Thanks for the information!
So C is the common wire.
The Nest learning in my current home made a big difference. Than again it was more than twice this units cost. I would say about a 10 percent savings per year on my Propane usage for the past 3 years. With that said it was done in a mix of repairs to the current furnace so my guess that contributed to the savings as well.
The current project though was free (Rebate) and the old thermostat is 17 years old so I thought it was a good investment not to mention I can monitor the heat there as I am paying for it for my son (In College type of thing) and his room mate.
I just assumed it was 24 Volt DC as its going to a Device that more than likely using DC for most of the other features(Wifi, battery charging, etc). I dabble in electronics as a hobby my DMM would have told me if I got it out in the first place.
From your information and user12345_a it appears that there is more than likely a C wire (Common) somewhere buried in the compartment. The wires do not connect to the Main board like my Rheem (more open clearance and is not tucked in as much as the York). Also the York is in a square layout from what I could see - compartment like - It appeared to be on top of the transformer). I am going to look for the install/owners manuals for the furnace. I know I have them in my file cabinet. The question would be which unit is which house...so I get to review all three (lol)
One thing User12345_a was talking was to use the Y wire and connect to the C once located. That should be easy enough.
You are probably at least the 10th person over the years though that has said this exact same thing on the sizes of the furnace (when I mention them online). On all the locations we own. The one location is basically a cabin that is a glorified one maybe two car garage - From memory that is a 60K BTU or whatever the smaller York Stellar Plus was at that time it could be a 80K.
I am confident the other 2 are both 120Ks. My father always rounded to the higher BTU furnace in BTU calculation whether right or wrong the fuel usage compared to similar houses has never been the issue. I know the cycling process (etc) is always a concern. I know they did the duct study/calculation on each home as they were both large duct changeouts. So My feeling it was probably good. I was in my mid 20's when we did the swaps. The place the furnaces came from was in Toledo since 1895 as a HVAC Supplier in downtown Toledo. Always interesting to watch them make custom Plenums while you waited and had ducts you never will see at a box store. Unfortunately they did not survive past 2009 as their location was revitalized by the city planning commission (Became a ball field and night life area)
With that said all houses (except my current) are within a few miles of Lake Erie and we do get days in -10 degree ranges quiet often a week maybe or so. In fact Wind Chills well below -40 are not atypical. As I age though it appears the weather has gotten warmer. I remember feet of snow. Including the Blizzard of 1978. Today anything over 6 inches is doomsday.
On the flip side, I have been told at my current residence (3800sqft and multiple floors in open country) is way under sized. The closest house to me is a mile away with no trees to speak of except two on the NW side of the house and a dozen orchard trees I planted 2 years ago. The house is decently insulated but the 90K Propane furnace (Aging 90% furnace) to me it is as well under sized but probably more noticeable as the furnace is older. This was also told by the last two inspectors (County and the home inspection group - they actually sent 2 people) that was at the house when we purchased the place. The Home inspector tore the furnace apart in writing in his documentation. The County guy said the way he saw things it would be close and probably ok due to the additional heat source that is in the large living room (13ft 6" X 33ft 3inch room) which is heated by a propane fireplace, also something about Propane in general as a heat source, and the insulation factor would he consider it good or accept it. I should also mention the first floor has high ceilings as well (over 8ft but the second floor is not 8 more like 7 something)
When we got down in the negative tens for 7 days that first year we moved in (prior to my father in law getting involved with it) the home fought to stay at 60 and never stopped. That same year we did loose the main Blower (first - just after that cold spell), igniter (glow plug) about a month later, one vacuum switch (replaced both along with hoses) - constant clicking If I remembered right was heard. It happened over time and my father in law did most of the work but the blower was covered under house warranty. After he went thru the furnace we replaced all the burners quick (big difference). This was after he spent a decent amount of time looking over/cleaning the heat exchanger (camera probe etc). Like I said this is the first furnace to be replaced as its the one I believe is at highest risk of issues (Carbon Monoxide/Failure). Supposedly Rheem in the Original owners manual claims the unit has a Life Time Heat Exchanger Warranty but I know better.
My father in law, before I bought the new furnace did a bunch a calculations about ducts as we are moving the furnace over to the right about 6 ft and we are also adding an additional room (10X14) to the HVAC setup that is on the first floor. Previously the room was not heated as it was a Old Pantry/Freezer Room.
First Time I ever saw Borax mixed with Wood Shavings for wall insulation. Evidently its very common in these old country homes...Evidently they used them with Ice from the Lake and stored meat items. At least that is how it was explained to me by a old timer. It was no fun running electric in that room I tell you that much. It also houses the Convertible Jet pump and Water Filtration and Softener for the well. Now its just a spare guest bedroom.
Thanks everyone for the help I will let you know what I find,