Boiler condensate pipe connection

Rather than sealing the pipe from soil stack to boiler and relying on that white device I would have thought this would be a better way.

It has a gas proof "seal" at the new U bend and should the pipe become blocked then there is a sort of tundish ( overflow ) where the small black pipe enters the large vertical black pipe. This would prevent the boiler becoming flooded and shutting down.

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It was suggested to me (by a company on one of the job quote sites) that a P-trap could have been inserted where you show the U-bend made of black pipe and elbows.

The installation company said that they would install a condensate trap, but arrived with the device in the photo. I think it's one of these:

The flexible pipe from the boiler does not fit tightly into the top of it, there's a fair amount of space creating an air gap to allow air in and up through the boiler there and, hopefully, avoid any flooding from the stack vent into the boiler.

I guess if it had been installed at the same time as the boiler, the alignment might have been a little better, although, then, all overflow pipe, a lower entry to the stack vent and a narrower diameter condensate trap made for the job would probably be the way to go.

But, I see the device now fitted is still "patent pending", so I was wondering if anyone has had any experience with them.
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I was wondering if anyone has had any experience with them

Yes, on a friends wash basin, started to leak ( smells ) after about a year,

The manufacturer's make this comment "Not recommended for use with shower trays unless there is access for maintenance"

Maybe debris prevents the membrane closing completely and needs to be cleaned,

Will the membrane survive the acidic condensate ?
I asked about its longevity, whether it would need to be replaced regularly. As he first explained it, I thought it was some sort of filter, although when I asked if it was a one-way valve, I received the affirmative. I was told it was used on sinks, so it should have no problem surviving on my condensate pipe.

Is the smell from your friend's coming from above or below the valve, I wonder? Maybe with a basin or sink stuff can accumulate above the valve.

Not a device to take bleach, you think?
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Check that the black flexible hose going into the HepVo valve isn’t too long, if it is it could hold the membrane open and allow smell through.
It was shortened quite bit, and, if it's not just the pipe bending, it pushes fairly easily across the few millimetres of play that there is.

I can't smell anything much, but one tends not to with the high winds we're having. I'm thinking the reason nothing was smelled until autumn was the fact that leaves tend to accumulate over and smother the back kitchen drain then – I'm not sure outside drains all have traps themselves.
The soil pipe is also the vent pipe (normally) so won’t have a trap on it. It will vent to atmosphere above highest window level. (Some May have a durgo valve in the roof space.

All appliances, WC’s etc entering the soil pipe will be trapped to prevent any foul air escaping into the property, the soil pipe itself is open directly to the foul sewer, hence why you were getting foul smells direct from the sewer.

Your outside gully’s (grids) will all be trapped, otherwise you would have noticed it by now
I think the raised ridge tiles are vent tiles.

As you can see, the stack vent connection doesn't go vertically up through the loft. If the blocked drain wasn't the reason the smell only became noticeable in late autumn, perhaps a rat (I've found one in the kitchen waste bin before) got up on the roof, thought it had found a source of warmth and ended up at the bottom of the stack vent.
I'm not sure if that flexible white pipe complies with any regulations for soil vent pipe use! You'll likely get away with it, but whoever did it was a true bodger!

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