Drain the Water System or Leave the Heating on?

[JuanFanjo]

Does anyone please have any advice for us. We're going away over Christmas (for about a week) and are wondering what to do to stop the house freezing up. (The last two years have been bitterly cold - UK).

We have a condensing boiler and last time we went away the pipe to outside froze up (condensate pipe?). So the water backed up into the boiler and it cut out. When we came home the house was freezing and the pipe outside frozen to the top. We had tried to lag it but that didn't work.

So this year we were wondering if we should just drain the whole water system before we go. Has anyone done that? How difficult is it? We don't have even a cold water tank. But the raidiators? How difficult to empty and how difficult to refill?

Any advice gratefully received!

leave the heating on low, definitely.

I'm sure there is a fix for the condensate pipe thing - will see if I can find what it is. (Though ideally it's best brought inside the house & connected up to eg the washing machine drain pipe if it's anywhere near)

\link{http://controls.tedcon.com/frost-sentry.php\this wasn't what I was thinking of but it is A solution - bit expensive & complicated though}

I can't find anything else

the condensate pipe can be connected to kitchen sink drainpipe, or bathroom drainpipe if they're nearer - as long as the whole pipe is within the house it shouldn't freeze - do you know a reliable plumber you can call on?

but don't empty the system - can you imagine coming back to a house at about zero degrees & then having to faff around getting the heating going again???

If you have a condensing boiler, you most likely don't have any tanks of water in the loft.

the things that will freeze first are those outside the insulated envelope of the house.

It will be extremely difficult to drain all the water out of the CH system. because it will linger in horizontal pipes, especially under floors. I would recommend that you leave the heating on, low, while you are away. Last winter was exceptionally cold, this year may not be so bad.

The problem with your frozen condensate pipe was very common last year, as it was so cold. The best solution is to have the condensate pipe run inside your house, to a convenient drain such as the sink waste pipe.

Many installers run the condensate pipe outside, because it is easier and cheaper than running a pipe indoors, which may involve getting behind kitchen units. They say this makes it a cheaper job, and their customers wouldn't want to pay the extra to reroute the pipe.

This annoys me, because it is a cheap job that will lead to expensive problems later. This is no secret.

If you can't get the condensate pipe re-routed internally, make sure it is well-insulated with an waterproof insulating sleeve such as Armaflex (it should be the BS grade which is as thick as your arm). Also try to get a trusted friend or neighbour to look in if there are any exceptionally cold nights.

Try to get a plumber, heating engineer or electrician to fit "Trace Heating" which is a heating electric wire, a bit like you find in an electric blanket, that is wrapped round the external part of the condensate pipe, and prevents it from freezing (it needs the insulation on top).

The internal rerouting is still the best solution if you can possibly do it.

Hi Thanks loads for these suggestions.

And yes the faff of trying to fill the system again is what was filling me with dread - but the last two years we've had that outlet pipe freeze, even with lagging on it (but probably not enough and not done properly).

I'm really quite annoyed now that the plummer didn't fit the pipe inside as the boiler was on a blank wall and the pipes were all bare and running straight down from the boiler into the under-floor space. So it would have been easier to route it inside than drilling a hole to outside! Grrrr. Now we have wallpapered over the boarding so will have to take that off. Grrr again.

I will take your advice and see if we can't open it up and route the pipe inside.

One more question - would it make the house damp to have that water running under the house onto the earth? Or is it, in reality, so little that it is absorbed into the soil? (The boiler is at the opposite end of the kitchen from the sink with the cooker inbetween)

thanks.

condensate is slightly acidic, and dissolves cement. Sometimes you will see where a pipe has been leaking, and you see a puddle-shaped patch of gravel and sand left behind, where it used to be concrete.

It is a very bad idea to let it get into the foundations of your house.

If it goes into a soak-away, it is supposed to pass through a vessel of limestone chippings first. They will be slowly dissolved as they neutralise the acid.

I think you need to get a plumber in for advice, before Christmas, JuanF

clearly there are ways round it, but you want to do it right

How long is the distance between the boiler & the sink? Because as long as there's some fall, it doesn't matter inside if it's a bit shallow, so it could go behind the cooker?

Thanks very much.
I think we may well invest in that heater for the pipe plus the insulation! The kitchen layout means it would be quite tortuous to get the pipe into a drain.

Thank you for all your help and avice!

