air conditioning for the shop (Florida Heat)
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  1. #1
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    Default air conditioning for the shop (Florida Heat)

    Good afternoon friends.
    So our shop is 3600 sq ft. We installed a 5 ton AC unit a few years back. Its an older r22 system. It was cooling the 2500 sq ft portion of the shop, but not super well. We have opened a wall and now use the whole 3600 SQ ft for us. The second part does not have any AC and it was fine in the fall and spring. Now the temp in there is 90-95+ and the remainder of the shop gets to 85. This AC runs 2 shifts and it is basically running straight for 16 hours. It is a residential unit. We are considering installing another 5 ton unit, but it seems like this one we have now is on its last leg. We have considered getting a 10 ton unit. Either roof mount, or split. Either way, we can get a 3 phase which will be a bit cheaper to run. What do you guys suggest? Anyone have any experience with this stuff? I have talked to a commercial AC company, but they were unsure on how to calculate anything with the machines and stuff going on in here to keep it at anything under 80 or so. We have 3 integrex 200s and 4 VTC mills running most of the time. We may have 1 or 2 on but not running during setups. So we have lots of radiators and cooling fans running around the machines to get it nice and warm. I'm not trying to get the temp down to 60 or anything, but under 80 sure would be nice. I am just afraid another residential unit would not last. Any input would be greatly appreciated!

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    Square fee and tonnage is not enough info. We have a 3600 square foot shop and also a five ton 2 speed residential class A/C. The winding for the high speed burned out as it was improperly installed almost 20 years ago. Now with only the low speed (who knows the tonnage now)and still completely comfortable. We went overboard on insulation and have slowed down the last few years so 3 or maybe 4 tons that is left is adequate.
    How much heat you generate with the machine tools and how good your insulation is will be most important to figure out what you need.

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    Yes, you are right. There is much more to factor in. Its a block building with insulated roof. Old windows but they don't seem to be leaking, just not very efficient at keeping heat out. We do generate a lot of heat with the machines. We are turning pretty hard on the Integrexs and I know that is putting off a lot of heat. The mills don't seem to be as hot. They don't really peel material off like the lathes do. Its a 14ft ceiling and no roof vents. One roll up door that stays shut 95% of the time.

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    insulating the ceiling is by far the most cost effective. Another thing to consider is putting exhaust fans on the machines and blow the hot air outside.
    i would replace the unit you have with the highest SEER rating you can find. The savings in electricity will pay for itself in no time. If your power company screws you with a demand charge, 2 five ton would be preferable to a ten ton.

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    Quote Originally Posted by Larry Dickman View Post
    2 five ton would be preferable to a ten ton.
    Do you know this by experience? I believe we can find a 10 ton that is 3 phase and would require less amps to run. But I am not really all that electrically experienced. I know I can buy 3 5 ton units for about the same price as 1 10 ton.

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    Quote Originally Posted by TiTillIdie View Post
    Do you know this by experience? I believe we can find a 10 ton that is 3 phase and would require less amps to run. But I am not really all that electrically experienced. I know I can buy 3 5 ton units for about the same price as 1 10 ton.
    I'm talking about the power companies demand charge. Two 5 ton units are way way cheaper to run that one 10 ton unit.

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    Two five tons are cheaper to run and cheaper to buy
    Also if you set the thermostats at different temps you can get more efficiency out of the by running only one when it is not very hot

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    Heat load of machines has 2 parts.

    Convert watts to BTU by multiplying by 3.42.

    Divide that by 12000 to get HVAC ton.

    We did this for cell site equipment where lots of heat generated, did not remove power to antenna as that was not that great.

    Motors driving cutting tools combined with cutting heat complicates things.

    10 horse power is easy.

    Blue chips not so much.

    There is likely some manufacturer data that may available to give guidance.

    Making building more efficient is best investment.

