Condensate pipe

[DJSwift]

Good evening all,
Been reading a lot on these forums, and thought it would be a good time to register as I would also like to share my input on other things etc.

One question I have is. Why does a condensate pipe have to be a minimum of 32mm ? In 2010 plumber who installed my new boiler installed 22mm condensate pipe outside. He put like some foam lagging on it.

To be fair, it never froze but then again we have not really had harsh winters in London.

This summer, the lagging was tattered and worn to bits. The pipe goes straight into the cast iron pipe and silicone was used to patch it up. I do not think its the right way. Ok so the silicone was leaking every time a toilet was flushed.

So last week I went up there, bought some lagging from Toolstation and cable tied it on as the previous plumber had done. Also removed the previous silicone so it literally had the condensate pipe hanging into the hole in the cast iron. And I used silicone to block the hole, again just like the previous plumber. Now I understand it might not be done properly but for now its a temp fix.

Ideally I want to sort it properly. I cannot plumb the pipe inside to a sink waste as its just too far and awkward.

I have been told 2 things, The pipe should be at least 32mm (im guessing smaller pipes are more likely to freeze) and also apparently the lagging I used was wrong.

So what lagging do I really need ? Also if the pipe from inside is in 22mm. To the point it reaches outside, can I make it into a 32mm ? Im not sure what is needed to scale up a pipe. I am sure there is something for it. Would that be ok though if I did it like that ? If anyone can send me a link to an item I can buy on the web which will be adequate.

And also the pipe that goes straight into the cast iron. Is it right the way it is with silicone ?

Sorry for a long post.

Kind regards
Swifty

 

[PrenticeBoyofDerry]

The pipe sizing on your condensate is down to freezing. Originally the manufacturer allowed the smaller diameter to be used throughout, and then came the winters and because older boilers trickle the condensate out, issue over freezing pipes and boiler lock-outs prevailed.
So the recommendation was to condensate to an internal outlet or increase and lag external pipework.
Condensates can be terminate at the soil pipe, but usually a strap on boss would be used or a cast connector.
With regards to the lagging, why do you consider this to be of the incorrect type?
The insulation used should be waterproof and weather resistant.

 

[dilalio]

Is this your own home?
Is the boiler still in warranty?
Have you had an RGI fail the install/refuse to issue a certificate due to the condensate run?

If the above answers are YES, NO, NO and it's never frozen, I would leave it as is! You can always make any adjustments at a later date, if it does freeze up!

 

[bernardgreen]

A 32 mm diameter pipe draning condensate will still freeze, it will just take longer become blocked than a 22 mm would take in the same weather conditions.

Lagging will have little effect if cold air can enter the end of the pipe.

 

[DJSwift]

Hi guys thanks for answering

@dilalio : Yes its my own home. I doubt there is warranty on the boiler as it was installed 5 years ago when I moved in.
And yes the guy at the time issued me a certificate. I just wanted things done properly. And no I have never known it to freeze. Probably I just would like to put the right lagging on. I think I actually did a better job than the installer as the stuff he used was so thin and fell to bits with several gaps in it.

@bernardgreen : Ideally I do want to change the lagging since its foam and once it gets wet it can start to get worn out. Hence I wanted to know whats a good quality external lagging.
There is no gaps for the cold air to enter as I totally sealed it

 

[Dan Robinson]

once it gets wet it can start to get worn out.

Also don't forget most foam lagging is not UV resistant.

 

[JohnD]

.... The pipe goes straight into the cast iron pipe and silicone was used to patch it up. I do not think its the right way. Ok so the silicone was leaking every time a toilet was flushed....

That's awful. What a bodger.

Armaflex is pipe insulation which can be used outdoors. It is a black rubbery material. More expensive than the common Climaflex type, but you won't need much of it.

You can get a proper strap-on connector to go on a soil pipe but I have not worked on cast iron. This example is plastic http://www.screwfix.com/p/floplast-strap-boss-110mm-black-sp319bl/82795
The silicone sealant is a bodge. If the boiler is in or near your bathroom or kitchen it would be a hundred times better to connect the condensate pipe to an existing indoor waste pipe, but some installers don't like the effort of getting behind kitchen units.

 

[dilalio]

The thing is, to connect into the cast using a strap on, you're going to have to rely on silicone (or at best sikaflex EBT) to secure it in place. Else: you'll have to cut a section out of the cast and replace with plastic pipe, using 2 fernco rubber couplings and a boss pipe 4"x2"x4" tee with reducers down to 20/22mm!
I would get some black Sikaflex and live with that to make the joint into the cast... Or go the whole hog and replace the complete stack with plastic!

 

[Nige F]

A hemp grommet and silicone (not Boss white) will do the job - one of my earliest "weekenders" way before condensing boilers it was for a waste pipe.

 

[Agile]

So many installers still use 22 mm and dont even bother to lag it.

I am sure there will be some silicones which would do a good job to seal outside. The problem is that anything more is very time consuming.

 

[DJSwift]

@PrenticeBoyofDerry : Sorry I missed your post and only just saw it. Well I replaced it with what was there originally. I bought this http://www.toolstation.com/shop/p48736

And then someone told me its the wrong one as its foam and snow can sit on it or rain can soak it. Even though the same one was on for at least 5 years previously. Hence my question if it was wrong. (I should have posted a link to what I bought in my first post).

@JohnD : Well the trouble is to find good tradesman. All seem nice at first but when they get your money it seems a different thing. Same thing with the guy who made my driveway in the summer. But thats a different story...
Yes it looks like a bodge and I had no choice but to improvise on the bodge. One guy wanted £120 just to put lagging on ? At that point, I thought it is worth me learning a thing or 2 and do it myself.
But me learning something, I ideally want to do it the proper way as I do not believe in cutting corners.

The original installer cut a hole in the cast iron pipe. I am not sure what size hole it it is, but I saw it when pulling out the previous broken silicone.

@dilalio : I shall have a look at what would be the cost of replacing the stack

@NigeF : Not sure what a Hemp grommet is. I tried to search on google and it brings up like curtains ?

@Agile : Well I don't mind taking the time as long as my boiler works correctly.


I took some pictures of what I did.

Might give a better idea what I am trying to say

 

[dilalio]

Looks fine to me

 

[ajstoneservices]

Armaflex is pipe insulation which can be used outdoors.

You may want to check that JD. Most of their products need further protection when used outdoors with the exception of HT I believe.

 

[bernardgreen]

Fitting an air gap where the pipe come out of the wall will allow the boiler to continue to operate after the long external run of condensate pipe has become blocked. Yes it means condensate will be dripping down the wall from the air gap but as least the house will be warm and protected from other pipes freezing and maybe bursting.

 

[Dan Robinson]

How can that leak "every time the toilet is flushed"?