new radiators not working properly

[dogz]

Hi, I've had some extension work done on my house. As part of which the plumber has changed the combi for a new condensing one after flushing the system. He's also added two towel rails and two rads. My problem is that only one of the four is getting hot (a towel rail), the others are barely warm.

I've tried bleeding everything, and isolating them individually so they are the only ones 'on' in the whole house but nothing has helped. Last night I took up the floorboards and noticed he's used plastic pipe, 15mm to the working towel rail and what looks like 8mm? to the others. Could this be the problem?

Thanks for any help and advice.

 

[Bahco]

Look at the CH FAQS for your answer particularly how they have been fed.

 

[dogz]

Thanks. I've looked at all the faqs. The only thing I can see is the bit about branching off the main feed & return pipes for new radiators. This does appear to be the case with my installation. Or are you refering to balancing the system?

Regards.

 

[dextrous]

Not sure why he used microbore - which may well have become clogged up with a bit of muck post-cleanse I suppose. Think I'd be getting the plumber back to resolve the issue.

 

[Bahco]

I would try balancing it now. Microbore will not make your life easy.