Worcester 28 si

[davebrown]

Hi, I have a problem with a worcester 28 si II. The problem is that the burner fires but will not go to full rate it modulates from 1mb to 6 to 12mb.
There is a flame present but when the pressure drops the ingnition sequence starts again but a flame is present could this be the board.

 

[bengasman]

Could be half a dozen things. When did you last have the boiler serviced?

 

[davebrown]

Hi the boiler is my next door neibourghs it has no been serviced in the last 4 years. He asked me to look at it as I am Gas Safe qualified (New to Trade). The boiler was not responsive when I arrived so I turned it off then on again and created a demand for hot water with no response from the boiler I assumed it was the fan but there was no power going to fan I then turned off boiler and on again and then fan came on and I got ignition but with the problem previously stated I thought maybe the fan was not running upto speed so stripped and cleaned it with the same result. When I created a demand from central heating there was a loud clicking from the board area which coincided with the flame trying to go to high flame but this would not explain why it was happening on hot water?

 

[bengasman]

Don't know the exact settings for this one by heart, but if it goes up to 12 mbar, you have more than 90% of max output.
If not serviced for 4 years, it could well be that the sensor is not properly in the flame causing the boiler to go to ignition pressure and start sparking.
M.I. recommends service annually, so after 4 years that would be a good place to start.

Might be worth your while to get access to CC, as a lot of guys will not discuss certain stuff that should only be done by RGI on open forum.

 

[davebrown]

Many thanks for your help one more question what is CC

 

[bengasman]

Many thanks for your help one more question what is CC

RGI-only section, see top of forum.

 

[glasgowgas]

Hi the boiler is my next door neibourghs it has no been serviced in the last 4 years. He asked me to look at it as I am Gas Safe qualified (New to Trade). The boiler was not responsive when I arrived so I turned it off then on again and created a demand for hot water with no response from the boiler I assumed it was the fan but there was no power going to fan I then turned off boiler and on again and then fan came on and I got ignition but with the problem previously stated I thought maybe the fan was not running upto speed so stripped and cleaned it with the same result. When I created a demand from central heating there was a loud clicking from the board area which coincided with the flame trying to go to high flame but this would not explain why it was happening on hot water?

thats the relay on the pcb gubbed giving an intermittent fault

take it out and have a look it will be scorched internally (the relay)