Halstead Ace Combi Boiler - erratic hot water supply

[charjoe]

Ok I am well cheesed.

I have a Halstead Ace boiler (4 -5 years old). Its been fine but the last 6 months there have been hot water issues. The fault is erractic, but ongoing. About 15% of the the time hot water will not work. If the heating is on (& the burner is lit), the water works. The problem occurs when the hot water needs to go on without the central heating - a chunk of the time the burner will not ignite. The temperature was fluctuating as well, but this has been sorted.

So far I have had a new diverter kit (senses when hot water/ heating is required), a new thermister, a new main PCB and a new gas valve with a filter in it, and a new switcihing unit (dont know the actual name of this part)

I thought all was sorted, but tonight it happened again....no hot water. Surely there cant be any more parts to replace lol.

What happens is - you turn the hot tap on & the hot water light turns on, but the burner & burner light will just not turn on......thats it......

Any hints??? A pint to the winning answer...

Kevin

 

[Gasguru]

Which thermister was changed?

Hinge down the controls panel....look at the vertical pin on top of the diverter...does it rise up and actuate the microswitch when running in hot water mode?

 

[charjoe]

Hello there - not sure if this reply is complete enough, but the replaced thermister was the one that controls the water temperature (since that was replaced, the hot water produced doesn't really fluctuate in temperature - it used to turn off after a couple of mins leaving showers a bit of a trial!)

Re the vertical pin - cant really see it, but the engineer (this is covered by a Homeserve Policy - phew as they must have been out about 15 times now) said the pin was rising. Would this actually stop the hot water coming on if it was functioning incorrectly?

Could it be the "safety cut out thermostat" connected by the yellow wires on the left hand side?

Which thermister was changed?

Hinge down the controls panel....look at the vertical pin on top of the diverter...does it rise up and actuate the microswitch when running in hot water mode?

 

[gas4you]

As always, I usually find it is the ch primary thermistor that gives more problems than the DHW one.