I am wanting to put an exhaust fan in my shop. It is 30x30x10 with no ceiling. It has 2 9' bay doors and 1 access door. It is extremely hot in the summer so I would like some air flow. Also I do wood work in it and am wanting to paint my truck and other projects. My father in law got me a 42" industrial exhaust fan with 1.5hp motor for free from a job he did. Is it possible to make this huge fan work. I am afraid of pulling too much air and messing up my paint job on the truck by pulling in dubree. This is an extremely expensive fan I do not want to pass up. But will it work for my garage and how.
Need help with exhaust fan
- Thread starter Nickt6494
- Start date
pseudorealityx
Well-known member
If you want to fix the heat issue, you need to insulate the shop. At best, moving a lot of air through the space is going to keep it at ambient temperatures.
That fan sounds too large for your application. I'm assuming it's a flat prop fan that would be installed in a wall??
In the case of a paint booth, you want all of your make up air to be filtered to avoid the air carrying dust and other "dubree" to your freshly painted surfaces.
That fan sounds too large for your application. I'm assuming it's a flat prop fan that would be installed in a wall??
In the case of a paint booth, you want all of your make up air to be filtered to avoid the air carrying dust and other "dubree" to your freshly painted surfaces.
MTW
Well-known member
Hi Nickt6494 Here are my suggestions to your questions.
A bit of background : I am an industrial electrical contractor that specializes in industrial ventilation equipment. I have installed and serviced many hundreds of paint booths, powder booths, dust collectors and ventilation systems over many years. I have worked with several mechanical contractors designing and installing this type of equipment in a vast array of shop types from automotive factories, bump shops, museums, to one man shops. And here is my advise to you and others that may need a ventilation system in their workshop.
First to answer your questions directly, then to provide some additional food for thought. Yes it is possible to make it work and no it's not to big if you set it up correctly. For a comparison lets take an average car paint booth. They are about 12' wide x 10' high x 16' deep, and normally come with about a 24-34” tube-axial fan and a 2-3 HP motor. A tube-axial fan is a lot more efficient that a simple wall mount ventilation fan. As you can see your shop is a lot bigger, your fan is less efficient, and your motor is smaller. Therefore your fan should be fully useable just the way it is, even though it's a bit larger. However the way you set it up and use it, can make a huge difference on how it can work for you.
Food for thought:
It is most advantageous to use the fan to supply air than to exhaust it. This is counter-intuitive to the normal way of thinking.
The many jobs I've worked on have proven this out many times over, most times to the project owners pocketbook detriment. Lets consider the paint booth example again. Any paint booth that works decent, must have an air make up unit to supply clean air to the booth for it to function as designed. Usually the fan for the air make up unit will be at least twice the HP (horsepower) size of the exhaust fan. Anything less and the booth will not function well or not at all. A booth installed without a air make up unit will try to **** air from any place it can get it. Normally this means from every crack and crevice that the building structure has, and this is exactly where most dust bunnies reside. Read as a very dirty paint job, you can get as good of a result just painting outside on a calm day. A properly engineered booth with an air make up unit will slightly pressurize the building that it is in. In this way clean air is trying to escape from every crack and crevice driving the dust bunnies away from the booth, not towards it. Read as a clean dust free paint job. Negative pressure in a building not only pulls in dirt and cold air in the winter, but also carbon monoxide fumes from every furnace and water heater burner you have, poisoning the occupants and making the burners erratic and unreliable. This is why all inspected jobs require the air make up unit, and need to be designed such that the supply fan starts before the exhaust fan.
Another analogy that I like to use is a cardboard box with a fan in it's side. Picture it in your mind's eye. If the box is closed the fan will do nothing, it spins, but it can't move any air, it can't get any air to move. It consumes very little energy because it is doing no real work. Only when you open the box does it get some air to move, and then it begins to perform some useful work. At this point it will begin to load the motor and use some current to do real work. If you need to see this in action take a regular old box fan, cover up the intake side of it. It still spins and make some turbulence in the box but no air comes out the exhaust side, the motor will change speed and the current will be lowered.
