1. What is a Combi Boiler Size Calculator?

Definition: This calculator estimates the required combi boiler size in kilowatts (kW) based on the number of bathrooms and radiators in your property.

Purpose: It helps homeowners and heating engineers determine the appropriate boiler capacity for efficient heating and hot water supply.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Size \) — Required boiler output (kW)
• \( Bathrooms \) — Number of bathrooms in the property
• \( Radiators \) — Number of radiators in the heating system

Explanation: Each bathroom adds 10kW (for hot water demand) and each radiator adds 1.5kW (for heating demand).

3. Importance of Correct Boiler Sizing

Details: Proper boiler sizing ensures efficient operation, prevents energy waste, and provides adequate heating and hot water without oversizing.

4. Using the Calculator

Tips: Count all bathrooms (including ensuites) and all radiators in your property. The calculator provides a baseline estimate - consult a heating engineer for precise sizing.

5. Frequently Asked Questions (FAQ)

Q1: Why is bathroom count so important?
A: Combi boilers heat water on demand, and multiple bathrooms increase simultaneous hot water needs significantly.

Q2: What if I have underfloor heating?
A: Each underfloor heating zone typically counts as 1-2 radiators in this calculation.

Q3: Should I round up the result?
A: Boilers come in standard sizes (24kW, 28kW, 32kW, etc.). Choose the next available size above your calculation.

Q4: Does property size matter?
A: This calculation assumes standard UK insulation. For larger or poorly insulated properties, consult a professional.

Q5: What about hot water flow rate?
A: This calculation ensures adequate kW for heating and water. For specific flow rates, check boiler specifications.