Ventilation Questions

[BabblingBeads]

OK, I need you gurus out there to help me out.

I have a contractor putting together an estimate for my ventilation. He want to purchase a Range hood that only has 300 cfms. It's my understanding that range hoods can be used if you take out all the filters etc and change the pipe going out to 8". Is this correct? Also I think the cfms are way off. My work benchs is about a 4' deep by 6' long and I will have two torches. The cheapest to make a hood would be $500 and this range hood is $300.

Can you help me in explaining to this contractor what I need?

Thanks.

[Dale M.]

Contractor need to understand that you need 100-125 CFM of air flow per square foot of hood opening (face opening)...

Basic rule is if hood in 2 feet deep and 3 feet wide it has a 6 square foot "face opening" and that requires 600 to 750 CFM of air flow (minimum)...

Its same specifications as a class "A" industrial/medical/research "standard" fume cabinet.

Dale

[cheng076]

I have always thought that there was damn little one could do to make a kitchen raange hood effective. Too small and much underpowered. I think the contractor is 'jacking up" the cost too much. I went to a sheet metal shop and had a hood 3.5 feet by 5 feet with tapered top into a 12" x 12" outlet made of 16 ga steel for $150.00. Shop around.

[Dale M.]

The absolute minimum "Kitchen Range Hood" I would consider is something like this...

http://www.amazon.com/inch-Wall-kitchen-range-hood/dp/B003QIH876

http://www.amazon.com/Stainless-Steel-Az668a75-Mount-Range/dp/B0039D34IK/ref=pd_cp_hi_2

As a example the both have over a "advertised" CFM of 700 which puts in the range of acceptable for a "off the shelf" solution, and if you have a little handy person skills (liking using a screwdriver and cutting holes in walls) you DIY it... Only modification I would make is to remove any filters as the are restrictive to air flow, and be-sure its NOT a recirculation style hood...

If I were to go with this type of hood I would really search the major shopping features of the i-net ( Bing - Google - The Find) and find heavily discounted units with high end performance... At one point I found a 900 cfm hood for $300 and it was a really nice looking unit (but that deal is long gone)...

[BabblingBeads]

Thanks guys for the information. My understanding is that my contractor, which is a co workers DH, went to 2 places to get estimates on fabricating a hood and the lowest was $500 which is way to high for me. Granted I am not sure what he ask them to make it out of. I am not sure what is the cheapest materials to make the hood out of . Any advise?

I will pass all this info on to him and see what he says.

Thanks bunches!

[Dale M.]

Assuming the hood will be a work space and not a show case space, I would ssuggest least expensive way to go would be "galvanized sheet metal" which is zink coated (prevents rust) sheet steel minimal thickness to be self supporting (retain shape) is all that is required...

Dale

[cheng076]

If you have a hood made the best material is steel. Galvanized is Ok but more expensive by a little bit. Plain ole 'black iron' sheet is great if you figure on painting it your favorite color. Any thickness from 24 guage to 16 guage depending on the design and size. Large flat areas tend to resonate/vibrate with the fan, again depending on the design.
Call a few sheet metal places yourself and explain what you need/want and see the prices; cut out the middleman. Draw out a basic design for your hood and shop it around. Doesn't need to be fancy justa basic upside down box. Some people have used a livestock watering trough. Looks cool and is cheep.

Think outside the box.

[BabblingBeads]

Great info guys. Thanks bunches :)

[SadiesJewels]

I made my own hood... It wasn't pretty :-)

I got sheet metal from Home depot (galvanised steel?) and cut it with tin snips. We riveted it together and nailed it to a wooden frame to secure it to the wall behind the torch. Cost was under $100.

Shame I had to leave it behind when we moved to Oz.