What to do with a 1000 CFM blower housing and motor

[Duane N]

My neighbor and I (mostly me
) replaced their upstairs split system A/C unit and gas furnace after 28 years of service after the compressor shorted to ground.  Instead of scrapping the blower out of the furnace I decided to make a portable fan filter unit so I can filter the air inside my home as I work on projects...mainly my kitchen remodel that still isn't complete.

Best part of this build was everything I used was free or leftover from other projects after building my kitchen cabinets.  I do commercial HVAC for a living so even the pleated 2" filters are free because sometimes technicians don't use all of the filters as they do maintenance inspections.

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[Stwood_]

Nice project. Looks good

[brnhornt]

I like it!  I have an HVAC blower sitting in my garage just waiting on a project like this.  I think you might have just filled up my weekend.  I was always leaning towards building it as a ceiling mounted garage/shop air cleaner.  Never thought of something like this!  What size casters are those?  Do you find the height off the ground gives you enough clearance for the fan's exhaust?  From a design perspective...do you find that having the exhaust facing down circulates the air in the room effectively?  I thought I would have to mount my fan on it's side so there would be a more definitive input and output flow so that it would in theory drive the air around the room and back into the filter/input.

Thanks again for the post!

[Duane N]

I like it!  I have an HVAC blower sitting in my garage just waiting on a project like this.  I think you might have just filled up my weekend.  I was always leaning towards building it as a ceiling mounted garage/shop air cleaner.  Never thought of something like this!  What size casters are those?  Do you find the height off the ground gives you enough clearance for the fan's exhaust?  From a design perspective...do you find that having the exhaust facing down circulates the air in the room effectively?  I thought I would have to mount my fan on it's side so there would be a more definitive input and output flow so that it would in theory drive the air around the room and back into the filter/input.

Thanks again for the post!

3" casters.  I'd like more room between the exhaust and the ground so I may end up blanking off the opening on the bottom and have it blow out one of the sides and only use 3 filters rather than 4.  The fan motor has 4 speeds and right now it's on the lowest speed to quiet it down.  I need to check the amperage of the motor because there's not much resistance on it.  I haven't used it much yet.

[TDKPE]

Since we're showing ours, here's mine.  HVAC blower from my last house.  I had to slow it down as it was from a ducted system, which runs at higher pressure than free-air, and seriously overloaded the motor without the duct network.*  Easy to adjust with a belt drive, though.  Not so easy with a direct-drive blower, but choking the inlet and/or outlet down will reduce the input power to prevent overloading the motor.

Converted the wooden stand I made for my Delta drill press way back when I was in high school.  Inlet on either side with course followed by HEPA filters, and very course filter on the outlet to break up the flow and keep fingers out.  My planer now lives on it.

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*Input power to the blower wheel varies as the cube of the speed, so just a 10% reduction in speed (all else being equal) results in a 27% decrease in input power.  Per the "fan laws", aka "affinity laws", and also applies to centrifugal pumps and axial propellers.

[Duane N]

Since we're showing ours, here's mine.  HVAC blower from my last house.  I had to slow it down as it was from a ducted system, which runs at higher pressure than free-air, and seriously overloaded the motor without the duct network.*  Easy to adjust with a belt drive, though.  Not so easy with a direct-drive blower, but choking the inlet and/or outlet down will reduce the input power to prevent overloading the motor.

Converted the wooden stand I made for my Delta drill press way back when I was in high school.  Inlet on either side with course followed by HEPA filters, and very course filter on the outlet to break up the flow and keep fingers out.  My planer now lives on it.





*Input power to the blower wheel varies as the cube of the speed, so just a 10% reduction in speed (all else being equal) results in a 27% decrease in input power.  Per the "fan laws", aka "affinity laws", and also applies to centrifugal pumps and axial propellers.

I like the dual purpose of yours.  If I had a dedicated wood shop I would have done something similar but right now I'm working in my attached, finished garage that is attached to my home so everything needs to be portable.

[Robert Adams]

28 years is about 3x what we expect to get from a compressor here. Lots of AC run time for most of the year in hot weather and here we have somewhat dirty power. I have hooked up a scope to it and its not very pretty and you can see why motors have an audible harmonic if you know what you are listening for. I have had no luck with the elec company and even talking to their service guys when they set up a meter on a commercial job they know it's a problem but with no fix. 


   I have a ceiling mounted air cleaner and it plugs up the prefilter after an hour of working on the mustang. That fine rust powder is like flour. I am only doing woodworking that the house demands these days as I needed a break from it. 

  I plan to add to the shop a paint booth and looking for a fan with a belt (for spark prevention) but they are rare these days. Most of the units being replaced are newer units that have those junk ECM motors. Those things have a horrible failure rate (and high replacement cost) and many don't fail but they have start up issues. They will try to start then thud then keep trying until they start, often they will be almost up to speed then thud out and restart.

[RichK]

I did something similar a few years ago but mine is 5-sided. An engineer friend suggested the pentagon shape because it makes more efficient use of the space. We used a wind speed tool (anemometer, about $25 on Amazon) to position plywood baffles to maximize suction and reduce dead space. Some people mount theirs to the ceiling. Mine is on wheels with a Formica laminated plywood top where my planer lives. I once wheeled the unit into my home office to get rid of ambient dust. I rigged it to exhaust out a window, used a leaf blower to agitate the dust, put the ceiling fan on high, closed the door and left it for a few hours. It helped my allergies until the dust accumulated again. It does a better job in my garage shop.