air conditioning for the shop (Florida Heat)

[TiTillIdie]

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

Yeah there is definitely a swing in size for temp during the day. Our parts are pretty open most of the time. I even know there is a swing in size if we need to add a bunch of coolant. I don't like to add coolant in the middle of the day, or even in the middle of any job really. I always add coolant between jobs or in the morning if its a longer run.

 

[garyhlucas]

Your internal heat load is exactly equal to your kilowatt hours x 3450 Btu. That is how much additional heat you have to remove to equal a similar size house.

 

[Scruffy887]

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

Watts converted to BTU. Forget blue chips. To imply that watts + blue chips = more BTU would be saying that there is more energy being generated on output than input. Think about it. But maybe you have a Flux Capacitor.

 

[Tony Quiring]

What I am saying is the motor dissipates a calculatable heat load based on the power it consumes.

However different interactions on the other side of the motor generate additional heat depending on the action.

Peeling a huge smoking chip likely more than skim cutting.

Air compressor is compressing air which generates given heat.

The motor in the compressor is drawing some level of energy that relates to the amount of work, simple.

But something like an air compressor may translate or convert the watts to BTU at a different rate.

The energy flowing through the windings of the motor heat those windings generating heat, is it watts x 3.42 or is it something else because it is a motor?

The air being compressed generates heat that is calculated completely different, rate and rise maybe needed.

Then friction of the moving arts that have nothing to do with motor energy or air pressure.

It all adds up to heat load.

He have no clue exactly how one relates motor power to chip heat as different machines have different internal losses.

Our background is communications equipment headload where variables are simple, 240 VAC in, 54 VAC out at say 1000 amps plus conversion losses then convert to BTU.

I seem to recall some data sheets for heat loads of machine like devices where motors operate machines that generate additional heat above that of the motor.

If flood cooing then the cutting heat may be removed by the coolant and managing it may be needed to reduce evaporation and or humidity.

It is important to certainly not undersize the unit but oversizing also is not good as it cools the air too soon and it short cycles reducing the actual net cooling.

There should be reliable data sources to determine net heat load of any given machine under assorted operations.


Insulating the building to reduce environmental heat load is one time expense that pays back for free so the engineering should look at building design.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[Scruffy887]

If the electrical input is 10,000 watts then you cannot get more than 10,000 watts worth of heat output. Some heat from motor, controls, bearings, blue chips. Coolant on the chips transfers the heat to the coolant, the heat does not go away. It just gets diluted.
The electrical load will give you the total heat output. Some areas will be hotter than others.
My lathe generates a lot of heat and it turns only .5" to 2" delrin rod stock. No coolant ever. The heat comes from the spindle coolers and controls. Delrin cuts like nothing but the machine is bar fed and main and sub spindle are constantly starting and stopping. Sub spindle starts, stops, reverses very quickly as well.

 

[Bill D]

Entrophy says all the electrical load is converted to heat. Friction, blue chips, lights etc all end up heating the shop.
The only power not turned into heat is light going out a window or hot chips and parts being moved outside.
So the other poster was correct just multiply the kilowatt hours by the btu factor and divide by 30 days.
Bill D

 

[Scruffy887]

Entrophy says all the electrical load is converted to heat. Friction, blue chips, lights etc all end up heating the shop.
The only power not turned into heat is light going out a window or hot chips and parts being moved outside.
So the other poster was correct just multiply the kilowatt hours by the btu factor and divide by 30 days.
Bill D

Everybody on this thread is "the other poster".

 

[Bill D]

California has a newish law that a roof must be a light color to reflect heat. No black tar roofs allowed. I see black asphalt shingle roofs not sure how they meet the code. I suppose it is magic gravel that reflects heat but absorbs light waves. Does black chrome reflect or absorb heat compared to shiny chrome?
Bill D

 

[metlmunchr]

A few basics of A/C for a machine shop.....

Cooling the building itself is pretty straightforward. Simple heat survey taking into account the construction and insulation of the building, just the same as any other building whether it be a house, store, church, or any other building.

The internal load is where things get specific. As Scruffy said, all electricity is converted to heat. Every kW-hr produces 3413 btu/hr. No more, and no less.

3 phase units will not operate cheaper than single phase ones. The same size unit will draw less amps on 3 phase than single, but it's pulling power on 3 hot legs rather than on two hot legs. The coefficient of performance (COP) is the number that tells the efficiency level of the unit. For example, a COP of 10 means the unit will produce 10 btu per watt-hr of electricity.

