Potterton Netaheat 10-16 Programmer/Boiler problem ?

[Elephant_Guy]

I have the above Netaheat boiler and an old fashioned (20 years old!!) Glo Worm mechanical/electric programmer.

About 2 weeks ago I found that I was unable to stop the boiler producing excess hot water, even after turning the programmer hot water control to 'OFF' the boiler continued heating water despite none being used. The only way to turn off the boiler is to turn the programmer/boiler electrical supply off at the mains. Despite this the central heating appears unaffected with the radiators remaining cool.

The lights on the programmer for it to come on 'once' or 'twice' when programmed now no longer light up and the unit lights up only when it is fully switched to the 'ON' position.

Thinking it was a problem with the programmer I replaced it with a new Grasslin QE2 front panel to no effect. The problem remains the same.

I replaced the thermostat within the boiler last year and it appears to work as the hot water does turn itself off for a few minutes before starting to heat again despite the programmer being switched off !!

Anyone got any ideas ?

Many Thanks

Elephant_Guy

 

[ollski]

2 X 2 port motorized valve or 1 X 3 port?

 

[Elephant_Guy]

2 X 2 port motorized valve or 1 X 3 port?

2 X 2 motorised valve. Heating works fine when I turn it on using programmer but also stays on all the time.

Thanx

 

[ollski]

microswitches in the hot water motorized valve head are sticking on....replace the actuator.

 

[Elephant_Guy]

Thanks, will give it a try.

 

[Elephant_Guy]

Hope solution is as you described but only changed valve less than 12 months ago !!!

 

[ChrisR]

Take it back then!

 

[ollski]

could alway swap the valve heads over temporarily just to prove it. It may be that the water is in such a poor state that the valve itself is sticking in the open position.