Tain Breezer

Dave Yates (PAH)

Tennis courts to be covered in a giant bubble. Each roughly 100' x 300'. We were contracted to run utilities and the GC (out of Canada) is to handle construction and supply of furnaces. First unit arrived today and is a used piece of equipment rated at 2,500,000 Btu's. They're claiming it's only four years old, but if I had to guess judging on looks alone, that's at least ten years young. Seems like way too much, Btu wise, for one of these shelters and the second unit (I was told today) is supposedly rated at 2,000,000 Btu's.

My gut feeling is that either one of these structures should be rated at 1,000,000 to 1,500,000 Btu's on a zero degree day while maintaining 65 degrees indoors. Seems like overkill & if true that will screw up the gas meter's accuracy.

Not really my business since I'm not supplying the equipment, but I'm curious. If these are grossly oversized, there's going to be problems with the utility supplier & I get into a bit of hot water (?). CYA

600' of gas line to run(G). 1,200' of 8" SDR 35 SS line too.

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Gary Fereday

Should be easy to calculate

The requierments. Just figure it "as usual" 1/2 parabola surface area and the necessary air lost to keep the thing inflated. The R value of the fabric. and go for it! The floor can be figured at 52* ambient if the place warms up. Sheesh Yates, does anyone there use engineers any more? or did they all go to high tech electronics a while back?

Gary Fereday

Maybe

Get the high school math teracher to help on this one? I just cannot think thru that any futher! bigugh

Gary Fereday

AND

I love the way that you become responsible if the utility co. has a problem. Nice big shoulders you have! bigugh

Dave Yates (PAH)

responsibility

The guy holding the wrenches is always the guy responsible. It's never the homeowner's, business owner's, architect's, engineer's, supplier's or GC's fault, is it? It's like playing spin the bottle and getting kissed every time!

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Gary Fereday

YUP !!! (nm) bigugh

Dave_4

the 2.5 mbh is not that far off....

floor@30,000sqft...55-65 degrees, R1 (no insulation); 300,000btu
roof @ 30,000sqft, bubble factor 1.4, 0-65 degrees, r1.5 on the fabric ;1,820,000btu
8700 cfm of air to keep inflated,@ .15 cfm/sqft (maybe too lite)of fabric plus one door open @ 100 fpm thru door;610,740 btu....

take credit for people @ 400btu each, & lights....maybe 300kbtu...

Dave Yates (PAH)

but

what about the thermos bottle effect of the bubble once inflated? Reading conflicting information on the web regarding these types of structures, I saw ratings as high as R-19 (AKA - blowing sunshine up skirts) for these air filled walls.

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bluenose_4

tennis courts

Used to work on a one the these ballons which had a oil-fired furnace. Heat was only major expense, owner/operator had a switch installed to immediately turn off heat/burner if there were no customers. Place would drop temp. really quickly, but furnace was 1.2 mbh , brought temp back up within ten minutes. Don't know the measurements though, it was three tennis courts.

Dave_4

the thermos effect?

...like reverse stratification??? matbe for cooling, let the upper layer heat up & only cool the lower 8'occupied space, but how to do this with heating....but even an r4.5 on the fabric knocks 600,000 off the load