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RFI from HVAC Systems

Sep 1st 2011, 19:08

W1MG

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
A member asks: What experience do you have regarding RFI from split air conditioning units that use DC inverter technology?

Any articles or material available on the subject? I did a search on the web and could not find anything useful. We are considering installing one of these systems but am concerned about RFI generated by them.
Sep 1st 2011, 19:09

W1MG

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
In a nutshell, HVAC systems using pulsed DC motors are notoriously problematic. The good news is that in many cases the problem can be corrected using filters and chokes. Unfortunately, these modifications can require experimentation and are typically beyond the scope of the average ham.

Should you decide to get an HVAC system with a pulsed DC motor, I would strongly recommend that you discuss your concerns with the contractor before you buy. In some cases, manufacturers have service bulletins and RFI suppression kits. I would also listen for noise with a shortwave radio before signing any contracts.
Jan 28th 2016, 04:18

KJ7OG

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
In my internet search for a possible HVAC system, I have seen reports that some manufacturers have RFI suppression kits.

Lennox kit #604552-01 + one or two replacement control boards. The kit has a filter for the IFC control and two ferrites for the thermostat wires.


American Standard (Trane) has a kit, and it can be installed at no cost.

Other manufacturers are still being searched out by me at this time.

Steve Bell KJ7OG

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