Condensate Drain Size - less than 32mm?

[mike2016]

I purchased a Zehnder MVHR which needs a Condensate drain. It comes with a 32mm weld or 40mm BSP adapter for the bottom of the unit. I was wondering is it possible to reduce part of the run to 22mm using Hep2o or something like that or why it needs such a large outlet, even more than my washing machine?!! Thanks.  

[MikeSharp01]

22mm sounds like loads doesn't  it but I guess the weld adapter is all about connecting simply into typical waste pipe sizes and if you do have a 22mm run you will still need to wrangle a way to connect that into the waste system somewhere. I think that I am saying perhaps best to stick to waste pipe sizes so you can get adapters, there must be small sized waste pipes out there I think the overflow from our roof tank is about 20mm but 32mm is the most common.

[Russell griffiths]

Why swap to hep when you can get solvent weld in smaller sizes, standard overflow pipe size, then you are not mixing pipe types. 

[Conor]

Building regs stipulate min of 22mm diameter for a condensing appliance so I don't see why not. 

[Marvin]

Think sometimes after a certain distance 32mm is recommended to stop siphoning. But also some appliances have anti-siphoning traps.

 

My MVHR has run fine with 22mm 4m across and 3m down to a 40mm waste for the last 4 years but I'm only moving air for 250m3 building

 

Good luck

 

Marvin 

[mike2016]

Sounds good! Many Thanks all!