Mini Split on the Roof?

[Jack Olsen]

I've started thinking about better ideas for heating/cooling in my garage. One thought was to add a mini split unit. But I was wondering, since I don't really have any ground space to set the thing, if it's possible to put the 'outside' unit up on the roof?

Along the same lines, are there roof mounted units for a ~500sf structure that are affordable? Do any offer both heat and cooling?

 

[JakeKohl]

I've started thinking about better ideas for heating/cooling in my garage. One thought was to add a mini split unit. But I was wondering, since I don't really have any ground space to set the thing, if it's possible to put the 'outside' unit up on the roof?

Along the same lines, are there roof mounted units for a ~500sf structure that are affordable? Do any offer both heat and cooling?

Yes, and yes. You'll need to get a little creative with the roof mounting bracket (me thinks you'll have no trouble there). They do have heat pump units and, although I powered them up only recently, I have two 18k BTU LG mini-splits and they are performing exceptionally well in cooling mode. My garage is well insulated with insulated garage doors and 24 x 36 in dimension. The 18,000 BTU unit will cool it from 84 degrees to 74 degrees in about 20 minutes. It also should be capable of offsetting the temperature loss through the un-insulated slab in the winter to maintain a comfortable temperature.

A couple of things to note, the outdoor units are extremely quiet but they do transmit some vibration/humm through their mounting structure. Outside, I can carry an easy conversation within three feet of the discharge of the outdoor unit but I can hear them inside the building when either one has the compressor on high. Mine are wall mounted on the exterior. Also, some units require a oil retention loop (usually an "N" shaped bend) in the refrigeration linesets when the compressor is mounted above the indoor unit.


Here are a couple of pictures - one showing my upstairs office indoor unit (mirror finish on the face), and a second of the outdoor unit installation (slightly before I finished up the install). I rely on these for heat and cooling in both the 2nd floor and garage areas.


DSC_3602 by Team Seacats, on Flickr


DSC_3020 by Team Seacats, on Flickr

 

[pseudorealityx]

What Jake said. You can find neoprene vibration isolators for these small condensing units. That should kill a lot of the vibration.

 

[Stuart in MN]

In addition to power for the condensing unit itself, you also need to have a 120vac convenience receptacle located within reach of the condensing unit, for maintenance purposes (in case a repairman needs to plug in a light or a drill or something.)

There may also be a rule about having a safety railing around a rooftop mounted unit, but I'm not sure on this...I know we have to do it for some commercial projects here, but it depends on the size of the roof and/or how close the unit is mounted to the edge. I don't know if it applies to residential installations, and it may only be a local requirement. At any rate, it's something worth asking when you talk to your local HVAC guy.

 

[Jack Olsen]

Thanks! That opens up some new possibilities.

 

[Jackfre]

Airtec makes a roof bracket that is adjustable for pitch. I've used them and they work very well. They also make the line set covers.

 

[tthornto]

We had 2 12,000 Btu Turbo Air units installed last year on the roof at my work (flat roof 2 story office building) to provide 24/7 cooling of network/telco rooms. No problems so far.

 

[Zeke]

I don't think you have to have a "split" system. There are single unit non-ducted systems as one might find on a mobile home. They would appear somewhat like a swamp cooler with heat and cooling vented directly into the conditioned air space. Just like a motel wall unit except made to sit on top of the structure.

Not easy to find, but they are made. I just lack the proper search terms. Try "Self-Contained One-Piece Package Mobile Home Air Conditioners"

 

[79firebird]

Yes they can be put on a roof. @ of my friends in mexico have theres on the roof. been there for 4 years and still work fine

 

[Jackfre]

The thru the wall units won't even begin to approach the efficiencies of the mshp's. For your 500' I'd look at a 12, 15 or 18, single evaporator depending upon how quickly you want to pull it down and of course construction of the building. Roof mount is a good solution. Make sure you know the minimum line set requirements for placement. Typically you will want 14/3 between the condensing unit and the evap. Given that it is residential, I don't think you need the roof mounted 120. Nice to have, but an extension cord will get you there. Fujitsu and Mitsubishi are 1 & 2 in the business.