Shop Cooling (Please check my theory)

[pkirby]

I'm trying to figure out a way to keep my shop's air temperature somewhat comfortable. I've done some research and have decided that the most practical thing to do (considering my budget) would be to keep the air moving by way of a fan. I would like to hear your critiques and suggestions for my plans below.

Conditions:
-Shop is 18,000 Cubic Feet
-Located in Atlanta, Georgia
-Metal building with R-3 blanket insulation
-Shop is being rented month to month (I can't do anything permanent)
-4 Lighthouse vacuum motors are bolted straight to table and produce a lot of heat inside

My Plan / Theory:
-Open garage door about 3' above floor and place fan in the open space
-Fan to be the 30" Orange one at Home Depot for $169 (Moves 5,500 CFM)
-Hopefully air will be circulated in such a way as to provide a temperature close to that of the outside air
-18,000 CF / 5,500 CFM = Turnover in 3.3 minutes
-Drawing below should explain it better:
15208

[gene]

in theory sounds good , but , it aint gonna work like that. have you looked at a port-a-cool fan at northern tools ? i just aint too sure how the moisture will affect things in your shop? they cool good , i have seen them at the I W F and other trade shows and they do a very good job, cheaper than A/C and portable

[knight_toolworks]

you really need to draw the air through your shop it's best to vent from the roof and draw the air though the doors. a big gable fan would be the best bet.

[myxpykalix]

Your hot air in the shop is going to rise so you need to evacute the hot air out some way with a roof or gable fan then create some cross ventilation at ground level.
Doing it the way you show is just circulating the hot air from the ceiling across you at ground level, Not good.

[pkirby]

I agree the best way would be to have an opening on the other side, so that a cross breeze could blow through, but I can't do that since my rent is month to month and they won't let me install anything permanent. Our challenge is to figure out how to get fresh air in and hot air out from the only opening which is my 10'x10' garage door.

[paulkiecka]

reverse the air flow. and angle the fan so it blows towards the roof. hot air rises and will naturally want to stay in the area above 10' and can get quite warm.(Think attack spaces) you can probably make a open bacl lean to for the fan so it will get the air circulating real well. the air can escape from above the garage doors.you might want to lean some plywood sheets along the bottom of the garage door not occupied by the fan(s) air would want to leave from there as well. after all it is kind of squishy that way :)

[dana_swift]

For a lot less money than you can air condition, run a de-humidifier. Then the fan feels much more comfortable as your body can cool itself more efficiently. In Atlanta I suspect humidity is as much the problem as sheer heat.

This presumes the shop doors are usually closed, which may make the temp too high in the summer tho.

Venting heat out the top still makes sense, then you only have to dehumidify the "make up" air.

D

[pkirby]

you can probably make a open bacl lean to for the fan so it will get the air circulating real well.

I understood the majority of your comments and they make sense, but could you please explain the above statment a little more.:confused:

Thanks

[kevin]

I had a small shop in Montreal a few years ago
Aircontioing was becoming a must .I use to start at 6:00 and finish at 2:00

All your doing is moving hot air around put the 169 towards an air contioner

[gerryv]

"-4 Lighthouse vacuum motors are bolted straight to table and produce a lot of heat inside"

Besides the good comments on fans and dehumidifying, could you remove the heat sources as much as possible? For example, could you mount this into one of Brady Watson's vac box creations or a Gary Campbell design Black Box and place that either 1. inside but venting out a window through an insulated exhaust pipe or perhaps 2. outside with the suction pipe coming into the Shopbot?

[knight_toolworks]

For a lot less money than you can air condition, run a de-humidifier. Then the fan feels much more comfortable as your body can cool itself more efficiently. In Atlanta I suspect humidity is as much the problem as sheer heat.

This presumes the shop doors are usually closed, which may make the temp too high in the summer tho.

Venting heat out the top still makes sense, then you only have to dehumidify the "make up" air.

