Ventilation (Again!)

[i09172]

Ahhh. Another ventilation thread! Anyway, like many folk, I'm having trouble determining the best ventilation to install for beadwork. I'm ready to upgrade my current system (two open windows and a fan) to a real ventilation system but I'm not sure what to get. Is this one offered by GlassCraft any good?:

http://www.glasscraftinc.com/product/product_detail.cfm?part_id=4881

It looks like it's just a hood with a in-duct fan similar to this one at Home Depot:

http://makeashorterlink.com/?K1D923ECC

If that's true then I could probably build something less expensive than the GlassCraft setup but I'm more concerned with getting one that's going to do the job effectively, quietly and last a while. I could also buy a squirrel cage fan from eBay fairly inexpensively but I'm thinking they might be too noisey to sit near for any period of time.

Any ideas or suggestions on other options would be appreciated. Are there other vendors selling ventilation units similar to the GlassCraft unit?

Thanks,
Kevin W. Miller
http://www.bluemoongemworks.com

[Dale M.]

The glasscraft hood is marginal at best.... The hood face is very large, and fan barely meets the 100 cfm per square foot of face opening rule... And the duct that come with it is flex aluminum and know to be inefficient in air flow.

Not to say its bad, if its the only thing you have got, or can get, or want to install, its better than nothing...

Some simple design work and well though out application of blowers and smooth walled sheet metal duct may get you a better system that specifically meets your needs for the same $$$ or less....

Do you home work...

Dale

[i09172]

The glasscraft hood is marginal at best.... The hood face is very large, and fan barely meets the 100 cfm per square foot of face opening rule... And the duct that come with it is flex aluminum and know to be inefficient in air flow.

Not to say its bad, if its the only thing you have got, or can get, or want to install, its better than nothing...

Some simple design work and well though out application of blowers and smooth walled sheet metal duct may get you a better system that specifically meets your needs for the same $$$ or less....

Do you home work...

Dale

Thanks, Dale. A part of my homework is asking questions of those who know more than me (most folk!).

Thanks again,
Kevin W. Miller

[Dale M.]

Ok... Here is some basics... You need at least 100cfm per square foot of "face opening" of hood. Blower then may be selected (roughly) by required CFM of face opening . You also have to calculate what size duct you will be using, 6 inch or 8 inch or 10 inch, and have to know how many turns and total footage of duct run. This will establish how much static pressure (resistance to flow) duct system has. This also has to be figured into blower size. As static pressure goes up, efficiency of blower goes down. So you may have to get a blower capable of more CFM (blower pressure) than face opening calculations dictate to over come static pressure...

Do not hesitate to ask questions!!!

Dale

[joebirder]

This may be on here already, But does anyone have any pictures of their ventalation? It might be helpfull to see what others that have a proper system have done to achieve it. I am in the process of setting up my ventalation. I want to just get a blower unit and fabricate the hood. Any pictures of something like this would be great....Work Safe..
Joe

[Dale M.]

Here is some ideas... and concepts....

http://www.artglassanswers.com/forum/viewtopic.php?t=90

http://www.artglassanswers.com/forum/viewtopic.php?t=150

Dale

[i09172]

This may be on here already, But does anyone have any pictures of their ventalation? It might be helpfull to see what others that have a proper system have done to achieve it. I am in the process of setting up my ventalation. I want to just get a blower unit and fabricate the hood. Any pictures of something like this would be great....Work Safe..
Joe


Hi Joe,

Here's a picture of our setup. I have another fan to mount on the left end of the hood next weekend so it isn't quite finished yet but does give you an idea of what it will look like. It's about 20 inches from the ends of the hood to outside of the exterior walls without turns. Each fan is rated at 650 CFM but I'm sure they produce somewhat less in this configuration.

22349

Kevin W. Miller
http://www.bluemoongemworks.com

[joebirder]

Thanks for the picture Kevin. Looks like a really good setup as it is. why you are adding another fan? Does it not suck enough fumes as it is?

[Dale M.]

Looks like a Glasscraft hood... The Glasscraft hood come with a 650CFM fan and is at minimum, it just barely meet the 100cfm per sqft face velocity "rule"..

Dale

[i09172]

Looks like a Glasscraft hood... The Glasscraft hood come with a 650CFM fan and is at minimum, it just barely meet the 100cfm per sqft face velocity "rule"..

Dale


That's correct and that's why there are two fans. One at each end. Should put me well over the 100cfm per sqft face velocity "rule".

Kevin W. Miller
http://www.bluemoongemworks.com

[MikeAurelius]

Okey dokey, I'm going to take a Devils Advocate position here...

Personally, I *hate* dual fan hoods, and this is from a purely air moving point of view.

The Glasscraft hood, has a square foot coverage area of 6.66. I use 125 CFM per square foot for ceiling mounted hoods - this is the number that is recommended by the ACGIH (American Council on Govermental Industrial Hygiene). 80 CFM is the bare minimum for an open-ended box, or a bench mounted hood.

Some localities will use a higher number, 150 to 175 CFM per square foot, depending on which standard they use. The ACGIH standard is the lowest I've found.

6.66 times 125 is 832 CFM total for the hood.

Yes, using dual 650 CFM fans is more than the 832 CFM called for by the standard, however, there is such a thing as too much air movement.

With higher than needed exhaust numbers, you are doing several things in the room - you are removing any conditioning of the air, be it heating or cooling. If you have insufficient make up air, a high rate of exhaust will cause an air pressure drop in the house which will cause back drafting of "appliances" such as a gas hot water heater or furnace, or even worse, from an odor point of view, sewer gas, as the low air pressure forces the normally wet drains to bubble back with air from the plumbing vent system.

A properly designed and installed ventilation system will eliminate all of the exhause concerns as well as the fresh air intake issues.

It will also eliminate problems with your flame dancing around from the fresh air being drawn up into the hood.

[i09172]

Thanks for the info, Mike. I'll let you know how it goes when the second fan is installed. I have a large window on another wall (and well away from either exhaust) so make up air won't be an issue and there are no gas appliances in the house which can backdraft. While these fans are supposedly "rated" at 650cfm I'm really doubtful that these "in duct" type fans are strong enough to backdraft through our septic system. But it'll be interesting to see how much "dance" I get on the flame.

Thanks again,
Kevin W. Miller
http://www.bluemoongemworks.com

[MikeAurelius]

Yeah -- I've got a fairly low opinion of in-duct fans - they are designed as booster fans for already moving air, not statonary air. Additionally, check the fans themselves to see what the termperature rating on them is - most in-line fans like this are rated to a maximum of 140 degrees F. If the fan blade is plastic, you may get some warping or complete loss of the fan blade at higher temperatures. On another glass board, it was reported that one person had a complete melt-down of his fan blades on this same unit because the fan blades were plastic.

[boroburner]

I have centrifugal fans960CFM on each station i have, and ill say those things suck!!!!!! I mean that in the best possible way. I can pass the "smoke test" with flying colors. The best thing is cause its an inline you can put it in the attic so its not as loud.
Ill post pics soon 4 yall.
B