Residential Heat Pump Guide

Sizing: The Question That Matters Most

Most homeowners' first question is price, but sizing actually matters more — an undersized tank runs out of hot water at peak times regardless of how efficient it is, while an oversized one costs more upfront than necessary. A typical 3-4 bedroom household is comfortably served by a 150-200 litre unit, with larger households or homes with multiple bathrooms needing 250-300 litres.

For apartments, the main constraint is usually space rather than capacity — a suitable, well-ventilated spot for the compact outdoor unit on a balcony, rooftop or utility area is all that's needed, and retrofitting into an existing unit is usually straightforward.

Budget vs Long-Term Savings

A heat pump costs more upfront than a basic electric immersion geyser, which puts some homeowners off before they look at the full picture. Most households recover that cost difference within 2-4 years through lower electricity bills, after which the system is essentially saving money for the rest of its working life — typically 8-15 years with reasonable maintenance.

Before choosing an installer, it's worth asking the questions covered in our best heat pump company guide, and comparing actual quotes from a proper site survey rather than a phone estimate. Our installation cost guide has current residential pricing bands to use as a benchmark.