Drain for Air Con/inverter Heat Pump

[Damian35]

Hi,

I'm installing a Mitsuibishi Electric 3.5kw inverter in the Uk.

I'm intending to install a rigid solvent weld 32mm drain rather than one of those flexible things to make future cleaning easier. However, I have two options for running the drain. I could drop vertically down and connect into a kitchen waste water drain, with a trap, etc. However, given the water could sit in the trap for sometime with minimal replacement with new water from the unit drain, I could foresee additional smells from this trap.

Alternatively, I could have a 1.5m horizontal run before dropping down to a suitable point outdoors. I was thinking about a fall of 1 in 40 for the horizontal but it doesn't seem sufficient to move the modest amounts of water likely to be produced by the unit. I'm not sure what the standard fall is for an air con unit to give a useful flow of water.

Any views much appreciated on the best option for draining an air con/inverter unit.

Many thanks,

Damian

[install monkey]

the flexi drain on the unit has an id of 12mm- u can connect 3/4 overflow- running horizontal off the unit would req a 1cm per mtr fall- bear in mond you have a 3 inch head from the drip tray to where the drain exits the unit- if you go for the gravity option then stick a u bend- ideally a removable one for cleaning- only has to be shallow to create an air break- alternativly theres a non return valve u can fit- usually called a fanny trap!- dont know the correct term- but theyre usually 28-32mm connections

[monkey spanners]

Have a wallmount with about a 1.5 meter level run to outside, run the drain in 3/4 crinkly drain hose just sat in the bottom of the level trunking. Been in about 9 years now and not had a problem with it.

Don't put a trap on it or it won't drain. If you need a trap as you are going into an existing drain then make or use a standpipe like you would have on a washing machine so there is an air gap.

[Damian35]

Hi,

Thanks all for the replies and sorry for not responding sooner.

Well I'm just getting around to installing the drain. The mitsuibishi installation instructions suggest either connecting the hose from the unit to either a flexible 15mm drain or inserting it into a 30mm rigid wate. I'm struggling with space to fit a 32mm waste, so thought about using 21.5mm overflow pipe.

I know that this is a daft question but the hose from the unit is around 17mm. This can be inserted in the overflow pipe but isn't a tight fit. I'm guessing that you'd normally wrap it with Ptfe tape, etc, to get a tight secure connection? I can't see any purpose made adaptors being available. Is this for normal sort of on-site approach for these drain connections or is there something more sophisticated?

Many thanks,

Damian

[Brian_UK]

Wrap the joint in self amalgamating tape if you can't get a better fit.

[install monkey]

http://www.pumphousepumps.com/product-category/air-conditioning/adaptors/cassette/

[monkey spanners]

http://www.ryanairconspares.com/air-conditioning-flexible-condensate-drain-pipe-adp-93-16mm-i-d#.UwKf8IX90jo

Crinkly drain hose, the uncrinkly sections are usually a tight fit on the spigot on the hose from the unit.