lennox energize in cooling for instance. The energized state is typically achieved by applying 24 volts AC, which is commonly used in HVAC equipment. not all reversing valves energize in heating most do not. Coils: The condenser and evaporating coil heat or cool the air depending on the directional flow of refrigerant. 99% of heat pumps I have seen are energized for cooling and are designed to fail heat. Refrigerant is the chemical mixture that allows for the heat exchange to occur. Figure 6. 1) At the thermostat, remove the wire at the O/B terminal. I just installed a new Ruud heat pumps a couple of weeks ago. A wire (usually orange wired to “O” terminal on the heat pump thermostat) runs from the thermostat to the condenser, where the typical air to air heat pump has a reversing valve. When looking at a reversing valve, the single port on the bottom is always the discharge line from the compressor. An electrical connection from the thermostat controls whether the reversing valve is energized or de-energized. Your stat has no common. In a heat pump, a reversing valve controls the direction of the flow of refrigerant. Therefore, it is important the check the manufacturer's specifications of the heat pump system that you are using before you can do a proper connection to the thermostat. This seats the piston so refrigerant must pass through the orifice. 4-Way Reversing Valve with operating control used for heat pumps. Start studying Reversing Valve 4 Way- Valve Heat Pumps. The reversing valve solenoid is an electromagnetic coil that mounts onto the reversing valve and is generally 24V on residential heat pumps. Condensing unit runs, but just won't push the gas back the other way. This determines whether you are going to heat or going to cool. Voltages is ~24v ac. The heat pump can be designed by the manufacturer to produce either cooling or heating with the reversing valve in the relaxed state. If it was -20 outside, and your reversing valve failed, you will still have heat, you can survive (don't tell that to my customers) without a/c but you will die without heat in reality. The reversing valve is powered in AC mode. Wire it in and set the reversing valve to stay on cool cycle and never reverse to heat and viola. Bad reversing valve – If you have a heat pump not heating, but it works in cooling mode, you might have a bad reversing valve. Either your system uses O or B, not both. Please check your heating and cooling system manual or consult a professional HVAC technician if you do not know which option to select. This is a job for your local Carrier expert. However, there are instances where the reversing valve is off when running cool mode. This reversing valve solenoid, partially controlled by the HP thermostat, is generally energized in the cooling mode (except as noted above). Will create a dead short when you turn the heat on. I have 2 units (0ne works well)and it appears that the switching valve is not operating. 0 = cooling reversing valve, energized in cooling mode. The reversing valve is energized for cool mode, de energized during heat pump mode operation. It allows the heat pump to operate in either the heating. It works fine in cooling. Also, with the thermostat in "system off", no voltages except on the R and RH terminals. Because many heat pumps can lose efficiency as outdoor temperatures fall below freezing, your system probably has a supplemental heat source – either electric resistance heating elements, or a gas or oil furnace. A refrigerant reversing valve with an electromechanical solenoid coil is used to reverse refrigerant flow during unit operation (see Figure 10-14). Maybe the fact that the reversing valve is energized to heat instead of cool is a clue that it's wired up wrong. B on the stat is reversing valve energized in heating mode. The reversing valve is energized when there is a call for heat or cooling mode by changing the direction of the refrigerant between the indoor and outdoor coils. It needs another expansion valve, and it needs a reversing valve. With the reversing valve de-energized the flow reverses. Basically before heat pumps refrigerant flowed one direction. If I cut breaker of to unit you can hear valve coil click as it is de-energizing, or if you put unit in heating cycle you can hear valve click as it is de-energizing. Some units use energized reversing valve during cool and some de-energized. Heat pumps and heat/cool units: many original equipment manufacturers connect the system tubing to the Ranco reversing valve based on which mode (heat or cool) the system will operate, should the solenoid coil fail. 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