Erratic heating system.

[foxhole]

Have a Greenstar boiler fitted last year , conventional fully pumped with 3 port valve, hot water tank and one room stat. Boiler replaced old potterton, all other components untouched. After a short while boiler would start up by itself and only turning the hot water on would stop it [but would not provide any hot water] Hot water would only be produced when the control panel turned it on at preset times. When boiler fires by itself it does not respond to room stat, though when running normally it will.
Consensus here was that it was a problem with the three port valve, so I changed that and also the controller and the engineer replaced the wiring to the boiler to eliminate wiring faults. Lived with it for a while and then the problem got worse, system would run continually unless the hot water was on and this provided no hot water.
So got heating engineer back last night and he fitted yet another 3 port valve [the last one had a minor leak so was happy to change to a Honeywell] .
System is back to running normally sometimes but still boiler runs on it's own at random times?

 

[dcawkwell]

Has anyone measured the voltages at the boiler with a multimeter to see if the boiler is actually being told to run? No? Then get someone who
knows what he is doing instead.

If it is running and there is no signal telling it to run then the fault
is in the boiler.

You can change external components as much as you like it won't
fix a fault in the boiler.

 

[foxhole]

Has anyone measured the voltages at the boiler with a multimeter to see if the boiler is actually being told to run? No? Then get someone who
knows what he is doing instead.

If it is running and there is no signal telling it to run then the fault
is in the boiler.

You can change external components as much as you like it won't
fix a fault in the boiler.

Had the manufacturers engineer out to it soon after it started acting up, could not find a fault at the boiler or reason for the strange behavior, he put it down to the 3 port valve being faulty, but as mentioned thats been changed.

 

[longdogs]

Had a similar problem last year: changed the batteries in the remote thermostat and re-set it according to the manufacturers instructions and the problem was resolved. Not sure if you have a remote thermostat though?

 

[twgas]

A number of Worcester boilers will fire up when they receive approx 110v on the switched live which comes from the "stalling" of the three port valve, IIRC fitting a capacitor between sw live and neutral will solve the problem, if indeed that is your problem.

 

[Agile]

Easy enough to identify by either fitting the capacitor regardless or removing the call for heat connection.

However, we are told the later Worcester and Viessmann boilers have the capacitor fitted at manufacture.

Tony

 

[twgas]

When did they start fitting the caps at manu

 

[Agile]

Someone mentioned it in the cc about a week ago when the same problem was being discussed ( again ).

 

[twgas]

I've not been in c for quite some time so obviously haven't seen it.

 

[foxhole]

Had a similar problem last year: changed the batteries in the remote thermostat and re-set it according to the manufacturers instructions and the problem was resolved. Not sure if you have a remote thermostat though?

Standard wired room stat.

 

[foxhole]

A number of Worcester boilers will fire up when they receive approx 110v on the switched live which comes from the "stalling" of the three port valve, IIRC fitting a capacitor between sw live and neutral will solve the problem, if indeed that is your problem.

I did read this and tried a capacitor with no effect, also read somewhere later that my boiler and valve don't have this problem.