On Sun, 10 Jan 2010 17:31:20 +0000, JonG wrote:

Given the current weather, anyone any ideas what causes problems with
condensing boilers when it isn't the condensate pipe? CAn flue pipes
themselves freeze?

I have a 3-month old Worcester Greenstar CDi COnventional, 30 IIRC. It
is mounted in the cellar, with the tope just below external ground
level. The Flue apparently does a dog-leg within the thick stone walls,
then exits about 12" above ground level, then has an extension kit to
raise the (often dramatic) pluming above window level. The condensate
pipe runs internally under the flooring, and empties into the drainage
sump. I've double checked, this pipe is clear and free-flowing.

There should be a flue gas sampling point on the flue connection just
above the boiler. (There are two caps: one for the air inlet and one for
the flue: you're after the one that communicates with the inner part of
the concentric flue assembly). If you pour water down the flue (not
air) hole it should run away via the condensate syphon/sump and pipework
to the drain. If it doesn't your condensate waste system is blocked
somewhere along the line.

If you've got water in the air intake you may have further difficulties.

--
John Stumbles -- http://yaph.co.uk

I'd rather have a full bottle in front of me
Than a full-frontal lobotomy