Trane furnace radio/TV interference

[modelman]

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.

[Mark]

Trane should be made to fix this and recall all the units that have been installed. I can pick this interference up on a 2 meter receiver in my car for blocks. The FCC should bust them if they don't fix it...

I cross posted this to some of the amateur radio groups.

Mark

[Alan Taylor]

Mark,

I had a severe interference MF to HF from a neighbours gas heater unit. Not sure what it was that was causing it but it was being effectively radiated by the external cables, power and control. I traced the interference to the unit using a portable rx. I silenced it by wrapping both cables tightly around a 6 inch ferrite rod. The cables held in place by cable ties and tape. Hope this helps.

73 Alan VK6BN

[Anonymous]

That's cool. I just had a problem with a carrier system with infinity controller. The customers wireless internet was causing the furnace to lockout. They ended up sending me this device to install around the thermostat wire.

What a pain to have to troubleshoot. I don't have a RX meter nor do I know what it is hehe

Canadian Heat

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[-zero]

I wonder if terminating one end of an unused wire to ground would be just enough?

RX? Is that a drug mule detection meter?

I'm thinking your thinking of an _RF_ meter.

-zero

[BT]

Modelman,

I have an American Standard two stage variable speed furnace and have the exact same problem. American Standard owns Trane and furnaces by either brand name are exactly the same, with the exception of the first letter of the model number and the label on the door. In other words, the Trane XV is the same as the American Standard Comfort-R.

I'm guessing that your furnace model number begins with TUY.

I tried to have the dealer resolve the problem without success. I had consulted with the regional distributor who claimed that there was a main board replacement fix. The dealer replaced the board under warranty. There was no change. For other reasons, the furnace was replaced. The new furnace, built a year later, has the exact same problem.

My noise sounds the same as you, starts when the inducer motor starts (before the blower fan comes on) and shuts off when the inducer fan shuts off (as soon as the thermostat stops calling for heat.) When the inducer fan increases in speed, the interference changes in pitch and may get louder.

The interference is enough that I can pick it up outside the house while listening to a strong nearby Class A radio station.

I recently saw a post on

that mentioned that Trane/American Standard now has a fix that involves shielding the inducer fan wiring. This may be the same thing that MLD reported and you mention above. Please report back what you experience, I plan to call for service too very soon, while I'm still under warranty.

While American Standard brand and Trane brand are the same, they have different wholesale distributor networks, so if one fails to help, perhaps asking the American Standard distributor for your region could at least have a clue, not sure. One thing that I am sure about is that calling the manufacturer is frustrating. At best, you just get redirected to call your local distributor. When I was having problems with my dealer, the manufacturer rep admitted that anyone who is locally licensed can be an American Standard HVAC dealer, they really don't care. I believe they might more tightly control the Trane brand dealers, but who knows.

You can try calling the manufacturer anyway at 888-556-0125. I would do this just to register your radio interference issue, in addition to complaining to FCC. Hopefully if enough of us do this, the problem will someday be resolved.