Full basement, 8' ceilings and a smooth cement floor. Nearly the entire basement ceiling has 2 levels of dropped ceiling. There was an original dropped ceiling that has small 12" x 12" tiles supported by a wood framework that is nailed to the bottom of the floor beams. Then at some point, someone decided to do another dropped ceiling 6" below the 1st one. The lower dropped ceiling is pretty easy to deal with, its the "modern" style with the 2' x 4' panels in an aluminum frame work that is suspended by wires. Getting the wires through the floor is the hard part. Most of the interior walls are built on top of the floor.

I'm not sure you guys are grasping my situation. The house has hot water heat. There is no furnace duct work. The house heating system has two complete and separate systems. Currently, each system has its own thermostat. Each system has a boiler that its only function is to heat the water in the closed system when it is needed. From the boiler, the heated water is pushed through the copper tubing by a circulation pump that is turned on and off by the thermostat. When the thermostat calls for heat, the pump starts pushing the water through registers along the floor that are all connected in series. The hot water passes through the register in the kitchen, then on to the front room, then the front bedroom, then the bathroom, then the 2nd bedroom, then returns to the boiler. The circulation pump passes the water through the entire system in about 45 seconds. When the water cools enough, the boiler fires and warms the water. When the front room reaches the set temp on the thermostat, the thermostat shuts off the the pump and the water stops moving until the thermostat tells the pump to run again. Since the house was built as a side by side duplex, both systems are a mirror image of each other with a shared common wall Both systems function correctly. It is a very efficient method of heating a house.

My issue is simple, one side or the other is not turning on because the wall between the two systems has been removed. We have lived here for 20 years, the problem started when the thermostats were changed. I had to replace one of the old mercury switchs because it started reading erratically, I didn't think have a new digital switch and an old mercury switch was going to work. I suspect the settings inside of the two "new" Thermostats are not in sink with each other, there was not a problem before the "new" thermostats. These new replacement thermostats are designated for "boiler heating systems" and are the only option for the mercury replacement thermostats available locally.

The original round dial thermostats are nothing more then a mercury switch. The power for the thermostat comes from the boiler control box (the replacement thermostat has an incoming power wire, an electronic switch, and an out going wire). If you connect both wires together at the thermostat, the circulation pump will start.

Maybe pictures might help.
Pic 1) The wall with the two thermostats. The "window" is the wall that used to separate the two front rooms. There is also a 8' wide opening and another window. That wall around the window and another one just like it is the only thing remaining from the 14' long wall. The west side thermostat is just below the lighthouse, and the east side thermostat is just on the other side of the two coat closet doors.

Pic 2) Kind of hard to see, but that thing along the floor is the heat register. The other rooms have a pretty cove over this, but all the registers are the same except the length of them. Excuse the dirt on the wall, this room is the next one to be updated.

Pics 3 & 4) This is the east side boiler. Notice the height compared to the door knob. The water heater beside it is a 40 gallon heater. Pic 4 is the side view of the same boiler. The circulation pump is the left most "thing" hanging on the copper pipe that delivers the hot water through the system. This is a very simply system. About all that can go wrong is the circulation pump, the boiler heat exchanger, or air getting trapped in the line at the registers. Every year I blead the air.