Some cold radiators some hot but no logic!

[brentnr]

We have a 5 year old house hence a 5 year old heating system, it is a sealed system and all radiators have TRV except for hall radiator where the wall thermostat is. The problem is that some of the radiators remain cold while the others are hot, I have checked the TRVs and all of the pins work fine. There appears no logic to which radiators are cold, for example on the top floor the radiator at the front of bedroom 1 is cold, the radiator at the back of the same room is hot, in bedroom 2 on same floor both the front and back radiators are hot. On first floor both radiators at front are cold the ones at back are hot. In living room the front radiator is cold the rear is hot. To add to my confusion for most of the cold radiators the outlet pipe is hot the inlet is cold. I have bled the system and there was no air in the radiators. If I turn up the pump to full speed then the cold radiators get hot but the outlet pipes are very hot and the inlet pipes are luke warm. Any ideas what I can do next?

 

[corgiman]

pins may be moving but that dont mean the washer is comingoff the seating

dont say "drayton" on those TRV's by any chance?

 

[solo]

Drayton......aaaccchh spit!

 

[corgiman]

Drayton......aaaccchh spit!

I concurr

 

[brentnr]

No it doesn't say Drayton on them - I assume that if I drain a radiator keep the outlet valve closed and the bleed valve open then I open the inlet that if the radiator fills up quickly then I can be sure that the valve is basically OK?

 

[bengasman]

let me in on he secret please guys, what is so disgusting about drayton trvs? price is a bit steep, but i never had any problems witht them. along the same lines, which brand or models would you say are better?

 

[Terrywookfit]

Yorkshire "Mistral"!!

Good price, 5 year guarantee, Bi directional, 10mm reducing set supplied as standard!!

Never had a faulty one in 6years!!

 

[JohnD]

No it doesn't say Drayton on them - I assume that if I drain a radiator keep the outlet valve closed and the bleed valve open then I open the inlet that if the radiator fills up quickly then I can be sure that the valve is basically OK?

that sounds fair, but you need to do the same with the valve at the other end as well to make sure it is not jammed or clogged.

What colour is the water that comes out?


edited:

you say you can get flow by turning up the pump.

Have you balanced the rads?

If not...
http://www.diydata.com/projects/centralheating/balancing/radiator_balancing.php

 

[Agile]

Your system is probably just not balanced!

Close each lockshield and open just ONE full turn!

Many stupid installers think you do not have to balance a system with TRVs. As the TRvs open/close the flow rate varies in each rad and that can mean little flow to some of them.

Only the older Drayton TRV used to stick. The later TRV4 have a stronger spring and dont usually give any problem.

The TRV4 is my preferred valve for quality and appearance.

Tony

 

[brentnr]

I have had a go at balancing the system using the method suggested by Agile and lo and behold I now have heat in all of the radiators.

I still have a problem with one of them where the oulet pipe is considerably hotter than the inlet, I am going to have that radiator off and flush it out and check that the TRV is not sticking.

For my own knowledge can anyone tell me how the pipe work is generally laid out in new houses, is there a "ring main" that the radiators all link off or is it some sort of daisy chain where the outlet of one radiator leads to the inlet of the next and so on?

 

[JohnD]

I still have a problem with one of them where the oulet pipe is considerably hotter than the inlet,

impossible, the hotter pipe must be the inlet.

also, your boiler will have a Flow pipe and a Return pipe. Each rad is connected with one end connected to the Flow and one connected to the Return. they are not daisy-chained.

Some large buildings have a single-pipe system but you will not have this.