Split System Heating and Cooling

As I mentioned in my previous post, we have now created a heating and cooling zone in our main room by rebuilding a wall and fitting a door. If we’re inside during the day we spend most of our time either in this room or in our study, so converting our heating in this space to zero emissions sources will put a significant dent in the emissions generated in our home.

The heating unit that we decided to go with is a heat pump, alternatively known as a split system or a reverse cycle air conditioner. Switching to this technology is ranked #42 on Project Drawdown. In traditional heating, you can convert one unit of energy into one unit of heat. With a heat pump you aren’t creating heat so much as moving it from one place to another, which means the heat output can be significantly higher than the energy input. This is the same concept used in refrigeration.

Heat pump heating and coolingEfficiency varied considerably across the units that we looked at. We decided to go with the most efficient unit that we could afford, and were quite surprised by how many units cost more with lower efficiency. We went with a 5-star Mitsubishi unit that we bought at Bunnings. Heating is rated at 3.2kW output for 0.65kW input, and cooling is rated at 2.5kW for 0.51kW input. Our unit is considered too small for the space, but we wanted to size it against our solar panels instead of our room size.

Our hope is that installing this unit will mean that we no longer run the gas ducted heating at all in a best case scenario, or only on the coldest days in a worst case scenario. In either case, we expect our heating bills to be slashed. By switching to electricity we generate ourselves instead of using natural gas, the unit will potentially pay for itself in fuel savings before it is out of warranty.

If you’re playing along at home…

…how much could you increase the energy efficiency of your home by switching to a heat pump for heating and cooling? If you already have a system for cooling, how much gas could you save by also using it to heat? Please share your experience in the comments below.

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