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Originally Posted by MicahWes

I can see that, but that isn't my point. If they used a tremendous amount of fuel in both summer and winter before the mini-split, they are still going to use almost as much now, maybe a little more if they had an unvented LPG heater before. Why would you spend, I'm guessing, nearly <edit> on an installed mini-split when you should get insulated garage doors with that money instead?

Because the cost to BTU ratio of propane is insane compared to the cost to BTU ratio for minisplits.

Also, because air sealing a garage with an unvented heater is the worst thing you can do. The only thing keeping those people from dying is the high ventilation rate of a garage.

I can see that, but that isn't my point. If they used a tremendous amount of fuel in both summer and winter before the mini-split, they are still going to use almost as much now, maybe a little more if they had an unvented LPG heater before. Why would you spend, I'm guessing, nearly 3K on an installed mini-split when you should get insulated garage doors with that money instead?

It,s a garage.

I know this is an old post, but how come no one really made any comments about the previous fuel usage in this space? If they used $1500 of LPG for heat, probably using an unvented heater, then they were losing a lot of heat. It doesn't seem possible to burn that much LPG with a single wall heater in one season. If they doubled their electric bill with a one-ton window unit AC, then they are gaining a tremendous amount of heat in the summer. This electric usage also seems impossible, unless they have a VERY small "normal" electric bill for their home. Why will this install pay them back anything really, unless they tighten the space up?

Originally Posted by auwing

There is no minimum line set length on a M series Mitsubishi units.
Mitsubishi makes a 3 pole switch part number TAZ-MS303 for an indoor service switch and its up to local code.

The TAZ-MS303 is often full of "un-obtainium" and is simply the overpriced version of the Leviton MS303-DS (the latter is less expensive and more easily obtainable). Just sayin'

There is no minimum line set length on a M series Mitsubishi units.
Mitsubishi makes a 3 pole switch part number TAZ-MS303 for an indoor service switch and its up to local code.

We are Mitsubushi Diamond Contractors in our area. Those wall brackets give acceptable clearance, good looking job. Put a lot of these in.

Good work

That is funny. We sometimes use the 3-pole switches when we have to.

Originally Posted by DeltaT

You must break all three wires between the out door unit and indoor unit to meet code, if it applied in your area. There is a special 3 pole double throw switch that can be purchased for this requirement. I forget who makes them but they are easy to find.

One conductor is used as the info transmitter and that is where the error codes start..if that switch point is not solid. Also, the starting or disconnecting of the power to the unit and/or the inside switch should be done in a specific order in order to lessen the chance of getting an error code.

I beleive that all of the inside switches should be made before powering up the outside unit first.

Code in most places is the switch must be visible from the fan unit, and within 50' of it. That pretty much makes it have to go inside the home. I read a post on an electrical site where the electrician would actually cover up the switch with sheetrock (Ha ha...!) Here's a cut-n-paste pic from the Mitsubishi Installation manual (with my comments added).
The Levitron switch is about $44 on Amazon.


This is what the electrician actually said... Click here for the web post

Another mactip of the day! Here is what I do when wiring mini split ac's during the rough in of a new house or addition. Either like I mentioned about running the feed thru the interior switch, or.... sometimes I just run 14-3 control cable in and out unspliced thru one of those adjustable depth single gang boxes that I normally use for granite countertop rough in to ensure the depth gets correct. Remember it is one continuous run of 14-3 in and out of the same switch box, with the proper length folded up inside the box. Next step, carefully mark the exact location of the box on your plans, how high and how many inches from the nearest corner. Next and best part- adjust the box so it doesn't stick out from the framing at all. leave a note for the drywall guy to leave it like that and bury over it with his wallboard. Trim out the house as usual, put a lockable disco on the outside at the compressor so a tag out, lock out can be performed and it will shut all power to the inside fan units. (good enough for me ) . At final, if the inspector throws a fit about where is the fan disco, blame the drywall guy and open up the wall where the switch box is. Say something derogatory about drywall hangers, and explain that if you only saw the box that they obviously buried, you never would have forgotten to install your thirty five dollar three pole switch to cut all lines to the 2 amp fan coil.........................

I'll bet they're gonna hang out in that garage and drink beer.

Nice, clean work!

Originally Posted by monkeyspanners

Nice install!

Have found switching the control wire will cause problems over time, theres no current but the voltage ranges up and down to about 70v i think, from both the indoor and outdoor boards so it doesn't take much of a resistance to alter or stop the signal.

What we have done in the past is run power from the outdoor disconnect to a switch by the indoor unit and then back out to the outdoor unit, that way either switch will remove all power from the system and you are not switching the interconnecting wire which the systems were never designed to have happen.

Ha, Jon, never seen anyone do that here.....

Nice install!

Have found switching the control wire will cause problems over time, theres no current but the voltage ranges up and down to about 70v i think, from both the indoor and outdoor boards so it doesn't take much of a resistance to alter or stop the signal.

What we have done in the past is run power from the outdoor disconnect to a switch by the indoor unit and then back out to the outdoor unit, that way either switch will remove all power from the system and you are not switching the interconnecting wire which the systems were never designed to have happen.

You must break all three wires between the out door unit and indoor unit to meet code, if it applied in your area. There is a special 3 pole double throw switch that can be purchased for this requirement. I forget who makes them but they are easy to find.

One conductor is used as the info transmitter and that is where the error codes start..if that switch point is not solid. Also, the starting or disconnecting of the power to the unit and/or the inside switch should be done in a specific order in order to lessen the chance of getting an error code.

I beleive that all of the inside switches should be made before powering up the outside unit first.

How is that working out for you guys, the service switches at the indoor unit. I always thought that the disconnect was supposed to be between the main power line and the outdoor unit, since the outdoor unit feeds power to the indoor unit.

I heard that if you interrupt power between the two units you will get error messages when you turn the power back on, but if you kill power upstream from the outdoor unit, you will not have any problems.

Are you guys getting any error messages?

-chris
aec.us.com

It is nice how you kept it up off the ground.

I notice Mitsubishi's installation instructions they say to insulate the condensate drain. Does anyone really do that or know why in the world do you need to?

Most codes should not require a service switch for the indoor section because the wiring going from the outdoor unit to the wall mount is a control circuit. I do understand that it is line voltage.

Originally Posted by sgagne199

Just curious if you guys out there are installing service switches at the indoor units with there ductless splits? I work with a master electrician that insists they must be there. We have been using white or ivory 2p1t switches indoors with old work elec. boxes.

I have been. Depends on what your local electrical inspector wants according to my experience. All the ones I've talked to said they are suppose to be there plus if the manufacturer calls for one then it should be there.

Baha no

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Just curious if you guys out there are installing service switches at the indoor units with there ductless splits? I work with a master electrician that insists they must be there. We have been using white or ivory 2p1t switches indoors with old work elec. boxes.