|
|
re: at a loss
1 oct 2005
jim has...
>...a dc thermal heater. it draws 35 amps/hr. it heats at a rate of 85 cfm.
nonono. incorrect units! maybe it draws 35 amps (at 12 v, ie 35x12 = 420 watts
or 1433 btu/h?) and the fan moves 85 cfm (with a 1433/85 = 17 f air temp rise?)
>my cabin space is only 170 cu. ft.
sounds small, eg 170/8 = 21 square feet, if you have an 8' ceiling.
that's less than 5'x5'. do you sleep standing up? :-)
>so realistically, after the initial warming up period from the first
>heating cycle, the heater will only stay on for a couple of minutes
>per cycle. it typically turns on about 4 times per hour. so for every
>15 minutes, the heater is on for 2 minutes. that is only 8 minutes of
>actual run time per hour. my figures would show this heater, under my
>application, to draw only 5 amps or less per hr. am i thinking too far
>into this, or am i completely off in my math?
your math is ok, but... you might say the heater uses an average current
of 35x2/15 = 4.67 amps, for an average 4.67x12 = 56 watts of heat power.
not much. your body provides about 100 watts of heat power.
nick
|
|
