line, and there is not enough pressure to force the water round the bend to the new rad.

Hope this helps.

P.J.

 

[brumylad]

take off one of the rads. that is not working, and check water comes out of the lockshield and thermostatic valves when they are opened.

 

[namsag]

It is not unusaul for tee`s to be duff and the pipe can actuall be pushed in too far effectively closing off one of the branches

 

[maxhat]

PJ

the valves are open.

Should i change the piping so the water is not split into 2 directions to keep the water pressure up? so i have one pipe with tees coming off only to go to a radiator.

max

 

[blahblah]

Similar to Namsag- could you have used a slip couling and simply blocked off the tee?
Shut both the valves off and open each on its own and check for flow both ways.

 

[blahblah]

Of course that should say 'coupling'.

 

[kevplumb]

could try turning off the rads that are working

 

[maxhat]

I switched off all the working rads and the ones that were not heating up heated up slightly.

I checked the valves by taking off rads and they are working fine.

Help!

 

[kevplumb]

did you open the auto air vent on the boiler and did you bleed the pump ?

 

[maxhat]

Yes i did open auto air vent & I bleed the pump.

Have i got my boiler working at the correct pressure it says in the book the min pressure is 0.7 bar, I currently have it at 1.0 bar but what is this optium pressure?

 

[kevplumb]

think its time to drain down and get the pipeslice out sorry

 

[maxhat]

What do you mean!

 

[brumylad]

If hot water is shooting out of both valves one each side of the radiators that are not getting warm and these radiators can be bled ok, then I can only think there is a blockage in the radiator preventing circulation.

If you bought the radiators recently, it might be worth returning one or all to the supplier and request an exchange. you might have got a dodgy batch ? I've never had one myself though.

 

[kevplumb]

only real answer is cut out the tee you think is dodgy