For an ideal shop setup with only one fan I recommend using the fan in reverse to pressurize the structure. Better yet is to use a reversing motor starter to be able to use it both ways for different purposes. Most wall ventilators are paired with a louvered shutter that blows open with the fan pressure and falls closed with gravity. This will not work with the fan in reverse as a supply air source. The fan will **** the shutter closed. You must install a motor to open the damper before the fan starts, or provide some manual linkage to do it yourself. The ideal situation is to install the fan as high as possible and as far away as possible from your overhead doors to get a good cross-flow of clean air.
In regards to the size of the fan and amount of air it provides, this can be adjusted by changing the pulley and belt sizes. And also by how much you open your door or window to provide the escape path.
Leaving the motor pulley the same and enlarging the fan pulley will increase the ratio and slow down the fan. Closing the door won't slow the fan but will limit the volume that it can move and increase pressure within the building, also decreasing the motor amp draw. If you really want to get **** use a variable speed drive on the motor and then you could adjust electrically whatever volume you wanted. Personally for shop use ,I don't think you could ever likely have too much fresh clean air. But remember used as an exhaust fan it will pull air into the structure likely from grade level where most dust bunnies reside, and definitely where your truck with wet paint will be camping out.
I have used this setup in my two shops for 20 years with great results. Here is how I use it. My repair/fabrication bench is located directly below the fan. When I am welding or burning something I run in exhaust mode, the smoke naturally rises and immediately gets sucked out because of close proximity to the fans low pressure area. When running a vehicle inside, painting or sanding I put the work near any overhead door and run in supply mode. I only crack the overhead door a few inches, this restricted flow keeps the pressure and velocity (speed) high. Any dust or mist that is airborne will be racing for the exit before it hits the floor. If there is any that settles to the floor a quick hit with a blow gun will get it airborne again and heading for the exit. Same goes for fumes, paint solvents are heavier than air and are on the floor, so they are naturally already at the exit point, ready to be pushed out as soon as they get near floor level. If you were running in exhaust mode you would be fighting mother nature trying to pull heavier than air fumes up to the top of the building. It's best not to fight mother nature, somehow she usually wins.
A bit of background : I am an industrial electrical contractor that specializes in industrial ventilation equipment. I have installed and serviced many hundreds of paint booths, powder booths, dust collectors and ventilation systems over many years. I have worked with several mechanical contractors designing and installing this type of equipment in a vast array of shop types from automotive factories, bump shops, museums, to one man shops. And here is my advise to you and others that may need a ventilation system in their workshop.
First to answer your questions directly, then to provide some additional food for thought. Yes it is possible to make it work and no it's not to big if you set it up correctly. For a comparison lets take an average car paint booth. They are about 12' wide x 10' high x 16' deep, and normally come with about a 24-34” tube-axial fan and a 2-3 HP motor. A tube-axial fan is a lot more efficient that a simple wall mount ventilation fan. As you can see your shop is a lot bigger, your fan is less efficient, and your motor is smaller. Therefore your fan should be fully useable just the way it is, even though it's a bit larger. However the way you set it up and use it, can make a huge difference on how it can work for you.
Food for thought:
It is most advantageous to use the fan to supply air than to exhaust it. This is counter-intuitive to the normal way of thinking.
The many jobs I've worked on have proven this out many times over, most times to the project owners pocketbook detriment. Lets consider the paint booth example again. Any paint booth that works decent, must have an air make up unit to supply clean air to the booth for it to function as designed. Usually the fan for the air make up unit will be at least twice the HP (horsepower) size of the exhaust fan. Anything less and the booth will not function well or not at all. A booth installed without a air make up unit will try to **** air from any place it can get it. Normally this means from every crack and crevice that the building structure has, and this is exactly where most dust bunnies reside. Read as a very dirty paint job, you can get as good of a result just painting outside on a calm day. A properly engineered booth with an air make up unit will slightly pressurize the building that it is in. In this way clean air is trying to escape from every crack and crevice driving the dust bunnies away from the booth, not towards it. Read as a clean dust free paint job. Negative pressure in a building not only pulls in dirt and cold air in the winter, but also carbon monoxide fumes from every furnace and water heater burner you have, poisoning the occupants and making the burners erratic and unreliable. This is why all inspected jobs require the air make up unit, and need to be designed such that the supply fan starts before the exhaust fan.
