HEAT PUMP SYSTEM: Configure the reversing valve for O (energized in cool) or B (energized in heat) and enable/ disable Emergency Heat and/or Auxiliary Heat. Professionals can sometimes repair the reversing valve, put will often need to replace it. Some units use energized reversing valve during cool and some de-energized. (Tapping on the valve, making sure there was power to the valve, made sure that I was using the B terminal instead of the O terminal, etc.) The reversing valve is energized for cool mode, de energized during heat pump mode operation. The reversing valve has two states, relaxed (unactivated) versus energized. Will create a dead short when you turn the heat on. This valve is specialized for heat pumps, and when issues arise with the reversing valve in your heat pump, there will be operational issues. This seats the piston so refrigerant must pass through the orifice. The energized state is typically achieved by applying 24 volts AC, which is commonly used in HVAC equipment. It will operate and blow heat like I've died and gone to hell, but it won't go the other direction and cool. 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. The energized state is typically achieved by applying 240 volts AC, which is commonly used in HVAC equipment. A broken reversing valve will mean a heat pump that is trapped in one mode or the other. I just installed a new Ruud heat pumps a couple of weeks ago. If the Reversing Valve is energized on a call for heating, what Terminal on the Sub-Base must be used? In most cases, the reversing valve is energized when running cool mode. Reversing Valve Position Selects “O” or “B” Setting For Heat Pumps Only O O B 2 Fn Circulating Fan OFF Off/10% – 100% (5% increments) However, there are instances where the reversing valve is off when running cool mode. It needs another expansion valve, and it needs a reversing valve. The blue on the reversing valve should be common or C and the orange should go to the O terminal of the thermostat. Also, with the thermostat in "system off", no voltages except on the R and RH terminals. A refrigerant reversing valve with an electromechanical solenoid coil is used to reverse refrigerant flow during unit operation (see Figure 10-14). selenoid the reversing valve goes into heat. 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. 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. This is called the 4-Way Reversing Valve, because it has four connections refrigerant pipes.Because the heat pump uses of reversible mechanical refrigeration cycle, such device is not required. Start studying Reversing Valve 4 Way- Valve Heat Pumps. i have got a chance to get a great deal on a armstrong a-coil and heat pump. The heat pump can be designed by the manufacturer to produce either cooling or heating with the reversing valve … Condensing unit runs, but just won't push the gas back the other way. When the reversing valve is called upon to shift from the "down" position, the pilot solenoid valve is energized, closing its compressor discharge pressure port and connecting the chamber on top of the piston to the compressor suction line. The main difference is that a heat pump can both heat and cool a home, whereas an air conditioner just cools a home. Initialization When the heat pump switches between its heating and cooling modes, it’s the change in the reversing valve that makes it happen. The reversing valve. Typical wiring diagram for heat pump with reversing valve energized in COOL TRANSFORMER Reversing Valve* B O RC JUMPER WIRE Compressor Contactor JUMPER WIRE * Reversing valve is energized when the system switch is in the COOL position Fan Relay Y RH 24 VAC 120 VAC Hot Neutral THERMOSTAT SYSTEM G W Figure 7. It allows the heat pump to operate in either the heating. Slap a reversing valve on there and when it calls for heat the reversing valve gets energized and the flow is backwards. 0 = cooling reversing valve, energized in cooling mode. I have 2 units (0ne works well)and it appears that the switching valve is not operating. A reversing valve is usually found close to the compressor or condenser of the heat pump. The heat pump can be designed by the manufacturer to produce either cooling or heating with the reversing valve in the relaxed state. 1) At the thermostat, remove the wire at the O/B terminal. im considering buying a armstrong heat pump to add to my existing gas only furnace to make it dual fuel. In a heat pump, a reversing valve controls the direction of the flow of refrigerant. Its easy to find out. heat so I could measure the voltage at the reversing valve and got 24 volts. There should be no voltage at the O/B terminal with No Call for heat or cool. The selenoid energized.The other unit wired the same way working fine. Reversing valves can easily be configured for opposite operation. 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. Cool Low Pressure Gas. 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