Re: you can fry a Nest thermostat - on the RFI hunt


Gerard Repko
 

Good info to know. I installed the ecobee thermostat, I’ll have to check how much RFI I get from it. I do have a switch on the side of the furnace in the garage that shuts it all down including the thermostat as it is powered from the original wiring to the furnace. Have a much larger HVAC system in the new house that I’ll have to check. The room off the garage that I’ve designated for my shack is pretty far from the HVAC, but I’ll be looking for all rfi once there.

On Sep 14, 2020, at 10:26 AM, Ryan - KJ7GIE <@KJ7GIE> wrote:

Wanted to share this bit of info I've run across in my hunt for RFI in my house. Using an AM radio I noticed my Nest Thermostat was _very_ noisy. There is also no way to turn the thermostat off; it will simply drain the battery and then shut itself down which is the only way to actually get the thing to go off. But, I also identified, as I was hunting online, more than a few people have fried their Nest Thermostats on 40 meters. I guess running a long wire, from HVAC to thermostat, and then filling the thermostat with tiny fuses and FETs just doesn't play nice with amateur radio.

So, I've got this source of RFI in my house I cannot turn off that is connected to a long wire that _may_ resonate / couple to 1 or more of the HF bands. How lucky can a guy get?

Additionally... I _know_ the HVAC itself is noisy as it impacts my 70cm performance! Has anyone else gone to this extreme to fix it? http://www.arrl.org/files/file/Technology/Solving%20Furnace%20and%20AC_RFI_KM4LHZ_v9.pdf

It's easy enough to turn the HVAC (blowers / condenser etc.) off while I'm operating. But the Nest is still active so I'm still on the hunt for ways to reduce / eliminate that issue (without replacing the unit as I really like my Nest thermostat). This is also pushing me towards the "wire on fence" outside HF antenna design and _not_ using a wire in the attic. My HVAC is in the attic so an attic based solution is looking less and less like a good use of my time.



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