Another analogy that I like to use is a cardboard box with a fan in it's side. Picture it in your mind's eye. If the box is closed the fan will do nothing, it spins, but it can't move any air, it can't get any air to move. It consumes very little energy because it is doing no real work. Only when you open the box does it get some air to move, and then it begins to perform some useful work. At this point it will begin to load the motor and use some current to do real work. If you need to see this in action take a regular old box fan, cover up the intake side of it. It still spins and make some turbulence in the box but no air comes out the exhaust side, the motor will change speed and the current will be lowered.
For an ideal shop setup with only one fan I recommend using the fan in reverse to pressurize the structure. Better yet is to use a reversing motor starter to be able to use it both ways for different purposes. Most wall ventilators are paired with a louvered shutter that blows open with the fan pressure and falls closed with gravity. This will not work with the fan in reverse as a supply air source. The fan will **** the shutter closed. You must install a motor to open the damper before the fan starts, or provide some manual linkage to do it yourself. The ideal situation is to install the fan as high as possible and as far away as possible from your overhead doors to get a good cross-flow of clean air.
In regards to the size of the fan and amount of air it provides, this can be adjusted by changing the pulley and belt sizes. And also by how much you open your door or window to provide the escape path.
Leaving the motor pulley the same and enlarging the fan pulley will increase the ratio and slow down the fan. Closing the door won't slow the fan but will limit the volume that it can move and increase pressure within the building, also decreasing the motor amp draw. If you really want to get **** use a variable speed drive on the motor and then you could adjust electrically whatever volume you wanted. Personally for shop use ,I don't think you could ever likely have too much fresh clean air. But remember used as an exhaust fan it will pull air into the structure likely from grade level where most dust bunnies reside, and definitely where your truck with wet paint will be camping out.
I have used this setup in my two shops for 20 years with great results. Here is how I use it. My repair/fabrication bench is located directly below the fan. When I am welding or burning something I run in exhaust mode, the smoke naturally rises and immediately gets sucked out because of close proximity to the fans low pressure area. When running a vehicle inside, painting or sanding I put the work near any overhead door and run in supply mode. I only crack the overhead door a few inches, this restricted flow keeps the pressure and velocity (speed) high. Any dust or mist that is airborne will be racing for the exit before it hits the floor. If there is any that settles to the floor a quick hit with a blow gun will get it airborne again and heading for the exit. Same goes for fumes, paint solvents are heavier than air and are on the floor, so they are naturally already at the exit point, ready to be pushed out as soon as they get near floor level. If you were running in exhaust mode you would be fighting mother nature trying to pull heavier than air fumes up to the top of the building. It's best not to fight mother nature, somehow she usually wins.
MTW
Well-known member
And to finish up the suggestions, because the post was too long:
Another use is poor mans air conditioning. My shop 7000 sq/ft is masonry construction with a gypsum roof and full of metal items which makes a tremendous heat sink. Once this mass becomes super heated it takes a real long time to get it cooled back down again. So what I do is run in supply mode in the evening, pumping in cool air at night removes all of the latent heat that my heat sink accumulates during the hot summer days. In the morning I shut her down and close the place up keeping it reasonably cool during the day time. If it's going to be super hot for a spell I just leave it running round the clock, in this way the heat sink can't build up to a super heated condition and is usually many degrees cooler than day time temperatures, do to the cooler sinking the building gets during the night hours. Just remember that you have to provide some exit point for the night time air for it to work well. Even with all windows and doors shut on mild days and nights, enough air gets out through my furnace, unit heater, and water heater exhaust pipes to make it work fairly well. I'm pushing clean hot air out those stacks, not pulling poison gas back down them. When working in the office I can open a window wherever I want some air flow and it provides some comfort without a local fan or running the air conditioning, works great for evacuating tobacco smoke when visitors come over.