    Sent from my SAMSUNG-SM-G930A using Tapatalk

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    I have 2 new machines in a new and soon to be enclosed <1200 FT2 space with 14 ceilings. I am getting 3) 24000 mini split heat pump units. Plan on installing them myself. My HVAC "friend" said 2)3 ton units at about 5k each to buy. Screw that. Getting them from Home Desperate at a bit over 4k for all three. Good for heat down to -13 too.
    50% of wall space is exterior wall, other 50% is interior wall with > 32 degrees "outside". No worries about 3 phase as each unit can grab a leg. But also run what I need.

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    A single 10-ton unit will often have two 5-ton compressors, only running the second compressor as necessary.

    I just purchased a 15-ton package unit for my 4,000 square foot metal-building shop. Probably 5 tons too much per the official calculations, but knowing it has two 7-1/2 ton compressors, it made sense to upsize.

    A larger unit running below its capacity can operate as cheaply as a smaller unit running wide-open.

    Be leery of the really high SEER units, as they typically have inverters and other “high tech” crap that will eventually raise your maintenance and repair costs over time, negating any savings from the higher SEER.

    I like the “base-model” units: best pricing, cooling-only, no inverters, easy to diagnose and repair.

    ToolCat

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    Something to be aware of, every single watt used in that space will be converted to heat. Every single lamp, computer, wire, speaker, and motor will effectively convert electricity into heat with near 100% efficiency, even if it may have to become light or vibration or movement along the way. It will all end up as heat. You have to add that to the environmental heat from outside if you want to have any reasonable expectation of cooling your building. I can't tell you the number of arguments I've had because some idiot doesn't understand why if a 5 ton unit is fine for his house, it should be perfectly fine for his shop that's only slightly larger with 400hp worth of machinery in it.

    Also, if you run a dust or mist system that vents outside, kiss your cooling goodbye. Normal commercial sized filters will not last, expect to double your filter size and usage, minimum. And normal commercial drainage provisions for a shop running coolant will likely not keep up, your AC unit is putting half it's work into removing moisture from the air, and that water has to go somewhere. Mills can be shockingly good at putting moisture into the air if you use water based coolant.

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    I can ask about details, as I don't know, but we just put in a 3rd unit. We have them set at 80 overnight (1 shift) and turn down to 75 in the morning. It gets from 80 to 75 in probably 5 minutes or so, and keeps it at 75 when outside is 90 and 70% humidity...

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    Quote Originally Posted by TiTillIdie View Post
    Yes, you are right. There is much more to factor in. Its a block building with insulated roof. Old windows but they don't seem to be leaking, just not very efficient at keeping heat out. We do generate a lot of heat with the machines. We are turning pretty hard on the Integrexs and I know that is putting off a lot of heat. The mills don't seem to be as hot. They don't really peel material off like the lathes do. Its a 14ft ceiling and no roof vents. One roll up door that stays shut 95% of the time.
    Our house is much smaller but is cinderblock, we had 1 1/2 inches of styrofoam installed on the outside with Drivit stucco over that. Inside hat channels with 3/4 styrofoam with commercial sheet rock screwed to the hat channels. Very energy efficient and quiet also. Agree with early comment ceiling insulation will give most bang for the buck.

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    Quote Originally Posted by TiTillIdie View Post
    Good afternoon friends.
    So our shop is 3600 sq ft. We installed a 5 ton AC unit a few years back. Its an older r22 system. It was cooling the 2500 sq ft portion of the shop, but not super well. We have opened a wall and now use the whole 3600 SQ ft for us. The second part does not have any AC and it was fine in the fall and spring. Now the temp in there is 90-95+ and the remainder of the shop gets to 85. This AC runs 2 shifts and it is basically running straight for 16 hours. It is a residential unit. We are considering installing another 5 ton unit, but it seems like this one we have now is on its last leg. We have considered getting a 10 ton unit. Either roof mount, or split. Either way, we can get a 3 phase which will be a bit cheaper to run. What do you guys suggest? Anyone have any experience with this stuff? I have talked to a commercial AC company, but they were unsure on how to calculate anything with the machines and stuff going on in here to keep it at anything under 80 or so. We have 3 integrex 200s and 4 VTC mills running most of the time. We may have 1 or 2 on but not running during setups. So we have lots of radiators and cooling fans running around the machines to get it nice and warm. I'm not trying to get the temp down to 60 or anything, but under 80 sure would be nice. I am just afraid another residential unit would not last. Any input would be greatly appreciated!
    we had ac installed in one of our bays last year. 1750 SQF with 16foot ceilings, the commercial guys calc it for a 4 ton unit. so they put it in. wouldnt get under 82º in 90º weather outside (seems they forgot it was 16 foot tall ceilings. 3 months later when our temps hit 118-120 it it wouldnt get under 85-86.
    they put a 7.5 ton unit in it at 118-120 outside it stays at 76º, when its 95 and below I can get it at 74-76 in 30 mins and it only kicks on a few times a day.
    at night when I leave its set for 85 during working hours its set for 76.
    our other bay has a very old 4 ton unit in 1750 sqf with drop ceilings that are 8 foot tall, lathes are in there. has no issues with 76º