D
a dehumidifier is an air conditioner. so I doubt the cost would be much different. Plus it tends to output heat.

[genek]

What type of ceiling do you have.

Is there an opening into the attic.

If it is a drop ceiling can you see the v part of the roof.

If there is an opening where you can place a fan to blow air up into the attic and draw air from under the garage door raise two inches you will get some cooling..

If not... Do you have a window... If so place a fan in the window or build a box that will fit the window and draw air from the ceiling and vent it to the outside..

Hot air rises.. By bringing the hottest air to the out side you cool the building some ...
Best bet is a portable a/c unit that vents through a window... This way when you move you take it with you.

[myxpykalix]

It seems kind of crazy to add to the heat only to have to find a way to also get rid of it. Do you have any sense of how much heat your vacumns add to the mix? I would assume since they are right at table level it seems like a lot.
I don't know what you cut but could you figure out and use some mechanical hold downs and stop using the vacumns?:confused:

[bleeth]

Paul:
With a shop that is 25 x 50 (mol) you need a few fans to circulate air in and out. Near the door and as high as practicable you should be exhausting and pulling in near the bottom. You also need some more circulation assistance scattered in the shop. Even with the cross ventilation in our shop it takes several fans to really make a difference. Having the exhaust from the vac motor(s) directed out the door is a must.
We use a couple rolling oranges, a large pole fan, and additional smaller wall mounts in some specific work areas.

[pkirby]

Thanks guys for all the help! Sorry for the delayed response but I didn't get home from the shop until 1:30am and I don't have internet access there. (Cooling isn't such a problem at 1:00am:D) I agree that I need to move the exhaust of the vacuum motors to the outside, but that is going to have to wait until I get caught up with work. I'm going to go with Dave's suggestions of putting in a few fans to keep the air moving. It looks like Dave is in the hottest part of the country so his advice should be solid:D Thanks again.

[dana_swift]

Steve- you need to learn more about dehumidifiers. You are quite correct they do use a chiller, but the requirements are different. A dehumidifier only needs to lower the temperature of the condenser coil to below the dew point. Usually only a few degrees when the humidity is high. It does not need to drop the temperature to air-conditioner levels. As a result mine draws less than 10 amps at 120v (when the compressor is on) to make my shop comfortable in the summer. I try to keep the RH around 50% so a fan will do the cooling I need.

I dont have an air-conditioner which would need a lot of juice. So in the hot months, I run the high electrical loads in the morning, let the heat blow out the open doors then dehumidify the air again and spend the afternoons on glue-ups and other activities.

Dehumidifiers usually cost a lot less than an equivalent air-conditioner. Yes it does contribute some heat to the shop, but since it is only getting the humidity to condense out, it spends the majority of its time with the compressor off.

Now you have me thinking about it, I will plug it into my Brand power meter and measure exactly how much it is drawing today. That will tell us all both the running costs and the heat it puts into the shop.

Expect another post later today with the results.

D

[dana_swift]

Here are the first results, I started the dehumidifier at 9am, and went and repeated the measurements at 11am, two hours later.

http://www.talkshopbot.com/forum/attachment.php?attachmentid=15233&d=1335976096

Note that in two hours I have use 1.2Kwh of electricity. Approximately $0.15. And put 1200 watts of power into the shop over two hours, not enough heat to compare to things like dust collection, shopbot, etc.

The Hyrgometer read 82% relative humidity at 9am and was down to 68% by 11am. A fourteen percent reduction in two hours.

http://www.talkshopbot.com/forum/attachment.php?attachmentid=15234&d=1335976103

My shop size is 1/3 the size of Pauls, so presumably my costs to dehumidify are about 1/3. A/C costs would be MUCH higher.

I just took pictures of the Brand power meter readout sequencing through some of the readout options, which shows that as the dewpoint drops the power required to dehumidify increases. It started out at 434 watts, and by the time the RH was down to 68% it was using 530 watts or 4.58 amps. The power factor is .98 so the load appears resistive to the power company (no extra power factor charges).

