Macerator

[ppppenguin]

I have friends who have one that's worked perfectly well for years in their downstairs loo. I suspect it comes down to correct installation and following the rule that nothing except p*ss, sh*t and bog roll should go into the pan.

[Stockden]

We have two, both of them from the "Sani" range. One of them (a Sanivite) takes the flow out of the kitchen sink and pumps it up (yes up -it's all part of the fun of living on the side of a hill. Not only are both upstairs and downstairs at ground level but the kitchen sink is about on a level with the septic tank). The other (sanivite iirc) deals with the downstairs loo.

I've heard all the stories, watched the videos and read all the amusing (and not so amusing) web posts prophesying immediate and catastrophic unpleasantness but all I can say is that both devices have worked reliably and without smell or mess since we moved here 4 years ago. That said, I have experience of sorting out the aftermath of yacht "heads" disasters so I'm not complacent and we take care over what goes into them. The loo has a sign on it that reads:

"Warning - This toilet is fitted with a macerator. Please do not put anything unusual into it. In particular no sanitary towels, wet wipes, cotton buds, food, kitchen towels, metal, wooden or plastic objects, string, sealing wax, cats, small children or anything at all really. Failure to observe this rule will suddenly make things unpleasant for everybody."

so far that (and making sure that visitors "go" upstairs has worked well.

The bottom line (sorry) is that there are places where there is no other alternative. If they're properly installed and the user avoids the modern habit of using the toilet as a disposal system for anything and everything you'll be fine.

Hugh

[boater sam]

Our company were main agents for all the macerators sold in the UK, fitted to many to count and had no problems, re-installed far too many badly fitted by others.

Golden rules,

1) Discharge pipe should go as high as necessary as near to the unit as possible.
2) From that high point on it should fall all the way to the soil connection without any dips or rises.
3) If 22mm copper is used, deburr inside of pipe cut completely.
4) If using 21.5mm plastic ( prefered ) use solvent weld only and ensure no excess in fittings.
5) No elbows anywhere, use bends only. We used Marley 2 piece adjustable o/flow bends everywhere. (other makes available etc. Use minimum number of fittings possible.
6) If run is overly long, consider using Blue polyE pipe and compression fittings, but properly supported. Mark it as "soil" at regular intervals. Or even 32mm pipe  ***but not on the rising section***
7) Tap into soil stacks with proper strap on bosses and reducer, even on cast iron and pitch fibre,  provides an access to vacuum out pipework.
8) Disable dual flush on cisterns
9) Advise users just how expensive it will be to send an engineer with all the sanitary equipment, to unblock and clean out if the wrong things are put in the loo.
 
Properly fitted and used not abused there will be no problems. We constructed hundreds of en-suites and facilities for disabled where all the waste water was pumped.

[ppppenguin]

I've read the installation notes for some of the units and mostly agrees with what Sam says. Always solvent weld, never push fit. Definitely go up before going across and avoid sharp elbows. I avoid elbows on ordinary gravity sink wastes etc. Some suggest using pairs of 135 degree bends rather than 90 degree bends but not always feasible. I would consider fitting tees at critical point with end stops for rodding.

Any problems with using 32mm or even 40mm pipe for the whole run, even if it's fairly short? Seems less likely to block than 21.5mm.

This may appeal to some: https://www.youtube.com/watch?v=eOwven0Rt94

Better version: https://www.youtube.com/watch?v=kbZsVd7j7l4

[boater sam]

Large bore pipework is fine, but not on the vertical rise. The volume of water in the pipe is greater than the volume of the box, so when any service is due there is far too much water to get rid of without flooding the place. Also there is the question of inertia getting the vertical pipe to commence flowing at a velocity to carry the waste, the pumps are not displacement pumps but impellers and it seems to make a difference. 22mm pipework on the rise is prefered.
I could cite an installation in a large shopping mall where there was around 40 metres of 104mm pipe falling the wrong way concealed in the ceiling. When the box was opened, releasing the non return valve, to unblock the machine ( fitted stupidly in a baby changing loo so full of nappy liners ) The s**t was everywhere!

[ppppenguin]

For a 2m rise and 4m horizontal I guess that 22mm all the way wouldn't be a problem as it's well within the capability of a macerator. Or is it still better to go up to 32mm or 40mm when the pipe goes horizontal?

[boater sam]

2 up and 4 out is a breeze for most macerators.
With a complete bathroom, loo, bath, & basin, running into a Saniplus we often did 4m vertical, 10m falling slightly to a 7m drop to ground drain. That's a 1st floor installation, pipework through roof space and down externally to a drain connection. Usually in council property with only a ground floor bathroom, no soil stack, and all on 21.5mm plastic overflow pipe, no problem.
If the falls are right there is really no need to go up in size on a domestic installation.

[pwdrive]

If not already planned, a full bore shut off valve in the discharge pipe close to the pump unit plus a suitable rodding point just in case.

Not a direct comparison to your proposal Jeffrey but I have a small float pump that pumps the effluent from the septic tank up to a manhole up the top of the garden which serves two soakaway drainage fields, 32mm blue pipe all the way, non return valve fitted near the top of the pump's vertical riser, from then on it's a gentle slope upwards to the above mention manhole, it about a 30 meter run all told, it gushes out the other end plenty.

Lawrence.

[ppppenguin]

OK, if I end up doing the job it'll be 21.5mm overflow pipe all the way. The only snag is that I can't see any swept right angle bends. Only elbows and 45 degree bends.

http://www.screwfix.com/c/heating-plumbi...=cat831604&productdiameter=21_5_mm

If I've got to go out through a wall and then turn to run along the wall I can't do it with 45 degree bends and elbows aren't recommended. So what do I do?

Also need to find a stop end (removeable) if I want a rodding point.

[pwdrive]

If you're feeling flush you could always go 22mm copper, stuff/fudge/mate plastic outlet pipe from the macerator to 22mm copper (22mm to 28mm coupler, plastic pipe stuffed up the 28mm end with plus some builders friend?) use a couple of 28mm to 22mm reducers and a 28mm swept bend for the right angles, no problem getting a shut off valve, swept Tee in the line with a compression stop end for rodding with a flexible wire, maybe insulate on the external run, all soldered except for the shut off valve.

Lawrence.