1. What is a Combi Boiler Size Calculator?

Definition: This calculator determines the appropriate size (in kW) of a combi boiler based on your heating and hot water requirements.

Purpose: It helps homeowners and heating engineers select a properly sized combi boiler for efficient operation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Size — Total boiler output capacity (kW)
• Heating kW — Space heating requirement (kW)
• Hot Water kW — Domestic hot water demand (kW)

Explanation: The total boiler size is the sum of your property's heating requirements and peak hot water demand.

3. Importance of Proper Boiler Sizing

Details: Correct sizing ensures energy efficiency, adequate hot water supply, and prevents short cycling of the boiler.

4. Using the Calculator

Tips: Enter your heating requirement and hot water demand in kW. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine my heating requirement?
A: Use our Heating kW Calculator or consult a heating engineer for a heat loss calculation.

Q2: What's a typical hot water kW requirement?
A: For a standard shower (10L/min), about 24-28kW is typical. Higher flow rates require more kW.

Q3: Should I round up the calculated size?
A: Yes, it's common practice to round up to the nearest available boiler size.

Q4: What if I have multiple bathrooms?
A: You'll need to account for simultaneous hot water use by increasing the Hot Water kW value.

Q5: Does this account for weather compensation?
A: No, this provides the maximum output needed. Modern boilers modulate down for efficiency.