Certainly, safety is the first issue. I guess that your heater is about
30,000 btu, so think in those terms when considering temperature rise on
heated surfaces. Your biggest problem may be the building codes if you
are using the device in a fashion different from the original intended use.
40 amps will make the old meter spin, but I like the idea of electric
heat as a portable solution since it doesn't exhaust water into the shop
in great quantities.
I work part time in a garage when it gets real cold on the floor in
winter because the process requires that the garage door be left open a
few inches. One of those "milk house heaters" (1500 watts) helps, but
the lower legs are still uncomfortably cold. Standing on a rubbermat
helps keep the feet somewhat okay. Recently, my boss threw a 150 watt
rubber matt onto the floor by the heater and wow!, what an
improvemnt!!!!! I don't quite understand why, but my lower legs are A
LOT warmer!!!

Pete Stanaitis
--------------------

Ignoramus24987 wrote:

I have a approximately 20x20 ft attached garage. Sometimes I want to
make it warm quickly. Often I am there for relatively short periods of
time (because I am constantly interrupted).

I bought a 9.6 kW, 240V duct heater on ebay. It has a 24V control and
various overheat protections.

My plan is to enclose it into a welded frame and sheet metal (found a
few nice sheets in a hospital dumpster), add a fan to it and a 24V
control system using a thermostat. I also have a grill type thing that
I can use to protect the coils from little curious fingers and
flammables.

My idea is to make something relatively compact (say 2x2x1.5 ft), that
I would set on the floor, turn on and get the garage warm in a few
minutes rather than wait for a long time. I would save some
electricity by only heating the garage when I need it, rather than
warming it up "just in case".

What I am looking for is some feedback on safety and such.

i