im considering buying a armstrong heat pump to add to my existing gas only furnace to make it dual fuel. This is a job for your local Carrier expert. Initialization Works fine in emergency heat. Reversing valves: Change the flow of refrigerant which determines if your interior space is cooled or heated. However, there are instances where the reversing valve is off when running cool mode. A refrigerant reversing valve with an electromechanical solenoid coil is used to reverse refrigerant flow during unit operation (see Figure 10-14). not all reversing valves energize in heating most do not. 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. The reversing valve is energized for cool mode, de energized during heat pump mode operation. If the Reversing Valve is energized on a call for heating, what Terminal on the Sub-Base must be used? there should also be a setting in the menu telling it whether to energize reversing valve on heating or cooling. Also, with the thermostat in "system off", no voltages except on the R and RH terminals. The solenoid does not actually shift the main valve, it only shifts a much smaller pilot valve that then uses system pressure to shift the valve. The reversing valve has two states, relaxed (unactivated) versus energized. With the reversing valve de-energized the flow reverses. I intentionally turned the Tstat up high enough to turn on the aux. lennox energize in cooling for instance. Professionals can sometimes repair the reversing valve, put will often need to replace it. Its easy to find out. Your stat has no common. The reversing valve is energized when there is a call for heat It needs another expansion valve, and it needs a reversing valve. The main difference is that a heat pump can both heat and cool a home, whereas an air conditioner just cools a home. Condensing unit runs, but just won't push the gas back the other way. I tried everything. The reason for this is a key component called the reversing valve. Shown here, the heat pump cooling works like any cooling system when it is in cooling mode. The energized state is typically achieved by applying 24 volts AC, which is commonly used in HVAC equipment. The reversing valve has two states, relaxed (unactivated) versus energized. The reversing valve solenoid is an electromagnetic coil that mounts onto the reversing valve and is generally 24V on residential heat pumps. 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. 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. i have got a chance to get a great deal on a armstrong a-coil and heat pump. 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. (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.) Now let's complicate it a bit more.....While not in the majority, there are some units out there that instead of energizing the reversing valve in cool mode, they work in reverse and require that you energize the reversing valve in heat mode, typically using the B terminal and blue wire. or cooling mode by changing the direction of the refrigerant between the indoor and outdoor coils. The heat pump can be designed by the manufacturer to produce either cooling or heating with the reversing valve in the relaxed state. Welcome to the forums. It is generally soldered to the pipes or copper tubing, which are typically going in and out the device towards the other parts of the heat pump. Either your system uses O or B, not both. Video of a confirmed diagnosis of a 3-way reversing valve not cooling but heating ok. It works fine in cooling. In a heat pump, a reversing valve controls the direction of the flow of refrigerant. REVERSING VALVE ENERGIZED IN COOL MODE ONLY REQUIRED FOR HEAT PUMPAPPLICAITON REVERSING VALVE ENERGIZED IN HEAT MODE Basic Installation Single Stage Thermostats 1E78-144 Non-Programmable 1E78-151 Programmable For additional information visit: www.white-rodgers.com B on the stat is reversing valve energized in heating mode. Refrigerant is the chemical mixture that allows for the heat exchange to occur. Voltages is ~24v ac. 4-Way Reversing Valve with operating control used for heat pumps. selenoid the reversing valve goes into heat. Reversing Valve and Solenoid. In a heat pump system when the reversing valve is energized (cool mode), the unit will run in cool mode and the refrigerant will follow the path indicated on the bottom. The reversing valve. The energized state is typically achieved by applying 240 volts AC, which is commonly used in HVAC equipment. If the reversing valve is energized during this test, ... the suction gases can absorb heat from the wayward hot gas bleeding across the valve diminishing the amount of sensible heat rise across the valve. Some units use energized reversing valve during cool and some de-energized. I just installed a new Ruud heat pumps a couple of weeks ago. Slap a reversing valve on there and when it calls for heat the reversing valve gets energized and the flow is backwards. It allows the heat pump to operate in either the heating. If the valve breaks, the heat pump will be trapped in one mode or the other. heat so I could measure the voltage at the reversing valve and got 24 volts. I have 2 units (0ne works well)and it appears that the switching valve is not operating. 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. This determines whether you are going to heat or going to cool. It will operate and blow heat like I've died and gone to hell, but it won't go the other direction and cool. This seats the piston so refrigerant must pass through the orifice. In Figures 2 and 3, the pilot valve has been configured so that when the pilot valve is de-energized, the system is in the heating mode, and energizing the pilot valve the system is in cooling 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) When looking at a reversing valve, the single port on the bottom is always the discharge line from the compressor. In most cases, the reversing valve is energized when running cool mode. 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. The selenoid energized.The other unit wired the same way working fine. 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. Refrigerant: The substance in the refrigeration lines that circulates through the indoor and outdoor unit. The heat pump can be designed by the manufacturer to produce either cooling or heating with the reversing valve … 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. Cool Low Pressure Gas. ... My Coleman 3700 THE 2.5 ton heat pump /ac will not switch to the cool mode. Bad reversing valve – If you have a heat pump not heating, but it works in cooling mode, you might have a bad reversing valve. So you should be able to check the wiring at the air handler. Will create a dead short when you turn the heat on. Wire it in and set the reversing valve to stay on cool cycle and never reverse to heat and viola. 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. 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. Reversing valves can easily be configured for opposite operation. A heat pump has a few extra parts that allow it to reverse the direction of heat exchange. I have found that the reversing valve is energized on the cooling cycle, but also even if thermostat is set to off position valve is still energized. The reversing valve is powered in AC mode. Start studying Reversing Valve 4 Way- Valve Heat Pumps. When the heat pump switches between its heating and cooling modes, it’s the change in the reversing valve that makes it happen. Please check your heating and cooling system manual or consult a professional HVAC technician if you do not know which option to select. Figure 6. 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 will energize the reversing valve to go into cooling. Maybe the fact that the reversing valve is energized to heat instead of cool is a clue that it's wired up wrong. 1) At the thermostat, remove the wire at the O/B terminal. The blue on the reversing valve should be common or C and the orange should go to the O terminal of the thermostat. On my newer CrapAir unit, it appears the reversing valve is stuck. A broken reversing valve will mean a heat pump that is trapped in one mode or the other. The determination for mode of operation is the presence or absence of an “O” signal from the stat. This reversing valve solenoid, partially controlled by the HP thermostat, is generally energized in the cooling mode (except as noted above). Basically before heat pumps refrigerant flowed one direction. 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