Air Source Hot Water Cylinder vs Immersion Heater: Which Is Cheaper?
Many homes across Ireland and Northern Ireland still rely on immersion heaters for hot water - but rising electricity costs have made them increasingly expensive to run.
An air source hot water cylinder offers a far more efficient alternative, delivering the same comfort at a significantly lower running cost.
How Immersion Heaters Work
Immersion heaters generate heat directly using electricity. For every unit of electricity consumed, you receive one unit of heat.
While this makes immersion heaters technically 100% efficient, it also means they are among the most expensive ways to heat water — particularly with modern electricity prices.
How Air Source Hot Water Cylinders Differ
Air source hot water cylinders use heat pump technology to extract renewable heat from the surrounding air and transfer it into stored hot water.
This process allows them to deliver three to four units of heat for every unit of electricity used, dramatically reducing energy consumption compared to immersion heaters.
Cost Comparison
Typical annual hot water running costs:
- Immersion heater: High and unpredictable electricity usage
- Air source hot water cylinder: Up to 70% lower electricity consumption
In real terms, a 250L air source hot water cylinder can cost under £1 to fully heat when used with off-peak electricity tariffs.
Verdict
For households looking to reduce hot water bills without sacrificing comfort, air source hot water cylinders are significantly cheaper to run than immersion heaters.
They offer long-term savings, improved efficiency, and a future-proof solution as energy costs continue to rise.
Traditional systems often require complex pipework or boiler integration. Air source cylinders with built-in heat pumps are easier to install, need only water piping, and come in sizes 80–250L. They’re also compatible with solar for even greater efficiency.
