radiator pipe cold after 2h

[david3331]

Hi I have a Worcester 42cdi combination boiler with 10 radiators during the first 2 hours the rad heating is good but after a while the front 2 rooms of the house 1st and 2nd floor loose the temperature to almost completely cold rad. The pipe valve is hot but the other rad pipe is cold and again after 2 hours start the heating but is not a constant heat as the other 8 rad. Why is that?
many thanks

 

[stardanny]

Hi.

Do you have TRV ( thermostat radiator valve )?

 

[david3331]

yes all rad has a trv valve opened to the max 5

 

[The Baker]

Was typing same question.

Tim

 

[david3331]

could it be possible that I have to replece this trv valves?

 

[stardanny]

Maybe the room the radiator sit is warm enough to automatic reducing flow to radiator by TRV.

 

[stardanny]

Try this...

remove TRV head and see what happen, if it get hot, working ok.

 

[david3331]

when the rad stop heating the room is quite cold and it takes about 2 hours to heat again in other rooms the rad heat is constant
why one of the pipes is cold and the rad valve pipe is hot?

 

[stardanny]

May need to balance the radiators, maybe pump run low speed. Try closing some hot radiators and see if cold radiator get hot, if do, balance problem.

 

[david3331]

I can't belived I have removed the trv head valve and fit it again and has start to heat. I don'y know if the problem was there but is heating now

 

[bengasman]

Sticky trvs are often caused by dirt/corrosion, check that system is clean