Condensing Boiler problem, but Not frozen condensate pipe.

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 before I risk any electrical connection again.

We have had reported temperatures as low as -10C in this area in the last couple of nights, so it is perfectly possible for unusual things to have frozen, but I would have expected it not to have worked first thing.

Any ideas, do flue pipes freeze?

For the comfort and convenience of the locals, I have posted this separately to The Shed, rather than simply cross-posting!

Cheers folks.

Reply to
JonG
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When it was actually very cold in about 1982 enough ice and snow and frozen flu gases collected on some of the neighbours balanced flues to stop them working. They had to chip the ice off a couple of times a day, usually at night.

Reply to
dennis

Check the condensate path is not blocked, it appears to be.

Reply to
Doctor Drivel

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Further thought is that the water I poured over it was finding its way in via the inlet part of the balanced flue, which would suggest that the initial water was meltwater and the warmer (or, at least, less extreme) temperature Is relevant.

Reply to
JonG

From a WB Greenstar manual

Display code: EA

Description: Flame not detected.

Remedy: Is gas c*ck turned on? Check gas supply pressure, power supply, igniter electrode and lead, ionisation sensing electrode and lead, flue duct and CO2 level.

...despite what you said it does sound like a blocked condensate pipe though

Reply to
Mike

Pages from fault manual.

formatting link

Reply to
Mike

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.

Reply to
YAPH

I had the same problem of cutting off, it turned out the condensate pipe was frozen as it enters the ground sump. A couple of kettles of boiling water sorted it.

It is a recently installed combi system so I had phoned the installer and he advised me as he has had numerous call-out for that very thing.

I know nothing of plumbing, however if the condensate pipe is frozen at some point the condensation maybe backing up and exiting inside your boiler.

Reply to
SS

It is incorrecty fitted. It should not ice up.

Reply to
Doctor Drivel

Cant argue with you as I am not a plumber, but from a laymans point of view if the condensate pipe comes from internal to external in very cold/extreme conditions then unless it has a heater of some sort on it then surely it is possible for it to freeze?

Based on what you are saying then there must be a standard that makes it impossible for it to freeze and if there is would you please advise as I will take this up with the installer as the boiler is only 6 months old.

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Reply to
SS

As you say, any external pipe with the occasional flow of water can freeze. It is normal practice for a longer run to be of a larger diameter, which needs a lot more ice to plug the pipe up.

Most condensate traps fill up and empty using a siphon action. The idea is that you get a few 100 mils of water every so often, rather than a drip, to lessen the likelihood of freezing.

Reply to
Fredxx

The external pipe should be 32mm to prevent freezing. And external insulation where necessary. All in regs. It should also be in the makers instructions.

A recent thread went over all this.

Reply to
Doctor Drivel

Any suggestions on the most suitable insulation to use?

Chris

Reply to
Chris J Dixon

Well I have the 32 mm pipe and is about 9 inches from where it exits outside to the trap so I will get something for way of insulation.

Reply to
SS

Externally, you need to use a waterproof insulation so it can't become waterlogged, also known as closed-cell. This is most commonly used on chilled aircon pipework. Armaflex is best known make.

Internally, it doesn't much matter.

Reply to
Andrew Gabriel

Remember insulation only makes it less likely to freeze up and a prolonged cold spell could still see the pipes freezing. Make sure you can remove and refit it in case you have to thaw it. IIRC in ~1970 there were about 22 days where it was below freezing day and night. I was recording weather stuff for a school project and the wet bulb never defrosted over that period. That was in west bromwich not the Scottish highlands.

Reply to
dennis

Armaflex is closed cell (which means it can't absorb moisture and itself freeze worsening the problem).

However if used outdoor it needs to be painted. I am not sure if that is re UV or Fire Retardancy although it meets BR "O" rating.

Reply to
js.b1

Mine drain pipe comes through the wall a course or so above dpc, then drops to outside slabs level using 2 x 45 elbows, then on to a gully about a metre or so sway. I've not had any trouble with freezing, even though the drain pipe has had a covering of snow at times.

Reply to
The Wanderer

Unless it is in a vented loft.

Reply to
Doctor Drivel

For computer room aircon drains I often see it foil wrapped instead.

Reply to
Andy Burns

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