Combi boiler - what to use to lag the condensate pipe?

[zebedee]

My combi boiler shut down last night due to a frozen condensate pipe, which I need to access next door to clear (with hot water). It seems I am very much not alone with that problem this week, especially with my type of boiler. The pipe is completely unlagged, running down the outside of the property for about 6 feet.

What is the best material to use, just plastic foam pipe lagging or a fabric one?

I guess with fabric if it gets wet and freezes, that will be just as bad. Ideally I'm thinking of building a slim plywood boxing to case it in, which could be packed with something, but then again the wall it runs down is the unheated kitchen wall so if it is really cold, I can't see any of this being any real help.

[dirkgently]

zebedee said:

My combi boiler shut down last night due to a frozen condensate pipe, which I need to access next door to clear (with hot water). It seems I am very much not alone with that problem this week, especially with my type of boiler. The pipe is completely unlagged, running down the outside of the property for about 6 feet.

What is the best material to use, just plastic foam pipe lagging or a fabric one?

I guess with fabric if it gets wet and freezes, that will be just as bad. Ideally I'm thinking of building a slim plywood boxing to case it in, which could be packed with something, but then again the wall it runs down is the unheated kitchen wall so if it is really cold, I can't see any of this being any real help.

Closed cell foam.
I have been called to three of these today,poor installation in my opinion.

[Smart roadster]

I used normal pipe lagging from a DIY shed. No problems yet.

[Logie]

Some Rockwool H&V glass section will do

[CatherineJ]

What does this pipe look like?

We have a combi boiler but I don't know what it looks like.

[zebedee]

cheers guys.

Dirk - did you use a holistic detective agency to identify the problem?

I agree, poor installation, they went through the wall as soon as it exits the boiler, they could have run it internally and gone through the bottom of the wall instead, minimising the run outside, or at least lagged it, which the instructions say should be done. Online forums are chock full of people complaining in the last week that their Worcester Bosch Greenstars have done this, how irritating, a boiler that fails when it stays cold for a while! Hopefully the lagging will sort it.

[zebedee]

CatherineJ said:

What does this pipe look like?

We have a combi boiler but I don't know what it looks like.

it will be a pipe that runs outside from your boiler (assume all condensers have one, though most of the complaints seem to be about WB models) It may go into a soakaway or a drain manhole

[moles]

Is the pipe 20mm? (ish) If so it should be lagged to prevent freezing and the installer should have done it. You can use bigger 32mm pipe which will does not have to be lagged. (lagging will not do a lot in this weather if the pipe is horizontal as it will always have standing water in it) so get bigger pipe and leave it un-lagged or change the gradient so that the water cannot wallow in the pipe.

[moles]

Will be a white plastic pipe.

CatherineJ said:

What does this pipe look like?

We have a combi boiler but I don't know what it looks like.

[zebedee]

moles said:

Is the pipe 20mm? (ish) If so it should be lagged to prevent freezing and the installer should have done it. You can use bigger 32mm pipe which will does not have to be lagged. (lagging will not do a lot in this weather if the pipe is horizontal as it will always have standing water in it) so get bigger pipe and leave it un-lagged or change the gradient so that the water cannot wallow in the pipe.

he should have used 32mm pipe but hasn't. It falls vertically from coming out of the wall all the way into the ground where it joins a manhole, so I was surprised that it had got the opportunity to freeze. I guess any condensation in the pipe would freeze whilst the boiler wasn't running, then as it trickled past at minus 8, that would freeze onto the ice already there and before you know it, its blocked. Can't really change to a 32mm now because it is all plumbed in, so will have to go for the lagging option

[moles]

Can you not leave the 22mm pipe in place and just put a new 32mm pipe on the section that is outside. You can get a 22mm-32mm connector and just lag the 22mm elbow as it leaves the house. What model Worcester is it?. Most have a syphon in them so it will let go of a cup full at a time as opposed to a constant trickle.

Edited by moles on Wednesday 7th January 14:53

[zebedee]

moles said:

Can you not leave the 22mm pipe in place and just put a new 32mm pipe on the section that is outside. You can get a 22mm-32mm connector and just lag the 22mm elbow as it leaves the house.

true, but it would need another reducer just before it goes underground. Its all a bit sensitive because it is on my neighbours land and whilst they don't mind me popping round with some rockwool and making a half-decent job of lagging it up, they wouldn't be too keen on me or a plumber messing about with pipes and so on. From the looks of the forums, mine has stayed frost free longer than others, so hopefully the lagging will be just enough in case of another sustained cold snap, if not, then I guess I will just have to have the conversation with my neighbour!

[Dover Nige]

I've got the closed cell foam stuff on mine, done by the installer which runs into a soak away. No problems here touch wood.