Help reuired with faulty Classic ff340 gas boiler

[supermoto1962]

Hello
I am having a problem with my central heating boiler and would appreciate some urgent expert advice.

I assume the pilot light is working as when the timer cuts in i can see the flame through the small window on the front of the boiler. In normal operation i would here a whoosh and the flame would increase and all would be fine.

Now what happens is the timer kicks in, i dont hear the whoosh and the flame is only tiny. Turning the thermostat up full and the knob on the bolier to its highest setting and leaving for a while would sometimes cure the problem with plenty of heat in the rads and loads of hot water but not anymore.

Does it sound like the 'jets' in the burner have blocked or could it be something else?

Have tried turning the main supply off, starting the system to burn off excess gas and then turning on the main supply in the vain hope of blasting the fault away but nothing.

Look forward to some expert advice asap as i'm freezing.
Regards

 

[gas4you]

Sounds like the gas valve had it to me. Check for 240VAC at the valve when call for heat is present, if so then the valve it is.

This needs a RGI to replace it and set it up for you.

These are an awkward valve to change

 

[supermoto1962]

Hi
Thanks for the reply.
Are you saying that there should be 240v volts present or not present?
Regards

 

[gas4you]

When you are expecting the boiler to fire there should be the voltage present at the valve.

 

[hect]

Sounds like main solenoid is sticking on G/V..........
When pilot establishes, flame rectification happens, an voltage is found on R4 - then stops sparking and main solenoid opens, so if you have 240Vac at GV2 then its ur valve

 

[Aquaheat]

As all have said before, check that you have 240v at the main gas valve solenoid when the boiler should be calling for heat. If you have that then your gas valve is shot.

Pain in the a**e to change but will require an RGI to install and correctly setup for you. Worth getting one in to check the fault out for you first.