cold house tonight - fixed over the phone

[Paul Drawmer]

In another post I've asked for some help with a slow loss of pressure from our boiler.

This evening the boiler shut down, tripped the circuit breaker and the house was cold and dark.

I immediately assumed that it was the end game of a leak inside the boiler, especially as it dripping water out of the casing!

The installation was done under the warm front /eaga scheme, so I rang the eaga 24 help line.

The girl on the help line, checked my installation details and explained that it might be the condensate drain that was frozen.

It was - two kettles of hot water, and re routing the drain with a better fall, and moments later I saw a satisfying stream of water from it.

Re-started the boiler - success!

If your condensing boiler has an exposed condensate drain - check is isn't frozen if your boiler shuts down.

[nomisesor]

You're lucky you can get to the pipes with your kettle - mine are about 7m off the ground. I have used old cycle inner tubes to divert the condensate into buckets whilst waiting for the weather to warm - and to re-route, easier said than done given the location of the boilers.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Deva Link]

Allegedly last year some plumbers put a message to thaw the condensate drain as part of their answer-phone message.

[Paul Drawmer]

nomisesor said:

You're lucky you can get to the pipes with your kettle - mine are about 7m off the ground. I have used old cycle inner tubes to divert the condensate into buckets whilst waiting for the weather to warm - and to re-route, easier said than done given the location of the boilers.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Doh! How do I close a thread?

[Mars]

This is happening to one of my rental properties. It seems a totally stupid design flaw to me. My mid-1980s NON-condensing boiler may be half as efficient as the Worcester Bosch we have in the rental but with a service every couple of years it plods on and on. Really irks me that these new ones have such a design flaw.

[Wings]

As a landlord it is a common problem for combi boilers, i was in fact tempted to post info on this just prior to the OP posting, caught me out on two call outs last year.

[Scraggles]

my drain valve has a leak, I was going to fix it in the summer, but never got around to it, so a small jug sits underneath the L bend from the combi

[ferg]

Mars said:

This is happening to one of my rental properties. It seems a totally stupid design flaw to me. My mid-1980s NON-condensing boiler may be half as efficient as the Worcester Bosch we have in the rental but with a service every couple of years it plods on and on. Really irks me that these new ones have such a design flaw.

I'm confused as to what the flaw is. Condensing boilers condense. There is a connection on the bottom to take this away. What happens after this is down to the installer, not the boiler manufacturer. Too many pretend plumbers fail to run external condensate drains in 32mm lagged pipework and with insufficient falls. If they are having to run too far externally then they should be looking at internal pipework, possibly pumped. It is quite possible that this may make their quote dearer than someone else... Go figure.

[nomisesor]

ferg said:

Mars said:

This is happening to one of my rental properties. It seems a totally stupid design flaw to me. My mid-1980s NON-condensing boiler may be half as efficient as the Worcester Bosch we have in the rental but with a service every couple of years it plods on and on. Really irks me that these new ones have such a design flaw.

I'm confused as to what the flaw is. Condensing boilers condense. There is a connection on the bottom to take this away. What happens after this is down to the installer, not the boiler manufacturer. Too many pretend plumbers fail to run external condensate drains in 32mm lagged pipework and with insufficient falls. If they are having to run too far externally then they should be looking at internal pipework, possibly pumped. It is quite possible that this may make their quote dearer than someone else... Go figure.

I agree that the installation is the problem, not the design per se, though the price of efficiency with condensing boilers is having extra components and having to dispose of the condensate.

However, given sufficiently cold weather for sufficiently long ANY system with an external outflow will freeze, regardless of diameter of pipe and drop - I can't post a picture but we've all seen frozen waterfalls - which are an infinitely large "pipe" (with no top) and a vertical drop.
32mm, lagging and a good drop should be sufficient, but if we're going to get this sort of weather more frequently, only discharge into an internally located drain will be guaranteed to work - presumably in places like Norway even their foul pipes run inside the house and into the ground without being exposed to the outside air?

I cursed the regs when hand digging a 12m trench for a new mains pipe from the road, but at least I know that my main won't freeze until the mammoths return.

[Mars]

I also agree with the above comments. I'm just irked that my old fashioned barely efficient boiler doesn't have this problem and yet these new designs do.

I've found some rubber foam insulation from RS with a 42mm inside diameter which ought to do the trick. Expensive at 40-odd quid, but looks like it'll be easy to fit.

[ferg]

nomisesor said:

However, given sufficiently cold weather for sufficiently long ANY system with an external outflow will freeze, regardless of diameter of pipe and drop - I can't post a picture but we've all seen frozen waterfalls - which are an infinitely large "pipe" (with no top) and a vertical drop.

