On Wed, 17 May 2006 07:57:52 +0100, David Hansen wrote:

I pointed out the specific circumstances in which it would save more
gas than people think in my original posting. Obviously if the
boiler has electric ignition then the saving will not even be that
of turning off a pilot light for some months.

If a boiler does _not_ have electric ignition but has a constant pilot
light then it is a dinosaur with seasonal efficiency in the region of 65%.
The controls are likely to be primitive, too. It will make far more sense
to replace it with a high-efficiency boiler with updated controls than put
in solar water heating.

(I'm not talking about the OP's installation which, we've already
ascertained, is a condensing boiler with proper controls.)