I am an unbelievably "low confidence" DIYer, having only ever rented properties, which limits the stuff you're supposed to do, for liability reasons.

However, we had a boiler issue where it was making horrible cthonic gurgling noises and then switching off, with the fault lights blinking.

When I called the manufacturer's helpline, the automated message suggested it might be the "condensation pipe". Once I realised no-one was ever going to answer, I went down, and located what I think was the correct pipe.

This black plastic pipe runs out of where the boiler is on the top floor all the way around the corner and. On the end it was just an open pipe hole leading into the drain. I noticed there was a blob of ice covering part of the end of the pipe so I snapped it off.

I then tried to restart the boiler, with no real hope, as the pipe was incredibly long and I had no way to check if there was a proper ice blockage further up. It started fine and all the radiators began to heat up.

Could this have fixed it, or was it just coincidence? What I don't understand is why just removing a relatively small block of ice from the end of the pipe could have solved this.

If it actually got better because the daytime is warmer than the night, I'm worried it will freeze again this evening.


You have probably fixed the problem - at least temporarily.

The boiler requires that this condensation pipe is clear and unobstructed and removing the ice from the end has cleared the blockage. However, it's likely that the pipe will freeze up again - especially in this cold weather.

The solution is simple - insulate the pipe. Either use something like this - the pre slit stuff will make it easier to fit as the pipe will be clamped in a number of places. If you can't get hold anything that's the right diameter for your pipe at short notice, wrap the pipe in bubble wrap. That should be enough to keep it from freezing.

  • +1: That's really helpful, but what I'd really like is to understand why a tiny blob of ice at the end of the pipe causes the boiler to fail at the other end. It doesn't seem like it could be pressure. I guess that's more of a science than a DIY question, so if it's not appropriate for the site, let me know. – deworde Feb 12 '12 at 19:12
  • @deworde - I'm not 100% sure myself :) – ChrisF Feb 12 '12 at 22:32
  • Since there were "fault lights" blinking, it's possible the furnace decided to turn off when the back pressure on the condensate line increased. Next thing, they'll install "black boxes" on the things – DJohnM Jan 15 '14 at 2:15

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