Odd problem

[kay-jay]

Customer has isdue with cylinder water boiling and rising up the vent and overflowing from rhe cwsc.

First visit - no issue everyrhing working as it should.

Problem reoccurred......

Second visit - actuator head on 3 port not energising/de-energising with changes in demand. Cylinder stat working manually when turning dial up and down but wont shut things down when temp satisfied. So diagnosis new actuator and new cylinder stat.

Actuator now works as intended de/energising as it should with changes in demand.

Cylinder stat still doing same f.fs!!!!
Ruled out wiring issue so assu.ed possible faulty new stat. Took it back for a replacement and the new one works a treat.......

Until 3days later(this morning when customer rings and the boiling noises and overflow are present again.

Any ideas what could be causing this??

 

[Ch4 plumbing]

Stat too low or not sitting on the cylinder properly?

 

[Shower Engineer]

Immersion heater left on and stat failed?

 

[kay-jay]

Stat too low or not sitting on the cylinder properly?

Nope

 

[kay-jay]

Immersion heater left on and stat failed?

Nope

 

[Ch4 plumbing]

Sticking zone valve?

 

[jam1979]

Is the pump the right way round

 

[kris]

Hey Kev , Did u replace the body of the MV as well as the head , gunk in pipe , paddle not totally closing ??

 

[kay-jay]

Hey Kev , Did u replace the body of the MV as well as the head , gunk in pipe , paddle not totally closing ??

That would only leave an open pathway to the cylinder.
The cylinder still would not boil as it couldnt get hotter than the boiler output........
Only scenario it could be the valve is alongside another problem ie boiler stat goosed. The immersion is off but I will do electrical checks to ensure it is isolated and rule that out as the unregulated heat source.

Tamz seems to think the overflow may not be related but a simple passing ball valve resulting in the waterlevel rising overnight. And the noise down to kettling on the hw.

I was under the impression that kettling is a scaled up heat exchanger in the boiler. So why would it kettle only on hot water on a heat only boiler given that the boiler output is the same for heating/hot water?

Anyone shed light on this theory?

 

[jtsplumbing]

Are you sure that its overflowing from cwsc and not the expansion tank ?

 

[kay-jay]

Are you sure that its overflowing from cwsc and not the expansion tank ?

Not yet. But it does overflow only when the hot water has been on and two mins after the cylinder seemingly boils