Squirrel cage question

[Lorraine Chandler]

Never mind we figured it out, and think/hope it will work just fine.


We are setting our squirrel cage blower unit on the "TOP" of the barley box hood torching area and enclosing in it in a wood box.

My question is how big should the box be around the blower unit? Would a clearance of 3 1/3 inches around the unit inside the box be sufficient?

There will be a hole in the top of the Barley box with a small section of ducting to draw fumes up into the blower from the torch. I might try it without the ducting also to see how well it pulls the fumes that way???

Thanks for any input
Lorraine

[cheeky monkey]

Mine is just a little bigger than the blower itself. I think the idea is that you want the air to pull from the venting so the size of box around the blower shouldnt really matter. My HVAC guy made it to fit. Here's a pic..... you can see it on the end of the large metal ducting. (The small duct is my dryer)

[AVC-Ed]

Actually, Mike says it is not a good idea to enclose a squirrel cage fan in a box. He says the heat build up from the motor can over time lead to a shorter life.

Most fans have a single intake port that can be directly ducted into and the fan motor should be open so it can get free flow of air.

The only fans that need to be totally enclosed are those where the motor is actually in the air stream and open on both ends to draw air into the blower. These fans are designed to have air flow over the motor to keep it cool, but this also raises the issue of the amount of heat the motor can take. Under normal usage, most fans are rated to air stream temps of 140 degrees max. Using a large torch, such as a CC+ or a Mirage (or larger) will generate higher than normal airstream temps, and you should monitor your airstream temps with a thermometer. Mike says he uses a normal meat thermometer pushed into the duct work. He works with a Beth Tiger Shark, and I've seen air stream temps in the 150-160 F temp, and he says that when he had a Mirage, it was as high as 180 F.

[RSimmons]

I've got my blower in a vacuum plenum (big box) and it works quite well. The box is big enough to allow for good air flow through both sides of the blower cage and the motor stays reasonably cool. I run a Phantom and only see a temp. increase when I'm running the outer flame, and then not much. My thermometer in the air stream rarely goes above 90 degrees, except when it's a lot hotter than that outside and the make up stream is already hot. Then is usually pegs at outdoor ambient. Running plenty of make up air through the system helps keep things cooler.

Robert

[Lorraine Chandler]

Thanks everyone. Cheeky monkey thanks for the pics..what a great setup!!

Robert you eased our minds..thanks

AVC-Ed. Thanks. I like the idea of being able to measure the temps and will do that. I do not think it will be an issue. I am using a Mega Minor and if I upgrade it will be to a Cheetah most likely.

Here are some pics of what my dH designed.

The first pic is of the top of my Barleybox. It will support the squirrel cage fan system and has two holes for the intakes.

The second pic is of the fan. It has intakes on both sides. DH put some rubber to help insulate it for noise and vibration and to also help the unit be level. We hope it works..it is easily removed if not.

The third pic is of the box and you can see how it is going to flip down over the holes cut in the wood nicely. The center piece of wood left in the top will support the unit.

When I first saw the fans I was shocked....I had no idea how huge they were. They didn't look that big on ebay where I bought the first one.

I just about fell over when UPS showed up with this gargantuan box!! I will let you all know how it turns out.


Thanks again everyone!
Lorraine

[RSimmons]

Now that you've got your box built......I'd recommend putting some sort of metal-backed insulation inside it over the wood. If nothing else put a layer of sheet metal inside in case a spark of some sort gets sucked up into the system. A metal-backed insulation will also help deaden the sound of the blower. Foil covered fiberglas external duct insulation works very well.

Robert

[NMLinda]

Hi Lorraine - thanks for posting pics. Hope you keep doing so: how your barley box is going together is very interesting. No wonder you were so surprised when your fan arrived - that's a serious woman's fan!

Linda

[Lorraine Chandler]

Thanks Robert..we will line the box...Good point.

Hi Linda, I am posting photos on my blog. It is so much easier than to keep posting them in several places.

It is coming together nicely but there is a lot of tweaking to do. I hope to be finished in the next two weeks.

Lorraine

[AVC-Ed]

Whoa nelly!! That looks like a furnace blower -- how many CFMs does it pull?

Mike agrees with Robert, line it with metal or foil fiberglass for safety and sound deadening. He's worried that you may have too much air movement with that monster. Be sure that you are able to supply the same amount of fresh air as the fan moves, otherwise you will be creating other problems.

[Lorraine Chandler]

Yea Ed! It is a furnace blower.

It is the smaller of the two we have. We do not know exactly what the CFM'S are but after researching them, this one at 1100 RPM and 3 speeds seems to be okay.

The lowest speed is quiet, doesn't bother my ears at all and pulls the test plums just fine. The second and third speeds are another story. I won't be using those.

So yes we are aware of the exhaust and replacement air. This motor may have to be changed out but test plumes look good on the low setting. We need 1000 CFM according to our hood opening dimensions. 2' X 4'

Here is how it looks on the 2X4 foot work area. Not that big really. It is a smaller one at 8 inches. The other blower was 10 inches.

We are trying to redesign with what we have on hand, so we wanted to give the smaller of the two blowers a try first.

Thanks for all of the advice
Lorraine