combi heating system

[fedup and cold]

i have a combi system with 9 radiators, all the feed pipes to the rads get hot but the return pipes are stone cold. sometimes a couple of rads get hot but all the rest are cold.
the pump is ok and i have tested the flow by pushing water thru the system. my plumber has tried a sludge remover and 101 different things

please help me

 

[kevplumb]

do you have trvs ??

 

[ChrisR]

PUt yourself in our position - we need a lot more info. See the fixed posts at the top.

 

[brumylad]

maybe you have a bipass valve which is wide open.

when did the problem start, or what changes were made to start it.

how old is the system

have you bled the radiators

have you tried balancing

It sounds most likely that the pump is not fuctioning (I'm sure its humming away cos u said it's working but there can be more to it than that).........try a search on this forum for "pump" & "test"

 

[kevplumb]

brum whats a

maybe you have a bipass valve which is wide open.

 

[COG]

How did he check the pump ? could be that the impellor is detached, motor will spin ok but nothing else.

 

[brumylad]

hi Kev,

some of these newer boilers I understand have auto bipass valves built in. Maybe someone has set it on the lowest seting or its malfunctioning so that the system flow just goes through the bypass and not the rads..................unlikely I know but he does say his plumber has tried

101 different things

 

[doitall]

Obviously a circulation problem.

Flow to all the rads gets hot so some circulation is present.

Not all the valves or rads would the same problem.

Pump is ok as heats is getting to all the rads.



Airlock in the common return