Boiler overflowing into Header Tank

[redconker]

Hi there,

I have a problem with my heating system overflowing into the header tank which is causing my system to clog up due to oxygenation.

I am told this is happening due to a combination of overpumping and resistance caused by sludge build-up in the system.

I have been recommended to make the system configuration change detailed in the attached picture plus clear / powerflush the system. Could you please Q&A the attached design and see if you agree to the overflow reasons and if the design is correct?

View media item 9156
The design inserts two motor valves and removes one of the pumps.

Background:
- I have only lived in the house for 15 months and do not know how long the system has been overflowing.
- I have a hot water tank with a thermo which connects to the controls
- I have a room thermo which also connects to the controls
- The boiler is a Potterton Kingfisher RSL100
- There are 2 pumps(Grundfos 15 -60) - 1 for the central heating and the other for hot water
- The house has 17 radiators
- The Boiler was serviced a week back and is fine
- Turning the pumps down causes either the C/H or H/W to not function well. ie. If I turn the water down, it takes much longer for the water to heat.

Other system issues:
- Hot water takes a long time to heat
- The system is noisy
- Some rads are hot at the top but not at the bottom

Thank you very much for any help you can provide.

 

[Bambergaspipe]

Can`t be ars*ed. fit an unvented system boiler., with cylinder, hot water at mains pressure.

 

[Agile]

I can see little point in making those modifications just to keep your plumber more busy.

The system probably does need power flushing and balancing though. He probably does not have a power flushing pump?

Possibly also cutting part of the pipework to remove partial blockages.

You should have kept to your original posting!

Tony

 

[redconker]

Hi there,

yesterday I fully powerflushed the entire system following 3 weeks soaking with sentinel x400. The system is now pumping around with a sentinel inhibitor.

I have also lowered the volume of water in the expansion tank by bending the ballcock.

But.... I'm still getting an overflow from the vent pipe. Can I join the vent and to the cold water feed at the boiler? Is this dangerous or a good option at this stage?

thanks.

 

[twgas]

I wouldn't recommend combining feed and vent on your boiler.
I would suggest that you cut out the pipe between the vent and feed and clean it out, the chances are its restricted with a build up of hardened sludge that has escaped the powerflush.