2 rads not working

[phillyshaw]

A 5 bed house with 20 radiators.
18 of the rads are on the original microbore system, the last 2 which are in the extension are in 15mm pipework.
The problem is that the 2 in the extension never heat up!
The client has had 2 plumbers out who have balanced the system and tried putting chemicals in the system but they still do not heat up.
I think they heat up when all other rads are switched off.
They are both suggesting a power flush at about £1300 but all the other rads work fine.
Could it be a pump undersized issue or will it need the power flush?

Any suggestions appreciated.
Thanks
Phil

 

[Killy Bing]

Imho get a plumber off here!

 

[phillyshaw]

That is really not helpful!!!!!

 

[Dotty]

You asked for a suggestion, you got one.

Going by what you've told us the system hasn't been balanced properly.

Post a thread in the 'I'm looking for a plumber / gas engineer' section of these forums remembering to include your location - [DLMURL="http://www.ukplumbersforums.co.uk/im-looking-plumber-gas-engineer/"]I'm looking for a Plumber or Gas Engineer[/DLMURL]

 

[Killy Bing]

Is the ch system dirty?
when were the radiators installed?
has the system been power flushed before?
Were those two plumbers reputable?
what pump is installed currently?
has a new boiler been installed recently?
were the new radiators installed by plumbers?
Where does the new pipework connect to the microbore system?
Did the radiators heat up when first installed?
Where is the microbore manifold?
how far is the 15mm run to the rads?

more helpful?

 

[GasmanxxxR1]

Under sized and incorrectly configured pipework is the problem imho

 

[Scott_D]

Is the 15mm for the extension tee'd into the microbore?

 

[AlexGas]

Is there air in the CH system?
Are there any air locks?

 

[PlumbBobBob]

is it a one pipe or two pipe system? only question that hasn't been asked already, i think.

 

[jtsplumbing]

Think all of you have frightened him off with to meny questions !

 

[AWheating]

from the little information available i would guess its a pipework problem. either incorrectly installed or undersized or both.

 

[sputnick]

Seems to be a reoccurring problem with microbore some (lazy/untrained) people just merrily connect 15mm to the nearest pipe and assume it will work. Probably a pipe work problem as already stated.