[RFI] RFI and furnaces

[Chuck Shinn]

Along with the furnace proper, do not neglect the connecting pipes and 
conduits. I recently found a VERY noisy gas line and connector to my 
tankless water heater which produced as much QRN as any other closely 
coupled wiring or guttering etc. I used large ferrites on my flexible 
conduits and gas line and also snapits on my AC condenser copper 
plumbing to reduce/eliminate the QRN. Other recent examples of unlikely 
sources include water mains connected to direct drive washers which 
excite associated cold water plumbing in a home. Sniffing is the only 
way to find this stuff. The opportunities are endless it seems. Best, 
Chas W5PG