Fresh air supply to a gas appliance

Glen

if I recognize this fellows email address - he's from north of the border and might be better served by the CSA 149 code. Not that yours isn't similar - but we don't talk CZ etc or air changes for that matter - regardless the rules are there. Cheers - great manual on ignition systems - the check is on it's way tomorrow.

Raymond Bissonnette

Fresh air supply to a gas appliance

Hi,

Can someone tell me more about the US fresh air requirements?

A friend sent me info found in the '92 edition of the NFC but it seems to have only 1sq.in./2000Btu/h (through vertical duct) and 1sq.in./4000Btu/h (through horizontal duct)

In canada, there are differences for inputs below and over 400,000 Btu/h and for appliances with or without a draft control device.

The differences in calculation are to important. There must be something else.

Any pointer is appreciated.

Regards,
Raymond

Unknown

Air for Combustion

Without getting into a mile long answer it depends on the space being defined as "confined" or "un-confined".

A confined space is defined by NFPA 54/ANSI Z223.1 "National Fuel Gas Code" as a space whose room volume is less than 50 cubic feet per 1,000 btu of total input to all appliances installed in the room.

The Mechanical code says 40 cubic feet per 1,000.

The new 2002 code now specifies that calculations must be made based on Air Changes per hour either .35 or .6 ACH's per hour.

Prior to that if all air was coming from inside it required two openings one 12" from ceiling one 12" from the floor sized 1 square inch per 1,000 BTU's. But not less than 100 square inches per opening.

Air from outdoors is required if the space is confined and there are two methods:

Method One - Two openings 12 " from top and bottom

Vertical ducts 1 SQ inch per 4,000 BTU

Horizontal ducts 1 SQ inch per 2,000 BTU

Method Two:

One permanent opening 12" from ceiling with equipment clearances of 1" from sides and back, 6" from front, using ducts horiz or vertical, sized 1 sq inch per 3,000 BTU's and not less than the sum of the areas of all the vent connectors in the confined space.

For industrial burners the rquirements are totally different and ANSI Z83.3 pertains Air Requirements for Industrial Burners. Too lengthy to post all those requirements.

If you are interested I sell a complete manual on Air for Combustion, contact me by e-mail and I will give you some ordering info.

Raymond Bissonnette

Thanks Timmie,

I'll be in touch.

Raymond Bissonnette

Hi Glen

I'm indeed from Canada and well acquainted with the B149.1 but I'm inquiring about our neighbours' requirements.

I'm currently working on a small utility program to help canadian (and maybe american) installers determine their fresh air requirement.

You can learn more about Breeze at www.gastraining.com

I'm sorry if I'm breaking any forum rule by posting the above link. Just let me know if I did.

Regards,
Raymond

Unknown

Yes Raymond and

I have communicated in the past. I make use of a pipe sizing program he got me.

Glen

no rules broken -

that I am aware of. Will look up your site.
Cheers from the Canadian Rockies.

Glen

Glen

Nice site -

and I'll look at the programs - beta versions too. Looks interesting and useful.

Glen

Nice site -

and I'll look at the programs - beta versions too. Looks interesting and useful.