Another good use is spring cleaning. During the winter months the shop accumulates a lot of dust and debris from cleaning parts and equipment while it is closed up. In addition to the wall fan, I place an old furnace blower in the middle of the shop pointing towards the cracked overhead door. Starting at the furthest location from the door I use the blow gun to start dusting towards the furnace blower. The blower aids in moving the heavier debris towards the exit point. My floor is old and has a lot of pock marks in it, making it difficult to sweep, this method cleans it more thoroughly than vacuuming it could. Works well for leaves, cottonwood seed balls, spider webs, and shards of materials that accumulate under benches, on pallet racks and equipment. Sometimes I even get up in the mezzanine and start at the top of the building, cleaning the trusses as well. Just be sure to don your respirator so you don’t take years off your life stirring up all that dust. To make it more convenient for opening the door when starting the fan, I leave a door remote near the fan controls so that it's quick and painless.
Anyone interested in installing a system like this could obtain anything you need from Graingers, they’re not the cheapest but they carry all of the items you would need, fans, shutters with motors, mounting sleeves for installing, electrical controls. Most of my system was rescued from industrial dumpsters and job sites. I bought a new damper assembly with the motor and a galvanized mounting sleeve. Rebuilt the fan with new bearings and belts, welded a cracked blade or two, built a control panel from used components. In the first shop I installed it in, I made my own wooden frame to mount it in the block wall, in the current shop I found it much easier to purchase a metal sleeve and install that just like a block in its opening, it was much easier that way. My fan was a 24” with a 1/2 HP motor. I installed a 2HP motor and changed the pulleys to speed it up significantly from its stock configuration. I have since scored some larger ones and plan to eventually install one of those on the other half of my shop. Like I said earlier, for a shop, I don't think you could have too much clean air in the summertime and when doing nasty projects inside.
I hope that helps and inspires you....MTW
https://dl.dropboxusercontent.com/u/13118477/ShopFan/Wall Fan Exterior.jpg
Another use is poor mans air conditioning. My shop 7000 sq/ft is masonry construction with a gypsum roof and full of metal items which makes a tremendous heat sink. Once this mass becomes super heated it takes a real long time to get it cooled back down again. So what I do is run in supply mode in the evening, pumping in cool air at night removes all of the latent heat that my heat sink accumulates during the hot summer days. In the morning I shut her down and close the place up keeping it reasonably cool during the day time. If it's going to be super hot for a spell I just leave it running round the clock, in this way the heat sink can't build up to a super heated condition and is usually many degrees cooler than day time temperatures, do to the cooler sinking the building gets during the night hours. Just remember that you have to provide some exit point for the night time air for it to work well. Even with all windows and doors shut on mild days and nights, enough air gets out through my furnace, unit heater, and water heater exhaust pipes to make it work fairly well. I'm pushing clean hot air out those stacks, not pulling poison gas back down them. When working in the office I can open a window wherever I want some air flow and it provides some comfort without a local fan or running the air conditioning, works great for evacuating tobacco smoke when visitors come over.
Another good use is spring cleaning. During the winter months the shop accumulates a lot of dust and debris from cleaning parts and equipment while it is closed up. In addition to the wall fan, I place an old furnace blower in the middle of the shop pointing towards the cracked overhead door. Starting at the furthest location from the door I use the blow gun to start dusting towards the furnace blower. The blower aids in moving the heavier debris towards the exit point. My floor is old and has a lot of pock marks in it, making it difficult to sweep, this method cleans it more thoroughly than vacuuming it could. Works well for leaves, cottonwood seed balls, spider webs, and shards of materials that accumulate under benches, on pallet racks and equipment. Sometimes I even get up in the mezzanine and start at the top of the building, cleaning the trusses as well. Just be sure to don your respirator so you don’t take years off your life stirring up all that dust. To make it more convenient for opening the door when starting the fan, I leave a door remote near the fan controls so that it's quick and painless.
