1. What is a Grundfos Central Heating Pump Size Calculator?

Definition: This calculator determines the appropriate Grundfos pump size for central heating systems based on heat load, system resistance, and temperature difference.

Purpose: It helps HVAC professionals and installers select the correctly sized pump for optimal system performance and energy efficiency.

2. How Does the Calculator Work?

The calculator uses two key formulas:

Where:

• \( Flow \) — Required flow rate (m³/h)
• \( Heat \) — System heat load (kW)
• \( c \) — Specific heat capacity of water (4.2 kJ/m³ K)
• \( \Delta T \) — Temperature difference across system (K)

System Resistance (Head) is also considered to determine the pump's pressure capability.

3. Importance of Correct Pump Sizing

Details: Proper pump sizing ensures efficient operation, reduces energy consumption, prevents noise issues, and extends equipment life.

4. Using the Calculator

Tips: Enter the system heat load, specific heat capacity (default 4.2), temperature difference (default 20K), and system resistance (head). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical ΔT for central heating systems?
A: Most systems are designed for 20K difference between flow and return temperatures.

Q2: How do I determine system resistance (head)?
A: Calculate pipe friction losses and fitting losses, or consult system design documents. Typical values range 3-8m for residential systems.

Q3: Why use Grundfos pumps specifically?
A: Grundfos offers high-efficiency, variable speed pumps ideal for modern heating systems with precise flow control.

Q4: What if my calculated flow is between pump sizes?
A: Always round up to the next pump size and consider a variable speed model for better control.

Q5: Does this account for multiple zones?
A: No, for multi-zone systems, calculate each zone separately or consult a professional for system design.