1. What is Chilled Water Pump Sizing?

Chilled water pump sizing determines the required flow rate (in gallons per minute) for a hydronic cooling system based on the system's heat load and the temperature difference between supply and return water.

2. How Does the Calculator Work?

The calculator uses the fundamental hydronic equation:

Where:

• 500 — Constant that incorporates the weight of water (8.33 lb/gal) and minutes per hour (60 min/h)
• Heat Load — Total cooling capacity required (in BTU per hour)
• ΔT — Temperature difference between supply and return water (in °F)

Explanation: The equation balances heat transfer requirements with the water's thermal capacity to determine necessary flow rate.

3. Importance of Proper Pump Sizing

Details: Correct pump sizing ensures efficient system operation, prevents energy waste, maintains proper system pressure, and ensures adequate cooling capacity throughout the system.

4. Using the Calculator

Tips: Enter heat load in BTU/h (often found on equipment nameplates or calculated from tonnage) and the design temperature difference (typically 10-20°F for chilled water systems).

5. Frequently Asked Questions (FAQ)

Q1: What's a typical ΔT for chilled water systems?
A: Most systems are designed for 10-12°F ΔT, though some high-efficiency systems use 15-20°F.

Q2: How do I convert tons to BTU/h?
A: 1 ton of cooling = 12,000 BTU/h. Multiply tons by 12,000 to get BTU/h.

Q3: What if my system uses glycol?
A: Glycol mixtures require flow rate adjustments - typically 10-20% higher flow for 30% glycol solutions.

Q4: How does this relate to pump head?
A: Flow rate is only half of pump sizing - you also need to calculate required head pressure based on system piping.

Q5: What's the 500 constant in the formula?
A: It's derived from (8.33 lb/gal × 60 min/h × 1 BTU/lb·°F) = ~500 when rounded.