Gas Central Heating Problem

[Buckstar]

I have a vented gas central heated system. Currently when the domestic water is running at the same time as the heating, hot water overflows into the feeder/expansion tank in the loft, this does not happen when either the hot water or heating run separately.

I have a Potterton Profile boiler (dial set to 3), Dyson pump, ACL Lifestyle Mid Position motorised valve, a hot water storage tank/immersion heater (dial set to 55c) is part of the system.

Please advise how I can stop the hot water overflow.

 

[45yearsagasman]

You will have a blockage in cold feed where it joins the system and around that area.The only way is to cut out and clean or replace affected pipes.Thats a starting point and after that you may and I stress may need a powerflush.

 

[Buckstar]

Thnx for prompt reply.

I am puzzled how a cold feed blockage creates a hot water overflow problem, are you able to explain please?

 

[seco services]

without going into detail
your system is under positive pressure the vent/cold feed are neutral and negative pressure to the pump.
so a blocked cold feed will result in the water going up the vent.

 

[Buckstar]

Thnx again.

Looks like I'll need to go back to school and redo physics to understand it fully!!

I'll get a plumber in....

 

[seco services]

run a magnet over the cold feed where it joins the primaries.

 

[bengasman]

Thnx for prompt reply.

I am puzzled how a cold feed blockage creates a hot water overflow problem, are you able to explain please?

Cold feed from the headertank (the small one) not the cold feed from your storage tank.