Cold radiator!

[Hpd]

Hi all. Ive got a 4 bedroom house with a single storey extension at the end of the house (furthest point from the boiler)... Boiler and hot water tank is in a cupboard upstairs, it is a sealed system.

All radiators heat up as they should apart from the one in the extension. I have followed guides on balancing the radiators with limited improvement, really only got the radiator working by closing off most of the other rads completely. As soon as I have barely cracked open the lock shield sides of them again the radiator in question goes cold.

The TRV head was missing on the faulty radiator but the pin seemed fine and moved freely, I have put a new drayton TRV head on it anyway.

I think this rad has been a bit faulty since the extension was built so may never really work, but id like to know if its possible
Are there any experts who can recommend the next steps?

Thanks!

 

[Madrab]

if the rad heats up when the others are off then it's not a restriction, if it turns off when the others are on then there's not enough flow getting to the rad. Is it on smaller gauge pipe than the rest and is it much further away?

 

[Hpd]

Thanks for the reply! It is on 15mm pipe like the rest of the house but also yeah it is the furthest away. I guess im out of luck?

 

[BlueLoo]

Probably tee'd of the nearest old rad and suffers accordingly.

I have exactly the same setup but i took my feed and return direct from the ch mamifolds .

A bit of a faff running the new pipes behind the skirting etc but the rad works as it should.

Consider where exactly the feed and return are from and see if it's the issue that can be repiped properly.

 

[Madrab]

Thanks for the reply! It is on 15mm pipe like the rest of the house but also yeah it is the furthest away. I guess im out of luck?

What boiler is it, an increase in pump speed may be possible and might help but really needs someone well versed in balancing systems to look at it TBH.

 

[Hpd]

What boiler is it, an increase in pump speed may be possible and might help but really needs someone well versed in balancing systems to look at it TBH.

It is an old boiler but the pump works great and is on the highest (of two) settings and always has been. Not sure if the thelps but yeah it might be time to call in the pros!