Ariston Clas HE boiler wont put heating on?

[b1gdeano]

Hi,

Hopefully someone can help with an issue I am having with my boiler. It wont put the central heating on, but does work to give me hot water. Basically if I turn the thermostat up the boiler refuses to kick in and heat the radiators.

Im not sure of the cause nor where to look to see if I can resolve it without bringing in an engineer. I am comfortable with electrics/electronics but not very clued up when it comes to boilers/gas/central heating systems to know where to look!

This did happen a couple of months ago too, turned the thermostat up and nothing happened, then a little while later it suddenly came to life and started to heat the radiators, but this time its really not doing anything!

Is anyone familiar with this boiler/issue?

As an aside the timer clock thing built into the boiler never worked since we moved into the house last year, so the boiler is set to the always on position, and controlled via the thermostat to tell when to come on and off.

Thanks in advance

 

[stem]

With a traditional boiler (by this I mean one that is connected to hot water cylinder and not a combi) if the boiler is heating up the hot water cylinder OK then it is working as it should, and the boiler is not at fault.

The central heating controls will most likely be the source of the problem. If your heating system is operated by a motorised valve then the usual cause is either the valve not opening properly. In which case some WD40 (other lubricants are available ) on the operating spindle and mechanism have been known to do the trick. Or, alternatively, the small microswitch inside the the motorised valve that is responsible for switching the boiler 'on' in 'heating' mode is not doing so. In which case the valve will be opening but not switching the boiler on. In this case a new valve or valve actuator will resolve it.

 

[b1gdeano]

Hi,

Not sure it is the controls as I have checked the thermostat and its visible wiring and all good there - also replaced the batteries in it just in case (digital stat)

Im not sure what is wrong with it as I just tested it again this evening and the thing started to work and put the heating on! Its so strange, something isnt right with it

Im suspecting its an electrical issue as its almost like it either doesnt get the signal to turn on, or it just ignores it!

 

[picasso]

Might have weather comp fitted.

 

[stem]

Not sure it is the controls as I have checked the thermostat and its visible wiring and all good there - also replaced the batteries in it just in case (digital stat)

Sorry, perhaps I wasn't very clear. The room thermostat operates the motorised valve, then the motorised valve controls the boiler when it moves to the heating position. I was suggesting that you check the motorised valve, they are normally the cause of intermittent boiler operation, especially if the heating has been unused for a while.

This assumes of course you have a motorised valve. Not all systems do, but you haven't given us much detail about the rest of the system.

 

[Combicert]

Got something that looks like this...?

 

[fixitflav]

Hi,

Hopefully someone can help with an issue I am having with my boiler. It wont put the central heating on, but does work to give me hot water. Basically if I turn the thermostat up the boiler refuses to kick in and heat the radiators.

Im not sure of the cause nor where to look to see if I can resolve it without bringing in an engineer. I am comfortable with electrics/electronics but not very clued up when it comes to boilers/gas/central heating systems to know where to look!

This did happen a couple of months ago too, turned the thermostat up and nothing happened, then a little while later it suddenly came to life and started to heat the radiators, but this time its really not doing anything!

Is anyone familiar with this boiler/issue?

As an aside the timer clock thing built into the boiler never worked since we moved into the house last year, so the boiler is set to the always on position, and controlled via the thermostat to tell when to come on and off.

Thanks in advance

What type of boiler - combi or heat-only? If heat-only, do you have a mid-position or either/or 3-port diverter valve, or 2 separate valves?