Heat Pumps, Air Conditioning & HVAC

A heat pump is a device that transfers heat from one place to another, typically from the outside air or ground into your home, or vice versa. It can be used for both heating and cooling purposes.

Heat pumps use a small amount of energy to transfer heat from a cool space to a warm space, making the cool space cooler and the warm space warmer. In heating mode, it extracts heat from the outside air or ground and transfers it indoors. In cooling mode, it extracts heat from indoors and releases it outside.

Heat pumps can be installed in most homes, but the suitability depends on various factors such as the climate, the type of heat pump, and the existing heating and cooling system. A professional assessment is recommended. Contact us today if you would like us to assess the best solutions for your propert.

Yes, heat pumps are generally more energy-efficient than traditional heating and cooling systems because they move heat rather than generate it. Their efficiency can be three to four times that of conventional systems.

Heat pumps require regular maintenance, typically once a year, to ensure optimal performance and longevity. This includes cleaning filters, checking refrigerant levels, and inspecting the system for any issues. Contact us today to find out about our heat pump maintenance plan.

The short answer is that it’s defrosting. The reason why is quite complicated.

First, it’s important to know that your heat pump gets heat out of the air by trying to cool the whole planet. It’s like a fridge running in reverse. The outside unit of the heat pump has a panel like the inside cooling plate in a fridge. You’ll often see ice form on the evaporator panel in your fridge – because it’s a very cold panel in a cool “climate”. Something very similar happens outside on your heat pump external unit.

On a cold night when temperatures are heading towards a frost, as the air cools it loses its ability to hold water. Relative humidity rises as the temperature drops. Eventually the air temperature falls to the dew point, which is where relative humidity has risen to 100 percent. A relative humidity of 101 percent is against the laws of physics, so below the dew point excess water can’t stay in the air any longer. This excess water separates out of the air as dew, condensing onto everything that’s not under shelter. If the air cools further, to zero or below, frost forms.

Your heat pump’s outside evaporator panel is out there in that dewy air, being kept very cold so that it can pull heat out of the air. Ice is inevitably going to form on the panel at low temperatures and high humidity. When the ice gets thicker, it will act as an insulator, and limit the amount of heat that can be extracted. The heat pump senses this and changes to a defrost cycle. While defrosting it won’t deliver heat.

The worst conditions for ice formation are when the dew point is close to, but still above, zero. On a still day the actual dew point temperature in the evening depends on the relative humidity at the highest air temperature during the day.

So if you have a relatively humid climate where the overnight temperature regularly drops to the dew point, but not quite to freezing, your heat pump is going to suffer from severe icing. And it will have to stop heating fairly often to defrost itself. It’s the Achilles heel of the heat pump.

All of this is why we think all heat pumps sold in New Zealand should be tested at 2°C in air that is at the dew point. We also say it should be mandatory to have the tested heat output at 2°C on the energy rating label.