# HVAC System for New Shop



## Nature Man (Jul 25, 2018)

I am in the design phase of a new workshop that will be about 560 square feet. Due to the wide fluctuations in temperatures here I want to install a system for cooling/heating, with the plan to keep the shop at a constant temperature throughout the year. Anyone have suggestions on the type of system to consider? Thanks! Chuck


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## kweinert (Jul 25, 2018)

What kind of wide fluctuations and how well insulated?

I myself have a 5,000 watt electric heater and a window A/C unit in my roughly 400 sq ft shop. It's marginal - it does keep the temps above freezing in the winter (about 55 degrees or so) and around 80 or so in the summer. I suspect that my cold temps are colder than yours but my highs may not be as high - or at least not as high as often.

Two walls are insulated as they're the house walls. 3rd wall has 3" fiberglass, ceiling has 6" fiberglass, and garage door has 2" styrofoam. Obviously the better insulated the better your system will work. I do plan on blowing in more in the ceiling at some point in time.

I personally don't have any experience with these but I've seen several posts on different woodworking groups where people have used the mini-split units to good effect. You might consider looking at one of those systems.

Reactions: Thank You! 1


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## Mike1950 (Jul 25, 2018)

1200 sq ft. Very well insulated inc.12" in attic and r 10 down 18" at slab perimeter. 80,000nat gas costs at most last winter $45 month. No air conditioning. 95 yesterday and shop was comphy 75. If a little insulation is good more is better

Reactions: Thank You! 1 | Agree 1


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## Bigdrowdy1 (Jul 25, 2018)

I am currently looking into the ductless units for my garage. I am eyeing the 18000 btu unit for here in Texas with my garage catching all the afternoon heat. Not worried about heating just cooling. The initial cost is on the high side ($1000.00 and up) but have heard lots of good things about these units.

Reactions: Thank You! 1


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## Nature Man (Jul 25, 2018)

kweinert said:


> What kind of wide fluctuations and how well insulated?
> 
> I myself have a 5,000 watt electric heater and a window A/C unit in my roughly 400 sq ft shop. It's marginal - it does keep the temps above freezing in the winter (about 55 degrees or so) and around 80 or so in the summer. I suspect that my cold temps are colder than yours but my highs may not be as high - or at least not as high as often.
> 
> ...


I haven't built my workshop yet, but am currently working through all the requirements of the build, which I plan to do next year. Temp range is 20-115. Today it is 110 -- way too hot to work in my garage where my woodworking is currently done! Chuck


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## Nature Man (Jul 25, 2018)

Mike1950 said:


> 1200 sq ft. Very well insulated inc.12" in attic and r 10 down 18" at slab perimeter. 80,000nat gas costs at most last winter $45 month. No air conditioning. 95 yesterday and shop was comphy 75. If a little insulation is good more is better


I'm planning 6" walls and investigating closed cell foam on the underside of the roof sheathing. Still don't think that will be enough to keep the inside comfortable in the hottest/coldest parts of the year. Chuck


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## Nature Man (Jul 25, 2018)

Bigdrowdy1 said:


> I am currently looking into the ductless units for my garage. I am eyeing the 18000 btu unit for here in Texas with my garage catching all the afternoon heat. Not worried about heating just cooling. The initial cost is on the high side ($1000.00 and up) but have heard lots of good things about these units.


Have had discussions about a mini-split unit, but one a/c guy indicated the filters would be way too hard to access and keep clean in a woodshop (dust) environment. Chuck


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## rocky1 (Jul 25, 2018)

@hillbilly1 - You might want to read through this one too Nick, since you're going to be doing climate control in the new shop. 

My garage in ND, the previous owner put in a small central heat/air unit. No duct work, couple vents out the end of the unit, return air and filter easily accessible. Insulated the garage heavily. I kept it heated and cooled year round, as it cut my costs to heat and cool the house. Garage was on the north side of the house, interior walls weren't insulated, so heating the garage kept the house unit from running so much. Summer time, even on the north side of the house the garage would heat up mid-summer during the hotter periods, and again, cooling it cut down on run time on the house unit. 

Insulation is great, but wrapping in plastic or Tyvek, to stop air leaks, makes a huge difference as well. Things you learn living in an old house in the deep freeze up there near the Canadian border. Dead of winter when it is the absolute coldest, the houses will warm up really nice. Just stay absolutely comfy. All the moisture in the house that's escaping will frost up and fill all the leaks in the house. Catch a day of warm weather, and let all that thaw, and it takes a week for the house seal up and warm up again.

