Frozen condensate pipe - how to prevent

[Thomas]

Hi

Awoke this morning to no heating due to frozen condensate pipe on new boiler :-( Boiler is in integral garage with no convenient internal drain, so condensate pipe runs the length of the garage and exits through wall with about 2" protruding over drain-pipe drain. Managed to pull about 18" slug of ice out with help of hair drier and all was well.

So, what is the best way to prevent this in future? Pipe is about 20mm but I dont really want to install a larger bore due to the need for a larger hole through the wall. I'm in two minds about insulation - there's very little to lag on the outside, but will lagging on the inside help or hinder? The garage is pretty well insulated and never anywhere near freezing. I was wondering about inserting a length of copper tubing or a metal rod up the pipe with the idea that this would take some of the heat from the garage into the final section of the pipe where the freezing is starting?

Thanks for any suggestions Tom

[Nightjar]

I would expect the problem to be in the outside section, so would start by lagging that and seeing if that cures it.

Colin Bignell

[John]

Is there a tee over the end to help prevent draughts going up the pipe?

[The Medway Handyman]

Could you modify something like this for the outside section?

[robert]

the end , increasing it and lagging the whole length might help matters. AIUI using 32mm pipe is the proper way to go where there is a danger of freezing. If you have and other waste pipes in the garage ie washing machine, emptying the condensate into this would be even better

[Lobster]

Can't see why either would hinder?

I'm thinking the problem is probably related to the overall length of the pipe. I suspect the drop on it is relatively shallow; maybe even has a dip in it where water could collect (not even anywhere near the frozen bit?) The point is that in most boilers, the condensate exits via a syphon arrangement rather like a urinal toilet flush; ie rather than dribbling water out gradually and continuously, which would certainly encourage freezing up, it collects in a reservoir which dumps all the water every half-hour or so. However, if you have a long, very shallow run on your pipework, and certainly if there's any chance of water collecting along it's route, that will cancel out (either wholly or in part) the benefit of the syphon arrangemnent.

Or maybe you don't have the syphon in your boiler?

I'd suggest lagging the entire length (if you can raise the temperature of the water exiting the pipe outside it can only help) and if necessary increasing the drop on the pipe *especially* where it goes through the wall (which may necessitate drilling a new hole).

HTH David

[ARWadsworth]

AIUI using 32mm pipe is the proper way to go where there is

I'll second that.

[Dave Starling]

This place is selling trace wire (5 watts/metre) that you cable tie to the condensate line to prevent freezing.

site says the stat only kicks in below 4c. I've not tried it so can't vouch for its success, but you shouldn't need a lot of heat in the pipe to stop it freezing if its lagged too.

Dave.

[Thomas]

Many thanks for all of the helpful suggestions and advice.

I've added an elbow to the external stub and wrapped the whole lot in foam insulation - I'm hoping this will prevent windchill and keep in some of the heat from the house. If that doesn't work then I'll upgrade to a larger bore and add more insulation - unfortunatley it's hard to see how I could increase the fall on the pipe.

Thanks again Tom

[Dave Liquorice]

Congratulations on the first "frozen condensate drain" posting of the

2010/11 season. B-)

As others have said the drain should be 32mm where there is a chance of freezing. What can be done?

Lagging inside should mean that the water is warmer when it gets to the outside so stands less chance of freezing.

Make sure there is a fall on the pipe where it goes through the wall, so water doesn't sit in that section of pipe. Condensate is only a dribble not a flow, so it might not clear like a flow would.

Cut the pipe inside and stick a bucket under it. Roughly every kg of gas burnt produces a kg (1 litre) of water. I'm not sure how 1kg of LNG equates to cu ft (or m) of gas at appliance pressure. I doubt you'd get a bucket full of water/day but even if you do it's in the garage...