Which one fits you better?
A direct electric cylinder uses resistance heating, while a heat-pump water heater moves heat from surrounding air into stored water. Compare useful hot-water energy, standing losses, available installation space and actual operating conditions.
Electric water heater
You want a simpler, cheaper installation and hot-water demand is moderate.
Heat-pump water heater
You use significant hot water and have suitable space, airflow and installation conditions for a heat-pump unit.
Comparison at a glance
| Aspect | What you should know | How to decide |
|---|---|---|
| Purchase / installation | Usually lower cost and simpler. | Higher equipment and installation cost. |
| Efficiency | Direct resistance heating. | Uses a heat pump, so electrical input can be much lower for the same hot-water output. |
| Space / noise | Compact and quiet apart from normal water noise. | Needs suitable air volume or ducts and has compressor/fan noise. |
| Best fit | Simple replacement or modest demand. | Higher recurring demand where energy savings justify the investment. |
What matters before you decide
The payback depends on hot-water use, electricity price, climate and installation cost. Compare annual energy demand and realistic seasonal performance rather than only the advertised COP.
Do not compare a single number
Hot-water demand depends on litres drawn, inlet temperature and the delivered setpoint. Heat-pump COP varies with air temperature and defrost, while a direct cylinder's main costs come from electrical use and standing storage loss.
Worked example: energy to heat daily hot water
To heat 120 L of water from 15°C to 55°C, the ideal energy delivered to water is approximately 120 kg × 4.186 kJ/(kg·°C) × 40°C ÷ 3,600 ≈ 5.58 kWh/day. Ignoring tank losses, direct resistance heating needs about 5.58 kWh, while a heat-pump system averaging a hypothetical COP of 2.5 needs 5.58 ÷ 2.5 ≈ 2.23 kWh. Over 365 days these are about 2,038 versus 815 kWh; at €0.22/kWh, about €448 versus €179 before storage and operational losses. These are illustrative thermodynamic calculations, not product test data.
- Measure typical litres drawn per day and confirm required safe operating temperatures from the heater manufacturer.
- Compare annual electrical use from the maker's energy label and site conditions, including storage loss and ventilation.
Decision: The heat-pump system may reduce electricity use substantially with suitable air, space and demand, but it usually has higher upfront cost and different installation constraints.
The thermodynamic example excludes tank heat loss and installation. Actual COP, air temperature and hot-water hygiene settings affect annual consumption.
Compare it with your own numbers
Estimate water-heating energy from litres and temperature rise; replace the hypothetical COP with the chosen model's annual energy data.
Decision checklist
Check real demand. Size the tank from peak simultaneous draws and recovery requirements.
Check siting and air. Confirm ventilation, noise, condensate drainage and cold-air effects.
Use annual energy data. Include storage losses and realistic seasonal COP.
Review hygiene controls. Follow manufacturer guidance for safe storage temperature and periodic disinfection.
When each hot-water system can make more sense
Purchase price is only one part of the decision. Hot-water demand, available space, ambient conditions and running hours all affect the comparison.
Direct electric water heater
- Usually simpler to install and easier to fit into a predictable space.
- Uses resistance heating, so electricity use closely follows the heat that must be supplied.
- Cylinder insulation and set-point temperature affect standing losses.
Heat-pump water heater
- Can reduce electricity use by moving heat instead of creating it directly.
- Needs more upfront investment and suitable space, airflow and noise conditions.
- Efficiency changes with ambient temperature and operating conditions.
Compare realistic annual hot-water demand, installation cost and expected electricity use rather than rated power alone.
Frequently asked questions
Which is better: Electric water heater or Heat-pump water heater?
There is no universal winner. The first option may suit you if you want a simpler, cheaper installation and hot-water demand is moderate. The alternative may suit you if you use significant hot water and have suitable space, airflow and installation conditions for a heat-pump unit.
Should I decide only by purchase price?
No. Even a large calculated kWh saving must be balanced against tank cost, installation, space, noise, actual COP and the safe hot-water regime.
What should I check before buying?
Heat-pump water heaters need air and create noise and cool exhaust air. Installation location matters as much as headline efficiency.