They’ve been a wonderful addition to modern living – you simply push a button and warm or cool air blows into your home. The best part, they’re so much cheaper to run than traditional heating solutions. So just how do they do it? How does a heat pump work and what makes them so cost-effective?
Ever heard the term ‘heat transfer system’? It’s another name for a heat pump…because that’s what they do. Heat pumps don’t really heat anything, they simply transfer heat from one place to another.
Heat pump hardware
Heat pumps are made up of two main parts – the indoor and outdoor units. They operate similarly to refrigerators in that heat pumps have coils (one in each of the indoor and outdoor units) and use refrigerant as the heat transfer medium.
How it works - heating
Using refrigerant-filled coils, the outdoor unit absorbs or draws warmth from the outside air and transfers it to the indoor unit’s heat exchanger before pumping it into your home as warm air.
That’s what makes heat pumps so energy efficient, they don’t have a heating element; they’re using warmth that’s already there rather than creating heat itself. Even on a cold night, there’s warmth to be found in the atmosphere. It just means the heat pump has to work harder to attain the same level of warmth as it would on a day 10 degrees warmer.
How it works - cooling
Unlike any other heat source, heat pumps come with another advantage – they have a reversing valve that allows you to use them as an air conditioner in summer. At just the press of a button, the flow of the refrigerant is reversed, drawing warmth from the indoor air. The warm air is then piped to the outdoor unit and expelled into the atmosphere via the outdoor unit’s heat exchanger.
Fixed speed vs inverter systems
Fixed speed systems only have a single speed motor so it’s either on or it’s off. Fixed speed systems run until the right temperature is reached then switch off. When the ambient room temperature drops (below a set number) the fixed speed motor switches on again. Because it only has the one speed it takes longer and therefore uses more energy to get to the desired temperature. Inverter systems have a variable speed compressor motor that slows down and speeds up as necessary to hold the temperature at a certain level. It is more efficient because the temperature is more easily