Richard Walker wrote:
Ed Sirett wrote:
On Mon, 08 Jan 2007 16:50:02 +0000, Richard Walker wrote:

Hi

Few years ago I bought a 2kW petrol generator to keep the home
running when the mains power failed. Used several times, no probs
except that the CH boiler locked out when the generator was switched
in. A reset and all worked fine.

Last week had another power cut but this time the CH boiler locked
out after about 30 secs even after re-setting (several times).
Everything else in the house works OK, including gas fired Rayburn
cooker, which is just the same sort of technology as the boiler.

Any thoughts on what is upsetting the boiler? -it's a normal wall
mounted balanced flue unit from Vaillant.

Thanks

What arrangements are used to switch over the suppies. What
arrangements are used to earth the installation?
A polarity problem is centre stage here, especially if the gas lights but
then goes out after a few seconds.
Thanks, Ed

The gennie is switched in with a dp change over switch which isolates
house from grid supply then switches gennie power into house. Normally
switch boiler off at its isolating switch before switching in gennie,
then switch boiler on when gennie has settled down. House is earthed as
normal, gennie chassis is connected to house earth but not separately
earthed.

Supply from generator is clearly lumpier than mains - a discernible
flicker to lights. Might this be the problem? And if so, I wonder why it
used to work but doesn't now?

Cheers
--
Richard

Generators are generally center tapped, so you end up with +115v on one
phase and -115 on the other.
This may cause a problem with your boiler.
With the generator running and the grid supply off, what are the voltage
measurements between...

L&N -
L&E -
N&E -


Sparks...