worcerster 28si (british gas c1) issues

[Access Gas]

Hi not sure if anyone has had a similar problem.

call for CH or DHW boiler fires - flame rectification does not sense flame spark electrodes keep firing - boiler goes to lock out after 3 attempts

cleaned flame rectification same issue

replaced flame rectification same issue

replaced pcb - boiler works for 1 week then same issue

after fiddling about with wires today i realised that as soon as the prongs on the pcb back plate touch the contacts on the pcb the problems occurs (when the pcb back plate is removed the boiler works fine)


The earth contact goes direct to the back plate, then a wire from the back plate to the boiler case, then the prongs on the back plate earth the pcb and then the pcb earths the pump.


saying that - i diconnected the earth wire from the back plate fired the boiler with the back plate removed and it worked, then fitted the back plate still with the earth removed and the spark electodes started firing again even though the flame was on and in high rate.

it seems when ever the earth conects to the pcb the flame rectification gets knocked out

im not an electrician by trade but am now realising to be a good boiler engineer you need to be a good electrician too.

Read more: http://www.ukplumbersforums.co.uk/plumbing-forum/41425-worcester-c1-28si.html#ixzz2A4FduNYY

 

[Billy Bob Bob]

reversed polarity checked for that yet?

 

[Access Gas]

im not an electrician but have a multimeter i put it on v- 2000 and the reading was 240

would the boiler work if the polarity was reversed? this boiler has been working for a number of years before this issue

 

[Billy Bob Bob]

im not an electrician but have a multimeter i put it on v- 2000 and the reading was 240

would the boiler work if the polarity was reversed? this boiler has been working for a number of years before this issue

has the customer fiddled with the electrics ? added any new spurs or points or a sparky been doing works?

 

[Access Gas]

not that i know of. although the point is near the sink and i think water may be splashing against the point.

 

[RGII79]

hi not sure if anyone has had a similar problem.

Call for ch or dhw boiler fires - flame rectification does not sense flame spark electrodes keep firing - boiler goes to lock out after 3 attempts

cleaned flame rectification same issue

replaced flame rectification same issue

replaced pcb - boiler works for 1 week then same issue

after fiddling about with wires today i realised that as soon as the prongs on the pcb back plate touch the contacts on the pcb the problems occurs (when the pcb back plate is removed the boiler works fine)


the earth contact goes direct to the back plate, then a wire from the back plate to the boiler case, then the prongs on the back plate earth the pcb and then the pcb earths the pump.


Saying that - i diconnected the earth wire from the back plate fired the boiler with the back plate removed and it worked, then fitted the back plate still with the earth removed and the spark electodes started firing again even though the flame was on and in high rate.

It seems when ever the earth conects to the pcb the flame rectification gets knocked out

im not an electrician by trade but am now realising to be a good boiler engineer you need to be a good electrician too.

Read more: http://www.ukplumbersforums.co.uk/plumbing-forum/41425-worcester-c1-28si.html#ixzz2a4fdunyy

check the dc voltage at the rectification cable to the earth terminal

 

[Access Gas]

ok i will do this, what sort of voltage should i get?

 

[RGII79]

ok i will do this, what sort of voltage should i get?

low fire 25 to 30 dcv high fire 80 to 90 dc

sounds like you have a problem with your earth somewhere

 

[RGII79]

check earth resistance ohms .5

 

[Access Gas]

this is what i thought so i called my electrician friend but he said if there was an earth problen then other appliances would be affected from the same ring or the rcd would be tripping.

he thinks the pcb could be faulty.

worcester couldnt help me much either. just said i have an electrical fault somwhere.

 

[Access Gas]

is earth resistance done by connecting earth to neutral with the multimeter

 

[RGII79]

when you pivot down the control board in the boiler is their an earth cable connected to the top cover that screws off
your pcb may not be earthed

 

[RGII79]

get a sparks in to check the earth sounds like something stray

 

[Access Gas]

yes the earth wire comes in with live and neutral the live and neutral go thraight in the board the earth connects to the earth terminal which is the top cover and the top cover has a wire connected to the boiler case and the top cover has 2 prongs which sit on the pcb once screwed down

it seems that the boiler only works when the earth or the top cover is not connected to the pcb as soon as i connect the earth direct to the pcb or screw the top cover down even with the earth disconnected the spark electrodes fire up and goes to lock out.