Step by Step - How to make a $50 Lasko Model 4914 into a 300+ CFM exhaust fan *pics*

Part 1 (of 4)​

So I've built and rebuilt a few of these now, and since Grasscity got me started in this hobby, I thought it only right to give back where I can.

A lil background, I'm 3 crops into my hobby and a former HVAC specialist. Now I've never had a can fan or any other kind of exhaust fan, nor do I need them after building this inexpensive solution to a very critical factor with your growroom. Those of us with high intensity MH and HPS systems know that heat can be a major problem if you don't have a fan sucking out the heat put off by that light. A lot of us affected by the recession don't have $100-$200 to throw into an expensive exhaust fan..with this tutorial, if you've got 50 bucks in your pocket, you too can have a system that can match most $300+ systems.

Here's a pic of the box and a piece of the instruction manual I thought kinda ironic. lol


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Materials needed:
Lasko Model 4915 Floor Fan (I found mine at Lowes)
Hammer
Flathead screwdriver
Great Stuff Insulating Foam Sealant
6" ventilation collar
Duct Tape
Mastic Air Duct Sealant (optional, but recommended)
Insulated Air Ducting (or whatever tubing you're using for your exhaust, but I highly recommend you spend the few extra bucks and get the fiberglass insulated air duct, it pays off.)

Step 1: Lets get that pesky grate off.

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Take your fan out of the box, and put the head of the screwdriver in the small corner of the grate, as shown in the pic. Then take your hammer, being careful not to give yourself a bad day, and hammer sideways with the screwdriver to slip it underneath the grate so you can pry it off. The guy I learned about this fan from said this can be taken off so you can reuse the fan, I say "why bother"? And with all the Great Stuff crap you'll have all over this fan before you're done, you're not gonna want to reuse it. After you break the grate off the fan, proceed to step 2.

Step 2: Lets get rid of those lil plastic spacing tabs.

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If you look around the black collar of the hole you created by removing the grate in Step 1, there's these lil plastic pieces, as pointed out in the pic, that will cause you difficulty when mounting your collar. Lets hammer and chisel them out with the screwdriver. Don't knock too hard, doesn't take much force to knock these lil tabs out. After you've done that, proceed to step 3.

Step 3: Let's mount our collar.

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Alright, you're done with your hammer and screwdriver, now lets get that collar glued on. After doing this a few times, I've realized how much easier and less messy this job is with latex gloves. Learn from my mistakes and use them the first time. Put your collar on top of the 6" hole you created. Should fit in very easily. Then take your Great Stuff (don't let the title fool you, this stuff is NOT great stuff to get on your hands) and seal around the outside of the collar. I also like to put a lil bit in the interior of the collar too, but be easy with this, doesn't take much and you can make a real mess on the inside of your fan.

Alright, now sit your fan somewhere to dry, and go smoke a spliff for your hard work. That's it for Part 1, Part 2 (which will cover duct taping the inside of the collar to the fan, and using your mastic to paint the duct tape and Great stuff seals to add extra strength to the seal) coming after it dries.

Part 2​

Thanks for the support

I wasn't going to make this post, but figured if you're doing this tutorial, I'd like to divide the different parts between drying sessions.

If you completed Part 1 of the tutorial correctly, you should have something like this...

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So here's Part 2 of the DIY 300+ CFM $50 Lasko Floor Fan (mouthful huh?)

Step 1: Lets get rid of our excess foam.

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Now if you're like me, you've got tons of big knives layin around, but personally I have my handy dandy duct knife from my former occupation, works great for this. As you see in the pic, level off the foam with your knife, using a cut/twist motion to cut into the foam, and twist the knife to break it off. Like a pro baby! Then the inside...

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Once again, level off the foam with the knife. Also try to remove any excess foam that may have dripped into your fan blades, as it can throw off the central balance of the fan possibly if you dont. You don't have to get anal about it, just get the big stuff. After you finish this, you're ready to grab your Mastic Air Duct Sealant and move onto Step 2...

Step 2: Air sealing the collar to the fan.

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So take your Mastic (and latex gloves), which comes in a tube or a bucket, and try to push it into the foam, getting into all the nooks and crannies, as well as filling in any slight dips in the foam. Don't be afraid to use your gloved hand to work with this crap.

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And the inside...

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Also make sure you seal the seam of the collar. This will ensure your connection stays airtight...

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After you've got a nice layer of Mastic Air Sealant covering all your foam, you can set this baby aside to dry for the night (should cure in a day or overnight), and light up another spliff for your hard work

Stay tuned for Part 3 of the tutorial, which will include covering all this mastic with duct tape, taping the other side of your fan shut, and then covering all the tape with mastic. See yall tomorrow

Part 3 (of 4)​

Ok, onto Part 3: Taping and Final Sealing of the Seams.

If you completed Parts 1 and 2 correctly, your fan should look something like this...

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Step 1: Applying the Duct Tape around the outside seams.

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Apply duct tape around the outside seams between the 6" collar and the fan. I use the duct tape very generously, but clean. Also apply a strip down the seam along the collar itself...

