Wilko58 Posted July 4, 2021 Share Posted July 4, 2021 (edited) Hi, I've been in my house since 2006 (it was built in 2001) and I frequently get a bad smell coming from the bathroom which I believe is caused by flushing the toilet which seems to empty the trap on the bath. The bath waste is in 40mm which goes to a 40mm to 50mm with a swept bend to take the basin waste and then the 50mm disappears down a void at the side of the main stack (roof vented) but not sure if it is connected to the main stack lower down (it probably is hence when the toilet is flushed the waste causes a vacuum and empties the bath trap). Edit: I should have added that running the bath tap and refilling the trap stops the smell! Anyway, my question is that as I seem to be having an issue with the bath trap emptying should I fit an AAV (on the 50mm pipe) while I'm doing the refurbishment (all pipes up to the stack being replaced)? Thanks in advance. Edited July 4, 2021 by Wilko58 Added more info Link to comment Share on other sites More sharing options...
PeterW Posted July 4, 2021 Share Posted July 4, 2021 If there is a basin on the same run then just add an anti syphon trap to that which will negate the need for an AAV on the bath if they use the same connection. 1 Link to comment Share on other sites More sharing options...
JOE187 Posted July 4, 2021 Share Posted July 4, 2021 This would definetly help as quick fix though WC should have AAv or vented to outside air! https://www.screwfix.com/p/mcalpine-1-anti-siphon-bath-p-trap-white-40mm/1606P?tc=ZB8&ds_kid=92700055281954514&ds_rl=1249404&gclid=CjwKCAjwuIWHBhBDEiwACXQYsUpd4a0KNonE8orEalBDtNnynLAMwnEY7ZaLkSE1VVlJXTJA_itYhBoCxxcQAvD_BwE&gclsrc=aw.ds Link to comment Share on other sites More sharing options...
Temp Posted July 4, 2021 Share Posted July 4, 2021 +1 Perhaps there already is an AAV on the WC and its faulty? Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 4, 2021 Share Posted July 4, 2021 (edited) 5 hours ago, Wilko58 said: all pipes up to the stack being replaced You mean all pipes connecting TO the stack being replaced? If so, then fit a strap on boss to 50mm waste and pick the bath and basin up independently, as high up as possible. Problem solved for the bath and basin then, but issue could still exist for the WC with that then having the water sucked out of the throat and the bad smells migrating to that. Do you have any idea where this soil pipe terminates / pics of stack above WC. Edited July 4, 2021 by Nickfromwales Typos Link to comment Share on other sites More sharing options...
Wilko58 Posted July 30, 2021 Author Share Posted July 30, 2021 Sorry all, I was caught up doing the preparation. I've uncovered more of the pipes and from what I can see, the main stack is 100mm pipe and appears to change to to 50mm in the loft space and is capped off with an AAV. the old bath waste was 40mm going into a T with a 32mm basin waste joining it and both going into a 50mm pipe - I thought hat joined the WC waste but it goes down into a void at the side of the 100mm pipe and I can't tell if it joins it further down or goes downstairs and outside separate from the 100mm pipe. I'm thinking of changing the AAV in the loft space (in case it isn't working) and add an AAV to the 50mm pipe - will that be a better solution? Thanks again Link to comment Share on other sites More sharing options...
joe90 Posted July 30, 2021 Share Posted July 30, 2021 It could be the AAV in the loft is “stuck” so repairing or changing would be good . As @PeterW says a trap on the basin with a built in AAV would be good. As an aside, my Bath trap is a low level one (minimum air gap) and the Bath used rarely, the water tends to evaporate in summer so I need to top it up some times. Link to comment Share on other sites More sharing options...
Wilko58 Posted August 2, 2021 Author Share Posted August 2, 2021 Thanks all. I'm installing a combined waste/bath filler which comes with an usual shaped built in trap but seems like it will work okay. Like @joe90 I don't use the bath that often and have an ensuite for showers so evaporation of the trap might also be an issue so I'll keep it topped up. I was going to fit the flap type waste to my basin which I guess will also serve as an AAV given that it could suck in air if it needed to or can/should I fit an AAV to the downpipe? Hopefully my last question on this so thanks so far. Link to comment Share on other sites More sharing options...
Pocster Posted August 2, 2021 Share Posted August 2, 2021 27 minutes ago, Wilko58 said: Like @joe90 I don't use the bath that often Same problem. When I’m in the bathroom sometimes I miss the toilet. - straight in the bath trap . Never dries out now ; but does smell a bit funny . 2 Link to comment Share on other sites More sharing options...
Temp Posted August 2, 2021 Share Posted August 2, 2021 1 hour ago, Wilko58 said: evaporation of the trap might also be an issue Leave the plug in. Relative has an empty house. With the plug in the traps seem to stay full for quite long periods. 1 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted August 2, 2021 Share Posted August 2, 2021 On 30/07/2021 at 17:31, Wilko58 said: appears to change to to 50mm in the loft space and is capped off with an AAV. Can you cut it back to the 110mm stack and fit a full sized AAV? The single 50mm one will not suffice. You could fit a 50mm T and bravo off that to 2x 50mm AAV’s to max out air intake, but you really need that AAV to be 110mm for it to be effective. Link to comment Share on other sites More sharing options...
