Considering my HVAC options

[Mikea57]

I've been lurking around here for a couple of months, what an awesome site! For my first post, I've got several questions about heating/cooling my shop. I've got a 26'X24' stick built stand alone workshop with an unfinished upstairs. Currently, the shop has exposed studs and no insulation both upstairs and down. The floor joists are spaced on 12" centers for the upstairs and I figure the usable upstairs area will probably be 26'X16' at the most. My son in law has offered me a heating/air unit for free which I'm considering taking. Both the inside and outside units are available. He says it's a 2 1/2 ton unit, but I don't know what kind of shape it's in. I know I'll have to install ductwork, so I'm starting with a blank slate as far as this whole project is concerned. I use my shop for primarily household type projects and it has several pieces of woodworking equipment (band, radial arm, and table saws, air compressor, drill press and a small generator to provide the main house with a minimum of power in the case of a power outage.) As my sons grow up I can see that at some point a car will also be parked in there to work on. I also do music recording and video production on the side and I'll be converting the upstairs into a small post production studio complete with acoustical treatments to prevent sound leakage to/from upstairs to downstairs and vice versa. I don't plan on keeping the unit going 24/7; I'll probably put in a programmable Tstat or maybe one that I can wake up via a cellphone call while on my way home.

My questions are:
- What's the best insulation for this type of building?
- Is a 2 1/2 ton unit too big for a building like this? (I suspect that it
is...)
- What size duct do I need and how many drops for the downstairs? I
figure 2 for the upstairs and they'll probably be flexible duct and maybe
a little larger since that will move the air slower so I won't have to
worry about the sound of rushing air in my sound studio.
- Since I don't know how old this system is or what shape it's in, I'm
wondering if it might be better for me to just skip this offer and look at
installing a new unit for the sake of efficiency. My electric bill is high
enough as it is and I don't want to go putting in an inefficient 'free'
unit if I'm going to have to throw money down the drain just to keep
the place comfortable.
- I've also been looking at minisplit units. Would I be better off with
maybe 2 of those (1 up, 1 down) with a single condenser as opposed
to the 'Normal' type unit?
- Any advice on a thermostat?

Thanks for the help guys. I'm just in the thinking stages right now, I haven't even started to put a plan together.

 

[Freejack]

Sounds like a 2.5 ton will be just slightly oversized for the application if you will be cooling both the upper and lower areas, using a 500 sqft/ton rule of thumb. That said, there are much better ways to calculate cooling load than rule of thumb.

Jake

 

[ron in sc]

My garage is about same size as yours, expect I do not have a second floor. I do have 14' ceiling in center. I have a Sanyo mini split and so far it cools just fine. It's also very quite. When blowing on low I can not even hear it.

 

[jocool1585]

Mike,

I have a similar situation. What did you end up doing?

 

[larry4406]

If you ever plan on having the upstairs considered to be code compliant "living space" while the downstairs is a garage, then you will not be able to combine the HVAC systems for these 2 floors due to fume concerns and flame separation between the spaces. Thus, start thinking 2 systems, unless you are going hydronic for heat.

My garage is 28D, 12T, 50W with a full loft above. The loft is future living space, currently no climate control. In the garage, I have a ducted HVAC system, 5 tons air (probably too big, but I had it already) and 110 kbtu/hr propane furnace. Ductwork is ceiling mounted, all fire stopped, flame spread insulation, 5/8 sheet rock, etc. The upstairs loft is 50W with various depth due to knee walls and ceiling rake. I was told that I would need probably a 3 ton heat pump for it. The garage has R-19 in the walls, and R-30 in the ceiling/loft floor. The loft is uninsulated since it was permitted as storage space.