..... if it is a shallow bath trap then it would have been fine as long as the hopper was there, if the hopper is now gone then it really should go to a 50mm seal.
Adding air break to stop siphoning
- Thread starter marblerun
- Start date
Is the bath trap definitely getting syphoned, or could it be getting blown? The anti vac valve should certainly be stopping the basin creating a vacuum when draining and then pulling on the trap, or is the basin upstream on the run?
Definitely getting siphoned. The two waste pipes combine on the outside wall as seen in 1st pic. Gravity then kicks in. The basin siphon is working as I can hear it in action.
Ah OK , should have checked back on the pic, that's the issue. Given the bath waste is downstream of the basin waste run, the slug of water from the basin emptying is rushing past the bath waste at the tee - given the basin waste is also 40mm at that point, that then creates a venturi effect and a vacuum in the bath waste run, pulling on the trap. In that scenario an antivac on the basin wouldn't really help.
Normally the basin waste would be tee'd in downstream of the bath, and the basin waste is 32mm so it's a lower volume running into a larger 40mm waste pipe, that coupled with the antivac would break the vacuum in that scenario, it won't work the other way around.
The bath run will need vented.
Normally the basin waste would be tee'd in downstream of the bath, and the basin waste is 32mm so it's a lower volume running into a larger 40mm waste pipe, that coupled with the antivac would break the vacuum in that scenario, it won't work the other way around.
The bath run will need vented.
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