Macerator Waste Pipe

[mistertrubbs]

I am about to fit a Saniflo which discharges into a 22mm pipe.The reccommendation is to use either copper or rigid pvc with glue weld joints for the outlet and not plastic.If I have a coil of 22mm plastic I can go from the macerator to the soil stack in sweeping bends without a single fitting.Can anyone tell me why this is wrong?

 

[denso13]

Probably work but the wall of the pipe is relatively thick therefore the bore might be too small. You absolutely sure you need a Saniflo?

 

[mistertrubbs]

Thanks for the reply Denso but macerator is the only way and I have even bought the Sanibest Pro light commercial macerator after reading all the horror stories in the hope that it can cope with the odd inappropriate item (from guests).Should I run it in 25mm mdpe,would that be ok? Also,since I'm fitting a concealed cistern,is a larger tank of water better than a smaller one with a macerator?

 

[Fluffster]

Run it at the maximum bore you can achieve. We never run in 22mm even though it states the machine can handle it, we use minimum 32mm with long bends. 25mm mdpe would be difficult to connect to the soil stack and again it is quite thick so the nominal value is tight.

Pete
ps the size of the cistern is regulated to a maximum flush of 6 litres

 

[mistertrubbs]

Thanks Fluffster,I feel like I'm getting somewhere now and I will,of course,stick to the regs as regards the 6 litre cistern.I was just curious.
One other thing that I've read is that if there is a long drop at the end of the pumped waste,an air admittance valve should be fitted to avoid syphonage which could affect the macerator's non-return valve.I'm presuming the larger diameter pipe helps and if I stepped it up to 40mm at the drop that should work ok.I really don't have space for a durgo.Thanks again for the benefit of your experience.

 

[Nige F]

.I'm presuming the larger diameter pipe helps and if I stepped it up to 40mm at the drop that should work ok.I really don't have space for a durgo.Thanks again for the benefit of your experience.

You will need a 40mm AAV - they are available

 

[Fluffster]

Syphonage is more likely if you have a drop of say 10m+ as this can cause a vacum and pull fluid etc from the unit. Always best to enlarge the bore on the run as soon as possible so go with the 40mm on the vertical. How long is your drop and do not forget to use a couple of 135d bends at the end. If the drop is over 10m there are 40mm air admittance valves available see link below however we have never had to use them as there is an air gap left when the pump cuts out.

http://www.screwfix.com/p/floplast-air-admittance-valve-32-x-40-x-50mm/42968

Good luck Pete