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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Shop A/C solutions...
Awl--
After much thermodynamic agonizing and wasted BTUs, and a little help on alt.hvac, alt.home.repair, "mini-splits" or ductless A/C's seem to be the way to go. Klimaire in FL makes a charged 24,000 btu unit for $799 + $160 s&h. Oh yeah, it's also a heat pump! You need a techie to vacuum/connect it, but I'm told if you (me) do all the mechanical setup, this can be a relatively nominal, uh, charge. PC Richards et al don't seem to supply these type units. Any other leads/sources/experiences? Any tips? -- Mr. P.V.'d formerly Droll Troll |
#2
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Shop A/C solutions...
While we're on the subject... My shop is a 4000 square foot metal building with just a little insulation. I've got 2 residential air conditioning units that keeps it bearable, but not comfortable in our Missouri summers. I've heard that our humidity is too high to use an evaporitve cooler in this area effectively, but I've always wondered how one of those would do in a shop that has two central air units running non stop. Would it actually add any cooling? Would it cause my equipment to rust? It would sure be cheaper to operate than a 3rd AC unit. |
#3
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Shop A/C solutions...
Don't know about evaporative cooling. Would that be *inside* the shop, or a
water tower-type deal outside the shop? Direct sun on roofs is a killer, and likely much worserer in a metal building. I think I've heard of insulating paints, that might help. But *any* kind of air gap would help enormously to reduce the load. If you have a flat roof, any kind of skin or sheathing a few inches off the top (a foot or so would be better) would help. I scattered milk crates over an exposed flat tar roof. Helped!! An air gap *inside* the building, w/ exhaust forced air, would help also. A hung ceiling would do very well. Could cut your A/C costs proly in half. Also reduces the volume requiring A/C/heat. If you hung a ceiling, in the winter/cold you could direct that hotter air back into the shop space. -- Mr. P.V.'d formerly Droll Troll "Dave Lyon" wrote in message news:a962g.908004$x96.138352@attbi_s72... While we're on the subject... My shop is a 4000 square foot metal building with just a little insulation. I've got 2 residential air conditioning units that keeps it bearable, but not comfortable in our Missouri summers. I've heard that our humidity is too high to use an evaporitve cooler in this area effectively, but I've always wondered how one of those would do in a shop that has two central air units running non stop. Would it actually add any cooling? Would it cause my equipment to rust? It would sure be cheaper to operate than a 3rd AC unit. |
#4
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Shop A/C solutions...
In article a962g.908004$x96.138352@attbi_s72,
"Dave Lyon" wrote: My shop is a 4000 square foot metal building with just a little insulation. I've got 2 residential air conditioning units that keeps it bearable, but .... It would sure be cheaper to operate than a 3rd AC unit. Have you considered that more insulation would cost _nothing_ to run, and enough of it could even get you down to running one A/C unit? -- Cats, coffee, chocolate...vices to live by |
#5
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Shop A/C solutions...
Have you considered that more insulation would cost _nothing_ to run, and enough of it could even get you down to running one A/C unit? -- Cats, coffee, chocolate...vices to live by Ya, but I'm not sure what kind of insulation would hold up to a full time machine shop. The insulation that is there, is a 4' wide roll with a green sort of plastic facing the inside of the shop. The plastic is starting to get holes and stuff in it from the years of abuse. I've seen shops where they have sprayed insulation on the inside of the walls. After a year or two, the walls are black with carbon dust and chips that can't be effectively cleaned. I'm just looking for a quick and easy solution, cause in the next few years I'll probably be building a larger shop at a different location. Or, selling the whole business and starting a different one. Anybody looking for a small owner financed machine shop with a reasonable customer base? |
#6
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Shop A/C solutions...
