Condensate pipe into washing machine waste

[Truman]

Some boiler manufacturers and industry guidance says that you can boss a condensate pipe for a condensing boiler into a washing machine standpipe. Is this assuming the washing machine standpipe is actually still being used by the washing machine?

I'm just wondering if a washing machine pump was discharging water and the boiler was in full condensing mode at the same time, could the standpipe be breached with water overflowing out of it?

Also, what fitting would the condensate pipe need to be connected to the vertical standpipe? Presumably it would need to be on an angle/fall rather than tee'ing in entering horizontally, otherwise when the washing machine drains, some water could flow along the condensate pipe couldn't it?
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[bigads28]

Yes a the condensate can go into the stand pipe provided the boiler uses a syphon style trap. There is only a small amount of water comes from the boiler so I wouldn't worry about the water not getting away with the washing machine discharge. As for the pipe run it on needs a few few degrees of run and the pipe is flexible enough so I just clip it to create the run. If the waste is accessible the the pipe can be cut and glue fittings used, if not I use those McAlpine clamps without any problems.

 

[AWheating]

best piped into the waste pipework after the stand pipe. just a case of dropping a tee into it and if needed reclipping the stand pipe.

 

[dmheat]

Some manufacturers allow this, most do not. If using the washing machine waste then tee it in downstream of the trap. Just dropping condensates into the stand up should be banned. It's an internal air break in the condensate and if the boilers own trap cracks and empties, which they do, you'll get POCs out that gap.

I've only had it happen twice in 12 years, but I have had to ID boilers for this, last week I was reading 400ppm CO from a tundish someone had installed internally on a condensate pipe, the trap plug had cracked and the trap was completely empty. Fortunately for the customer their boiler had an unrelated fault that was preventing it from working.