Reactions: Thank You! 1


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## TimR (Jul 26, 2018)

I’ve been happy with split system on 24x36 shop with apt overhead. Ours is a Mitsubishi which was recommended by an HVAC friend for its quality and ability of technicians to get good factory support. We have one outside unit running two indoor units, one up and one down. We have 4” walls and open cell foam, and electric bills in the year we’ve been here range from $70 - $120 per month, and we my shop even has a garage door (good insulation on it). I would guess once our house is done and the building is a shop only, that electric bill will drop about in half or close to it. Ask me in a couple months, hopefully into house by then.

Oh...cleaning filter is easy for the unit...but I do run dust collector as much as possible.

Reactions: Thank You! 1


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## hillbilly1 (Jul 26, 2018)

We're still settling into the house, so I'm a little ways out from setting up the shop, but from what little bit of research I've done so far, Mitsubishi split system is highly recommend.

Reactions: Thank You! 1


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## Herb G. (Jul 26, 2018)

They make heat pump window shakers these days too. Just something else to consider.

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## Mike Hill (Jul 31, 2018)

41 years in const business - experienced. See the gray beard. For the cost, I wouldn't go to the ductless (mini splits). They're more of the dainty type of HVAC. ON the good side - some of them units will run sorta VAV - meaning its always blowing air and just changing the temp of the air - rather than the off/on of a "regular" system. Nice, but in a shop - 0verkill when an $50.00 fan can do the same. If you don't want a window type unit, I'd probably go with a package unit, on the ground blowing directly into the space - probably blowing high and sucking low. Might think about maybe a pre-filter (just another filter for bigger particulates) in front of the main filter on the suck side. Gas heat would probably be more expensive initially, but easier on pocket book in operating - at least around here - cheap nat. gas. However, if you don't get real cold in the winter - then a heat pump unit should suffice. Rule of thumb - 200 to 300 sf per ton in office type conditions. So figure at least 2 tons, however, unless you insulate well - might consider more, maybe 3 tons. If you are running dust control - remember that will suck out some or a lot of your conditioned air and you have to account for that loss. Least expensive would be the window units - you can install yourself. I scrounged up a cute little portable roll-around A/C for my shop. Found it in a burned building we were renovating. Taped some extra filter material over the intake and set it to blow directly on me when it gets too hot. I also have a fan to move air and a radiator type electric space heater (enclosed) for when it gets too cold and I want to work.

The biggest 115 volt window unit that HD has should be big enough and $400. The largest they have - 230V is just over $800. Hard to pass up those prices. Their ductless prices are about double those for close to the same size - much more sophisticated.

Reactions: Thank You! 1


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## Nature Man (Jul 31, 2018)

Mike Hill said:


> 41 years in const business - experienced. See the gray beard. For the cost, I wouldn't go to the ductless (mini splits). They're more of the dainty type of HVAC. ON the good side - some of them units will run sorta VAV - meaning its always blowing air and just changing the temp of the air - rather than the off/on of a "regular" system. Nice, but in a shop - 0verkill when an $50.00 fan can do the same. If you don't want a window type unit, I'd probably go with a package unit, on the ground blowing directly into the space - probably blowing high and sucking low. Might think about maybe a pre-filter (just another filter for bigger particulates) in front of the main filter on the suck side. Gas heat would probably be more expensive initially, but easier on pocket book in operating - at least around here - cheap nat. gas. However, if you don't get real cold in the winter - then a heat pump unit should suffice. Rule of thumb - 200 to 300 sf per ton in office type conditions. So figure at least 2 tons, however, unless you insulate well - might consider more, maybe 3 tons. If you are running dust control - remember that will suck out some or a lot of your conditioned air and you have to account for that loss. Least expensive would be the window units - you can install yourself. I scrounged up a cute little portable roll-around A/C for my shop. Found it in a burned building we were renovating. Taped some extra filter material over the intake and set it to blow directly on me when it gets too hot. I also have a fan to move air and a radiator type electric space heater (enclosed) for when it gets too cold and I want to work.
> 
> The biggest 115 volt window unit that HD has should be big enough and $400. The largest they have - 230V is just over $800. Hard to pass up those prices. Their ductless prices are about double those for close to the same size - much more sophisticated.


