Hot Water Cylinder Sizing Guide
Choosing the wrong size cylinder leaves you with inadequate hot water (too small) or wasted energy reheating unused water (too large).
Sizing by Household
- 1–2 persons: 120–150 litre cylinder
- 3–4 persons: 150–180 litre cylinder
- 5–6 persons: 180–210 litre cylinder
- 6+ persons or high demand: 250–300 litre cylinder
Unvented vs Vented Cylinders
Unvented cylinders (mains pressure) deliver hot water at higher flow rates — great for power showers and filling baths quickly. They require annual inspection by a qualified engineer. Vented cylinders (gravity-fed) are cheaper and simpler but deliver lower pressure.
Recovery Time
A larger boiler will reheat a cylinder faster. Match your boiler output to your cylinder size for optimal performance — we'll advise on the right combination when you enquire.
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