How to Choose Refrigeration Valve Suppliers?

Understanding HVAC Solenoid Valve Sizing

Achieving optimal performance from solenoid valves in refrigeration and air conditioning systems requires precise attention to application requirements during selection. These critical components serve as electrically operated ‘stop-valves’ that control refrigerant flow with binary operation – either fully open or fully closed. Unlike modulating valves, solenoid valves don’t regulate flow incrementally.

If you want to learn more, please visit our website.

Manufacturers like Sporlan offer diverse solenoid valve options varying in size and design, each engineered for specific applications within HVAC systems. Selecting the right valve isn’t merely about matching line size – it requires understanding system capacity, pressure drop requirements, and operational parameters.

Solenoid valves are typically classified according to their stem and plunger action:

1. Direct Acting Valves

Energizing the coil directly opens the main port of the valve, allowing full flow. Direct acting valves pull the plunger against inlet pressure and are typically limited to small applications or systems with low-pressure differentials across the valve.

2. Pilot Operated Valves

Energizing the coil opens a pilot port which releases pressure above the main disc/piston/diaphragm, allowing it to move to an open position for full flow. These valves utilize pressure differential across the valve to enable higher flow capacities without requiring a large solenoid coil.

Critical Operating Requirement: A minimum of 1 psi pressure differential is necessary to allow the disc/piston/diaphragm to return to its normal position. Without this minimum pressure drop across the valve during operation, the main port will not return to its normal position.

A common industry practice has been selecting solenoid valves based solely on line size – a potentially problematic approach that fails to account for critical operational parameters.

Consider this scenario: If you’re working with a system having a 5/8 inch OD liquid line, you might instinctively select any valve with 5/8 ODF connections. However, this approach overlooks crucial capacity considerations.

For example, Sporlan offers four valve series with 5/8 OD connection sizes, with capacities ranging from 6.0 tons to 23 tons. When a system requires 15 tons capacity, choosing based only on line size could result in:

1. Undersized valve: Leading to a starved evaporator and reduced system efficiency
2. Grossly oversized valve: Failing to maintain the minimum 1 psi pressure drop, preventing the disc/piston/diaphragm from returning to its normal position

These scenarios can cause system malfunction, reduced efficiency, and potentially damage to components – highlighting why proper sizing methodology matters.

The correct approach to solenoid valve selection follows this sequence:

1. Select based on system capacity with a minimum of 1 psi pressure drop
2. Choose from available connection sizes that meet the capacity requirement
3. Use bushings and couplings if needed to adapt to desired connection sizes (this will NOT affect valve performance)

This methodology ensures proper valve operation while maintaining system efficiency. Remember that connection adaptations are acceptable, but compromising on proper capacity sizing is not.

Let’s walk through selecting a liquid line solenoid valve for a 15-ton system using R410A refrigerant with 5/8 OD connections.

Available Options:

1. E14 Valve:
2. Provides a little over 3 psi pressure drop across the valve
3. Has a 5/8 OD connection option

4. Meets minimum pressure drop requirements with exact connection size

5. E19 Valve:

6. Provides a little over 1 psi pressure drop across the valve
7. Only available with 7/8 OD connections
8. Would require connection adapters but still meets minimum pressure requirements

For detailed specifications, reference the Sporlan Solenoid Valve Selection Guide.

Ensure every job is sized right, both technically and financially. Property.com Pros get exclusive access to the ‘Know Before You Go’ tool, providing key homeowner and property data (like permit history and home value) before you even arrive. Plus, boost your credibility with Property.com Certification and stand out in our premium, invitation-only network. Limited spots available per region. Learn more about becoming a Property.com Pro today.

Improper solenoid valve installation and sizing can lead to various system issues. Here are common problems and their solutions:

Installation Issues to Avoid:

1. Incorrect Flow Direction:
2. Problem: Valves installed backwards won’t function properly

3. Solution: Verify flow direction arrows during installation

4. Improper Mounting Position:

5. Problem: Horizontal mounting of valves designed for vertical installation

6. Solution: Follow manufacturer’s mounting orientation guidelines

7. Debris in the Valve:

   CHT TECK supply professional and honest service.

8. Problem: System contaminants preventing complete closure
9. Solution: Install filter-driers and ensure clean system practices

Troubleshooting Sizing-Related Problems:

1. Valve Fails to Close:
2. Potential Cause: Insufficient pressure differential (oversized valve)

3. Solution: Confirm minimum 1 psi pressure drop; replace with properly sized valve

4. System Capacity Issues:

5. Potential Cause: Undersized valve restricting flow

6. Solution: Verify actual system capacity and valve rating

7. Solenoid Coil Overheating:

8. Potential Cause: Wrong coil voltage or excessive cycling
9. Solution: Verify correct coil specifications and address rapid cycling issues

Proper valve sizing prevents these issues before they occur, saving costly diagnostics and repairs.

