# Forum Home Renovation Heating & Cooling  Air con hole size

## Bros

To all those who have installed split system Air cons how bit is the hole that takes all the ref piping, consensate drain and power cable.  
I will be installing mine but I will get a fridge mechanic in to run the lines and evacuate the system as I don't have the gear.

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## Brian7886

um i usually make mine about 70mm diameter if im hole cutting.  
through brick id typically take out a 1/4 to a 1/3 of a brick width.

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## Bros

> through brick id typically take out a 1/4 to a 1/3 of a brick width.

  You take out the brick rather than use a hole saw?

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## Marc

Don't do like that guy who cut out a hole in the wall the same size as the evaporator unit.  :Smilie:

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## Bros

> Don't do like that guy who cut out a hole in the wall the same size as the evaporator unit.

  I never thought of that, were you advising him. :Wink:

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## phild01

I have done a couple and I reckon they were about 75mm dia, though if things were tight you could do it a bit less.

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## Bros

Supplementary question is can the piping come out anywhere along the evaporator unit as I want to do some of the work before hand like climb into the ceiling and drag some cable across and lift a sheet of iron so I can drill down through the top plate.
I think I need to have my head examined to putting an Air con in in summer. 
Oh the unit is a Mitsubishi Heavy Industries 3.5Kw unit

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## Brian7886

> I have done a couple and I reckon they were about 75mm dia, though if things were tight you could do it a bit less.

  i use 70mm. Real small air cons with small pipe sizes i would use 63mm.

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## Brian7886

> You take out the brick rather than use a hole saw?

  no holesaw through brick. I just drill a few 10mm holes in the brick and take out the size piece i need with a chisel in the hammer drill.  
3.5kw MHI, through gyprock/cladding etc i would cut a 63 or 70mm hole.  
What i would also do is make the bottom of the interior hole the top of my exterior hole. That way the piping and most importantly the drain, is running down hill.

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## Bros

Brian I must have made my post confusing what I want to know is can the hole be anywhere in the width of the evaporator unit or does it have to go to a particular place?

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## Brian7886

> Brian I must have made my post confusing what I want to know is can the hole be anywhere in the width of the evaporator unit or does it have to go to a particular place?

  idealy on the right hand side so the pipes (that are on the indoor unit) go through the wall with connections on the outside. You can however go out the left hand side and join your pipes behind the evap. Going out the middle of the unit is a mission as the flared joins will be in the wall.  
A MHI (which are the most common units i sell) should have a marking on the wall plate (that you fix to the wall to hang the head on) for where the hole can be. Pretty much on the right hand side of the wall plate it has a 1/4 circle kind of cut out in the bracket, thats roughly where it should be made

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## Brian7886

i just read your post. If you are taking pipe work through the ceiling, i would suggest bringing the pipes in the left hand side of the unit and joining them in the back of the indoor unit (out of the box the unit will have the pipes bend into the back of the unit already).  
Drill the top plate out, cut your hole on the left side and feed the pipes down the cavity and out the left hand hole. Unless that part of the roof is easy enough to get to where you could drill the right side and feed the tails (what we call the pipes on the indoor unit) up the wall through the top plate

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## Bros

No Brian it is back to back through the wall what I want is the whole evaporator is 798mm long what I want to know where on the 798mm can the external hole be drilled as I want to come through the top plate with the cable only. I want to do some preparatory work before I get the unit. The condenser will be on the ground under the evaporator simple installation except for where the piping hole goes.

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## Bros

Brian don't worry as I finally located an installation manual.

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## Brian7886

Ok well ideally, make your hole roughly 60-70mm (to centre of hole) from the right end of that 798. Sorry i thought u had the unit etc  
Sent from my iPhone using Tapatalk

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## Bros

Thanks Brian

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## PlatypusGardens

> Don't do like that guy who cut out a hole in the wall the same size as the evaporator unit.

  
Hahahahaha who did that?

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## Bros

> no holesaw through brick. I just drill a few 10mm holes in the brick and take out the size piece i need with a chisel in the hammer drill.  
> 3.5kw MHI, through gyprock/cladding etc i would cut a 63 or 70mm hole.  
> What i would also do is make the bottom of the interior hole the top of my exterior hole. That way the piping and most importantly the drain, is running down hill.

  Well I didn't quite put that much slope in it about half a hole. What a mongrel of a job I think it is a toss up between appliance repair and air conditioning installing. Drilled the hole and what did it find but a cyclone bolt, well with a bit of work that was cut off as I have heaps, tomorrow morning early up into the roof to run some cables.

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## Brian7886

thats plenty of slope mate. I just typically do that, as im the poor prick that has to attend leaking drains, and theres nothing worse than trying to cut the hole lower later on. So i just make sure i have a good fall from the word go

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## Marc

> Hahahahaha who did that?

  Early days of split systems, DIY owner installed a wall aircon 30 years earlier and decided to replace it with a split one and do the install himself once more. Fortunately a cladded wall not brick ...  :Smilie:

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## PlatypusGardens

> Early days of split systems, DIY owner installed a wall aircon 30 years earlier and decided to replace it with a split one and do the install himself once more. Fortunately a cladded wall not brick ...

    :Rofl:

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