water softener smell

19 Apr 2022
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United Kingdom
Hi Chaps -

1st post here so be gentle!

Recently had kitchen remodelled and we've installed the water softener to drain into the cloakroom pan waste via 40mm washing machine pipe setup. softener is in a 600mm cupboard in kitchen and usual tightness for space. Model is a Monarch Midi.

I've attempted to draw a picture! Excluding water feed lines.

The softener smells of the drain all the time. There's a p-trap but I'm presuming its drying out due to only 2x of us using the property and the machine regenerating once every 2 weeks odd. The smell is worse if we go away for a few weeks.

The washing machine waste is capped off as I don't have a machine there, rather a beer fridge. No sink to keep it regularly topped up.

1) I'm aware there needs to be an air gap and I'm trying to source one in the UK for the softener drain lines. Impossible in its own right. Fountain softeners have something but it's not going to help with the smell.
2) Can I somehow install 2 x McAlpine Tunvalves - 19/23mm or equivalent to act as a return check valve.

any other options?


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1. If:
1a. The item you note as a P trap is a running trap (see McAlpine TR10) AND
1b. Neither of the flexi tubes are a tight fit in the 40 mm vertical pipes
1c. Then you should not be getting smells back. They would not be able to pass the water seal, and the seal would take weeks to dry out, not days.
2. If the flexis are tight in the 40 mm pipes, you could use a 50 to 40 mm adaptor and a short length of 50 mm pipe to provide an air gap.
3. As it stands, you will not know if the overflow is running without opening the softener. A tun dish would show the overflow running, and would help solve the air gap problem.
4. What is the outside diameter of the flexis?
thanks for reply.

1a - I will double check and see, I know height was a restriction to ground and its behind kitchen units.
1b) I tried taping around the flexi pipes to create a seal - obviously this hasn't helped
1c) longer than days but I have a place in Spain and when I come back after a month its evident because house has been visited less frequently. The cupboard the softener lives in smells of mouldy drain.
2) I can remove the duct tape to open the air gap.
3) noted
4) they're about 12mm (1/2 inch).
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Just to close this off as few ever do.

I continued to get the problem so installed an in-line HepvO and problem resolved. Back from Spain after 2 months and whilst the P trap was partially dry - enough to break the seal, the foul smell could not pass.

Happy days.

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