I bought a $40 1.5 kW ceramic heater at Ace Hardware, a length of 4"
metalized dryer duct, and a 4" to 6" duct adapter. A bit of metal bashing
turned the 6" end of the duct adapter into a square, flanged surface that
could be sheet-metal screwed to the outlet of the heater. Two feet of duct
goes on the 4" end with a hose clamp. We stick the end of the duct up into
the cowl on top of the nose gear scissors (Archer). Half an hour of
preheating with this raises the temperature exiting the front of the cowl to
well above freezing (circa 40 degrees F) when the air temp is -10 degrees F.
We experimented with leaving the cowl plugs in or not, and it seems to heat
the engine faster with the heat rising through the cylinder fins and out the
cowl inlets. If there is any significant breeze (which might reverse the
air flow) we put the cowl plugs in and give it 45 minutes. More gentle
heating than the $25 preheat service (big propane heater stuffed into only
one front cowl inlet), and the whole rig cost around $50. Of course we
scored the only tiedown next to a hangar, with outside outlets within five
feet of the wingtip, but others run long cords over the ramp temporarily for
tools, etc.

--
Bob (Chief Pilot, White Knuckle Airways)


"George Patterson" wrote in message
news:Y06nf.14684$OK6.11811@trnddc03...
skym wrote:
On ebay, .....

Ok. I have a portable propane model, so I don't have direct experience
with either of these. Both appear to be adaptations of the sort of
"ceramic" electric heater that sells for around $30 at Home Depot. The
Sporty's unit looks like it would do a much better job, since it pulls
it's intake air from the cowl. If I were using it, I would stick the
discharge in the gap at the bottom of the cowl, though.

I have two of these units for helping heat poorly heated rooms in my home.
They do that job very well. I even got decent results using one to heat up
an unheated garage -- it kept things from freezing, at least. Based on
that, I believe Sporty's claims about the efficiency of their unit. Dunno
if it's worth that kind of money, however.

The main disadvantage I see is that these units require electricity.
They're also not going to be weatherproof. That means the portability is
of limited use.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.