In article JQ62g.936717$xm3.550691@attbi_s21,
"Dave Lyon" wrote: Ya, but I'm not sure what kind of insulation would hold up to a full time machine shop. The insulation that is there, is a 4' wide roll with a green sort of plastic facing the inside of the shop. The plastic is starting to get holes and stuff in it from the years of abuse. I've seen shops where they have sprayed insulation on the inside of the walls. After a year or two, the walls are black with carbon dust and chips that can't be effectively cleaned. I guess I have seen exposed fire-retardant cellulose sprayed on things, but would consider it a poor choice for a shop. Generally there needs to be an inside wall covering (often more sheet steel in steel buildings, or drywall) to keep the insulation from direct fire exposure, reduce physical abuse, and make cleaning possible. Some types of ceiling insulation (generally not foams) are OK to leave the inside face exposed, but it's never a good idea on walls, as you have seen. I'm just looking for a quick and easy solution Cheap, fast, good pick (no more than) two? One product which can work, but is not cheap, is a spray-on exterior polyurethane foam roof - especially good if your present roof leaks, as it gets you insulation and a new weather surface. I don't recall seeing that suggested for walls, and doubt it would be. White steel panels spaced in 4-6 inches from your present walls and fill behind with insulation of choice (whatever's cheap) would be the best wall solution I can think of that's durable and cleanable. -- Cats, coffee, chocolate...vices to live by |
#7
Posted to rec.crafts.metalworking
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Shop A/C solutions...
On Fri, 21 Apr 2006 15:26:33 GMT, "Dave Lyon"
wrote: Have you considered that more insulation would cost _nothing_ to run, and enough of it could even get you down to running one A/C unit? -- Cats, coffee, chocolate...vices to live by Ya, but I'm not sure what kind of insulation would hold up to a full time machine shop. The insulation that is there, is a 4' wide roll with a green sort of plastic facing the inside of the shop. The plastic is starting to get holes and stuff in it from the years of abuse. I've seen shops where they have sprayed insulation on the inside of the walls. After a year or two, the walls are black with carbon dust and chips that can't be effectively cleaned. I'm just looking for a quick and easy solution, cause in the next few years I'll probably be building a larger shop at a different location. Or, selling the whole business and starting a different one. Anybody looking for a small owner financed machine shop with a reasonable customer base? Spray urethane and cover with sheet steel siding (or sheet aluminum, or wallboard, or what-have-you)on the inside to make it easy to clean and fire-proof. *** Posted via a free Usenet account from http://www.teranews.com *** |
#8
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Shop A/C solutions...
Short answer: no, a swamp cooler won't work for you.
An evaporative cooler works by evaportaing water into the air OF THE ROOM. The evaporation cools the air and raises the humidity. It works fine in the desert where the dew point is in the single digits. It also works ok in more moist areas where you want to cool down a really hot area like a furnace room or warehouse. Where it doesn't work is where you want to keep the temp fairly comfortable AND the humidity down. In your case, your current AC units are spending a fair amount of time and energy ($$) pulling water OUT of the air. Using an evaporative cooler will just be at cross purposes. Not to mention dumping a lot of moisture into the air to rust your tools....... You should investigate ceiling fans, floor fans, sealing up the walls, or even a sprinkler for the roof. You might also check on the efficiency on your exisiting units. The small 5k btu units are really bad, going to a heavy duty 12k btu might be a better option and get your efficiency rating up in the 12 or 13 range. A central AC unit is expensive but it would allow you to direct cool air to your work area, let the other parts of the shop get hotter. Dave Lyon wrote: While we're on the subject... My shop is a 4000 square foot metal building with just a little insulation. I've got 2 residential air conditioning units that keeps it bearable, but not comfortable in our Missouri summers. I've heard that our humidity is too high to use an evaporitve cooler in this area effectively, but I've always wondered how one of those would do in a shop that has two central air units running non stop. Would it actually add any cooling? Would it cause my equipment to rust? It would sure be cheaper to operate than a 3rd AC unit. |
#9
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Shop A/C solutions...
In your case, your current AC units are spending a fair amount of time and energy ($$) pulling water OUT of the air. Are you saying that the act of drawing the moisture out of the air uses more energy? I was under the assumption that dehumidifying the air was just a nice byproduct of running your AC unit. If I understand what you are saying, a room at 90 deg will be cooled quicker and easier by an AC unit if the humidity in that room is low than it would if the humidity was high? |
#10
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Shop A/C solutions...
That is correct--likely substantially more, depending depending. Water
vapor has substantially more mass than dry air, plus the heat of fusion, ekc. And the suggestion sprinklering the roof is good also--at least a tar flat roof. -- Mr. P.V.'d formerly Droll Troll "Dave Lyon" wrote in message news:S172g.694836$084.661738@attbi_s22... In your case, your current AC units are spending a fair amount of time and energy ($$) pulling water OUT of the air. Are you saying that the act of drawing the moisture out of the air uses more energy? I was under the assumption that dehumidifying the air was just a nice byproduct of running your AC unit. If I understand what you are saying, a room at 90 deg will be cooled quicker and easier by an AC unit if the humidity in that room is low than it would if the humidity was high? |
#11
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Shop A/C solutions...
