Condensate drain improvement

[Chris J Dixon]

My boiler is in the integral garage, and the condensate drain was taken through the wall, vertically down for a short distance to join with an existing 32 mm pipe, the drain from a sink. This then runs at a shallow angle for about 3 metres, where it joins into the rainwater downpipe, eventually discharging into a soakaway. (I didn't fit the sink, I know it is not really correct.)

As I had freezing problems, last year I lagged the external pipework with 25 mm thickness Armaflex. The extreme weather last winter still caused me some problems, at the junction with the downpipe. Luckily, I was able to thaw it relatively easily, and then kept the pipe clear by periodically running water from the sink to prevent any ice accumulation.

There are no possible alternative drainage points.

Since, by its nature, the downpipe will be open to air, I don't see much point in trying to get sheet insulation around the junction point.

(1) I could consider routing the solvent-weld drain internally through the garage, to reduce the exposure, but it would be a fiddly run, and the junction point issue still arises.

(2) In addition to (1), I could, adapting a recent suggestion in a different context, use a swept-tee in place of a 90 degree bend, and insert a solvent weld screw-cap end in the "unused" leg of the tee, just before it passes through the wall. When it freezes, I could remove the cap and allow it to drain into a bucket. This is fine so long as it doesn't have to be left unattended.

(3) I could use trace heating, either with the installation as it is, or having modified as (1) above. I guess this still requires me to lag the heated area, with hand-crafted chunks of expensive Armaflex.

Any thoughts and experiences on the best way to proceed, for greatest cost/benefit?

Chris

[Ret.]

I have a very similar problem - albeit with a shorter run. My boiler is also on the outside wall of my integral garage. The drain goes out of the wall some 14" above the concrete path running alongside the garage. It then runs down the garage wall to a 'slot' which was cut across the path and the drain (still 22mm) sits in this slot and then drains into a proper condensate soakaway buried at the edge of the path. The pipe is insulated from the point it exits the garage wall (and I have also created a 'box' to enclose this section, out of some left-over uPVC soffit), it is also insulated with normal pipe foam insulation from that point up to the soakaway. The 'slot' is mortared over. Last winter I also had problems with the pipe freezing up. After defrosting I prevented further freezing by laying bin-sacks full of old towels and sheets over the section of path where the pipe is buried. Not an ideal solution and I have been trying to think of something more permanent ever since. I did think of ignoring building regs and cutting a hole in the garage floor immediately below the boiler and burying the condensate drain deep down there. After reading about the problems that condensate can create with foundations, however, I decided that this would not be a good idea!

When I had my boiler serviced this spring, the engineer (same one who installed my boiler), told me that he had had dozens and dozens of call outs to frozen condensate pipes last winter. ISTM that this is really something that should be sorted out properly at installation. If condensate drains are prone to freezing (and shutting down the boiler), then manufacturers and installers should be coming up with solutions to ensure that this just doesn't happen.

[Olav M]

I had a similar problem years ago. 1935 house, modern kitchen sink, draining out trough wall to 3" cast iron waste outside. Sudden change from horizontal to vertical at a regular (not swept) bend was inclined to clog. I replaced with a swept Tee. The "swept" route carries flow, the unused leg is closed by a stop-end plug. All push-fit by the way. Like your option (2). Access is easy by prising off stop-end. Never had to do it since. I think the "swept", has probably cured problem.