I will post again later this afternoon after its run a while longer and achieved something closer to 50% RH. I will let you know what the electrical load has increased to, which will still be under 10 amps.

One other note: Tulsa high for the day is expected to be 88 degrees F. The shop is staying in the low 70's from the thermometer part of the hygrometer. In August the shop will run around 85-90F with 50% humidity when it is 100F+ outside.

D

[paulkiecka]

I understood the majority of your comments and they make sense, but could you please explain the above statment a little more.:confused:

Thanks

part of the problem is bad typing. Those orange fans blow air parallel to the floor, but if you built a stand( basically a frame to lean it back at an angle maybe even 30 to 45 degrees, the air flow would be heading up towards the ceiling where all that hot air is collecting in the pocket above the garage doors.my other comments were to close off the rest of the opening below the garage doors to force more air out of the top space.

[gerryv]

I'm with Dana on this. I've read or heard a number of times that the two cheapest means of air conditioning are dehumidifying, which allows the body to cool itself naturally, and reducing sources of heat.

Because we're excavating anyway, we're currently looking at burying pipe under the footings of our new workshop at about 7' down and simply pulling cool air through it as the temp at that depth is about 55 degrees year round. There appears to be a growing body of knowledge and experience on keeping the pipes drained and mould free.

[kevin]

I had one problem with a job to much humidity in Montreal.I made a wall unit with high humidity in late Sepetember out of African Mahoney ,Then 2 weeks later it got cold he had a wood fire place took out all the moister out in one shot 2 of the 6 doors warped .On fogy days here I don.t open the doors
Its a good subject

[myxpykalix]

Gerald,
If you have the option at all you might try to make a "cold room" in your excavation. It is simply 4 bare cinderblock/concrete walls surrounded by earth and no lights.
I have a large cold room under the porch of one of my houses and have some inline vent fans running from that room to the basement apt and upstairs and it keeps both floors relatively cool except on extreme heat days. Other then that they don't use the AC.

[knight_toolworks]

all I know about dehumidifiers is I used one in my kiln it provided the heat and removed the moisture.

[knight_toolworks]

as far as heat from the vac motors it is a fair amount. in my 1000sf concrete underground shop I saw at least a 5 degree temp increase using two feins it was worse with my 220v motors.

[gene]

Gerald ,
I have heard of burying pipes underground , running a liquid thru them and extracting the heat or cool from them (geothermal) but i havent heard of puling air thru them . Is this due to your location?

[gerryv]

Hi Gene,
I think if you search Earth Tubes you'll see quite a bit of info pop up. Unfortunately though Google is becoming more and more difficult to find good info on for me at least. Wikipedia has a fairly balanced discussion I believe under the name ground-coupled heat exchanger.

In my case, because I'm excavating anyway, it could come down mostly to the cost of thin walled, smooth 4" PVC pipe and apparently some sort of silver based liquid "stuff" to coat the ID to prevent mould. Not much of a financial risk if it's less efficient than hoped.

From the various bits I've read so far, it seems that having drains at the low points is also important for the same reason. Damp, dense soil seems to be better than light, dry - makes sense. I like the idea of a fully passive, cheap way of moderating air temp as we get anywhere from 100+F to -10F where I live.

The key seems to be going deep enough to get into the zone where the earth's temp. is fairly constant. The numbers I've seen most are 55 F at 7' down. but I'm going on Geezer Recall on that so don't take it to the bank (chuckle).

