Okay, let's break down what you're dealing with and how to approach finding a solution. The fact that you successfully wired five thermostats to a standard Line/Load configuration is a good start. Here's a methodical approach to figuring out the remaining two

Understanding the Problem
"Funky Wiring"

This is the key. You need to determine exactly what makes the wiring different. Is it just the wire colors used? Is the electrical box wired differently?

Old Thermostat Types

Old thermostats could be wired in a variety of ways. Some used a simple bi-metal strip to switch the circuit, while others might have incorporated relays.

Multi-Wire Systems

If your wire count is low, but you have multi-strand wires, this could make things complicated quickly. If you have multi-wire connections, they need to be replaced.

Steps to Identify the Wiring


Turn off the Power! Seriously, at the breaker. Safety first.2. Detailed Documentation (Pictures & Notes)



Take very clear pictures of the wiring before you disconnect anything further. Get close-ups of the wire connections to the thermostat, and wider shots showing the wiring inside the electrical box. Document the wire colors and where they're connected. Write down the exact connections. Example: "Red wire connected to terminal 'R', black wire connected to terminal 'W', bare copper wire connected to ground." Note any unusual components in the box. Are there any relays, transformers, or other devices besides just the wires and the thermostat?3. Inspect the Wires



Wire Gauge

Note the gauge (thickness) of the wires. 14 AWG is typical for 15 amp circuits, 12 AWG for 20 amp circuits.

Wire Insulation

Is the insulation in good condition, or is it cracked or brittle? Old wiring can become unsafe.

Number of Wires

How many wires are present in the electrical box? This can give hints as to the system's complexity.4.

Follow the Wires (If Possible)



Trace the wires back to the source. This is the most definitive way to know their purpose. Where do they connect to?5. Meter Testing (With Power OFF)



Continuity Testing

With the breaker OFF, use a multimeter in continuity mode to check which wires are connected together. This might help identify which wires belong to the same circuit.

Resistance Testing

With the breaker OFF, you could measure the resistance between different wires. This might reveal if any wires are connected through a load (like a heating element).6.

Meter Testing (With Power ON - Extremely Carefully!)



Voltage Testing

With the breaker ON and EXTREME CAUTION, use a multimeter to check the voltage between different wires and ground.

Line Voltage

You should find 120V or 240V (depending on your system) between the "line" wire and ground.

Load Voltage

When the thermostat is calling for heat, you should see the same voltage between the "load" wire and ground.

Neutral Voltage

The "neutral" wire should be close to 0V relative to ground.

Possible Wiring Scenarios and Solutions Two-Wire System (Simple but limited)

Some older thermostats simply interrupt a single circuit (one "line" wire in, one "load" wire out). You should be able to measure voltage across the two wires, when the stat is calling for heat.

Multiple Line Wires

Some older high-voltage thermostats had two line wires passing through it. They are then used to control zone dampers or multiple heating elements. Some new thermostats can accomplish this, but it will require documentation and testing to verify that.

Line/Load + Neutral (Less Common for baseboard heaters)

Some systems run a neutral wire to the thermostat. This allows the thermostat to power itself without drawing power through the heating element. Digital thermostats will need to be wired this way.

Misidentified Wires

Double-check that you haven't simply misidentified the wires. Redoing your wiring may be a solution, but document first!

Finding a Compatible Thermostat1. Consult with a Qualified Electrician

If you are at all uncomfortable or unsure about the wiring, stop and call a licensed electrician. They have the experience and knowledge to diagnose and correct wiring problems safely.2.

Contact Thermostat Manufacturers' Technical Support

Provide the detailed documentation you collected to the thermostat manufacturers' technical support teams. They can review the wiring and recommend a compatible thermostat or provide advice on how to adapt your wiring to work with a modern thermostat. Be patient and persistent; they might need time to analyze the information.3.

Search for Thermostats Designed for Specific Wiring Scenarios

Look for thermostats that are specifically marketed for compatibility with older wiring systems or systems with specific voltages or wiring configurations.

Important Considerations Safety First

If you're not comfortable working with electricity, do not attempt this yourself. Hire a qualified electrician.

Local Codes

Ensure that any work you do complies with local electrical codes.

Proper Wire Connections

Use the correct wire connectors and ensure they are properly tightened. Loose connections can cause fires.

Grounding

Always ensure that the grounding wire is properly connected.*

Tamper Resistant Screws: Replace electrical box screws with tamper-resistant screws.Good luck! Flag for review