Macerator causes spyhoning of ground floor water traps!

[Houlther]

When the macerator flushes it causes the water in the traps for the sink and washing machine to spyhon out. I was think of installing something like a anti-syphon p trap for the washing machine and sink. The macerator which I have on the 1st floor.

I saw mentions of an AAV, but not sure if I could use this instead of the anti-spyhon p traps

The pipe running from the macerator down to ground floor is a 36mm. There is a sink that has a 36mm running to the inlet of the macerator. This doesn't go into a soil stack. Seems a 36mm pipe has been extended from ground to first floor where the macerator discharge is connected to

 

[Madrab]

The macerator should never have been joined to the other grey water waste system like it has. High risk of pumped toilet waste backing up into the washing machine and sink. As it's a pumped system for toilet waste you really want it separated. Is it a basin (not sink), that's in the same location (bathroom?) as the macerator that's connected to it?

Not what you want to hear I'm sure, but it really should be set out on it's own run to the soil stack and then onwards to the combined drain/sewer.

Sink and washing machine waste run is 40mm? Not 36mm (32mm)?

 

[Hugh Jaleak]

As above, Macerator must have a dedicated outlet run, complying with Manufacturers instructions, directly to a soil pipe or drain.

It cannot have any other appliances connected to the pumped run, you are very lucky not to have received a fountain of minced waste from the sink or washing machine drain!

 

[Houlther]

The macerator should never have been joined to the other grey water waste system like it has. High risk of pumped toilet waste backing up into the washing machine and sink. As it's a pumped system for toilet waste you really want it separated. Is it a basin (not sink), that's in the same location (bathroom?) as the macerator that's connected to it?

Not what you want to hear I'm sure, but it really should be set out on it's own run to the soil stack and then onwards to the combined drain/sewer.

Sink and washing machine waste run is 40mm? Not 36mm (32mm)?

Yes, there is a basin connected to the macerator inlet. The sink in the image for ground floor is actually a basin.

 

[Houlther]

As above, Macerator must have a dedicated outlet run, complying with Manufacturers instructions, directly to a soil pipe or drain.

It cannot have any other appliances connected to the pumped run, you are very lucky not to have received a fountain of minced waste from the sink or washing machine drain!

I had a look at the model and it seems that it can pump vertical. Wondering if I could have the pipe go into the roof, but unsure how this would exit the roof since it is an apex. Removing the floorboards seems to be a pain as they have be stapled onto a sheet of ply which sits on the joist.

 

[bernardgreen]

Removing the floorboards seems to be a pain

Becoming sick due to sewage in the washing machine and/or the basin can be gut rottingly painfull

 

[just pumps]

It should never had been installed like that in the first place regardless of own pipe run or shared pipes.

 

[Houlther]

Understood. At the ground floor between the basin and washing machine there is a toilet which has its own soil pipe that runs to the sewer. Could the macerator discharge be diverted here using the wc pan with boss adapter (image below). This avoids using the grey water pipe and syphoning of the traps

 

[Madrab]

Yes, a much safer and more acceptable solution. Albeit the boss is strictly speaking only there to be used as a vent but we all know they are used as a waste connection for other outlets.

I suppose the other question there would be would be why a proper stack wasn't just taken up to the upstairs bathroom in the first place?

 

[Houlther]

Out of curiosity would the boss be used as a vent?

Restriction on path the stack could have taken and work involved so this is how someone had plumbed it

 

[Madrab]

Sometimes if a toilet is on an extended run or more then one toilet on the same run, the head of the run might need a vent to avoid the traps being pulled. Sorry just had a look at your pics and you are referencing a soil pipe socket boss adapter and not a WC pan connector with boss, I presumed you meant something like this

90° Bend Adjustable Length Rigid WC Connector with 1¼" Universal Vent Boss | McAlpine Plumbing

Optimize your toilet installation with the 90° Bend Adjustable Length Rigid WC Connector, featuring a 1¼ Universal Vent Boss for versatile use.

mcalpineplumbing.com

I understand why the stack may not have been taken up but there is always a way and it would have been by far the most preferred option rather than using a jobby masher. Terrible things so they are IMO.