Anyone interested in installing a system like this could obtain anything you need from Graingers, they’re not the cheapest but they carry all of the items you would need, fans, shutters with motors, mounting sleeves for installing, electrical controls. Most of my system was rescued from industrial dumpsters and job sites. I bought a new damper assembly with the motor and a galvanized mounting sleeve. Rebuilt the fan with new bearings and belts, welded a cracked blade or two, built a control panel from used components. In the first shop I installed it in, I made my own wooden frame to mount it in the block wall, in the current shop I found it much easier to purchase a metal sleeve and install that just like a block in its opening, it was much easier that way. My fan was a 24” with a 1/2 HP motor. I installed a 2HP motor and changed the pulleys to speed it up significantly from its stock configuration. I have since scored some larger ones and plan to eventually install one of those on the other half of my shop. Like I said earlier, for a shop, I don't think you could have too much clean air in the summertime and when doing nasty projects inside.
I hope that helps and inspires you....MTW
https://dl.dropboxusercontent.com/u/13118477/ShopFan/Wall Fan Exterior.jpg
Last edited:
MTW
Well-known member
Camper
Yes a drum switch (Barrel) could be used. What type depends on your motor, single or 3 phase. Personally I use a magnetic reversing motor starter not a drum switch. With the magnetic starter it can be interlocked with a timer to allow the damper to open before the fan starts. The damper motor doesn't have enough power to open, when the fan is pulling on it. This allow it to be "idiot proof", anyone can operate it properly with no prior knowledge. You turn the selector switch on to the direction you want, the damper begins to open, and a timer allows the fan to start, once the damper is fully open.
MTW
Yes a drum switch (Barrel) could be used. What type depends on your motor, single or 3 phase. Personally I use a magnetic reversing motor starter not a drum switch. With the magnetic starter it can be interlocked with a timer to allow the damper to open before the fan starts. The damper motor doesn't have enough power to open, when the fan is pulling on it. This allow it to be "idiot proof", anyone can operate it properly with no prior knowledge. You turn the selector switch on to the direction you want, the damper begins to open, and a timer allows the fan to start, once the damper is fully open.
MTW
pseudorealityx
Well-known member
MTW makes a lot of good points... a few problems though.
1) A fan's motor is going to use amps even if it's not moving air.
2) If the velocity is high, the pressure is LOW. Bernoulli and all that.
And again, for a garage shop, a 42" prop fan with a 1.5 hp fan is over sized. That fan is designed to pull/push somewhere between 9000-14000 cfm. That's 60 air changes per hour, which is basically a decent commercial clean room. In a professional commercial paint booth, that could be a realistic number, but not for this application. Notice the size of the shop in MTW's picture... that's only a ~32" prop fan. The OP's is 70% larger, and on a smaller building.
Assuming you want to keep the pressure drop through your intake louver at a reasonable level, you're looking at a big louver... at least 48"x48". That's going to get spendy in a hurry. Also, you would want to filter that air, and a filter box big enough for 10,000 cfm isn't any small thing, even with low MERV filters.
1) A fan's motor is going to use amps even if it's not moving air.
2) If the velocity is high, the pressure is LOW. Bernoulli and all that.
And again, for a garage shop, a 42" prop fan with a 1.5 hp fan is over sized. That fan is designed to pull/push somewhere between 9000-14000 cfm. That's 60 air changes per hour, which is basically a decent commercial clean room. In a professional commercial paint booth, that could be a realistic number, but not for this application. Notice the size of the shop in MTW's picture... that's only a ~32" prop fan. The OP's is 70% larger, and on a smaller building.
Assuming you want to keep the pressure drop through your intake louver at a reasonable level, you're looking at a big louver... at least 48"x48". That's going to get spendy in a hurry. Also, you would want to filter that air, and a filter box big enough for 10,000 cfm isn't any small thing, even with low MERV filters.
MTW
Well-known member
pseudorealityx
You are correct the motor will use amps even when not connected to a fan. Most small motors are very inefficient when not run at the full load nameplate value. Usually they will draw about 3/4 of their nameplate rating when running at no load on a bench.
I cant speak to Bernoulli Laws never studied that, that’s what mechanical engineers do, such as yourself. As far as the velocity go, what I will tell you is, I'm not talking about the fan throughput velocity, I'm referring to the exit slot under the door. With my door 1/2 open you can't detect any air movement out on your skin, however when it is only open a few inches the air is moving rapidly and quickly. In regard to the pressure you are correct, it is low, a fan of this type is only rated at 0.375 In. SP maximum. When the building is closed up with no exit points besides my exhaust stacks, the pressure builds to the point where whistling noise becomes evident at my tightly sealed weatherstripping on my overhead and man doors.