In article S172g.694836$084.661738@attbi_s22,
"Dave Lyon" wrote: Are you saying that the act of drawing the moisture out of the air uses more energy? It does. Condensing water vapor (gas-liquid) causes it to give up the latent heat of vaporization. If I understand what you are saying, a room at 90 deg will be cooled quicker and easier by an AC unit if the humidity in that room is low than it would if the humidity was high? Correct. -- Cats, coffee, chocolate...vices to live by |
#12
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Shop A/C solutions...
Dave Lyon wrote:
In your case, your current AC units are spending a fair amount of time and energy ($$) pulling water OUT of the air. Are you saying that the act of drawing the moisture out of the air uses more energy? I was under the assumption that dehumidifying the air was just a nice byproduct of running your AC unit. Of course it does, most of the energy by some accounts. The air cannot get cool until the water is out. Thus opening the door is a BAD idea. If I understand what you are saying, a room at 90 deg will be cooled quicker and easier by an AC unit if the humidity in that room is low than it would if the humidity was high? Absotootly AC notes; My ~2400 sq ft shop that cost ~2k to heat in a new england winter last year is kept generally below 80, and DRY by a single 24k btu wall ac unit. I plan on adding some more, probably a mini split later AC is a lifestyle; you turn it on in june and off in september. You shut the windows and doors unless it is really cool and dry out. You NEVER shut it off. I will turn mine on energy saver at night[fan is only on with compressor] The AC in your car is as big as the one in your house so it can pull the tiny confines of the car down to 70 in a few minutes. I find people who complain about the cost to heat the house, but sleep with the window open and how their ac 'sucks' but they keep the door open for some fresh air........ |
#13
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Shop A/C solutions...
Dave Lyon wrote: In your case, your current AC units are spending a fair amount of time and energy ($$) pulling water OUT of the air. Are you saying that the act of drawing the moisture out of the air uses more energy? I was under the assumption that dehumidifying the air was just a nice byproduct of running your AC unit. Taking the water out of the air costs cost 540 BTU's per pound, same as the heat needed to change water to vapor. So, it takes energy to squeeze the water out. The reason the AC unit pulls the water out is that once the coil temp gets down to the dewpoint temp, all the "cold" below that temp goes into dropping the dewpoint. So if the coil temp could be as low as 38 degrees and the dewpoint is say 60 degrees, your ouput air will never get below 60 degrees until you pull some moisture out. If I understand what you are saying, a room at 90 deg will be cooled quicker and easier by an AC unit if the humidity in that room is low than it would if the humidity was high? Exactly right. A 1 ton (12kbtu/h) AC that puts out a gallon of water per hour is spending 4320 (ie (8*540 )or 1/3 of the cooling capaity to pull water out. Only 2/3rds left to cool. Another factoid for your luncheon enjoyment: Your comfort level is much more a factor of the dewpoint than the relative humidity. It really comes down to how effective your sweat function is working. At 10F or 20f dewpoint (desert air), any sweat is immediatly evaporated. At 70F dewpoint, the whole sweat thing doesn't work well (difference between 98F body temp and the dewpoint). Most people feel dewpoint in the 60's to be "fairly humid" and starting to get uncomfortable. 50's is "nice", 40's is "dry" What all that says is that pulling the dewpoint down WITHOUT changing the temp will FEEL cooler. So keep the door closed!!! Cheers. |
#14
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Shop A/C solutions...
Exactly right. A 1 ton (12kbtu/h) AC that puts out a gallon of water per hour is spending 4320 (ie (8*540 )or 1/3 of the cooling capaity to pull water out. Only 2/3rds left to cool. Thank you. My mind works better with numbers. I have a much better understanding of the energy needed to cool a room now. |
#15
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Shop A/C solutions...
You need R.H. of at most 15% to get an evaporative cooler to work well.
I can get a drop of about 20 degrees with a portable unit I've got at that R.H., at 20% and above all I get is hot, wet air. Really good only for the Southwest where the humidity is low for most of the hot season. It evaporates water into the incoming air, so it increases the R.H. inside, so, yes, there's a good chance it'll start equipment rusting. Insulation, paint, partitioning and/or an exhaust fan(s) located high up will work better. Stan |
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