Wondering which hot water system is genuinely the most efficient choice for your home?

Discover why heat pump hot water units are increasingly the best recommendation, and why some plumbers still try to talk homeowners out of them.

And learn how the location of your hot water unit and your plumbing layout can save water and energy for the life of your home.

Listen to the episode now.

Hello! This is Episode 413, and Way #13 of the ‘44 Ways to Create Your Sustainable Home’ series here on the podcast. We’re still in Section Three: Sustainable Services and Infrastructure.

Way #13 is: Select an Efficient Hot Water Unit and Get the Plumbing Layout Right.

Hot water accounts for approximately 23% to 25% of your home’s total energy use. That makes it the second largest energy consumer in your home after heating and cooling. 

And a hot water system typically can have a service life of ten to fifteen years, so the running cost difference between an efficient system and an inefficient one, compounded over that period, is not trivial.

People will often choose a hot water unit purely based on upfront cost, ignoring the fact they’re setting themselves up for higher costs long-term in their energy bills. This is absolutely a decision worth making with intention, in an informed way.

There are four main types of hot water systems used in homes around the world: electric resistance (the same technology as a kettle), gas (storage or instantaneous), solar hot water, and heat pump hot water. They differ considerably in upfront cost, running cost, and how well they support the sustainability of your project.

The standout recommendation for most homes is now the heat pump hot water system. 

It doesn’t generate heat directly the way an electric resistance element does. Instead, it extracts heat from the surrounding air and uses it to heat the water in the storage tank. A well-selected heat pump can deliver around four units of heat for every one unit of electricity it consumes, roughly 400% efficient compared to the one-to-one ratio of electric resistance.

Even better, when paired with rooftop solar PV, a heat pump hot water system can match or outperform traditional solar hot water in both flexibility and running cost in most climates, including much of Australia.

When I spoke with Brendan Lang, electrician and founder of Get Off Gas, in Episode 345 and Episode 346, one of the things we discussed was how often plumbers talk homeowners out of a heat pump hot water system, despite a heat pump being the right choice. 

The pattern is consistent: a homeowner has done their research, the plumber arrives and says something like, ‘they use a huge amount of electricity, they don’t work in winter, a good gas unit is simpler and more reliable.’ 

Brendan said those myths often come from a knowledge gap, or from plumbers more familiar with gas systems and stories from early adoption that aren’t relevant anymore.

Brendan’s explanation of cold weather performance is one I love. He said heat pumps just get a little less efficient in cold weather, they don’t stop working. And they’re still more efficient at their least efficient than a gas system is at its most efficient. He described it like looking for a car park at Bunnings on a Saturday. At 7am there are plenty of spots. At 11am it takes longer, but you still find one. The heat pump is just working a little harder to find those hot air molecules in the atmosphere when temperatures drop.

Where your hot water unit is located, relative to where the hot water is actually being used, can have a meaningful impact on both water efficiency and energy efficiency. 

Grouping wet areas together, and positioning the hot water unit close to the rooms that use it most, can reduce the wait time at the tap and the waste that comes with it. 

This is a design decision made during floor plan development, and it’s much simpler and cheaper to get right at the drawing stage than to address later.

In this Episode, I cover:

• Why hot water is the second largest energy category in your home, and why the system you choose locks in costs for 10 to 15 years
• The four main hot water system types (electric resistance, gas, solar hot water and heat pump), how they compare, and where each one suits or doesn’t
• Why heat pump hot water is increasingly the default recommendation, including the 300 to 400% efficiency, all electric compatibility, and combination with rooftop solar
• The most common myths about heat pumps, including running cost, cold weather performance, and space requirements, and what’s actually true
• How to assess a plumber’s recommendation, including what to do if they push back against a heat pump
• Why plumbing layout matters as much as the hot water unit itself, including grouping wet areas, locating bathrooms above each other, pipe lagging and reducing hot water waste
• The discussions worth having with your designer / architect, builder and plumber early in your project
• Why a planned changeover beats an emergency replacement, and the rebates and incentives worth investigating

Plus a whole lot more.

LISTEN TO THE EPISODE NOW.

RESOURCES

Episodes 345 and 346: Get Off Gas with Brendan Lang: 

• Episode 345 ‘How to Get Off Gas: Electrifying Your Home’ >>> https://undercoverarchitect.com/podcast-how-to-get-off-gas-electrifying-your-home-brendan-lang/ 
• Episode 346 ‘Electrifying Your Home: Solar Power, Heat Pump Hot Water and Air Conditioning’ >>> https://undercoverarchitect.com/podcast-electrifying-your-home-solar-power-heat-pump-hot-water-air-conditioning-brendan-lang/ 

’44 Ways to Create a Sustainable Home’ e-guide >>> https://undercoverarchitect.com/ways 

Access the support and guidance you need to be confident and empowered when renovating and building your family home inside my signature online program, HOME METHOD >>> https://undercoverarchitect.com/courses/the-home-method/