After the recent discussions on RFI from the newer furnaces, I found myself in the position of having to make a quick decision on a new furnace when my old Lennox began pumping carbon monoxide into the air stream. In our rural area, I didn't have the luxury of being able to choose from all available manufacturers, but was able to get a couple of Trane dealers out to bid on the system.
When I raised the issue of RFI from Trane variable speed systems, one dealer took the time to check with Trane and was told that the problem was taken care of with recent changes to their control board. However, neither Trane nor the dealer would guarantee that they would/could fix the problem if I encountered it. I ended up going with a dual-fuel Trane heat pump system (XR90, XR13) that does NOT have the variable speed feature. With this system, there is no detectable noise in the HF spectrum and 160 and 80 are quiet.
With my old system and Honeywell programmable thermostat, running 1500 watts output on 160 often resulted in the furnace not coming on when it should and I had to reset AC power to the system to get it to work again. The new system has a touch-screen Honeywell thermostat and it appears to be totally immune to the 160 meter signal.