And yep you are correct it is a little big for the application in it's current configuration. The Dayton supply fan listed here is rated for 19,302 CFM @ 0.125 In SP http://www.grainger.com/Grainger/DAYTON-Supply-Fan-wDrive-Package-7AD09?Pid=search
I would provide a damper that is the same size as the fan for easy installation. And if the pressure drop gets a little larger through it, all the better to reduce the efficiency of the fan, as this restriction will reduce the actual volume of flow. The same go’s for running an exhaust unit in reverse, such as the venturi being reversed along with the pitch on the blade. Slowing the thing down by changing the drive components should get it to a point where it is useable for him, and if done, the motor size could be reduced as well.
Most job's I work on when the fan gets remove so does the louvered damper that’s paired with it. That is how you reduce the spendy part.
In regards to the filter box you are correct that could get spendy as well. The solution there is to elevate the fan to reduce the contaminates that it picks up. I'm not trying to imply that you won't get any dirt pumped in the building, but the more elevated it is installed the less it will see. I paint many items including my trucks with less dirt in them than your average dusty bump shop does. My shop has some space between the fan and the bay that I paint in, so most dirt that comes in has some time to slow down and fall out before it gets to the object being painted
I'm not trying to be combative, I agree that it's a little big for the application, but it could be made to work with some modifications, if he is willing to experiment with it. Clean room type airflow, on a limited budget sounds like a good deal to me
MTW
You are correct the motor will use amps even when not connected to a fan. Most small motors are very inefficient when not run at the full load nameplate value. Usually they will draw about 3/4 of their nameplate rating when running at no load on a bench.
I cant speak to Bernoulli Laws never studied that, that’s what mechanical engineers do, such as yourself. As far as the velocity go, what I will tell you is, I'm not talking about the fan throughput velocity, I'm referring to the exit slot under the door. With my door 1/2 open you can't detect any air movement out on your skin, however when it is only open a few inches the air is moving rapidly and quickly. In regard to the pressure you are correct, it is low, a fan of this type is only rated at 0.375 In. SP maximum. When the building is closed up with no exit points besides my exhaust stacks, the pressure builds to the point where whistling noise becomes evident at my tightly sealed weatherstripping on my overhead and man doors.
And yep you are correct it is a little big for the application in it's current configuration. The Dayton supply fan listed here is rated for 19,302 CFM @ 0.125 In SP http://www.grainger.com/Grainger/DAYTON-Supply-Fan-wDrive-Package-7AD09?Pid=search
I would provide a damper that is the same size as the fan for easy installation. And if the pressure drop gets a little larger through it, all the better to reduce the efficiency of the fan, as this restriction will reduce the actual volume of flow. The same go’s for running an exhaust unit in reverse, such as the venturi being reversed along with the pitch on the blade. Slowing the thing down by changing the drive components should get it to a point where it is useable for him, and if done, the motor size could be reduced as well.
Most job's I work on when the fan gets remove so does the louvered damper that’s paired with it. That is how you reduce the spendy part.
In regards to the filter box you are correct that could get spendy as well. The solution there is to elevate the fan to reduce the contaminates that it picks up. I'm not trying to imply that you won't get any dirt pumped in the building, but the more elevated it is installed the less it will see. I paint many items including my trucks with less dirt in them than your average dusty bump shop does. My shop has some space between the fan and the bay that I paint in, so most dirt that comes in has some time to slow down and fall out before it gets to the object being painted
I'm not trying to be combative, I agree that it's a little big for the application, but it could be made to work with some modifications, if he is willing to experiment with it. Clean room type airflow, on a limited budget sounds like a good deal to me
MTW
Welcome to GJ . . . Nick. Sounds like you have nice big shop and the free fan is great, and "may" benefit you as others have described above.
However, Insulation is always a good idea. If the big fan can reduce shop temp at night, the insulation will maintain that temp for portion of the next day.
Post up some pics of what all you've got going on for insulation/ceiling/etc.
Finally, update your GJ Profile with at least Country and State. Good luck.
