Condensing Boiler problem, but Not frozen condensate pipe.

JonG · 2010-01-10T17:31:20+00:00

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.Everything has apparently been fine til today, we had hot water and radiators the morning. May or may not be relevant that this is the first day for a fortnight where daytime temperatures here have struggled to marginally above freezing. At lunchtime, I noticed that the light on the boiler was flashing, and the display gave an error code "EA", which appears to be about as specific as the average Microsoft error code. I pressed the reset button, and it appeared to fire up, but only for 20 seconds or so, then I noticed water dripping from under the boiler. Closer inspection revealed quite a lot of water behind the panelling, suggesting it had been leaking for several hours at least, or intermittently for longer. Switched it all off and took out the fuse.Inside, there is water lying on a ledge above the level of the sump/ condensate apparatus, but no obvious source.Outside, the flue did not appear to be frozen - there were some water drops on the lower pipe, and it all sounded perfectly hollow. To be sure, I poured a large jug of fairly hot water over it, back inside, more water then appeared inside the boiler apparently from somewhere around the flue exit, so presumably either from what I had poured on or possibly from something melting internally.I'm reluctant to turn it back on with the free water, currently have a fan heater on it...

Jan 10, 2010 21 Replies

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Mike 16 years ago

A number of Worcester Bosch models require 21mm* plastic pipe for the condenser drain, there is nothing in the installations instructions about terminating it to 32mm (are such adaptors even available?)

Yes 21mm, bloody funny size but available from the sheds, but not from BES.

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Doctor Drivel 16 years ago

21mm is overflow pipe size. When running it externally it should be 32mm. 21.5mm to 32mm: BES Nos: 11939 or 11940 for the 40mm

A soakaway can be made by using a larger pipe with holes in one side to divert water away from the house. Cheaper than buying one.

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