Hi Folks,

I have just come back from a short break to find that my ancient Baxi boiler
(model WM 381 RS CHB) has blowm its 3A mains fuse. Upon replacing the blown
fuse, same thing happens again. The boiler itself is ancient (I can take a
photo if anyone's interested, so the electrics don't appear to be too
complicated.

I suspect the cause has been that there was apparently heavy rainfall when
we were away, so much so that I suspect some water has got in the flue pipe
and back into the unit, shorting something. The pilot was still lit when we
returned, so gas flow appears to be fine. Also, for this particular model
(balanced flue job) the small amount of control electrics that there appears
to be are located under the main combustion chamber, and there is no
evidence that they have got wet. To be honest I'm a bit baffled as to what
could have shorted, and would appreciate if someone could give me a pointer
in the right direction.

Control unit appears to be fine, and switched on briefly before the second
fuse blew. I'm about to nip out for some more fuses so I can check that the
boiler (rather than room thermostat or pump) is to blame by unplugging the
boiler and replacing the fuse, and see if everything else fires up (pump
etc). the boiler appears to be quite old, and so there must be a limited
number of things in it which could be the problem (hopefully).

Does anyone have any suggestions what the problem could be, or are familiar
with this boiler (standard CH boiler - not a combi - gravaty fed tanked
HW/CH system - balanced flue)

Thanks for any help or suggestions!

Leigh

In article , L Reid newsgroup
@removethisxycom.demon.co.uk writes

To be honest I'm a bit baffled as to what
could have shorted, and would appreciate if someone could give me a pointer
in the right direction.

Could be the pump. Disconnect it and try another fuse. Also have a
sniff around the pump to see if you can detect the unmistakable smell of
fried windings.

Needless to say, you shouldn't run the boiler for any length of time
with a non-functioning pump.

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"Mike Tomlinson" wrote in message
...
In article , L Reid newsgroup
@removethisxycom.demon.co.uk writes

To be honest I'm a bit baffled as to what
could have shorted, and would appreciate if someone could give me a
pointer
in the right direction.

Could be the pump. Disconnect it and try another fuse. Also have a
sniff around the pump to see if you can detect the unmistakable smell of
fried windings.


Thanks Mike. I tried unplugging the boiler and replacing the fuse (leaving
the pump the only thing in circuit which would come on when the H/W is
switched on by the controller). This seemed to work fine, and did not blow
the fuse. Unfortunately when I plugged the boiler back in, rather than the
fuse blowing, it appears all is well again and everything is functioning
normally. I guess I'll just need to hang out for the next deluge and see if
it happens again.

Regards,

L Reid

"L Reid" wrote in message
news
Hi Folks,

I have just come back from a short break to find that my ancient Baxi
boiler
(model WM 381 RS CHB) has blowm its 3A mains fuse. Upon replacing the
blown
fuse, same thing happens again. The boiler itself is ancient (I can take a
photo if anyone's interested, so the electrics don't appear to be too
complicated.

I suspect the cause has been that there was apparently heavy rainfall when
we were away, so much so that I suspect some water has got in the flue
pipe
and back into the unit, shorting something. The pilot was still lit when
we
returned, so gas flow appears to be fine. Also, for this particular model
(balanced flue job) the small amount of control electrics that there
appears
to be are located under the main combustion chamber, and there is no
evidence that they have got wet. To be honest I'm a bit baffled as to what
could have shorted, and would appreciate if someone could give me a
pointer
in the right direction.

Control unit appears to be fine, and switched on briefly before the second
fuse blew. I'm about to nip out for some more fuses so I can check that
the
boiler (rather than room thermostat or pump) is to blame by unplugging the
boiler and replacing the fuse, and see if everything else fires up (pump
etc). the boiler appears to be quite old, and so there must be a limited
number of things in it which could be the problem (hopefully).

Does anyone have any suggestions what the problem could be, or are
familiar
with this boiler (standard CH boiler - not a combi - gravaty fed tanked
HW/CH system - balanced flue)

Thanks for any help or suggestions!

Leigh


Hi Leigh,

I've got a manual for this boiler.

As you say, the internal circuit of the boiler is straight forward.
Connections as follows.

Ter Live boiler thermostat

other side of boiler thermostat gas valve solenoid.

other side of gas valve solenoid Ter N.

gas valve solenoid has a suppresion capacitor wired in parallel with it.

Has suppression gone short circuit?

best regards

Bill