While most people know that dehumidifiers remove excess moisture from the air, fewer realize that they also function as highly efficient heaters. Real-world experiments have shown that consumer-grade dehumidifiers achieve a heat gain of 2—formally known as a Coefficient of Performance (CoP) of 2.
For a typical house the ideal humidity is about 40% which will prevent damp and mould – and provide a healthy environment. This is at a negative cost once the de-humidifier has been purchased. The electricity cost for the dehumidifier is offset by double the saving in heating bills.

What Does This Mean in Practical Terms?

For every 1 kWh of electricity consumed, a dehumidifier can output 2 kWh of heat. In comparison, a conventional electric heater or radiator provides only 1 kWh of heat per 1 kWh of electricity. This effectively makes dehumidifiers twice as efficient as standard electric heaters, potentially cutting heating costs in half.

In a typical household, using a dehumidifier as a supplementary heat source could save between £25 and £40 per month on energy bills.

How Does This Work?

The heating effect of a dehumidifier is a direct result of the latent heat of condensation. When water evaporates—like when boiling a pan of water—energy is required to change its state from liquid to gas. Conversely, when water condenses back into a liquid, that energy is released as heat.

A dehumidifier works by extracting moisture from the air and condensing it into water. This process releases about 0.627 kWh of heat for every litre of water condensed.

Case Study: The Meaco Arete 25L Dehumidifier

To test this concept, we conducted an experiment in a two-bedroom flat with a humidistat set to 55% humidity.

• Power measurement: A plug-based power meter was used to track electricity consumption in kWh.
• Water extraction: The condensed water was weighed to calculate the latent heat of condensation.

Results

• The Meaco Arete 25L Dehumidifier consumed 1 kWh of electricity.
• It extracted 1.65 litres (kg) of water from the air.
• The heat released through condensation:
• Adding the energy directly consumed by the dehumidifier:

The Efficiency Advantage

In contrast, a standard electric heater provides just 1 kWh of heat per 1 kWh of electricity. The dehumidifier, on the other hand, doubles that efficiency, making it a smart alternative for heating while also improving air quality.

If you’re looking for a cost-effective way to heat your home, reduce humidity, and prevent dampness, a dehumidifier could be a game-changer.