A
reversing valve is pivitol to the proper operation of a heat pump system.
This entry isn’t about explaining the operation and function of a
reversing valve. It is about the process of selecting a reversing valve.
Step 1: Determine the refrigerant of the system.
The reality is that you should already know this, but you’d be surprised how often this simple fact is forgotten and a valve only approved for R-22 is installed in an R410A system. Check the refrigerant. It only takes a second and will prevent a possible catastrophic failure.
The reality is that you should already know this, but you’d be surprised how often this simple fact is forgotten and a valve only approved for R-22 is installed in an R410A system. Check the refrigerant. It only takes a second and will prevent a possible catastrophic failure.
Step 2: Determine the tonnage of the system’s circuit you are installing
the reversing valve in.
Determine the tonnage of the refrigeration circuit. You then need to look at the manufacturer’s data for the valve and select a valve that allows about a 2 psi suction pressure drop. If you select too small of a valve the pressure drop will be too high and you will take an efficiency hit. If the valve is too large you will be over paying for the valve and there is a great chance of not being able to cycle the valve in all operating conditions.
Determine the tonnage of the refrigeration circuit. You then need to look at the manufacturer’s data for the valve and select a valve that allows about a 2 psi suction pressure drop. If you select too small of a valve the pressure drop will be too high and you will take an efficiency hit. If the valve is too large you will be over paying for the valve and there is a great chance of not being able to cycle the valve in all operating conditions.
Step 3: Confirm that both minimum and maximum delta P is met.
The valve will list a minimum delta P for operation. This the minimum differential pressure between the suction line and discharge line for operation of the valve spool. If you can not meet this minimum delta P you must select a smaller valve.
The valve will also list a maximum delta P. If you have a greater delta P than this the valve will be unable to move itself against the pressure. Usually if this is the case you will be forced to use some controls to equalize pressures prior to switchover.
The valve will list a minimum delta P for operation. This the minimum differential pressure between the suction line and discharge line for operation of the valve spool. If you can not meet this minimum delta P you must select a smaller valve.
The valve will also list a maximum delta P. If you have a greater delta P than this the valve will be unable to move itself against the pressure. Usually if this is the case you will be forced to use some controls to equalize pressures prior to switchover.
Step 4: Select line sizes, coil voltage, and configuration
In some manufacturers cataloges you will have the option of selecting from 2 or 3 different line sizes. Select a line size as close to your refrigerant piping size as possible. Avoid necking down as this will also introduce additional pressure drop. Coil voltage is a simple selection based upon your control voltage. And configuration simply indicated the order of the connections on the valve. Very few manufacturers offer any options on this item.
In some manufacturers cataloges you will have the option of selecting from 2 or 3 different line sizes. Select a line size as close to your refrigerant piping size as possible. Avoid necking down as this will also introduce additional pressure drop. Coil voltage is a simple selection based upon your control voltage. And configuration simply indicated the order of the connections on the valve. Very few manufacturers offer any options on this item.
