The White Rodgers IF73 is a non-programmable, auto changeover multi-stage/heat pump thermostat for low voltage heating and cooling systems. It supports heat pumps (with/without aux or emergency heat), standard heat & cooling systems, two stage heat & two stage cool, standard heat only systems, standard central air conditioning, gas or oil heat, electric furnace, hydronic (hot water) zone heat - 2 wires, hydronic (hot water) zone heat - 3 wires. Requires common for 24 VAC at the thermostat. Below are the key specifications, installation, operation, configuration, and troubleshooting instructions.
Assemble tools: hand or power drill with 3/16 inch drill bit (if needed), flat blade screwdriver, wire cutter/stripper, spirit level or plumb bob and line (optional—thermostat does not need to be level to work properly). Shut off electricity at main fuse box until installation complete. Label wires before disconnecting. This thermostat is for low voltage systems (requires common for 24 VAC at the thermostat); not for line voltage. Install away from drafts, direct sunlight, or heat sources for accurate sensing.
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 thermostat is a non-programmable, auto changeover multi-stage/heat pump thermostat. It controls heating and cooling systems based on temperature setting with precise operation. Features automatic changeover, multi-stage support, emergency heat option, compressor protection. LCD shows room temp/setpoint, up/down arrows, SYSTEM switch (HEAT/OFF/COOL/AUTO/EMER), FAN switch (ON/AUTO). Terminals: R (hot), C (common), G (fan), Y1/Y2 (compressor stages), W1/W2 (heat stages), O/B (changeover), E (emergency).
Applications:
| System Type | Supported |
|---|---|
| Heat Pump (No Aux. or Emergency Heat) | Yes |
| Heat Pump (with Aux. or Emergency Heat) | Yes |
| Standard Heat & Cooling Systems | Yes |
| Two Stage Heat & Two Stage Cool | Yes |
| Standard Heat Only Systems | Yes |
| Millivolt Heat Only Systems – Floor or Wall Furnaces | No |
| Standard Central Air Conditioning | Yes |
| Gas or Oil Heat | Yes |
| Electric Furnace | Yes |
| Hydronic (Hot Water) Zone Heat – 2 Wires | Yes |
| Hydronic (Hot Water) Zone Heat – 3 Wires | Yes |
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.
WARNING! Do not use on circuits exceeding 20-30 VAC 50/60 Hz (1.5A per terminal, 2.5A max total); higher voltage damages control/causes shock/fire. Do not short terminals on gas valve/primary control to test; short/incorrect wiring burns out components/causes injury/property damage. Conform to NEC Class II circuits. Do not operate cooling below 50°F (compressor damage).
ATTENTION! This product does not contain mercury but may replace one that does. Do not open mercury cells; if damaged, wear non-absorbent gloves, clean up spilled mercury, place in sealed container. Refer to www.white-rodgers.com for disposal. Handle to avoid static discharge.
A standard heat/cool thermostat consists of three basic parts: 1) Cover (snap-on or hinge type); 2) Base (captive screws); 3) Switching subbase (mounting screws). Shut off electricity at main fuse box until installation complete. Remove front cover. With wires attached, remove wall plate. Loosen screws and remove wires one at a time, labeling each. Remove old thermostat body from wall.
Remove old thermostat. Mount new subbase to wall/adaptor plate with mounting screws. Connect wires to corresponding terminals. Reattach base to subbase and install cover. Ensure level using spirit level or plumb bob/line (optional). Keep area clear of wires.
Terminal Designations: R (hot), C (common), G (fan), Y1/Y2 (compressor stages), W1/W2 (heat stages), O/B (changeover), E (emergency), L (fault).
Heat Pump (No Aux.): R hot, Y1 compressor, O/B changeover (O cool, B heat).
Heat Pump with Aux.: Add W1/W2 aux/emergency, E emergency.
Standard Heat/Cool: R hot, W1/W2 heat, Y1/Y2 cool, G fan, C common.
Two Stage Heat & Cool: W1/W2 heat stages, Y1/Y2 cool stages.
CAUTION! Requires common for 24 VAC. Refer to equipment manuals for specifics.
Restore power. Set SYSTEM to HEAT/COOL, FAN to ON/AUTO, adjust setpoint to test.
CAUTION! Do not operate below 50°F.
Non-programmable thermostat. Setpoints are manually adjusted using up/down arrows. No scheduling features.
Press and hold SYSTEM button for 5 seconds to enter menu. Use up/down to adjust, SYSTEM to advance.
| Menu # | Display | Function | Options | Factory Default |
|---|---|---|---|---|
| 1 | HP SS | Heat Pump Stages | 1 or 2 | 1 |
| 2 | COOL | Cooling Stages | 1 or 2 | 1 |
| 3 | HEAT | Heating Stages | 1 to 2 | 1 |
| 4 | dS | Keypad Lockout | On/Off | Off |
| 5 | dF | Fahrenheit/Celsius | °F/°C | °F |
| 6 | dI | Daylight Savings | On/Off | On |
| 7 | EC | Emergency Heat Offset | 1 to 10°F | 5°F |
| 8 | AL | Alarm Temperature | 40 to 99°F | 99°F |
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Display Blank | Power loss or low batteries. | Check batteries and 24VAC wiring; restore power. |
| System Not Responding | Wiring error, no power. | Verify wiring, circuit breaker; consult manual. |
| Incorrect Temperature | Calibration needed, sensor issue. | Check remote sensor; calibrate if applicable. |
| Alarm Sounds | Temperature limits exceeded. | Check settings, reset alarm. |
| Fan Not Running | AUTO no call; wiring. | Set ON; check G terminal. |
| Short Cycling | Differential settings. | Adjust in configuration menu. |
| Compressor Won't Start | Protection lockout. | Wait for delay; check flashing indicators. |
Reset Operation: Remove wires from R and C (do not short), remove batteries for 2 minutes. Resets to factory defaults.
Homeowner Help Line: 1-800-284-2925; www.white-rodgers.com