Mini splits are a quick and easy way to add cooling if little or no coolant is used, such as Scruffy's case where he's turning delrin. But if the shop is running coolant on most ops, mini splits will require a lot of cleaning to maintain operation and they are very difficult to clean as compared to other types of equipment.

Cooling capacity has to be based on daytime load when in operation, and not on some average of X kW-hr per month divided by 30 days. Such an average is guaranteed to produce undersized equipment. The number required for accurate load calculation is the average load in kW during daytime operation. If you run 2 or 3 shifts, the capacity will be more than adequate for the evening and night shifts as the solar load on the building won't be present to the extent it is during the day.

Extensive use of coolant requires the equipment be selected based on the balance between latent load (humidity removal) and sensible load (maintaining space temperature). All major equipment mfgrs publish extensive data on latent vs sensible load for each of their systems, and anyone with good knowledge of design practices can make that selection so long as you can give them average daytime electrical load and the average number of gallons of coolant you're having to replace during the day shift.

In my experience (15+ yrs in commercial, industrial, and institutional HVAC), the typical residential HVAC contractor is clueless when it comes to sizing a system for something like a shop where the internal load is often greater than the environmental load. That's why you get stories like some of the above where a/c is installed and it won't cool the space. If they'd just turn off all them damn machines, it'd cool just fine

Ignore any advice to put outdoor units in the shade. There's a pervasive urban myth that shade will make a condensing unit more efficient. The reality is just the opposite. The solar gain from sun shining on the unit is so miniscule that you'd have to use laboratory measuring techniques to define it. OTOH, the loss of efficiency from sucking all the crap that falls off trees is real. Wash your car and park it in the sun, and it'll be clean tomorrow. Park it under a tree, and note all the sticky shit that's stuck to it tomorrow. That same stuff sticks to condenser coils as the condenser fan draws air thru the coil, and then any dust that's drawn thru the coil sticks to the tree stuff rather than passing on thru.

If you're air conditioning a shop, it's a good idea to move the air compressor outside if possible. In round numbers, if a shop is using an average of 15 to 17 cfm of air, it'll take one ton of cooling just to overcome the hear generated by the compressor. 30-35 cfm will take 2 tons, and so on. Reduces your available capacity to cool the space where it's needed as well as costing you some significant money to offset the heat added by the compressor.

Finally, the shop owners I know who have air conditioned their shops have all said it paid back in increased productivity. People who don't have to spend time mopping sweat and chasing offsets to hold parts in tolerance produce more work and fewer scrapped parts, and they're much less likely to leave for a job down the road at a place that's not a sweatbox.

 

[Big B]

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.

Ceiling insulation isn't nearly as big of deal for cooling as it is for heating. That old rule about heat rising and cool air dropping and all.

 

[Big B]

What I am saying is the motor dissipates a calculatable heat load based on the power it consumes.

However different interactions on the other side of the motor generate additional heat depending on the action.

Peeling a huge smoking chip likely more than skim cutting.

Air compressor is compressing air which generates given heat.

The motor in the compressor is drawing some level of energy that relates to the amount of work, simple.

But something like an air compressor may translate or convert the watts to BTU at a different rate.

The energy flowing through the windings of the motor heat those windings generating heat, is it watts x 3.42 or is it something else because it is a motor?

The air being compressed generates heat that is calculated completely different, rate and rise maybe needed.

Then friction of the moving arts that have nothing to do with motor energy or air pressure.

It all adds up to heat load.

He have no clue exactly how one relates motor power to chip heat as different machines have different internal losses.

Our background is communications equipment headload where variables are simple, 240 VAC in, 54 VAC out at say 1000 amps plus conversion losses then convert to BTU.

I seem to recall some data sheets for heat loads of machine like devices where motors operate machines that generate additional heat above that of the motor.

If flood cooing then the cutting heat may be removed by the coolant and managing it may be needed to reduce evaporation and or humidity.

It is important to certainly not undersize the unit but oversizing also is not good as it cools the air too soon and it short cycles reducing the actual net cooling.

There should be reliable data sources to determine net heat load of any given machine under assorted operations.


Insulating the building to reduce environmental heat load is one time expense that pays back for free so the engineering should look at building design.

Sent from my SAMSUNG-SM-G930A using Tapatalk

It seems like it would be a lot easier to look at how many kilowatt hours is used in a month and subtract for any that is used outside of the shop like for a lighted sign or that kind of thing. Trying to map out everything that takes power and how much it is on seems like a lot of unnecessary work.

 

[Big B]

A few basics of A/C for a machine shop.....

Cooling the building itself is pretty straightforward. Simple heat survey taking into account the construction and insulation of the building, just the same as any other building whether it be a house, store, church, or any other building.

