Kettling boiler requiring boiling of kettle

[adrianthegasman]

I have a problem with a Worcester Highflow 400 RSF which my heating engineer is struggling to solve. To begin with the diverter valve went, replaced and solved the initial problem. Shortly after the system was producing a kettling sound when the hot water ran. Hot water was VERY hot and occasionally tripped the overheat even with thermostat set to minimum. CH working fine.

Firstly the thermostat was changed, no effect. The heat exchanger was then chaged - slightly surprisingly, no effect. Strangely it then worked for a little while although hot water was still very hot. Engineer could not explain why it started working.

Last night cold water started squirting from the diverter valve (heating engineer on holiday typically). We now have no hot water. Any ideas what the underlying problem might be?

 

[Whitespirit66]

Any ideas what the underlying problem might be?

Your 'engineer'.

 

[Agile]

Yes. I must agree with that.

This is a very straightforward boiler and any reasonable engineer should be able to diagnose the faults. If they need help then Worcs has a tech help line.

They are a rather common problem of blockages caused by dirt in the system.

Tony

 

[adrianthegasman]

Point taken - the possibility of a faulty engineer is being managed. The job is made particularly difficult as the previous occupants of the house installed it in an area where it is not possible to get access from above the boiler - one side only. He has been in contact with Tech Support and followed their advice so far.

Any thoughts on which parts tend to become blocked and why? I do not live in a hard water area.

 

[dcawkwell]

Try the central heating is it working ok?

If so the pump is ok and as said possible blockage problem.
Strip it down flush out and away you go.

This is a similar problem that occurs on the oil combi boilers and it is usually a blockage around the plate heat exchanger area.

Could also be air lock problems if the air vents aren't working.