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Step 2: Apply duct tape on the inside seams.

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And now the inside. Some might call this overkill, I say "why not?" Don't forget the inside seam on the collar itself!

Step 3: Paint the duct tape with Mastic Air Sealant.

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This is where things get messy in this part. Paint all the ducttape with Mastic, and make sure you paint it generously, that way you'll have a contractor-grade seal on your fan, great for high CFM pressure Dont forget the inside...

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Alright, that's it for your fan's construction!!! Hope you have the victory spliff ready and waiting for ya! If you followed the steps properly, you should have something that looks like this..

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Now I know a lot of you are thinking "Ooooook...so that's 1 6" hole to connect my intake air duct to, what about my exhaust line?" Well I'll show you that in the next part of the tutorial. In the meantime, sit your fan somewhere to dry and light that spliff up mon! The Mastic needs time to cure, and you definitely shouldn't be shy on the drying time when it comes to something you want lasting air seal with. 2-3 days is a good time to ensure this baby is completely dry. See yall soon!

Part 4 (of 4)​

Well here we are, at our 4th and final part of this tutorial. In this part we'll review fitting your fan's output to a 6" flex duct and securing that connection. I'll also show you how to attach flex duct correctly.

If you followed all the other parts of this tutorial correctly, you should have something that looks like this...

Make sure to check your seal completely. Remember, any job worth doing is worth doing right, and this is especially true with your ventillation system.

Step 1: Tape the other side of the fan shut.
You'll notice your fan has an intake on each side of it, so we're going to tape the opposite side shut so we only have 1. All that's needed is duct tape. You can paint it with Mastic if you please as well.


Step 2: Fit loose 6" duct to 6" collar.





Let's go ahead and fit your intake hose (from your reflector) to the fan. To do this, you can use duct tape, but I'm using the big zip ties. What you want to do here is pull the black hose of the flex out, and then roll the silver lining into the fiberglass insulation, like you're rolling up your sleeve and the black hose is your arm (nice analogy huh?). Before you attach the flex to the collar, put a ring of mastic air sealant around the inside of the black hose. Slide the hose over the collar and slip it down as far as it will go, then tighten the zip tie around it, leaving it high enough so we can ziptie the silver lining and fiberglass insulation over it. To tighten your zip ties, you can try to do it by hand, but I have a handy dandy zip tie squeezer that works really good, you'll find them in the ventillation aisle at HomeDepot.


Step 3: Hooking up your output.







This is a lil frustrating, but trust me it's possible to get that 6" flex over the rectagular hole, just have to pinch the hose and slip it over. Before you attempt to fit the flex duct, I'd have about 4-5 5" pieces of duct tape ready to go. Once you manage to fit the duct over the hole, take the pieces of duct tape and secure the connection. You can go crazy here, just make sure you get the seal secure enough and totally air sealed. Make sure you seal the bottom! (showed in the second pic from the top). After you're satisfied all the holes are covered, grab your handy dandy Mastic air sealant, and paint the crud out of that duct tape so it's nice and strongly sealed now. Let that dry for about an hour, then you can slip the silver lining and insulation over the Mastic covered duct tape and duct tape it securely to the fan as well. You don't really have to paint this duct tape as there's no air seal here, but you can if it makes you happy.



Well there you have it ladies and gentlemen blades. You have your ultra inexpensive awesome 300+ CFM fan, all for about $60 in materials! Tell your friends

 

Refer to Original Post. It's all combined now

 

Refer to Original Post. It's all combined now

 

The fan is dry, but keep in mind that dry doesn't necessarily mean cured, which means closer to hardened. Give your fan 3 days to fully cure before turning it on with pressure.

 

^^^ This would be the man who first introduced me to this fan. Gotta give credit where credit is due ;-)

 

The whole tutorial (Parts 1-4) is now combined in the original post

 

Needed another pic post

 

Thank you everyone for the compliments. I look forward to doing more tutorials of duplicate projects in the future. Hope this helps many.

velanarris- MarGreenThumb posted that he's had his running for about a year and a half straight 24 hours a day and have had no problems or complaints. Mine has been running for about the same, and no problems. Who knows how long it'll last, no problems foreseen but we'll see.

morde- Thank you Glad it helped you out! I try to do tutorials how I personally wish more were done, and I know that involves detail so I try to point out things that confused me when I was trying to follow a tutorial. I look forward to your reviews with future projects

JollyStoner- Wow "genius", thanks for the flattery When you're establishing an exhaust system in your grow room, your main objective is to achieve passive air intake from your fresh air vent. There's an equation that tells you exactly how many CFM's you need to generate to achieve this per meaurements of the room. I'll look for it after I make this post and will insert the address here...

Edit: Here's a post I made a while back asking the same question, you can sift through the 2 page thread and find your answer better than I can explain it.
http://forum.grasscity.com/grow-roo...t-cfm-fan-would-i-need-negative-pressure.html


Sativanya- Silicone...hmmm..might work, but the foam insulation (Great Stuff) expanding when it leaves the can really helps in this project, but try it n let us know

 

Has anyone constructed one yet? I'd love to see some completed pics