[myxpykalix]

This experiment might cost you a couple hundred bucks but it might save you some money in the long run. I would take some 6" pvc pipe and bury it down in the ground below your slab as deep as you could put it and have a pipe coming up from the slab in 2 locations. Then use a fan like this to let the ground cool the air.
http://www.ventingdirect.com/nutone-ilrf-in-line-fan-radon-mitigating-150-cfm/p877549?source=gg-gba-pla_877549____11248312164&s_kwcid=TC%7C7809%7Callproductpla%7C%7CS%7Ce%7C112 48312164&adtype=pla&cagpspn=pla&gclid=CMeJhIT04q8CFUSK4AodhReVDw

The only thing that i question is whether by doing this you might be spewing radon into your shop?:eek:

[myxpykalix]

Gerald here is a couple resources you should read up on if you are going to be building, i would try to incorporate some of the ideas for solar heating. i have a solar hot air heater and in the middle of winter i was getting 150+ degree heated air. There are some resources for cooling i've seen but you will need to look within the site.
http://www.builditsolar.com/index.htm
http://tech.groups.yahoo.com/group/SimplySolar/

paul, you also might want to check out some of these because it might have some links to help you with cooling.

[pkirby]

Thanks Dana for the experiment, that's really good info. I noticed you said the high was around 88 and you were keeping the shop in the low 70s. I would love to achieve those kind of results. I know lower humidity feels better on the body, but are you saying your dehumifidier keeps the actual shop temperature down and maintains it throughtout the day? Also, I'm assuming you have the doors closed with no exhaust going the the outside:confused:

[jerry_stanek]

My dehumidifier puts out heat so I don't see a savings.

[dana_swift]

Paul- most welcome!

The dehumidifier raises the temperature a bit, with its 550 watts as I measured yesterday. When the shopbot and dust collector are running the temperature will go up much more. (I was not cutting anything yesterday.) Insulation and a lot of concrete & dirt keep the temperature down. Even so some days in August I have thought maybe I should buy an air conditioner. The worst my summer days get is 90s in the shop from the thermal mass, the dehumidifier makes 90+ degrees in the shop bearable.

When my shop gets uncomfortable warm is when my vacuum pump (5hp) is running all day with the bot and dust collector. Even then the 500 watt dehumidifier and a fan is all I use to combat the heat. As much as possible I run the high horsepower equipment in the morning when it is cooler.

Another note on the dehumidifier- I paid a whopping $150ish for mine. The good news is you can try it for not much money. I expect you will find it gets you through most of the summer quite comfortably. I am not in a metal building, and that may be a solar collector all by itself and an air conditioner may be a requirement for you. Even so, you will cut your A/C use by half or 2/3 using an inexpensive de-humidifier.

When I bought the de-humidifier for the shop I was expecting to buy an A/C unit. To be large enough to cool the shop it would need to be a 220v unit and cost much more to buy and to run. When I saw the dehumidifier in the same section, I started thinking about what I really needed and decided to give the low cost solution a try. I have been using the dehumidifier for several years now and find it adequate. On the hottest days, you could probably get me to change my mind. Someday I may go ahead and buy an A/C also. I dont like being hot any more than anybody else.

Part of the forum is sharing what works for each of us. Others may not find my solution adequate for their needs. I would even expect that. But I would not discourage anyone from trying something that might help them even if its of no use to me.

When it was suggested that I was giving bad advice, I decided to measure it (since I already owned a power meter) and check my impressions with real numbers. Yesterday evening I turned off the dehumidifier about 7pm. The humidity went to about 65% and slowly went down to 60%. What that tells me is in some obscure corner there was a puddle of rain water from last weeks storms that was slowly evaporating resisting the dehumidification. The total Kwh from all of yesterdays run was: 5.503 according to the Brand power meter. That cost less than one dollar to run all day.

When I just leave it on, its set to turn off at 50% RH. Which is where it usually operates.

It works for me. (with a fan)

At a minimum it should give the forum users an alternative to think about. With a little hard numbers to go with the suggestion..

D

[steve_g]

For what it's worth... I just finished stickering some walnut and maple I scavenged around the neighborhood and went to put in the new storage building I'm just finishing up. It's 95° outside now but the inside of my building felt like I had AC on... When I built the (southern exposure) Shed I used foil back sheathing on all walls and roof. I'm a believer now... and any new building anyone builds would benefit from this!

Steve