[RFI] Could RFI from my transmitter cause the failure of a furnace

[Kenneth R Goodwin]

In a prior HVAC system, RFI getting into the thermostat lines would activate
the A/C compressor such that it sounded like I was keying the compressor.
Actually the start relay was being keyed and luckily the compressor has a
time out mechanism that doesn't allow the compressor to turn on again until
something like a period of 3 minutes has passed (pretty standard protection
mechanism in all A/C systems).  The XYL found it funny that she could hear
the compressor sending CW.  In addition to snap-on ferrites, I had to
install W2RU's Worked All Furnaces device which was an RFI choke and bypass
capacitor in each line of the thermostat at the furnace.  I would have
thought that the next HVAC system having a far more complex control system
(all variable speed and not a bang-bank controller) would have had even
worse RFI problems but not so even though I used the same thermostat wiring.
So yes, I think RFI can damage a HVAC system but probably from the secondary
impacts of the RFI as in this case when the compressor was being commanded
ON with each dit and dah. Far more likely the power surge did a number on
your inducer.  Ken K5RG