1. What is a Combi Boiler Sizing Calculator?

Definition: This calculator estimates the appropriate size of a combi boiler based on the number of radiators and bathrooms in your home.

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

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Size \) — Recommended boiler size in kilowatts (kW)
• \( Radiators \) — Total number of radiators in the property
• \( Bathrooms \) — Number of bathrooms (including en-suites)

Explanation: Each radiator typically requires 1.5kW of heating capacity, while each bathroom adds 10kW for hot water demand.

3. Importance of Correct Boiler Sizing

Details: Proper boiler sizing ensures efficient operation, adequate hot water supply, and prevents energy waste from an oversized unit.

4. Using the Calculator

Tips: Count all radiators in your home (including towel rails) and all bathrooms. The minimum recommended size is 24kW for most homes.

5. Frequently Asked Questions (FAQ)

Q1: Why does bathroom count affect boiler size?
A: More bathrooms increase hot water demand, requiring higher capacity to maintain flow rates.

Q2: What if I have underfloor heating?
A: Each underfloor heating zone typically counts as 1 radiator in calculations.

Q3: Should I round up the calculated size?
A: Yes, always round up to the nearest available boiler model (typically 24kW, 28kW, 32kW, etc.).

Q4: Does this account for home insulation?
A: This is a basic calculator. Poor insulation may require +10-20% capacity.

Q5: What about high-output radiators?
A: For large radiators (> Type 22), count each as 1.5 radiators in your calculation.