boiler condensate drain

[Andrew L.]

Thanks for previous replies from Ed Sirett & Andrew Gabriel, which solved my problem - empty condensate trap! It's a plastic bottle stuck on with velcro. Cheap looking but easy to fill & clean.

I have another question about the condensate drain. This is piped outside (22mm plastic pipe) but ends 6 inches above the ground - dribbling directly on to the concrete.

Should I pipe it 14ft down to the main drain, or connect to the soil pipe 18" away, or can it be left alone?

Is the water pure condensation, or does it contain any toxins?

Andrew L.

[Andrew Gabriel]

It's slightly acidic. It would probably stain the concrete, and splashes might harm any mortar in the longer term. It should not be run in metal pipework. If soil pipe is plastic, I would use that.

External condensate pipework needs some protection against freezing. Manufacturers instructions on this point vary, but will typically be to run it in minimum 32mm plastic pipe outdoors and/or to insulate it. Some boilers collect an amount internally and then pump it out all in one go, which also helps prevent freezing.

[Andy Hall]

Given all of this, the best solution would be to install a 32mm trap inside at a convenient place (e.g. near to the existing exit through the wall and run a short length of 32mm waste to the soil pipe. Arrange the existing 22mm plastic pipe to end above the water in the trap.

This will over the freezing issue and provide an air break to eliminate the risk of the trap in the boiler being sucked out by siphoning.