New cloakroom waste puzzle

[sjromaine]

Just built under stairs for cloakroom. WC and basin. Need advice on waste. Nearest and only soil pipe is cast iron and through two solid walls. It's also built into an internal corner outside with no access on two sides. I don't fancy coring two walls and replacing a ground level chunk of cast for a soil pipe tee. At the mo there's a 22mm condensate from boiler in garage drilled and siliconed into this soil. What options do I have? I'm thinking of a macerator to take WC and basin waste output through 32 or 40mm and picking up the condensate pipe on the way. Expand the fitting into soil using a McAlpine bossconn. Would my condensate need a check valve as the macerator will output under pressure and could cause backflow into my boiler? Confusing. Thanks.

 

[Newboy]

Personal view is that macerators should only be used as a last resort. I'd core and replace part of the stack before I'd fit a macerator. Don't combine the condensate - doing so offers no advantage and, as you point out, could give you other problems.

A combined basin & WC macerator output can be in 22 mm (Saniflo)

 

[Madrab]

Macerators are the devil's own incarnate, unless it's used absolutely correctly, it will block. I don't know why they don't include that in their guarantee I refuse to go to them now, nasty things but that's just my experience or course
Agree with Newboy...easiest and most concise way would be to cut the cast and replace with a new section with a 2" boss. Then run the waste through the wall. You could also core the side of the cast and use a bolt on boss, bring the waste out next to it and bend through 90deg to connect to the cast.
If you wish to replace a section then to be complete make it a piece of push fit cast you replace it with.

 

[Hugh Jaleak]

Really should have planned where you were going to run the drainage before you even thought of anything else! If the new WC is to be a permanent fixture, then personally I'd be looking at a way of making a direct connection to the drain, it's worth the extra work and upheaval, and a fit and forget solution.

If you must use a macerator, (and I'm with the chaps above), it must have a dedicated, direct connection to the stack. Under no circumstances attempt to combine the outlet from the macerator with the condensate pipework, it is a recipe for disaster.