BoilerBuying Guide2026-03-10
Combi Boiler Flow Rate Explained
Flow rate (litres/minute) determines how much hot water a combi delivers at once.
When sizing a combi, flow rate matters as much as heat output. Here's why.
What flow rate means
Flow rate is how many litres per minute of hot water the combi can deliver at a usable temperature, which drops as incoming water gets colder.
Why it matters
A combi with too low a flow rate struggles when several taps run at once, especially in BC's cold winter water temperatures.
Key takeaways
- Flow rate = hot-water capacity
- Drops with colder inlet water
- Match it to simultaneous use
- Critical for multi-bathroom homes
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