OT It must be cold

[ARWadsworth]

Thats 5 phone calls already this morning from people with frozen condensates.

[Ronald Raygun]

What do you do when you get these calls? Do you tell the caller to boil a kettle to unfreeze the drain themselves, or do you go out there and charge them sixty quid to boil a kettle to unfreeze the drain? :-)

It seems lunacy to plumb these discharges to the outside, unless these boilers are designed to be used only in temperate climates where it never gets below freezing. Yet systems tend to be fitted with frost stats, so there clearly is an assumption that it could get freezing cold. There seems to be a design contradiction here.

What do they do on the continent, or for that matter in Americanada, where seriously low temperatures are the rule rather than the exception? Do they not use condensing boilers? Or if they do, do they plumb the condensate drain into the normal domestic waste water?

Why don't we do that here? Or do we generally only discharge to the outside when there is no waste plumbing conveniently nearby?

[Tony Bryer]

22mm pipe outside?

[ARWadsworth]

To be fair it is not my job. I only installed the electrics on these boilers. However I left my telephone number on the programmers instruction manual and in panic people just call me as it is the first number they can find. If the customer is prepared to listen I tell them how to de-ice the condensate or how to stick a bucket under the boiler and discharge the condensate into that.

You are correct. Something needs to be done. We have had several mild winters followed by two severe ones and the problems only started coming to light last year.

I have no idea what the cold countrys do.

[ARWadsworth]

It is 22 going through the wall and then 32mm after.

I did see one frozen 32mm condensate last week. The snow had built up around the drain that the condensate discharged into, melted a little and then frozen causing ice to cover the grate. This then blocked the condensate pipe and allowed the water to back up and freeze. Mind you there were icicles as big as elephants knobs hanging of the gutter it was that cold.

[Jules Richardson]

The condensate for our furnace here in norther Minnesota just goes to the normal sewer system (via a small holding tank/pump unit which raises it up about 6ft as the furnace is in the basement below the sewer line level

- I'm hoping there's a check valve involved somewhere ;-)

We're well out in the sticks so have a septic system outside - so far that's never frozen up, thankfully (it's -21C outside right now)

cheers

Jules

[PeterC]

Gulp - mine's 22mm. Somehow it didn't freeze up last Winter and has been OK so far. It does have a slope of about 30º, so that might be the reason.

[Andrew Gabriel]

The condensate from mine is slightly warm once the boiler has been on for a while and enough has warmed up the internal U-trap. That might help prevent freezing over the external 3' length to the main stack in 32mm. It is also the bathroom basin waste. If it froze outside, it would eventually back up into the basin and overflow that onto the floor, but that's never happened. AFAIK, it's never frozen at all in 8-9 years.

The boiler has detection for blocked outlet by detecting the level in the internal U-trap rising too far, but that's never happened, and probably can't in my installation. A bit of debris blocked the heat exchanger outlet a couple of times, which it doesn't detect, until the level in the heat exchanger builds up enough to block off the flue outlet and it won't light. Before it gets this bad, it's making lots of gurgling noises. A couple of times a year, I pour a few pints of water rapidly into the flue outlet, which in my boiler will effectively wash out any debris collecting in the bottom of the heat exchanger, and it's never happened since I started doing that. (Don't do this with your boiler unless you know the design well enough to be sure it won't harm it.)

[PeterC]

Just as was planning an attack you say don't do it! No, seriously, I would't risk that without knowing what would happen - I can visualise all sorts of disasters!