Reddit reviews MG ELECTRONICS MGT2420 TRANSFORMER,24VAC 20VA UL APPROVED

Those terminals are a low voltage output. With a tiny transformer like that, very low current. What is it, 24VAC?

This is a newer and bigger one, terminals are still exposed.

https://www.amazon.com/MG-ELECTRONICS-MGT2420-TRANSFORMER-APPROVED/dp/B0010GR07O

I have a heat only system as well. My old thermostat only used two wires. I called ecobee and we were trying to get 24v power to the ecobee. I ended up buying a transformer from Amazon and used the power from there.

External Transformer plug into power supply wires coming from this adapter connect to RC and C terminal and thermostat wire R wire to RH terminal and W wire w1 terminal.

This is the transformer I went with bc it woukd be easier for me.

MG ELECTRONICS MGT2420 TRANSFORMER,24VAC 20VA UL APPROVED https://www.amazon.com/dp/B0010GR07O/ref=cm_sw_r_cp_apa_6YxeAbX9XCVRH

This is the transformer I used: MG ELECTRONICS MGT2420 TRANSFORMER,24VAC 20VA UL APPROVED https://www.amazon.com/dp/B0010GR07O/ref=cm_sw_r_cp_apip_mxnesFLaQ7Kdh

I added a C wire (using the excellent Fast-Stat CommonMaker) after receiving the E195 error but continued to see the error. It's important to note that I was reading a solid 24 v on the R wire at this point. I then learned, after extensive research, that the transformer on my boiler was not sufficient to power both my boiler electronics and the Nest. So I then purchased an external transformer and wired that into the CommonMaker in my furnace room and voila - problem solved.

Do you know if this would work?

This needs a 24-volt (not 24w) AC power supply. You will need a matching connector, but this transformer should work just fine.