Conclusion

Proper solenoid valve sizing is essential for optimal HVAC system operation. Remember to select valves based on system capacity first, ensuring at least 1 psi pressure drop, before considering connection sizes. This approach prevents both undersizing (which starves the evaporator) and oversizing (which prevents proper valve closure).

Valves must be sized correctly in accordance with the system requirements to ensure proper and stable operation throughout the full range of flows required for refrigeration loading and condenser water temperature conditions. Proper sizing is determined by maximum required condenser water flow rate and available pressure drop (available pressure to push the water through the valve). The following steps should be taken in sizing and selecting a valve for normal installations:

1. Determine the water flow required at maximum load conditions. The maximum water flow is usually specified by the condenser manufacturer. If this information is not readily available, a good “rule of thumb” is 3 GPM water per ton of rated refrigeration capacity, assuming 85°F maximum tower water conditions. If the water temperatures vary significantly from these numbers provided, a typical value’s required water flow can be calculated as follows:

• Determine the maximum load conditions, i.e., the maximum BTU’s/hour to be removed. It is important to add heat gains from refrigeration equipment and the heat of compression. If these figures are not available, it is customary to add 25% to the load.
• Determine the incoming water temperature at the time of maximum load.
• Determine the outlet water temperature, which must be less than the condensing temperature of the refrigerant and can be found in the condensing unit manufacturer’s data. If this value is not available, assume 10 °F above inlet temperature.
• Required Water Flow (GPM) =

NOTE: TEMPERATURE IN F°

2. Determine the pressure drop available for the valve. The value should be selected to provide required maximum rated flow at a pressure drop that is acceptably low in comparison the pressure drop that is available from the system.

The available pressure drop can be described generally as the Supply Pressure, minus the Sum of the Pressure Losses between the Supply and Return sources, minus the Return (to tower) Pressure at rated maximum flow. Important note: all pressures and pressure drops should be determined or calculated at rated maximum flow. Specifically:

• The Supply Pressure is taken from the outlet of the pump providing the water or from the water supply pressure.
• Subtract the pressure drop in the Condenser at the rated water flow, usually available as part of the chiller specification.
• Subtract line losses due to fittings, long runs, strainers, etc., usually a low value between 2 and 5 PSI unless there are long runs, high line velocities or many fittings.
• Subtract the Return Pressure in the line to the cooling tower from the same elevation as the Supply Pressure.
• Multiply the result by a safety factor, usually between .75 and .85

3. Select the appropriate flow capacity value by calculating the flow coefficient (Cv) required using the following formula:

WHERE:
Cv=FLOW COEFFICIENT
Q=FLOW (GPM)
P=AVAILABLE SYSTEM PRESSURE DROP

The preceding sizing consideration is for “normal” applications. For applications having extreme operating conditions such as widely varying water temperature, unusual pressure differentials, etc., a Metrex application engineer should be consulted.

It is important to avoid over-sizing valves. A properly selected valve is sized to be fully open or nearly fully open during conditions where maximum flow is required. Remember it is the valve’s job to provide control by restricting the flow of water as required through a wide range of varying system conditions including load, condenser water temperature and available system pressure. Although Metrex valves are engineered to operate efficiently through the widest range of any valve of this type, control valves of this nature do not operate well at the extreme low end of their operating range if sized too large.

Further, it should be noted that pilot valves require a minimum pressure drop to achieve proper operation. Consult individual Valve Data Sheets for a discussion of minimum requirements.

Following these steps carefully will ensure optimal valve sizing resulting in dependable and efficient system control. If any questions arise in valve application or sizing, do not hesitate to contact one of our application engineers.

Remember: it is our goal to provide “Set and Forget Reliability.”

SIZING EXAMPLE 1

XYZ refrigeration has an R-22 chiller, where the condenser manufacturer specifies a rated flow of 100 GPM with a pressure drop through valve of 6 PSI. The outlet pressure of the cooling water pump is 45 PSI and the water goes through a strainer with a pressure drop through valve of 4 PSI. There are no unusually long pipe runs or fittings. The cooling tower is on a hill and has a return pressure of 5 PSI. What two-way commercial valve would work in this application? Following the steps as numbered from above:

1. Design Condenser Flow (from chiller manufacturer) = 100 GPM

2. Available Pressure Drop:

In this example, the desired valve should have a Flow Coefficient of at least 23.

If you are looking for more details, kindly visit Refrigeration Valve Suppliers(fa,ru,fr).