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- EXTRA EDITION
Some small-capacity water-cooled refrigeration systems use municipal water as their cooling medium. These systems will typically add a regulator to control water flow through the condenser. These regulators are commonly referred to as water regulating valves. They serve two purposes: They regulate water flow to maintain the system’s high-side pressure and stop the flow of water when the system cycles off so as not to waste water.
These valves can also be used on larger systems using a water tower instead of municipal water. In those designs, it is generally best to use a three-way water regulator. They have an additional port to bypass the water around the condenser as the port that controls water flow to the condenser closes.
The system’s high-side pressure is exposed to the underside of the regulator’s diaphragm. As the condenser pressure increases, the diaphragm flexes, and, through a mechanical linkage, opens the valve to let more water flow through. As the condenser pressure decreases, less pressure is applied to the underside of the diaphragm and an opposing spring on the opposite side of the diaphragm closes the water valve. The spring pressure and the high-side pressure oppose one another to balance the correct amount of water flow through the valve. When the system shuts down, the high-side pressure is too low to oppose the spring pressure and the regulator completely shuts down.
When selecting one of these water regulating valves, knowing the specific refrigerant is typically not required. One model regulator can handle several refrigerants since its operation is solely based on pressure. However, special springs or bellows may be required for systems using extreme high-pressure or very low-pressure refrigerants. Valve selection is generally based on three factors:
1. Required water flow through the condenser in gallons per minute;
2. Rise in the refrigerant’s high-side pressure from off to on; and
3. Actual water pressure available to force water through the valve.
It is best practice to use the valve manufacturer’s engineering literature when selecting a valve for a new installation. When replacing a valve, a technician should match the valve by model number, or by its original specifications, to ensure the proper size valve is selected.
Generally, it is rather simple to adjust the system’s operating high-side pressure (valve’s opening point). These regulators will typically have an adjustment screw on the top of the valve body. Using a standard service wrench or screwdriver, turn the adjusting screw counterclockwise to increase the opening point, and clockwise to lower the opening point. When adjusting these valves it is important to also check and verify that the valve truly closes when the system cycles off, as the high pressure drops to its standing pressure. If the valve does not totally close off when exposed to the system’s standing pressure an excessive amount of water would be wasted during each off cycle.
Since these regulators can be used on an untreated, open water source, they may need to be cleaned as part of a maintenance inspection. Some valves do have the ability to be manually flushed to clean the valve seat. Check the valve manufacturer’s literature for the proper procedure to manually flush a valve when required.
If the valve needs to be replaced, you will normally need to recover the system’s refrigerant charge in order to remove its pressure bellow connection from the system, which, admittedly, is not generally a desirable procedure. One trick used by some technicians is to double pinch and pinch-hold the cap-tube connection to the system, break it off, and braze it shut. This allows the removal of the regulator without having to recover the refrigerant. The only disadvantage to this trick is you will need to use and have an additional port on the system to connect the new regulator pressure bellows. Sometimes there is not one available and a technician will either need to double up on a port with the addition of a tee or be forced to recover the refrigerant to change the valve.
Publication date: 6/3/2013