However, Insulation is always a good idea. If the big fan can reduce shop temp at night, the insulation will maintain that temp for portion of the next day.
Post up some pics of what all you've got going on for insulation/ceiling/etc.
Finally, update your GJ Profile with at least Country and State. Good luck.
pseudorealityx
Well-known member
Agreed on all points MTW
Also, just for perspective, if you run that fan constantly, you're gonna spend ~$30/month on electricity. $360/ year.
I just think something like an ~18" fan with a 1/4 hp motor would be sized better, not require a massive louver/damper setup, and cost you ~80% less in electricity.
Also, just for perspective, if you run that fan constantly, you're gonna spend ~$30/month on electricity. $360/ year.
I just think something like an ~18" fan with a 1/4 hp motor would be sized better, not require a massive louver/damper setup, and cost you ~80% less in electricity.
MTW
Well-known member
As to the cost of running the fan, pseudorealityx is correct, at my commercial rate it is more than $30 a month 24/7 for a 2Hp unit.
In my neck of the woods I usually only need to do that about one or two weeks of the year, some years none.
It still beats the cost of running the air conditioning in the office on miserable days though and makes the shop area much more comfortable.
A smaller fan would be better suited to a garage type building, for less money purchased new, but the OP was asking if he could make the large free unit work.
I tried to frame the post in more general terms, so that others reading, who may already have a exhaust fan installed, could see it in a new light, while still trying to answer his questions directly.
For those willing to experiment with their time and cash, they could be rewarded with a ventilation system that could exceed their expectations.
For me it also saved the floor space of installing a small paint booth for reconditioning electrical enclosures and pieces of equipment that I work on. It enables me to do a small paint job or a nasty repair during the winter months without filling the shop with contaminates and creating hazardous conditions inside. Just remember to shut down your heating equipment and other sources of ignition during the painting operation.
And as always if you tightly seal and insulate your structure it will always pay big dividends, with or without a ventilation system.
Be smart and stay safe, think before you act. I hope that sharing my knowledge will help the other readers of the forum out there. I found it to be a interesting place to peruse when time allows.
In my neck of the woods I usually only need to do that about one or two weeks of the year, some years none.
It still beats the cost of running the air conditioning in the office on miserable days though and makes the shop area much more comfortable.
A smaller fan would be better suited to a garage type building, for less money purchased new, but the OP was asking if he could make the large free unit work.
I tried to frame the post in more general terms, so that others reading, who may already have a exhaust fan installed, could see it in a new light, while still trying to answer his questions directly.
For those willing to experiment with their time and cash, they could be rewarded with a ventilation system that could exceed their expectations.
For me it also saved the floor space of installing a small paint booth for reconditioning electrical enclosures and pieces of equipment that I work on. It enables me to do a small paint job or a nasty repair during the winter months without filling the shop with contaminates and creating hazardous conditions inside. Just remember to shut down your heating equipment and other sources of ignition during the painting operation.
And as always if you tightly seal and insulate your structure it will always pay big dividends, with or without a ventilation system.
Be smart and stay safe, think before you act. I hope that sharing my knowledge will help the other readers of the forum out there. I found it to be a interesting place to peruse when time allows.
Strouty
Well-known member
sands35
Well-known member
(didn't catch all the comments - sorry!)
No ceiling is probably issue #1. Not sure how your roof is constructed, but they are a pretty good heat source. Without a ceiling and insulation, the roof vents will not work right. hence, all that heat just goes into the garage proper.
If you are painting, then the ceiling will probably make it cleaner. Less opportunity to have stuff accumulate in the rafters. An opportunity to hang temporary plastic "walls" too.
If you add a ceiling, then you can install the fan more or less like a "whole house fan". louvers in the ceiling and a vent cap under a gable. One thing to be aware of is how the motor is designed to be oriented. Normally, the motor shaft needs to be horizontal, not vertical. The bearings will die in short order if it's not supposed to be mounted vertically. Standard household AC vent ducts and parts will work fine. You can set it up to either blow or to ****, multiple distribution points are possible too.
No ceiling is probably issue #1. Not sure how your roof is constructed, but they are a pretty good heat source. Without a ceiling and insulation, the roof vents will not work right. hence, all that heat just goes into the garage proper.