The internal load is where things get specific. As Scruffy said, all electricity is converted to heat. Every kW-hr produces 3413 btu/hr. No more, and no less.

3 phase units will not operate cheaper than single phase ones. The same size unit will draw less amps on 3 phase than single, but it's pulling power on 3 hot legs rather than on two hot legs. The coefficient of performance (COP) is the number that tells the efficiency level of the unit. For example, a COP of 10 means the unit will produce 10 btu per watt-hr of electricity.

Mini splits are a quick and easy way to add cooling if little or no coolant is used, such as Scruffy's case where he's turning delrin. But if the shop is running coolant on most ops, mini splits will require a lot of cleaning to maintain operation and they are very difficult to clean as compared to other types of equipment.

Cooling capacity has to be based on daytime load when in operation, and not on some average of X kW-hr per month divided by 30 days. Such an average is guaranteed to produce undersized equipment. The number required for accurate load calculation is the average load in kW during daytime operation. If you run 2 or 3 shifts, the capacity will be more than adequate for the evening and night shifts as the solar load on the building won't be present to the extent it is during the day.

Extensive use of coolant requires the equipment be selected based on the balance between latent load (humidity removal) and sensible load (maintaining space temperature). All major equipment mfgrs publish extensive data on latent vs sensible load for each of their systems, and anyone with good knowledge of design practices can make that selection so long as you can give them average daytime electrical load and the average number of gallons of coolant you're having to replace during the day shift.

In my experience (15+ yrs in commercial, industrial, and institutional HVAC), the typical residential HVAC contractor is clueless when it comes to sizing a system for something like a shop where the internal load is often greater than the environmental load. That's why you get stories like some of the above where a/c is installed and it won't cool the space. If they'd just turn off all them damn machines, it'd cool just fine

Ignore any advice to put outdoor units in the shade. There's a pervasive urban myth that shade will make a condensing unit more efficient. The reality is just the opposite. The solar gain from sun shining on the unit is so miniscule that you'd have to use laboratory measuring techniques to define it. OTOH, the loss of efficiency from sucking all the crap that falls off trees is real. Wash your car and park it in the sun, and it'll be clean tomorrow. Park it under a tree, and note all the sticky shit that's stuck to it tomorrow. That same stuff sticks to condenser coils as the condenser fan draws air thru the coil, and then any dust that's drawn thru the coil sticks to the tree stuff rather than passing on thru.

If you're air conditioning a shop, it's a good idea to move the air compressor outside if possible. In round numbers, if a shop is using an average of 15 to 17 cfm of air, it'll take one ton of cooling just to overcome the hear generated by the compressor. 30-35 cfm will take 2 tons, and so on. Reduces your available capacity to cool the space where it's needed as well as costing you some significant money to offset the heat added by the compressor.

Finally, the shop owners I know who have air conditioned their shops have all said it paid back in increased productivity. People who don't have to spend time mopping sweat and chasing offsets to hold parts in tolerance produce more work and fewer scrapped parts, and they're much less likely to leave for a job down the road at a place that's not a sweatbox.

Totally agree with this great advice but I have something to add. If you have a lot of coolant in the air instead of finding ways to take it out of the general atmosphere of the shop consider taking it out at the source. The plant that I spent most of my career in had many hundreds of machines that mostly ran coolant or cutting oil and when I hired in there in the 70's you could hardly see from one of the first building in the complex to the next. In the late 70's or early 80's they started to duct machines together and use a Mistkop to take the fluids out of the mist inside of the machines and spin it out of the air and dump it right back in the machine. The difference was night and day.

I recommended that a friend who owned a cnc shop add them because the air quality was so bad. He did and the difference was dramatic.

I'd imagine that there are other brands of mist collectors out there but those are the brand that we used.

 

[FredC]

Ceiling insulation isn't nearly as big of deal for cooling as it is for heating. That old rule about heat rising and cool air dropping and all.

Attics in the south get sweltering hot pretty early in the morning. A friend is an air conditioning installer, told me about almost dying in the attic from heat stroke (he passed out and one of his workers finally checked on him). I did some work in my attic and even with a white roof, ridge vent and foil on the underside of the deck to reduce radiation heating you can not work up there a couple of minutes after noon.

Without insulation the ceiling will radiate large amounts of heat to the interior of a house or a shop. Bet the A/C guys have a formula for that.

 

[Big B]

Attics in the south get sweltering hot pretty early in the morning. A friend is an air conditioning installer, told me about almost dying in the attic from heat stroke (he passed out and one of his workers finally checked on him). I did some work in my attic and even with a white roof, ridge vent and foil on the underside of the deck to reduce radiation heating you can not work up there a couple of minutes after noon.

