The White Rodgers M30 is a mechanical line voltage thermostat for electric heating systems such as baseboard, ceiling cable, and radiant heat. It features a single pole switch, temperature range of 45°F to 80°F, 3°F differential, and 22A rating at 240 VAC. Designed for non-inductive loads, it includes options for temperature limiting and tamper-resistant design. Below are the key specifications, installation, operation, and troubleshooting instructions.
Assemble tools: hand or power drill with 3/16 inch drill bit (if needed), flat blade screwdriver, wire cutter/stripper, level. Shut off electricity at main fuse box until installation complete. Label wires before disconnecting. This thermostat is for line voltage systems (120/240 VAC); not for low voltage. Install away from drafts, direct sunlight, or heat sources for accurate sensing. Includes wall cover plate, mounting screws, temperature limiting pins.
WARNING! Failure to read and follow all instructions carefully before installing or operating this control could cause personal injury and/or property damage. Save these instructions.
The M30 is a single pole mechanical thermostat for electric heating, with snap-action contacts for reliable operation. It cycles the heating load on/off based on bimetal sensing. Knob setting: Turn to desired temperature; no OFF position (use circuit breaker for shutdown).
Applications: Electric Heating: Baseboard, Ceiling Cable, Radiant Heat; Voltage: 120/240 VAC; Non-Inductive Loads Only.
CAUTION! To prevent electrical shock/equipment damage, disconnect power at main fuse/circuit breaker until installation complete. Label wires prior to disconnection. If in doubt about wiring, consult qualified heating/air conditioning contractor. This control is a precision instrument, and should be handled carefully. Rough handling or distorting components could cause the control to malfunction.
WARNING! Do not use on circuits exceeding 240 VAC 50/60 Hz (22A non-inductive); higher voltage damages control/causes shock/fire. Do not use on inductive loads. Inductive (motor) loads will damage control and could cause shock, fire hazard or failure of thermostat. All wiring must conform to local and national electrical codes and ordinances.
A standard thermostat consists of basic parts: Cover, Base, Subbase. Label each wire with terminal designation before disconnecting. Disconnect wires one at a time; do not let fall into wall.
Remove old thermostat. Mount new base level on wall using provided screws. Connect wires to terminals (single pole: hot to one terminal, load to other). Push excess wire into wall, secure base, attach thermostat cover. Use temperature limiting pins to restrict range if needed. Power up and test.
Terminal Designations: L1 (Hot), Load to Heater.
240 VAC (Single Pole): Connect L1 to power hot, load to heater terminal. Use circuit breaker for shutdown.
120 VAC: Connect to appropriate terminals for single pole operation; consult codes.
Schematic: POWER IN -- L1 Thermostat -- HEATER LOAD -- NEUTRAL.
CAUTION! All wiring must conform to local and national electrical codes. Do not use on inductive loads. For aluminum wiring, use CO/ALR connectors.
Restore power. Turn knob to setting above room temperature to test heating.
Not applicable; heating-only thermostat without fan control.
Not applicable; use circuit breaker for emergency shutdown.
Not applicable; heating-only thermostat.
Non-programmable mechanical thermostat. Set desired temperature via knob.
No electronic configuration; use temperature limiting pins to restrict knob range. Ensure proper wiring for single pole operation.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Heater not turning on | Knob set too low, power off, wiring issue. | Adjust knob above room temp; check power and wiring. |
| Heater runs continuously | Stuck contacts, faulty bimetal. | Inspect for damage; replace thermostat. |
| Erratic operation | Loose wires, damaged sensing element. | Tighten connections; avoid distorting bimetal. |
| Overheating | Short cycle or load issue. | Check differential (3°F); ensure non-inductive load. |