Interesting analogy, but not really relevant, surely. The condense from a boiler is warm when it leaves the boiler and, provided the length of pipe is within limits and lagged, will not reach freezing point until it's in the ground below frost level. Too many chancers take liberties and pay the price.

[johnthegas]

yet again, Ferg is bang on - This is nothing to do with the boilers but all to do with shoddy installations by poorly or unqualified engineers!

[Paul Drawmer]

Paul Drawmer said:

...It was - two kettles of hot water, and re routing the drain with a better fall, and moments later I saw a satisfying stream of water from it...

Yep, installation error. There was a 1.5M run that was horizontal, but actually had a sag in it. Now re-clipped with a decent fall.

Ferg in the other thread on this subject said:

Just the first instructions I found....

Pity my installer hadn't seen them.

[nomisesor]

ferg said:

nomisesor said:

However, given sufficiently cold weather for sufficiently long ANY syyearstem with an external outflow will freeze, regardless of diameter of pipe and drop - I can't post a picture but we've all seen frozen waterfalls - which are an infinitely large "pipe" (with no top) and a vertical drop.

Interesting analogy, but not really relevant, surely. The condense from a boiler is warm when it leaves the boiler and, provided the length of pipe is within limits and lagged, will not reach freezing point until it's in the ground below frost level. Too many chancers take liberties and pay the price.

Agree, "within limits" - and my analogy uses the usual strategy of taking something to an extreme to make a point - note, though, -18 degrees C, while extreme by UK standards, has been seen in this country twice in the last year. The condensate is warm (presumably a max of ~99 degrees) but it is of very small volume ?a max of 10cc / minute so, even if it leaves the boiler at 99C, it will rapidly cool despite the best lagging if there is a temperature gradient of ~120C. You postulate a short, well insulated run, entering the ground and in that circumstance, freezing is not likely. However, many of those having problems will have a longer run exiting the property above ground - and therefore exposed to very low air temperatures. The boiler room / eaves room in my house is 4.5 x 3.5m, with the roof sloping from 2.5 to 0m, so the pipe runs inside the (frost-free) room are about 6m long, exiting at ~ 7m above ground into a gutter - only about 50mm being exposed to frost. Unfortunately the gutter has frozen, with icicles (of condensate) hanging off it, and presumably the ice has backed up to engulf the condensate pipe outflows.
The layout was acceptable for most climatic conditions (which many installers will have worked to), but failed in the current weather.
It is easy to assume that any problems are due to the client pressing down on quotes - but many will have accepted that their plumbers knew best and allowed them to install according to their expertise / regulations - my system (2 Vaillants, 3 wet underfloor circuits, 2 radiator circuits, and a megaflo) wasn't built down to a price. I expect that the plumbers who installed it 12 years ago didn't think that, given the climate over the preceding decade or two, they needed to set up the condensate drain system to cope with prolonged sub-zero temperatures and I don't blame them for that. On the assumption that this type of weather will be a problem again, we'll just have to re-route the condensate pipes and put in place other measures against cold weather.

If we've got it bad, think of the Arctic with freezing seawater, or, worse, some of our outer planets - ammonia, methane and nitrogen rain!

[ferg]

nomisesor said:

exiting at ~ 7m above ground into a gutter

This is very bad practice. Do you have some sort of neutraliser on the pipework? Lime chippings? If not, then the condensate pipework doesn't comply with the manufacturers instructions so would make it impossible to have the 'Benchmark' paperwork signed off.

Discharge must be into a foul drain or neutralised soakaway.

[nomisesor]

ferg said:

nomisesor said:

exiting at ~ 7m above ground into a gutter

This is very bad practice. Do you have some sort of neutraliser on the pipework? Lime chippings? If not, then the condensate pipework doesn't comply with the manufacturers instructions so would make it impossible to have the 'Benchmark' paperwork signed off.

Discharge must be into a foul drain or neutralised soakaway.

I trusted the plumbers to install correctly. We'll get it sorted by re-routing the pipes into a foul drain - currently (when not frozen) it goes into the gutter, downpipe, then rainwater drain with trap, from which it travels about 10m to the main sewer.

If any was to escape we have about 30cm of soil overlying a massive bed of blue lias limestone - sufficient to keep water softener companies in business and to neutralise the world's condensate for millenia...

[Mazdarese]

I had the same issue last year. All the local sheds had run out of appropriate lagging, so I used an old sleeping bag and tie-wraps to insulate the pipe outside. My 'lagging' is still in place.

[ferg]

nomisesor said:

If any was to escape we have about 30cm of soil overlying a massive bed of blue lias limestone - sufficient to keep water softener companies in business and to neutralise the world's condensate for millenia...

LOL!!