Without insulation the ceiling will radiate large amounts of heat to the interior of a house or a shop. Bet the A/C guys have a formula for that.

Sounds like a good market for solar powered attic fans. We have an attic fan that we used before we had central air in our house and in the summer I could feel the heat radiate from the fan so I make a cover out of 1" foil backed insulation and covered it in the attic and the problem is gone.

I'm sure not suggesting that anyone who is air conditioning a building leaves the attic uninsulated but do think that attic insulation is much more useful in keeping heat in than keeping heat out.

 

[metlmunchr]

Totally agree with this great advice but I have something to add. If you have a lot of coolant in the air instead of finding ways to take it out of the general atmosphere of the shop consider taking it out at the source. The plant that I spent most of my career in had many hundreds of machines that mostly ran coolant or cutting oil and when I hired in there in the 70's you could hardly see from one of the first building in the complex to the next. In the late 70's or early 80's they started to duct machines together and use a Mistkop to take the fluids out of the mist inside of the machines and spin it out of the air and dump it right back in the machine. The difference was night and day.

I agree anything you can do to take the coolant out of the air before it gets to the a/c system is one of the best things you can do. More healthy for the employees, saves money on coolant, less a/c maintenance due to coolant glop on coils and in drain pans, and decreased cost of operation of the a/c system. Every 1.5 gallons of coolant you remove from the air saves 1 ton of a/c, and every gallon of recovered coolant saves $1-$2 depending on cost and concentration of the particular coolant. Doesn't take too many machines running to add up to significant money over the course of a month.

 

[CarbideBob]

Finally, the shop owners I know who have air conditioned their shops have all said it paid back in increased productivity. People who don't have to spend time mopping sweat and chasing offsets to hold parts in tolerance produce more work and fewer scrapped parts,

I wonder how one puts a number dollars on this big shop or small.
Even if one or two man what is the difference in output?
In a very big shop are union rules that cooled Gatorade must be provided is the temp above xx outside, Would AC give a production boost?
It would be nicer for sure but production seems the same as wintertime.
I have not seen lower production or higher scrap in the summer when supervising in such . Attitudes and grumpy ......... lots of that.
A supervisor may get a air conditioned office on the floor. That AC maybe puts more heat on the floor as it runs inside the building.
One needs to live the environment that all work in. Programmers, engineers, mangers say they know but they do not do the sweat in so many shops.
Run heat treat when it is hot outside and stay with your team for a full shift. One has to do this on second as first and third are much easier outside temps.

Should we mention the filed complaint that the girls are wearing too short of shorts. This tweaked someone hard for some reason.
I was not sure how to handle this and begging the union rep for help.
Bob

 

[Big B]

I wonder how one puts a number dollars on this big shop or small.
Even if one or two man what is the difference in output?
In a very big shop are union rules that cooled Gatorade must be provided is the temp above xx outside, Would AC give a production boost?
It would be nicer for sure but production seems the same as wintertime.
I have not seen lower production or higher scrap in the summer when supervising in such . Attitudes and grumpy ......... lots of that.
A supervisor may get a air conditioned office on the floor. That AC maybe puts more heat on the floor as it runs inside the building.
One needs to live the environment that all work in. Programmers, engineers, mangers say they know but they do not do the sweat in so many shops.
Run heat treat when it is hot outside and stay with your team for a full shift. One has to do this on second as first and third are much easier outside temps.

Should we mention the filed complaint that the girls are wearing too short of shorts. This tweaked someone hard for some reason.
I was not sure how to handle this and begging the union rep for help.
Bob

Our plant was about 40 acres under one roof and was mostly air conditioned and I can tell you that there was major grumpiness when the air was down or decreased but I do think it was good for productivity not just from a personnel standpoint but the machines ran better in cooler temps. We had two major heat treat areas in our plant and it was nice in the winter if you came in from a cold car to stand in heat treat for a few minutes on the way to the work area and warm up.

As to short shorts, we didn't allow shorts of any kind in our plant until I was near retirement but we did have a couple of hot young ladies work as janitors in our toolroom and the foreman asked to have them replaced with someone that "wasn't such a distraction" to the men running machines.

We also had a situation one time where we had a guy who stunk to high heaven. I think the last time he showered was when he was born. He was sent to train on a job and work with a friend of mine. My friend refused to work near him because of the stench. He talked to his supervisor about it and the super called his committee person and told the union that he's your guy, you talk to him. I can't remember how it was resolved but I was glad that I wasn't the committee person.