Storage water heaters hold pre-heated water in an insulated tank for high instant draw but suffer standby loss. Tankless units heat water on demand for endless supply and no standby loss, but output is limited by flow rate and they need larger utility connections.
| Property | Storage Tank | Tankless |
|---|---|---|
| How it works | Heats and stores water in an insulated tank, reheating to keep it hot | Heats water instantly as it flows through a heat exchanger, only when a tap is open |
| Hot water supply | Limited by tank capacity; can run out during heavy back-to-back use until it reheats | Continuous as long as demand stays within the unit's flow rate; no tank to deplete |
| Standby loss | Loses heat continuously from stored water even when idle | Essentially none when idle since no water is stored hot |
| Rating basis | Rated by storage volume plus first-hour or recovery rate | Rated by flow rate (e.g. liters/gallons per minute) at a given temperature rise |
| Install & space | Bulky floor unit; simpler to swap; standard supply connections | Compact wall-mounted; often needs upsized gas line or higher electrical capacity and adequate venting |
| Typical standard | Sold with capacity and efficiency ratings per regional appliance standards | Sold with flow-rate and efficiency ratings per regional appliance standards |
Typical industry values for planning — confirm exact figures against the manufacturer datasheet and local code before ordering.
Choose a storage tank when you need high simultaneous demand at low upfront cost, have space for the tank, or want a simpler like-for-like replacement without upgrading gas or electrical supply.
Choose tankless when you want endless hot water, minimal standby loss, and space savings, and your gas line or electrical capacity can support the higher instantaneous load.
Our engineers spec the system and supply against it — send your project for a package quote.
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