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    Quote Originally Posted by Winterfalke View Post
    I can't tell you the number of arguments I've had because some idiot doesn't understand why if a 5 ton unit is fine for his house, it should be perfectly fine for his shop that's only slightly larger with 400hp worth of machinery in it.
    It would work just as good as a house.... if you had 10 ovens in your house running with the door open all day.

    Our shop is pretty well insulated on the ceiling and block construction. I think we are just under conditioned. Getting a second 5 ton unit is probably going to be our best bet. We can set it to run the new unit 99% of the time and the 2nd unit only when necessary. This way the old unit doesn't have to work so hard and the new one can take the brunt of the work.

    Next question, is it possible to duct 2 units into one duck system? I am sure there will need to be some sort of check valve to keep the air from running backwards. Or maybe just run the blower and not the compressor. This way the air is still evenly distributed.

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    Next question, is it possible to duct 2 units into one duck system? I am sure there will need to be some sort of check valve to keep the air from running backwards. Or maybe just run the blower and not the compressor. This way the air is still evenly distributed.
    My church has 5 air conditioners for the sanctuary, 4 with common ductwork, with 5 thermostats in various areas. The blowers run 24 / 7 & the compressors cycle on & off.

    Paul

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    I think this is exactly what we need to do. are the 4 units next to each other or spread out as well?

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    Quote Originally Posted by TiTillIdie View Post
    I think this is exactly what we need to do. are the 4 units next to each other or spread out as well?
    In one room in the basement there are four gas furnaces, 2 with AC coils in the plenum, in the next room there are two air handlers with AC coils. These all feed more or less two ducts that blow air along two sides of the sanctuary. There are four big intake ducts, two at the front and two at the middle of the sanctuary bout 1/4 in from the side walls. There are four thermostats above the air returns in the middle of the sanctuary.

    In the second room with the two air handlers for the sanctuary there is another air handler with separate ductwork that goes to & from the choir area. There is a thermostat for this area.

    The five compressors are lined up in a row 3 - 5 feet apart outside the wall closest to the furnaces & air handlers. I don't know the tonnage.

    Church seats 240. See:all souls biltmore village - Google Search

    Years ago I took care of cooling of an auction house in a tin tobacco barn. The owner would buy cheap used big window air conditioners which I mounted through the wall up high in a row down ones side. I bypassed the thermostats so they were off or wide assd open. We would get about 5 years on a $100 - $200 AC. When one died, get one out of the stockpile in the back & put it in.

    Paul

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    Standard measuring temp for parts is 68.
    That has to be way cold in Florida.
    Disregarding the people, do the machines care about temp and swing?
    Worked in a non A/C grind shop in Michigan. Just for fun I mapped it and could tell you the shop temp by my machine size comps over 4-6 hours.
    I was surprised but it was accurate. Maybe there is more than being comfy to this A/C stuff.
    Bob

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    I like to keep my shop at 68° all year long, I start sweating at 71...

    Sizing the units properly is quite important, you don't want to oversize too much, but definitely don't want to be under either. I'd also rather have 2 smaller units than 1 big one. Outdoor temps and insulation matter a lot, put the outdoor unit in the shade and good air flow if possible.
    The good newer models are quite a bit more efficient than the old stuff.

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