Protection from freezing for cast iron downpipes

Section62

Martin_the_Unjust said:

FreeBear said:

Martin_the_Unjust said: Plus, your washing machine really should not be draining into a downpipe.

Depends on where the downpipe discharges to. If it is going in to the foul water drain, not a problem. Only if the water is ending up in a storm drain or soakaway does it become an issue.

Pretty sure downpipes shouldn’t discharge into the foul sewer.

It depends exactly what the "downpipe" is, and also whether it discharges into a foul sewer or a combined sewer.

Cast Iron suggests the installation was within the era where it was common for sink wastes to drain via a 'downpipe' (with or without a hopper at the top) into an open gulley.

Too many unknowns to know whether the OP's situation is allowed or not.

twopenny

I lived in a 1930s house with cast iron down pipes for 60yrs and they never froze.
Two walls north and east - went through several big freezes.
Only once did a pipe freeze but that was a small overflow pipe that was dripping. 
One spectacular stalagmite.

Is it possible that the gutter isn't draining properly and trickling into the downpipe? When were the gutters last cleared.

BUFF

dharm999 said:

In the real cold weather we had before Christmas one of our cast iron down pipes froze causing the utility to flood as the washing machine couldn’t drain away water.  

Hopefully it did not freeze enough to actually crack the cast pipe - that gets expensive.
As others have said the solution is to make sure that the pipe/drain is kept clear & not blocked.

Apodemus

dharm999 said:

Apodemus said:

Martin_the_Unjust said:

There shouldn’t be any water in the down pipes to freeze. 

You need to investigate further as, if there is water standing in your down pipe, you have a blockage somewhere.

... or perhaps simply a trickle of water constantly running down the pipe, which is freezing in cold weather.  By any chance, does a condensing boiler drain to this pipe?

I have had a new system boiler fitted, and it drains into the same pipe work that the washing machine drains in to.  All these pipes are inside, with one pipe only going out in to the down pipe.  This one pipe that feeds in to the downpipe is old, probably original, as it’s cast iron.  No idea what it was used for.

Back to my original question, anyone know of anything that would be what I am looking for?

Well, that would appear to answer the question of why it is freezing - the trickle of water from the condensate drain freezes in the outside pipe, the ice builds up to the point where it restricts, then blocks the pipe.

As you point out,  How you prevent it from freezing is your real question and I'm afraid, I have no sensible solution to that.  Some form of insulation would seem to be the only answer.

Eldi_Dos

Once you have insulated downpipe,cover with U shaped pipe boxing (UK Boxings) and cover top with stop end.

As a stopgap measure you could put salt down sink when you feel temperature is going to drop low enough to cause repeat..

TELLIT01

Martin_the_Unjust said:

FreeBear said:

Martin_the_Unjust said: Plus, your washing machine really should not be draining into a downpipe.

Depends on where the downpipe discharges to. If it is going in to the foul water drain, not a problem. Only if the water is ending up in a storm drain or soakaway does it become an issue.

Pretty sure downpipes shouldn’t discharge into the foul sewer.

Our house was built in the 1930s and everything flow into a single drain, whether that be sewage, rainwater, bath water etc.