Installation: Nordyne CM65 Series 24 Volt Convertible Heating Thermostat Instruction Manual

Overview

The CM65 Series 24 Volt Convertible Heating Thermostat is a wall-mounted, low-voltage control for residential heating systems. It senses room temperature and switches the connected appliance circuit on or off as needed to maintain the selected temperature.

The CM65 model is designed for heating and can be converted for heating and cooling by adding an SB-6A-5ABO or SB-6A-5JBO sub-base. The CM65A version is supplied with one of these heating and cooling sub-bases already installed. A manual temperature lever and Fahrenheit/Celsius scales make adjustment straightforward for homeowners and service technicians.

Specifications

• Model family: CM65 Series 24 Volt Convertible Heating Thermostat and 24 Volt Heating/Cooling Thermostat with sub-base
• Electrical classification: Class II low-voltage circuit
• Nominal operating voltage: 24 volts
• Maximum circuit rating: 30 VAC, 1.0 amp maximum
• Air-conditioning wiring: Four- or five-conductor wiring is required when optional cooling control is used
• Temperature range: 50°F to 90°F or 10°C to 30°C
• Temperature differential: 2°F or 1°C
• Temperature sensor: Bi-metal coil with dust-protected open-contact switches
• Heating anticipator: Adjustable from 0.20 to 1.0 amps
• Cooling anticipator: Fixed 4700-ohm resistor on the SB-6A sub-base
• Approximate dimensions: 3 x 3-1/2 x 1-1/2 inches, or 76 x 89 x 38 mm

Detailed Description

The thermostat uses a bi-metal sensing coil to respond to changes in room temperature. As the coil moves, it operates protected electrical contacts that control the heating circuit. The temperature-setting lever changes the point at which those contacts open or close.

The CM65 package includes a thermostat cover and mounting body. The CM65A package includes the cover, mounting body, and a heating/cooling sub-base. The sub-base provides terminals and switches for heat, cool, fan, and ventilation functions.

The adjustable heating anticipator helps match thermostat operation to the connected heating control circuit. Its setting must correspond to the appliance control requirements. The cooling anticipator is built into the compatible sub-base and is not adjustable.

Terminal markings may include RH for heating power, RC for cooling power, W for heating control, Y for cooling control, G for fan control, and O for a cooling-system function. The exact wiring arrangement depends on the appliance and whether the system uses one transformer or separate heating and cooling transformers.

Safety

• Disconnect electrical power to the appliance before installing, removing, or servicing the thermostat.
• Follow local electrical codes and ordinances for Class II low-voltage circuits.
• Handle the CM65 as a precision instrument. Do not attempt service procedures beyond the approved installation and adjustment steps.
• Replace the thermostat if internal service is required or if damage affects the sensing mechanism, switches, terminals, or housing.
• Never short appliance control terminals to test operation. Doing so can damage the thermostat and may invalidate its warranty.
• If the appliance has a time-delay control, expect the equipment to start or stop after a delay even when the thermostat contacts change state.

Location Requirements

Install the thermostat where it can accurately sense the normal room temperature and where wiring, adjustment, and future service are accessible.

Recommended location

• Place it in a frequently occupied room such as a living room or family room.
• Mount it on an interior wall approximately four to five feet above the floor.
• Choose an area with normal air circulation and convenient access to the control wiring.

Locations to avoid

• Direct sunlight or locations near lamps, televisions, radiators, heat registers, or other heat-producing equipment
• Humid areas, because moisture can shorten thermostat life
• Outside walls or walls beside unheated rooms
• Drafts from doors, windows, stairways, or other openings
• Corners, alcoves, areas behind normally open doors, room dividers, or large furniture
• Walls exposed to frequent vibration, including locations near frequently used doors

Setup and Installation

Installing the CM65 for heating

1. Disconnect power to the heating appliance.
2. Grip the thermostat cover at its top and bottom edges and lift it away from the mounting body.
3. Hold the mounting body against the wall and mark the approved mounting-hole locations.
4. Set the body aside and drill the mounting holes with a 3/32-inch drill bit.
5. Pull approximately three inches of five-conductor cable through the wall opening, then strip about 3/8 inch of insulation from the wire ends.
6. If a future heating and cooling conversion is planned, tape the unused wire ends so they remain available for later installation.
7. Connect the conductors to the appropriate screw terminals and tighten each terminal securely.
8. Bend the wires so they cannot interfere with the temperature selector.
9. Push the wiring back through the wall while leaving enough slack for service. Seal the wall opening with noncombustible insulating material.
10. Fasten the thermostat body to the wall. Exact leveling is not required.
11. Reinstall the thermostat cover.
12. Complete the low-voltage connections at the appliance using the appliance wiring diagram.
13. Restore electrical power after all connections have been checked.

