20 rad system two rads not getting hot.

[rapid]

Hello guys, got a job today to service a boiler and balance central heating system (20 radiators). balanced the system but two rads arent getting worm at all. at one of the rad, pipe connected to the trv was hot but no heat getting into the rad, so i removed the TRV and turn the lock shield to full still nothing happen. then minutes later pipe went cold, but all rads nearby are hot and i only have turn the lock shield valves to less than a turn. any ideas?

 

[REDSAW]

my guess, there on droppers?

ps. you cant have balanced the system if 2 rads remain cold now can you?

 

[Simon F]

when you say you removed the trv do you mean the complete valve or just the head?
could be stuck inside trv body.
if the problem rads are not the index circuit then most likely a valve issue.
did you try closing other rads to see what happens then?

 

[rapid]

sorry i mean the TRV head, removed the trv head and use a pliers to press the valve pin repeatedly, the TRV looks fine to me.
turned all rads off the other problem rad got hot then i turn others back on (by about a turn) then it got cold again.
i will try that again 2mora. see what happen.

 

[EPH]

Are they Danfoss Trv's?

 

[rapid]

the second problem rad has got one but i m not sure about the 1st one

 

[SimonJohns]

Don't do a turn. Do an 1/8 or less