In article ,
John Rumm writes:
the_constructor wrote:
The condensate pipe on my combi boiler comes out of the wall and rests in
the hopper of a downpipe but with this rather cold weather that we have all
been having, it has tended to freeze up quite a bit.

This got me to thinking.

The basin and bath waste pipes never seem to freeze up and these are
directly into the soil pipe. I assume, rightly or wrongly that this is
because (a) the ubends are inside the house and (b) because of the gasses
inside the soil pipe come up into the waste pipes.

Working on theory (b), would it help if I take the condensate pipe from the
hopper and feed it into the bath waste pipe using a 'T' connection and
reducing plug thereby keeping the open end out of direct contact with the
outside air. I have plenty of drop on the pipe to do this, or should I lag
the pipe, though I don't think lagging is the answer.

Your thoughts as always would be most gratefully appreciated.

The basin pipes etc don't freeze because the water is dumped down them
in batches rather than a trickle. If you were to leave a tap dripping in
a basin you may find a different result.

Most condensing boilers include a concentrate trap that is also designed
to empty periodically rather than in a continuous stream for the same
reason. The open hopper will cool the passing water faster as well.

Another factor is that the condensate pipe is usually 21.5mm
(overflow type) pipe, but it's supposed to be 32mm minimum
if routed outdoors. Do you have a run of 21.5mm plastic outdoors?
Sometimes I see this, but it's been protected by 22mm pipe
insulation.

Condensate from my boiler is luke warm, and that seems to prevent
it from freezing. Many years ago, I installed a dehumidifier which
ran permanently with a plumbed-in condensate drain pipe. For this,
I ran a length of resistance wire (in PTFE insulation) along the
inside of the condensate pipe and extending an inch or so from the
end. I ran it from a low voltage AC supply on an outdoor frost stat.
That worked fine. There are more professional equivalents of this
available, but they are not at all cheap (tend to be used on things
like outdoor sprinkler installation pipework).

--
Andrew Gabriel
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