modelman wrote:
Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out AM
broadcast reception throughout my house. I also see snow on a TV
connected to an external antenna.

The radio noise occurs as soon as the draft inducer motor starts up;
the pitch of the interference is related to the motor speed. The draft
inducer motor is a dc motor driven by a PWM controller on the main
circuit board. It is well known that PWM systems generate strong
harmonics throughout the radio spectrum, resulting in radio
interference. However, properly designed PWM systems include filtering
and shielding to suppress the radio frequency currents from the wiring.

I contacted my installer, who is totally unfamiliar with the problem.
The electrician who was sent to my house to investigate the problem
also doesn't understand what's going on. I had to explain the
difference between an RF ground and dc or house ground to him.
Although everything appears to be well grounded from a dc perspective,
I suspect that portions of the system are radiating RF energy.

Several days ago I emailed Trane about the problem, but haven't
received any response.

Although there has been past discussion in this group about radio/TV
interference emanating from Trane high efficiency gas furnaces, I
haven't seen any definitive fix. Does anyone know if Trane has a fix
for this problem. Do they have a shielded cable and or rf filter kit
to suppress this noise? Since my system is under warranty, I won't
attempt any modiifcations to the system.

Has anyone experienced this problem?

Thanks.

Hi,
First you'll have to find out whether the interference is coming thru
the power line or thru the air. It can be cured but needs some expert
knowledge. Maybe Trane has noise suppressor kit of sort? Better check
with them.
Tony, VE6CGX