Heat and AC
#15
(07-26-2022, 08:46 AM)srv52761 Wrote: Aha! A fellow Hoosier from my neck of the woods, kinda (Grant county).

2” of closed cell foam will indeed act as a vapor barrier and be air-tight and give you about an R-15.  2” of open-cell will retard the air flow and give an R-7.5 value.

For northern Indiana even the closed cell might be on the low side for a conditioned space.  Consider more.

The labor cost should be almost identical, so now would be the time to do it.

Thank you.  We indeed are close.  I live in the Kokomo area.
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#16
I’m in east Texas and my shop is 30x60 with 14’ sidewalls metal building, but I went with a 6/12 pitch so 21’ at peak.
I did 2” of closed cell on the ceiling and 3” of open cell on walls.

I heat and cool with a 36k BTU mini split.

That’s enough to keep it at 72 year round as long as your within 6’ of the floor which is where I live most of my life.
As I go up in my lift or in one of the lofted storage areas it gets warmer.

I also put in a walled off 10x20 area for my wife.
The main unit didn’t do as well in that area due to airflow so I added a 12k btu mini split to that area as well.

I use one of the lofts for computer work and have my 3D printers there, so I added another 18k btu unit in that area.

If I hadn’t walled off my wife’s area, or wasn’t using the loft for occupied area then a single 36k would have been fine.

I’m sold on the mini splits for shops.
Yes they get dirty but nothing a good vacuum can’t handle

My first was sold as a DIY unit those have Pre charged line set with what I’m told are proprietary fittings.
That was a pretty easy install only required normal tools most of us have.
The other 2 are not sold as DIY units so the lines had to be flared and vacuumed. Not tools most have, but can be acquired for not much cost, and are available should I need to install another in the future. The outdoor half of the unit is precharged so once you vacuum and test the lines, you just release the refrigerant and your in business.

Condensate drain from the indoor part is the biggest planning issue, as these things will pull buckets and buckets of water out of the air.
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#17
(07-31-2022, 08:07 PM)JDuke Wrote: I’m in east Texas and my shop is 30x60 with 14’ sidewalls metal building, but I went with a 6/12 pitch so 21’ at peak.
I did 2” of closed cell on the ceiling and 3” of open cell on walls.

I heat and cool with a 36k BTU mini split.

That’s enough to keep it at 72 year round as long as your within 6’ of the floor which is where I live most of my life.
As I go up in my lift or in one of the lofted storage areas it gets warmer.

I also put in a walled off 10x20 area for my wife.
The main unit didn’t do as well in that area due to airflow so I added a 12k btu mini split to that area as well.

I use one of the lofts for computer work and have my 3D printers there, so I added another 18k btu unit in that area.

If I hadn’t walled off my wife’s area, or wasn’t using the loft for occupied area then a single 36k would have been fine.

I’m sold on the mini splits for shops.
Yes they get dirty but nothing a good vacuum can’t handle

My first was sold as a DIY unit those have Pre charged line set with what I’m told are proprietary fittings.
That was a pretty easy install only required normal tools most of us have.
The other 2 are not sold as DIY units so the lines had to be flared and vacuumed. Not tools most have, but can be acquired for not much cost, and are available should I need to install another in the future. The outdoor half of the unit is precharged so once you vacuum and test the lines, you just release the refrigerant and your in business.

Condensate drain from the indoor part is the biggest planning issue, as these things will pull buckets and buckets of water out of the air.

Thank you for the response.

Did you go with 3" in the walls and 2" in the ceiling because of being in Texas and being more concerned about heat coming through the walls as opposed to me being in the north where I am more concerned with heat going out the ceiling?  It was recommended for me to have 3" on the ceiling and 2" on the walls.

Has the tightness of the building caused by the spray foam been an issue?

Did you explore the option of using gas to heat and a through the wall AC unit? Especially the cost of running both setups?

Thanks
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#18
I didn’t really have a specific reason why I went with the thickness other than I did some calculations on cost and that’s as much as my pocketbook would stomach at the time.

I went with closed on ceiling and open on walls so I’d have higher R for heat gain surface as you said, I also have porches on both long sides to help reduce solar gain from walls.

I didn’t consider gas for heat at all, I have natural gas in the house, but with the Texas climate you can heat with a candle, AC was my number one reason for going mini split.

I grew up in Arkansas with wood heat, and no AC. I told my wife early on, I make good money and as long as we can afford it, we will set thermostat cold, and if she’s cold I’ll get her a sweater or a blanket. In 21 years of marriage we have argued about many things, but thermostat setting hasn’t been one of them.

I did not consider a through the wall aka window unit at all, as the concept is severely flawed from the outset.

The compressor on an AC by design is very hot, having it just a few inches from the evaporator coil like a window unit is a very inefficient design.

I also priced a pro install of a ducted unit and it would have been 2-3x the cost of DIY mini splits, and yes I understand at least 50% of that cost difference is the installation.

Building tightness has not been an issue, I have insulated garage doors on each end of shop, and you can’t make garage doors completely air tight.
I have a contractor friend that absolutely hates spray foam because of how difficult it makes locating the source of roof leaks.
I haven’t had any leaks I’m aware of, so maybe there is at least some downside to foam other than cost, but that hasn’t been my experience yet.
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