Very helpful! Thanks. Temps here go from 20 - 115, so I battle both extremes. Plan to insulate well. Hadn't even considered impact of dust collection on conditioned air. Chuck


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## Mike Hill (Jul 31, 2018)

Nature Man said:


> Very helpful! Thanks. Temps here go from 20 - 115, so I battle both extremes. Plan to insulate well. Hadn't even considered impact of dust collection on conditioned air. Chuck


If you exhaust you dust outside, then it does affect the inside conditioned air greatly. If you exhaust inside - not so much.

Reactions: Thank You! 1


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## rocky1 (Aug 1, 2018)

Mike Hill said:


> 41 years in const business - experienced. See the gray beard. For the cost, I wouldn't go to the ductless (mini splits). They're more of the dainty type of HVAC. ON the good side - some of them units will run sorta VAV - meaning its always blowing air and just changing the temp of the air - rather than the off/on of a "regular" system. Nice, but in a shop - 0verkill when an $50.00 fan can do the same. If you don't want a window type unit, I'd probably go with *a package unit, on the ground blowing directly into the space - probably blowing high and sucking low. Might think about maybe a pre-filter (just another filter for bigger particulates) in front of the main filter on the suck side. Gas heat would probably be more expensive initially, but easier on pocket book in operating - at least around here - cheap nat. gas.*  However, if you don't get real cold in the winter - then a heat pump unit should suffice. Rule of thumb - 200 to 300 sf per ton in office type conditions. So figure at least *2 tons*, however, unless you insulate well - might consider more, maybe 3 tons. If you are running dust control - remember that will suck out some or a lot of your conditioned air and you have to account for that loss. Least expensive would be the window units - you can install yourself. I scrounged up a cute little portable roll-around A/C for my shop. Found it in a burned building we were renovating. Taped some extra filter material over the intake and set it to blow directly on me when it gets too hot. I also have a fan to move air and a radiator type electric space heater (enclosed) for when it gets too cold and I want to work.
> 
> The biggest 115 volt window unit that HD has should be big enough and $400. The largest they have - 230V is just over $800. Hard to pass up those prices. Their ductless prices are about double those for close to the same size - much more sophisticated.




That is exactly what I had in my garage in ND! Very well insulated, and wrapped in plastic. Worked slick, ran cheap!! No Dust Control.

Reactions: Thank You! 1


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## rocky1 (Aug 1, 2018)

Mike Hill said:


> 41 years in const business - experienced. See the gray beard. For the cost, I wouldn't go to the ductless (mini splits). They're more of the dainty type of HVAC. ON the good side - some of them units will run sorta VAV - meaning its always blowing air and just changing the temp of the air - rather than the off/on of a "regular" system. Nice, but in a shop - 0verkill when an $50.00 fan can do the same. If you don't want a window type unit, I'd probably go with *a package unit, on the ground blowing directly into the space - probably blowing high and sucking low. Might think about maybe a pre-filter (just another filter for bigger particulates) in front of the main filter on the suck side. Gas heat would probably be more expensive initially, but easier on pocket book in operating - at least around here - cheap nat. gas.*  However, if you don't get real cold in the winter - then a heat pump unit should suffice. Rule of thumb - 200 to 300 sf per ton in office type conditions. So figure at least *2 tons*, however, unless you insulate well - might consider more, maybe 3 tons. If you are running dust control - remember that will suck out some or a lot of your conditioned air and you have to account for that loss. Least expensive would be the window units - you can install yourself. I scrounged up a cute little portable roll-around A/C for my shop. Found it in a burned building we were renovating. Taped some extra filter material over the intake and set it to blow directly on me when it gets too hot. I also have a fan to move air and a radiator type electric space heater (enclosed) for when it gets too cold and I want to work.
> 
> The biggest 115 volt window unit that HD has should be big enough and $400. The largest they have - 230V is just over $800. Hard to pass up those prices. Their ductless prices are about double those for close to the same size - much more sophisticated.




That is exactly what I had in my garage in ND! Very well insulated, and wrapped in plastic. Worked slick, ran cheap!! No Dust Control.

Reactions: Like 1 | Thank You! 1


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## David Hill (Aug 1, 2018)

If ya didn't hear him the first time......


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## DKMD (Aug 1, 2018)

My shop is converted two car garage-detached. Temperature range is similar here. Spray foam was the best investment I’ve ever made. 4” in the walls and 6” on the underside of the roof. I’ve got a two ton electric heat and air unit with a washable fiberglass pre-filter. I don’t run the dust collector as much as I should, and I change the pleated filter in the unit two or three times per year.

The unit is probably overkill with the insulation I have... to me, the foam is far more important than the heat/AC.

Reactions: Thank You! 1 | Agree 2


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