Radiators going cold

[egibberate]

Hi,
I've recently had some building work done during which three new 'double radiator/double convector' were installed. There are four radiators downstairs altogether. When the heating is switched on all the radiators are hot, however, after a while two of the new radiators go cold and one remains hot. If I bleed a cold radiator, cold water comes out (not air). If I switch the radiators off & then switch them back on half an hour later they're all hot for a while and then two go cold again.
Thanks for reading this & I appreciate your time & expertise.

 

[wheeto]

Do they have thermostatic valves?

 

[tamz]

I had a job years ago when trv's were first coming out, where the customer just couldn't understand why some were turning off and kept insisting there was something wrong with the radiators.
After about half a dozen visits to check and explain i got fed up listening to her going on about it so removed the heads, cut the pins and put the heads back on. Happy customer.
I continued to do her work for the next 10 years or so until she moved and she used to say "I've never had a bit trouble with my radiators since you fixed them that time. They are always nice and warm"
The next owners must have wondered why the valves didn't work.

 

[egibberate]

Do they have thermostatic valves?

Yes they have thermostatic radiator valves

 

[bobster]

hi mate have you balance the system since installing new rads?

 

[wheeto]

Yes they have thermostatic radiator valves

And are they turned up?

 

[Gray0689]

If you had an extension put on and new rads with trv
It could be as simple as it's well insulated

 

[dontknowitall]

Is the room stat still calling for heat when the rads are cold?

 

[gasmarc]

it sounds like a balancing issue ,A very simple thing to do is get the rads you want hot first and then crank them down to an acceptable level and the open up the other ones sorted