Google Nest Wiring to Extremely Old Furnace

Wondering if its even possible to use this Nest Thermostat with our VERY old furnace. We’ve ran a 3 wire down to the furnace which does have a fan and power terminal. I’ve been reading that the nest needs at least 3 things to function properly, which are basically heating control, common or constant power and fan (I think). So we bought a furnace 3 wire and ran it to the furnace, but I have no idea how/where to hook it up, or if it’s even possible. I’ve got 2 photos attached here. 1 photo is of the power terminal on the furnace and the other is the fan control (which has power running from the terminal on the furnace). We have a 2-way switch upstairs (separate from old thermostat) that when flipped, runs only the fan.

Anyone run into anything similar before?

Lest me be the 1st

NEST

SUCKS

!🍻

Has that furnace been checked and verified ok? Usually the heat exchanger is rotten or cracked in something that old.
You will not find any Nest supporters here, or anywhere in the pro world. They are a nasty trouble prone device that isn’t worth its price in scrap.

Furnace has been working fine for the last two winters. We’ve been rehabbing this house and I’m not ready to dump a bunch of cash into a new system just yet.

Is there any sense in using a “smart” thermostat with such a crap system? What do the pros recommend for products?

A technician onsite would be best to advise how to connect that if it is possible. From what I see, it is not.

Since this is not a DIY site, that is all the info I can offer.

I’m thinking I’m going to return the Google Nest and just run a standard Honeywell thermostat that’s been working fine. When we upgrade the furnace and install AC, etc. I’ll worry about using a smart thermostat. Thinking Ecobee might be the better choice, unless people have better recommendations.

I’m embarrassed to say, but I think I still have one of those fan limits on my truck, but the box is pretty wasted.

Originally Posted by codyecp

Furnace has been working fine for the last two winters. We’ve been rehabbing this house and I’m not ready to dump a bunch of cash into a new system just yet.

Is there any sense in using a “smart” thermostat with such a crap system? What do the pros recommend for products?

How do you know this?

When was the last time that heat exchanger was checked?

When was the last time a combustion analyses was performed?

At the very least invest in a low level Co Detector Not the UL POS the big box stores sell’

Ecobee and Honeywell both make great Wi-Fi thermostats. Anything is better than NEST. At least look into getting a LOW LEVEL CO MONITOR. It could save lives.

Does anyone else miss the days where mom set the thermostat to some arbitrary temperature & nobody worried any further? When we were hot, we put on shorts. When we were cold, we put on a sweatshirt…..

Originally Posted by rexp

Does anyone else miss the days where mom set the thermostat to some arbitrary temperature & nobody worried any further? When we were hot, we put on shorts. When we were cold, we put on a sweatshirt…..

Yeah I sort of miss those days but there was no thermostat involved it was a fireplace or the windows open. In the winter it was 80 in the summer it was 95 to 105.
Edit: I thought about it for a few more minutes and no I actually don’t miss those days.