BoilerBuying Guide2026-02-24
How to Choose a Combi Boiler: A Buyer's Guide
Match output to your heat loss and hot-water demand, then weigh efficiency, brand and warranty.
Choosing the right combi boiler comes down to correct sizing first, then brand and features.
Start with sizing
The most important step is matching output (BTU) to your home's measured heat loss and peak hot-water flow — not square footage or the old unit.
Then weigh features
Compare efficiency (95% AFUE), warranty length, recirculation, smart-thermostat compatibility, and local parts support.
Key takeaways
- Size to heat loss and hot-water demand
- Look for 95% AFUE and a long warranty
- Consider built-in recirculation
- Prioritize local parts and service
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