re: duct sizing
12 oct 2005
steve groulx wrote:
>thanks nick. i appreciate the details and your help with this matter.
you are welcome.
>love the basic program.
it's the official ashrae 55-2004 standard language :-)
>> pe drew gillett (deanegathotmail.com) writes:
>>>doors are huge cheap ducts. in fact using them you can keep any room
>>>within 5 degrees f of any adjacent room...
maybe less. a 10x10' room with 2 r20 exterior walls and an 8 ft^2 r4
window and a thermal conductance of 9.6 btu/h-f would need (70-30)9.6
= 384 btu/h to stay 70 f. if 70 f air thermosyphons through a 3'x6'
door with 384 = 16.6x9ft^2sqrt(6')dt^1.5, dt = 1 f.
more accurately, 16.6x9xsqrt(6)(70-t)^1.5 = (t-30)9.6 makes
t = 70-((t-30)/38.1)^(2/3). plugging t = 69 in on the right
makes t = 68.984 on the left. repeating makes t = 68.985.