Installing the CM65A or adding a heating/cooling sub-base

1. Disconnect power to the appliance or appliances.
2. Remove the thermostat cover by gripping it at the top and bottom.
3. Remove the mounting screws, pull the thermostat body from the wall, and disconnect the low-voltage conductors from the screw terminals.
4. Unwrap any wires previously taped for future use. If a five-conductor circuit is not present, install the additional conductors required by the appliance configuration and strip approximately 3/8 inch from their ends.
5. Feed the wires through the sub-base wire entry and connect them to the matching terminals.
6. Check the red jumper between RH and RC. Add or remove it as required by the transformer arrangement and the applicable wiring diagram.
7. Push the wires into the wall opening, leaving service slack, and close the opening with noncombustible insulating material.
8. Secure the sub-base to the wall. Precise leveling is not required.
9. Place the thermostat body on the sub-base and tighten the captive screws.
10. Replace the cover.
11. Complete the low-voltage wiring at the appliance or appliances according to the equipment wiring diagram.
12. Restore power to the furnace or connected system.

Transformer jumper guidance

A single-transformer system generally uses the RH-to-RC connection so the heating and cooling controls share the transformer supply. With a two-transformer arrangement, the jumper configuration depends on the specific sub-base and wiring diagram. The SB-6A-5JBO configuration requires the jumper to be removed when separate heating and cooling circuits are used. Confirm the arrangement at the appliance before energizing the system.

Operation

Heating mode

1. Turn on electrical power to the appliance.
2. For a CM65A or a CM65 with a heating/cooling sub-base, set the heat/cool switch to HEAT and the ventilation switch to AUTO.
3. Move the temperature lever until the right-hand heating contacts close. The heating equipment and air-circulator blower should start.
4. Check the air temperature at the supply registers.
5. Move the lever until the heating contacts open. The heating equipment and blower should stop, subject to any appliance time delay.
6. Replace the thermostat cover.

Cooling mode

1. Turn on electrical power to the cooling appliance.
2. Set the heat/cool switch to COOL and the ventilation switch to AUTO.
3. Move the temperature lever until the left-hand cooling contacts close. The cooling system and air-circulator blower should start.
4. Check the air temperature at the supply registers.
5. Move the lever until the cooling contacts open. The cooling equipment and blower should stop, allowing for any built-in equipment delay.
6. Replace the thermostat cover.

Continuous air circulation and ventilation

1. Set the heat/cool switch to OFF and the ventilation switch to ON. The air-circulator blower should operate without heating or cooling.
2. Set the heat/cool switch to HEAT. The blower should continue running while the heating system cycles.
3. Set the heat/cool switch to COOL. The blower should continue running while the cooling system cycles.

Independent blower operation for a CM65 heating-only installation depends on the connected furnace controls. Refer to the furnace operating instructions for that function.

System shutoff

1. Set the ventilation switch to AUTO.
2. Set the heat/cool switch to OFF.
3. Confirm that heating, cooling, and fan operation have stopped.

Troubleshooting

• System does not start: Confirm that appliance power is restored, the thermostat mode is correct, and the temperature lever has been moved far enough to close the appropriate contacts.
• Fan does not run: For a sub-base installation, check whether the ventilation switch is set to AUTO or ON as intended. Confirm the fan-control wiring at the thermostat and appliance.
• Heating or cooling operates in the wrong mode: Check the heat/cool switch position and compare terminal connections with the appliance wiring diagram.
• Cooling is unavailable after conversion: Verify that the required additional conductors are installed and that the heating/cooling sub-base is wired correctly.
• Heating cycles appear unsuitable: Check that the adjustable heating anticipator is set for the connected heating control circuit. Do not guess at the setting; use the appliance requirements.
• Equipment starts or stops late: A furnace, air conditioner, or other appliance may include a time-delay control that intentionally postpones operation.
• Thermostat readings seem inaccurate: Check for sunlight, drafts, nearby heat sources, poor air circulation, humidity, or vibration at the installation location.

Pros & Cons

• Pros: Simple manual temperature control, Fahrenheit and Celsius scales, adjustable heating anticipator, compact wall-mounted design, and heating-to-heating/cooling conversion through compatible sub-bases.
• Cons: Installation requires low-voltage wiring knowledge, correct transformer-jumper configuration, and careful location selection. Cooling operation requires the compatible sub-base and suitable four- or five-conductor wiring.