Squirrel Cage Question???Pictures???

IF-Designs · #1 2006-09-04, 8:19am

Can anyone with a Squirrel Cage Fan Ventilation Setup Show me how you have it setup? I am having troulble trying to visualize how these blowers are setup to be used and I really could use a few photos to help me visualize what I would need to build to house this type of blower. Any help is appreciated but photos would be most helpful Thank you!

aimee · #2 2006-09-04, 9:49am

My friend Sandy here in Omaha has one set up for her studio in her house. She actually uses two squirrel cages. One for the one room and another for the other room. I only have these few pictures from some of the classes she's had. I do know that the vents are hooked to the suction part of the cage. The cages are outside with a cover built over them. The cages are also wired to seperate light switches her honey installed so she can switch them on and off, so she can have one or both running. The venting she used is the same as you would use for a dryer or whatever. Each work station has a flap so they can be closed if not in use. They work great, we have to leave a couple of doors propped open or they'll pull air from the basement and cause the pilot light on the furance to go out.

SadiesJewels · #3 2006-09-04, 5:09pm

Wow ... that's very different to my set up. I have it inside on a frame mounted over the workstation with a hood around it. I made the hood myself - not at all a beautiful thing but it certainly does the job. I imagine outside would be quieter as it's very noisy where I have it. Next time I set up I'll do what the above has - that should cut the suck down a bit I think too - mines really too powerful for the job.

I'll see if I have a picture on this computer ...

sadie

SadiesJewels · #4 2006-09-04, 5:13pm

Nope ... when I get to the other computer later today I'll try and remember to post - not much to look at really just a home made ugly hood!

Sadie

MikeAurelius · #5 2006-09-05, 4:45am

I do not recommend this type of ventilation system to anyone. All you are doing is exhausting the flame plume, NOT the fumes that raise above the torch or to the side of the torch.

Using frit or fuming with this type of set up will allow glass powder or metal vapor to enter the room atmosphere.

Also the comment about having other doors open in the house or the furnace pilot light troubles me - this indicates that not enough fresh air is being supplied to the room. This is a very important issue. You need to provide a source of fresh air (from the outside) to replace every cubic feet of air exhausted.

If the total system exhausts 1250 CFM, you need to provide 1250 CFM of fresh air. This has to be located at least 10 feet from the exhuast duct, and has to be from the outside. You cannot use just indoor air to provide make up air. Using indoor air without an open window or doorway to the outside will draw down the air pressure in the house, causing backflow from any source, furnace or hot water heater exhaust ducting, plumbing vents, dryer vents, etc.

I cannot stress enough the importance of a properly designed exhaust system ESPECIALLY if you are teaching.

aimee · #6 2006-09-05, 7:48am

These are outside doors that we're opening. Not indoor doors. We know that we need fresh air from outside, not inside. And they did lots of test before hand and the ventilation is removing all of the fumes.

She is not doing the teaching herself and all of the instructors that have been in have thought the system worked awesome.

MikeAurelius · #7 2006-09-05, 8:09am

In the last picture shown above, is the sliding glass door open? And is that the exhaust duct going out the wall right next to the door?

There is a requirement that fresh air intake needs to be at least 10 linear feet from a exhaust duct. Just looking at the picture, (and without seeing the outside wall and how the duct is routed), it appears as if exhausted fumes could very easily be drawn back into the room through the open sliding glass door.

I understand that instructors have thought it worked awesome, however, instructors don't always have good information about what is and isn't good ventilation.

I also know that what looks good on paper, and passes an incense test, isn't always a good or workable design. I'm not asking you to defend this studio or anything else, just pointing out some obvious deficiencies for anyone looking to emulate this particular design.

RSimmons · #8 2006-09-05, 8:22am

I've got a squirrel cage fan on my vent hood. In the picture you can see a big box hanging over the hood. I built the box as a vacuum plenum around the blower. It pulls air in from the bottom of the box (attached to the hood) and out the pipe at the top through the roof. Makeup air comes mostly from a blower that is ducted (from the bottom of the window to the right of the table) up through the table top. I've checked the system with smoke tubes with everything running and it draws nicely. It's also amazingly quiet.

Robert

IF-Designs · #9 2006-09-05, 8:26am

Thanks folks keep em coming if you got em! Im gonna show all this stuff to the BF and see what he can come up with!

aimee · #10 2006-09-05, 8:55am

The door is open but the exhaust isn't going out anywhere near there. They are going out on the other side of the house.

I would rather not agrue about this system, it works great. These were just some pictures takes of the people in the glass, I wasn't trying to capture how the exhaust system looks or works so it's hard to tell everything about it.

bclogan · #11 2006-09-05, 12:40pm

Here's mine. A local sheet metal shop built a hood to fit. the piece where the fan blows out fits into the window.

.

SadiesJewels · #12 2006-09-06, 10:18am

Ok ... I found the picture of mine. I had originally intended it to be more of a rectangular cone but dh jumped in ahead of me and placed the frame it is attached to up before I had explained the final shape to him - so I ended up with this box instead.

It vents directly to the outside - the blower is inside the box mounted on the wooden frame. Intake air is at the other end of the studio 20 ft away.

Sadie

BlueBetween · #13 2006-12-05, 6:11pm

any more pictures of the actual squirrel cage installation please? Not just the hood - the blower part how it all hooks up.

And, are they very noisy???

Thanks!
Pam

donnam · #14 2006-12-06, 8:18pm

Please explain what a vacuum plenum is?

Dale M. · #15 2006-12-06, 8:30pm

Quote:

Originally Posted by donnam

Please explain what a vacuum plenum is?

Never heard that particular phrase, but plenum is another word for duct.....

What first comes to mind for me, is the duct work that is installed in a home that has "built in" vacuum system...... But what do I know?..

Dale

MikeAurelius · #16 2006-12-07, 5:27am

A vacuum plenum is the same as a regular plenum (like what you have on your furnace), but it is on the suction (or vacuum) side of the fan. This is the type of system I use on my workstation enclosures. There is a metal plenum mounted on each workstation to distribute the vacuum (suction) of the fan across the entire width of the enclosure. I'll try to post a picture of it later today.

MikeAurelius · #17 2006-12-07, 6:51am

Ok, here's an example of a suction (vacuum) plenum. On the picture below, the fan is mounted on a rectangular box which forms the plenum. The underside of the hood has two long and narrow cut outs to draw from the entire width of the hood.

The fan draws down the air pressure in the plenum, making it lower in pressure than the surrounding area, this creates a negative partial pressure inside, causing air to rush in from the hood area.

I've since modified this installation and removed the fans from the hood and instead put a duct starter ring and duct to the fan. This makes a much quieter installation.

IF-Designs · #18 2006-12-07, 10:03am

Thanks Mike! Where did you get those fans BTW? All the squirrel cage tpyes Ive seen are open on both sides or is this the different kind you were refering too the suction one or something?

MikeAurelius · #19 2006-12-07, 11:28am

They are all grainger fans..... and a good number of them have closed backs...

BlueBetween · #20 2006-12-07, 11:34am

this might be a dumb question... not having the fan in my hands... but from looking at pictures, I can't tell... how does the round part get attached to the system? and the fan I'm looking at says the round part is 6 1/2 yet my duct will be 8 - so how does that connect?

I'm thinking I'm going: Hood --> duct --> through wall --> blower (in a protected box, outside). Do I also need duct off the square part or can I just put my rodent netting right in there?

Thanks,
Pam

MikeAurelius · #21 2006-12-07, 1:22pm

You can reduce size right at the blower -- many times there's no other way to do it. You don't have to duct off the square part, just put screen over it.