Wilko58 Posted August 11, 2021 Author Share Posted August 11, 2021 On 02/08/2021 at 17:08, Nickfromwales said: Can you cut it back to the 110mm stack and fit a full sized AAV? The single 50mm one will not suffice. You could fit a 50mm T and bravo off that to 2x 50mm AAV’s to max out air intake, but you really need that AAV to be 110mm for it to be effective. Thanks Nick. I can't get to where the 100mm changes to 50mm but I could add another using a branch but I do have room to add an AAV to the 50mm pipe after the bath and basin wastes if I can find the right fitting. Link to comment Share on other sites More sharing options...
Nickfromwales Posted August 11, 2021 Share Posted August 11, 2021 7 hours ago, Wilko58 said: Thanks Nick. I can't get to where the 100mm changes to 50mm but I could add another using a branch but I do have room to add an AAV to the 50mm pipe after the bath and basin wastes if I can find the right fitting. Take some pics of where you can / want to connect and post them here. Link to comment Share on other sites More sharing options...
Wilko58 Posted September 15, 2021 Author Share Posted September 15, 2021 (edited) On 11/08/2021 at 17:38, Nickfromwales said: Take some pics of where you can / want to connect and post them here. Hi, Apologies once again for taking so long to reply. I've attached a pic of what I intend to do, the WC Stack has the pipe removed for clarity, the AAV for that is in the loft and only on 50mm pipe. Cheers Edited September 15, 2021 by Wilko58 Real name put in by mistake Link to comment Share on other sites More sharing options...
Nickfromwales Posted September 15, 2021 Share Posted September 15, 2021 Ideally the AAV should be above the trap height of the basin. Can you extend that 50mm pipe up alongside the SVP and terminate in the attic? Link to comment Share on other sites More sharing options...
Temp Posted September 15, 2021 Share Posted September 15, 2021 If it helps... I don't think the AAV pipe has to be straight up. Link to comment Share on other sites More sharing options...
Wilko58 Posted September 17, 2021 Author Share Posted September 17, 2021 On 15/09/2021 at 15:29, Nickfromwales said: Ideally the AAV should be above the trap height of the basin. Can you extend that 50mm pipe up alongside the SVP and terminate in the attic? I might be able to put the AAV above the trap height, depends on the space behind the WC Frame where it is going. The 50mm pipe drops down and then enters the stack below the floor level (I can't actually see it) and the WC 110mm pipe goes into stack and down a 110mm pipe but going upwards to the attic and AAV is a 50mm pipe. On 15/09/2021 at 21:27, Temp said: If it helps... I don't think the AAV pipe has to be straight up. The AAV in the picture seems to rely on the weight of the valve to keep it shut so anything other than vertical could impede the operation. Link to comment Share on other sites More sharing options...
Temp Posted September 17, 2021 Share Posted September 17, 2021 5 hours ago, Wilko58 said: The AAV in the picture seems to rely on the weight of the valve to keep it shut so anything other than vertical could impede the operation. +1 to mounted vertically. What I meant was you might be able to run a pipe horizontally then vertically up in the same boxing as the 110m soil pipe and put this small AAV in the loft as well. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted September 18, 2021 Share Posted September 18, 2021 14 hours ago, Temp said: +1 to mounted vertically. What I meant was you might be able to run a pipe horizontally then vertically up in the same boxing as the 110m soil pipe and put this small AAV in the loft as well. That’s what I suggested, as they cannot be boxed in. They need accessibility. Link to comment Share on other sites More sharing options...
Nickfromwales Posted September 18, 2021 Share Posted September 18, 2021 @Wilko58 Sorry to be asking this a bit late on, but have you proved the 110mm AAV is functioning properly / at all? Does the 50mm tee in under the 1st floor boards, or does it tee in at ground floor level? Link to comment Share on other sites More sharing options...
Wilko58 Posted October 1, 2021 Author Share Posted October 1, 2021 On 18/09/2021 at 08:59, Nickfromwales said: @Wilko58 Sorry to be asking this a bit late on, but have you proved the 110mm AAV is functioning properly / at all? Does the 50mm tee in under the 1st floor boards, or does it tee in at ground floor level? The 110mm stack only goes downwards from 1st floor and is 50mm up to the attic where the (50mm) AAV is. I didn't realise that the AAV had to be accessible which means I can't have one at all in the bathroom - the stack is still boxed in and the WC frame is going to be boxed in as well and won't be able to be taken apart without taking the bowl off the wall. Do you think I should remove the AAV in the bathroom if it's not going to be accessible? I should add that the basin waste is one of the flap type so can't dry out as there is no water in it but in effect it should also work as an AAV given that air could be sucked through it. To be honest, I haven't checked the AAV in the attic as it isn't that easy to get too but I'll change it anyway. Once again many thanks. Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 2, 2021 Share Posted October 2, 2021 Ok. That’s fine. Can you just end this by fitting a 110mm vertical stack to replace the rising 50mm? Is the 50mm currently being hidden in boxing in which you’d like to keep at a reduced profile? Link to comment Share on other sites More sharing options...
Wilko58 Posted November 1, 2021 Author Share Posted November 1, 2021 On 02/10/2021 at 08:34, Nickfromwales said: Ok. That’s fine. Can you just end this by fitting a 110mm vertical stack to replace the rising 50mm? Is the 50mm currently being hidden in boxing in which you’d like to keep at a reduced profile? Hi Nick, Sadly no, it's all boxed in and in the bedroom on the other side of the bathroom wall so unless I rip it all out it isn't accessible. To be honest, I've left the new AAV in place even though it isn't readily accessible but it is now almost level with the basin trap. I've also changed the AAV in the attic although it's still 50mm. Many thanks for your and everyone else's help. I'll now close this so no need to reply. Cheers Link to comment Share on other sites More sharing options...
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