Added Rad, no heat

[blobcat]

Hi,

I have added a new rad to an existing pressurised system. I had to run the 15mm pipe 10' upstairs to cut into the existing pipes as I could not dig the floor up to reach the downstairs rads.
I have T'ed into the flow and return feed to a rad upstairs.
The problem is that the new rad does not heat up. I have bled the system, nice and clean water and the TRV and lock valves are both open. Is my problem that the heat will not flow downstairs? And if so how do I fix it.
When bleeding the system the pipes became hot but then cooled down. I have shut off the rad upstairs that I have T'ed into but still no heat in the new rad.
I have also repressurised the system.
Any tips/ideas much appreciated

 

[kevplumb]

shut all the rads off exept the new one

 

[ChrisR]

Yes, if no go then make sure water comes out of both rad valves when you disconect your new rad. Easy for one to stick shut, or to have ptfe tape across the pipe or similar. Look into the ends of the rad unions!Surprisingly common!

 

[blobcat]

Hi thanks for ideas,

I have closed off the lock valve and TRV, I then bled off the pressure and opened the TRV, nice clean water flowing, so TRV working.

Next, I shut off all but two rad's (too much trouble to get to them) and the new rad heated up fast and fully.

I have opened the other rads back up and now the new one has cooled off again.

The system is pressurised and around 1 bar cold. The other (14) rads do not have lock valves on the return side they just have normal shut valves. All of these rads get very hot.

Pls advise what I need to do to rectify the situation.

 

[ChrisR]

Fine, the output of ONE of the two valves is clear. CHeck also both the inputs to the rad, and the output from the lockshield valve. Like I said above!

If there's no restriction you have a "balancing" problem. It's possible the restriction is where you teed off the other pipes.

 

[blobcat]

Thanks Chris,

The lock valve is working fine as I bled off of that one as well with the TRV closed (didn't mention it in the previous post).
If it is a balancing problem is it an issue that the rads have normal open/close valves rather than lock valves?