We've been having quotes for new heatings systems and I've been querying the freezing condensate problem with various plumbers incl Brit. Gas.
They all say that, leaving aside last year's extreme cold, the problem of freezing externally plumbed condensate pipes was usually due to the pipe being too narrow in diameter.
The solution they've all recommended (if you can't plumb inside) is to have a wider diameter condensate pipe running down to your external drain. I think the same diameter as a washbasin drain pipe, rather than the narrow copper pipe type drain.

for my own boiler, I was careful to choose a place for it that was adjacent to the soil pipe stack, which runs in an indoor duct in the corner of the kitchen, next to the sink

Most boilers go in a kitchen or utility room, so there is almost always a sink and drain in the room, even if you have to change the position of something else to get close to it.

Considering the cost and upheaval of having your boiler stop working in cold weather, choosing to put your boiler somewhere else is IMO not a good idea.

The 'frozen condensate pipe' issue was all over the Daily Mail last winter - they did a big spread on how all condenser boilers had been fitted with the wrong diameter of condensate drain pipe and anyone whose pipe froze was now having to pay about £150 to have it fixed.
I think I would rather pay £150 and have it fixed permanently then mess about re-routing or moving boilers or heating pipes.

yes, if it is outdoors, it does need to be a plastic pipe of 32mm or more; and it does need to have a good fall on it so the water runs through quickly, and it does need to be completely lagged with Armaflex or similar with no gaps. The British Standard grade for outdoor pipes (or those in unheated areas such as lofts) really is as thick as your arm, so it will look quite unsightly, and it will not fit where the pipe is clamped close to a wall, you need Munsen Rings to give enough room for the insulation to run behind it. Any horizontal runs or dips where water can lie will eventually freeze even if insulated.

Best of all though is to have a boiler in a place where you can run an internal drain so it is not exposed to frost. I realise it is a bit late if you've already had a boiler fitted in an undesirable place.

The cost and inconvenience of having a pipe freeze, and your boiler stop working in cold weather, will convince you.

p.s. useful little video on here

What are the odds on a 32mm plastic pipe for condensate drain ever containing enough water for long enough for it to freeze and block? Nigh on impossible - and lagging outside pipes on top? Bit OTT / belt and braces no? This was an issue unique to particular weather circumstances and the installation of large numbers of condenser boilers with the wrong diameter drain. Replace the drain and it won't happen again.

greentown, I think your wider diameter pipe was the solution I was seeking in my earlier search

how easy is it to join a 32mm pipe onto an existing narrow copper pipe though? are there adaptors?

It's not hugely difficult Ponders. I'm fairly sure you can get plastic 'Push-Fit' connectors in B&Q or Screwfix - copper pipe in one end of the connector - plastic out the other. If you have a local plumbers merchant with a real plumbing person behind the counter, they would be able to tell you.
To best deal with the freezing problem though the connection would (ideally) need to be inside your house but I guess you would have a narrow diameter hole going through your external wall.
Assuming you wouldn't have the gear to drill ot a bigger hole, the next best thing is to make the connection as near as possible to the pipe exit from your external wall.
Make sure there's as steep a drop as possible down to the drain.
Technically, a person might argue that this work should be done by an 'Approved Person' under building regs and all the other various rules governing everythng we do - but that would be up to you.
I'm not a plumber though so if you have any doubts at all, - they're the lads for the job - shouldn't take long and definitely shouldn't be more than £150.

thanks, greentown - it wasn't me with the problem though, it was juanfanjo, I wonder if she'll be back? Maybe I should send her a message

(I have an antique non-condensing boiler, luckily. But will file away the information for the future )

if you want to DIY, you can hire a "Core Drill" from a local tool hire co, it will make a very neat, perfectly round hole of the size you want (this is also the best way to make the hole in a wall for an extractor fan or cooker hood). It is so easy that you wil be trying to think of extra holes to make.

BTW you only need a Gas Safe engineer to do things relating to gas, which includes opening up the case of the boiler.

The condensate pipe is just plumbing.

Hi all
thanks very much for the extra info (been away for the weekend so was called back to thread by Ponders- thanks!)

I think we have a core drill or if not know someone who does (handyman friend) so that looks like the waaaaay easiest option as there was no practical way to get the pipe to a drain inside the house when I checked. Thinking of it - we could get said friend to do the work for a less than usual fee - result!

I really appreciate the time you've taken to help.