If you are painting, then the ceiling will probably make it cleaner. Less opportunity to have stuff accumulate in the rafters. An opportunity to hang temporary plastic "walls" too.
If you add a ceiling, then you can install the fan more or less like a "whole house fan". louvers in the ceiling and a vent cap under a gable. One thing to be aware of is how the motor is designed to be oriented. Normally, the motor shaft needs to be horizontal, not vertical. The bearings will die in short order if it's not supposed to be mounted vertically. Standard household AC vent ducts and parts will work fine. You can set it up to either blow or to ****, multiple distribution points are possible too.
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Strouty
Well-known member
Revisiting this thread, I am getting ready to try and install a new unit and would like to use MTW's rationale, his ideas have worked for me in the past on my air compressor plumbing so I think he is dead on with this as well.
larry4406
Well-known member
Strouty- thanks for awakening this.
I am interested in the switching which operates the louver prior to starting the fan in forward or reverse. Please post this when you get to it. I have a 24" belt drive whole house fan to mount in a gable of a future equipment shed which will also serve as a paint booth
I am interested in the switching which operates the louver prior to starting the fan in forward or reverse. Please post this when you get to it. I have a 24" belt drive whole house fan to mount in a gable of a future equipment shed which will also serve as a paint booth
James-W
Well-known member
I realize this is an old thread and the opening poster no doubt has already done whatever it is he is going to do. But I was thinking that he has really two separate issues, one is keeping the shop cool and the other is venting a paint booth. To keep the shop cool, insulation and air-conditioning would be the best option. A fan bringing in more of the same hot humid air is not going to do very much for cooling down the shop area and making it more enjoyable for working.
I don't know about codes for home paint booths but I am pretty sure there are codes for paint booths in body shops and places like that.
I don't know about codes for home paint booths but I am pretty sure there are codes for paint booths in body shops and places like that.
MTW
Well-known member
Hi again Stouty and the forum.
I haven't been to this post in a while, but today here in Michigan it's 86 and sticky. I'm back to running my fan 24 hours a day for some good relief. It made me think about this post and sure enough Stroudy dug it up again.
You asked earlier about my control setup and I didn't make time to do anything with it. The controls you would use is dependent on the motor and the damper motor that you have. I use a 3-phase 2HP fan motor and a 120 volt damper motor. So my controls being three phase is probably not applicable to most of you. It consists of a 3-phase reversing starter and a timer along with a remote operator station.
I would suspect that most of the board members would be using single phase Motors and therefore the control setup would be different. As I privately conversed with another member of the board even a 3-phase fan can be used on a single phase supply system with a VFD. A VFD cost a bit more but allows the functionality of having the variable speed as well as reversing.
For an example the shutter and damper motor that I use is from the Grainger catalog. The model they sell now is slightly different than the one I purchased years ago, but it's essentially the same thing. Damper Motors also come in various voltages, so again your controls depend on what you have.
For the timer I use a little electronic cube relay timer. For the remote operator controls I use a push button station with some selector switches. A 2 position switch controls the damper motor. The manual mode just opens the damper but doesn't allow the fan to come on for natural ventilation. The automatic Mode starts the timer coutdown, once the timer completes, then it starts the fan starter.
A second 2 position selector switch controls the fan rotation direction. The fan starter is interlocked with the timer so that the fan cannot start until the timer times out, meaning that the damper is fully open.
Then it has a control transformer to step down 240 volt to 120 volt to operate the controls and the damper motor. It also has a main disconnect switch to kill all the power to the controls.
So in order to design a controller for the system you really have to know what parts you're using to make the system. For a totally manual operation a light switch could be used to control the damper and a drum switch could be used to forward reverse control a single phase motor. The motor require some type of overload protection. Single phase motors many times have it built in the motor. Three-phase motors rarely do and require a starter to provide the thermal protection.
So that's the basics, you would need to submit what you're using for components in order to help you design a controller.
A side note if you're interested in the Grainger shutter and damper motor get the part number from Granger and look it up on zoro.com, it's a sister company using the same stock but better prices.
MTW