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ChatterBank1 min ago
Wc Plumbing.
11 Answers
Scenario : Upstairs En-suite created comprising WC, WHB and shower. Ensuite at front of house....drainage away at side/rear of house (Victorian mid-terrace) therefore Macerator fitted with discharge pipe vertical into attic and falling away to connect with existing SVP.
Problem : 1. Macerator fires up at WC flush but Shower-tray seems to backfill through gravity.
2. Occasional 'blowing-out' of WHB trap when Macerator working.
3. Macerator *not* working when shower in use; needs to have third-party to press manual button to prevent tray over-flow.
4. Something seems to be leaking somewhere as clean-water was dripping through hall ceiling yesterday.
I am seriously considering junking macerator and trying to place a gravity run and although I am au-fait with the Building Regulations and what they have to say about domestic drainage, wondered if there is any 'practical' reason why a WC outlet cannot be connected to a smaller diameter pipe.
Having an internal vertical 110mm svp is not an option in this area and the floor-joists (naturally!!!) are at right-angles to the run required. I have sufficient space under the house for a smaller diameter pipe to run vertically from the En-suite to below ground floor level and then discharge into the existing SVP.
Any help, advice or practical suggestions will be gratefully received.
Problem : 1. Macerator fires up at WC flush but Shower-tray seems to backfill through gravity.
2. Occasional 'blowing-out' of WHB trap when Macerator working.
3. Macerator *not* working when shower in use; needs to have third-party to press manual button to prevent tray over-flow.
4. Something seems to be leaking somewhere as clean-water was dripping through hall ceiling yesterday.
I am seriously considering junking macerator and trying to place a gravity run and although I am au-fait with the Building Regulations and what they have to say about domestic drainage, wondered if there is any 'practical' reason why a WC outlet cannot be connected to a smaller diameter pipe.
Having an internal vertical 110mm svp is not an option in this area and the floor-joists (naturally!!!) are at right-angles to the run required. I have sufficient space under the house for a smaller diameter pipe to run vertically from the En-suite to below ground floor level and then discharge into the existing SVP.
Any help, advice or practical suggestions will be gratefully received.
Answers
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Some very strange things going on here, Jack.
Is your shower waste connected directly to a dedicated inlet in the macerator? If so, there should be a non-return valve. It may be stuck open.
Syphonage from the WHB would easily be cured by fitting it with an "Anti-Vac" trap.
If the shower waste fails to start the macerator up, then it's most likely the float/pressure switch at fault. It should sense added water from ANY source. Usually, the weight of water triggers the electrical switch.
I've only fitted a couple of these in my life, and only then because I was asked to. My preference would have been for a gravity system... even though it meant a bit more cost/work.
Building Regs allow a 75mm discharge pipe on ONE WC only in the line... BUT, only if the pan spigot is less than 80mm........... I can't say I've ever seen one, except on a 100 year old Victorian pan!
The leaking fresh water needs investigating obviously. It's difficult to imagine how it's relevant here though.
That's probably enough for starters. Main questions: how are the WHB and the shower connected to the macerator?
Is your shower waste connected directly to a dedicated inlet in the macerator? If so, there should be a non-return valve. It may be stuck open.
Syphonage from the WHB would easily be cured by fitting it with an "Anti-Vac" trap.
If the shower waste fails to start the macerator up, then it's most likely the float/pressure switch at fault. It should sense added water from ANY source. Usually, the weight of water triggers the electrical switch.
I've only fitted a couple of these in my life, and only then because I was asked to. My preference would have been for a gravity system... even though it meant a bit more cost/work.
Building Regs allow a 75mm discharge pipe on ONE WC only in the line... BUT, only if the pan spigot is less than 80mm........... I can't say I've ever seen one, except on a 100 year old Victorian pan!
The leaking fresh water needs investigating obviously. It's difficult to imagine how it's relevant here though.
That's probably enough for starters. Main questions: how are the WHB and the shower connected to the macerator?
Giving this some more thought Jack................... could the macerator outlet run vertically down to downstairs (probably only 20mm pipe needed (see manual for this - in some instances a larger diameter may be needed - maybe 32mm).
Once it's downstairs, the pipework could be run under the floor to a discharge connection at the back of the house.
For a conventional gravity discharge, many times I've run a 110mm soil pipe along the downstairs ceiling (boxed in). With doorways etc, I realise this could be a tortuous route though.
I assume you have a suspended floor downstairs. Is a standard 110mm run completely out of the question though? Floor voids are usually plenty deep enough for this.
Once it's downstairs, the pipework could be run under the floor to a discharge connection at the back of the house.
For a conventional gravity discharge, many times I've run a 110mm soil pipe along the downstairs ceiling (boxed in). With doorways etc, I realise this could be a tortuous route though.
I assume you have a suspended floor downstairs. Is a standard 110mm run completely out of the question though? Floor voids are usually plenty deep enough for this.
Shower fitted to lower Macerator inlet; in fact, my low profile shower tray had to be raised to ensure sufficient fall to trigger motor....but this still only happens infrequently.
WHB fitted to higher inlet; this usually activates motor.
Macerator itself is sited 'within' the wall in the original door-opening itself (bloody silly arrangement, if you ask me) so almost impossible to examine without breaking through the plasterboard in the hallway outside the Ensuite.
The WC has only, and will ever only, deal with 'water'.
I understand what the BR state, but wondered if a 'Heath-Robinson' arrangement would work, whilst not strictly being to 'code'.....:o)
WHB fitted to higher inlet; this usually activates motor.
