I just had to replace my 50 year old Lux Aire with a new furnace last
February. I did research and settled on an American Standard 80
single stage. Am. Std. is made by Ingersoll Rand the same company
that makes Trane. (There are around 40 brands but only around 6
companies making them.) Ing.Rand also makes Bryant I believe. My
furnace has an AC motor with starting cap. around 80K BTU and 80%
efficient. Zero RFI on HF. The industry has terms for DC motors and
AC starter cap motors but I forget what they are now. Don't get
suckered into a super high efficiency furnace. That's a two stage
design with a lot of complex circuits, sensors, etc. that crap out
eventually and cost $$$ to repair. Also, in order to achieve the high
efficiency, they have to use a variable speed DC motor. The speed is
varied by modulating the duration of the DC, which means square waves,
which means RFI. Run from that; accept lower efficiency as the cost
of ham happiness. You CAN get a hush kit from Trane for the variable
speed furnaces. It is a bunch of ferrite snap on cores, and some
other stuff, bypass caps maybe, and some shielded wire, for around 200
bucks. It looks like a PITA to install and why bother when you can
just get an AC motor. Then the HVAC contractor can do his thing like
he always has, no fuss, no explaining what radio is blah blah, having
him use you for a beta test, having to come back to get it
right....fugeddaboudit.
73
Rob
K5UJ
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