Macerator itself is sited 'within' the wall in the original door-opening itself (bloody silly arrangement, if you ask me) so almost impossible to examine without breaking through the plasterboard in the hallway outside the Ensuite.
The WC has only, and will ever only, deal with 'water'.
I understand what the BR state, but wondered if a 'Heath-Robinson' arrangement would work, whilst not strictly being to 'code'.....:o)
We have original ceiling features and they would be compromised by any 'boxing-in', similarly there is no suitable corner in which to lose a vertical svp, either.
As this is a former guesthouse, we already have some lead pipework runs cut into the bedroom floor joists. It wouldn't be too much work to strip these out and replace with pvc pipes connected either directly to the sanitaryware or to the macerator.
The main concern being the reduction from the 110mm WC spigot to, almost immediately a 32mm pvc pipe. You're correct about the suspended floor, we have about 800mm, it's simply the logistics of getting what's upstairs downstairs....
As this is a former guesthouse, we already have some lead pipework runs cut into the bedroom floor joists. It wouldn't be too much work to strip these out and replace with pvc pipes connected either directly to the sanitaryware or to the macerator.
The main concern being the reduction from the 110mm WC spigot to, almost immediately a 32mm pvc pipe. You're correct about the suspended floor, we have about 800mm, it's simply the logistics of getting what's upstairs downstairs....
Yes, a very silly installation as you say. The macerator connections do sound completely normal. I still suspect a fault somewhere in the float switch.
In fact, installation instructions do insist that there should be an access panel, one that is larger than the unit so that it can be removed for maintenance.
If you plan to keep the unit, I'd strongly advise creating access via the plasterboard. A very simple operation usually. I'm sure you're familiar with the sort of thing I'm talking about. Until the unit can be got at, we're just guessing.
If only "water", then certainly a 38mm run is all that's needed. You know this would be against regulations though............. but sometimes, one has to be "creative".
After all... a Gents urinal needs only a 38mm diameter waste pipe. At the risk of being indelicate, there is a female version I think (don't quote me though. I'd need to do some research.)
The main problem with fitting a 38mm run to a WC would be when it's flushed. The volume of water could easily overload the pipework's capacity to remove it........... then the pan overflows.
Altering the amount of water delivered per flush could overcome that though. (Lower the float level in the WC cistern... and reduce the "travel" on the operating cable/lever to deliver less water per flush.)
I don't see why that wouldn't work ............ just don't let any guests use your loo though.
In fact, installation instructions do insist that there should be an access panel, one that is larger than the unit so that it can be removed for maintenance.
If you plan to keep the unit, I'd strongly advise creating access via the plasterboard. A very simple operation usually. I'm sure you're familiar with the sort of thing I'm talking about. Until the unit can be got at, we're just guessing.
If only "water", then certainly a 38mm run is all that's needed. You know this would be against regulations though............. but sometimes, one has to be "creative".
After all... a Gents urinal needs only a 38mm diameter waste pipe. At the risk of being indelicate, there is a female version I think (don't quote me though. I'd need to do some research.)
The main problem with fitting a 38mm run to a WC would be when it's flushed. The volume of water could easily overload the pipework's capacity to remove it........... then the pan overflows.
Altering the amount of water delivered per flush could overcome that though. (Lower the float level in the WC cistern... and reduce the "travel" on the operating cable/lever to deliver less water per flush.)
I don't see why that wouldn't work ............ just don't let any guests use your loo though.
Quite! :o)
It's a private shower-room......and means I don't have to walk to the other end of the house for a nocturnal 'visit'...which also means going up and down half a flight of stairs in either direction.
That was my thought that the smaller diameter pipework arrangement might be overwhelmed by the WC flush, although am I mistaken in thinking that a macerator must create a similar amount of pressure via its' power-assisted flush?
Now you have reassured me that the idea is not necessarily utterly impractical, even if it is a little unusual, I'll see if I can have a word with a local plumber.
Thankyou for your thoughts and help. :o)
It's a private shower-room......and means I don't have to walk to the other end of the house for a nocturnal 'visit'...which also means going up and down half a flight of stairs in either direction.
That was my thought that the smaller diameter pipework arrangement might be overwhelmed by the WC flush, although am I mistaken in thinking that a macerator must create a similar amount of pressure via its' power-assisted flush?
Now you have reassured me that the idea is not necessarily utterly impractical, even if it is a little unusual, I'll see if I can have a word with a local plumber.
Thankyou for your thoughts and help. :o)
Ok Jack. I'd love to know how you get on.
Macerators pump in a sealed system. Pump pressure just shoves it all down the outlet pipe. It can't come out anywhere (except at the end of course.)
WC flush systems are "open- vented". Hence possible over-filling of the pan if the outlet is "squeezed". No problem though. As I said in the previous post, modern WC flush systems can be easily doctored to reduce the quantity of water.
You still have your two options though. Create an access panel to get at the macerator... or go down the reduced soil pipe route for the WC.
Macerators pump in a sealed system. Pump pressure just shoves it all down the outlet pipe. It can't come out anywhere (except at the end of course.)
WC flush systems are "open- vented". Hence possible over-filling of the pan if the outlet is "squeezed". No problem though. As I said in the previous post, modern WC flush systems can be easily doctored to reduce the quantity of water.
You still have your two options though. Create an access panel to get at the macerator... or go down the reduced soil pipe route for the WC.
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