Rinnai vs Dux: which hot water system is better?

Terry gets asked this most weeks: Rinnai or Dux? Both are solid brands he happily fits and services, so the honest answer is that it depends on how your home is set up and what you want to spend. Here is how the two stack up after 40 years of fitting and repairing hot water across Western Sydney.

Two brands, two different strengths

Rinnai built its name on the Infinity continuous flow range, which most of the trade treats as the benchmark for instantaneous gas hot water. Dux has been an Australian manufacturer since 1915 and plays right across the board: electric storage, gas storage, and the Airoheat heat pump. So this is less about which badge is better and more about which type of system fits your house.

Where Rinnai wins

If your home is on natural gas and you hate the idea of running out of hot water, a Rinnai Infinity is hard to beat. It heats on demand, so a full house can shower back to back and the water stays hot. Running costs are low because nothing is sitting in a tank losing heat overnight. Sizing is done by flow rate: roughly 16 to 20 litres a minute for one bathroom, 24 to 26 for two, and 32 for three or more.

The other quiet advantage is parts. Rinnai has one of the widest parts networks in Sydney, so if something needs a valve or a board in year eight, Terry can usually get the part fast and have you back in hot water the same day. That matters more than people think when a unit is meant to last 15 to 20 years. Fitted, a continuous flow unit runs roughly $1,900 to $3,500 depending on size and the gas and water connections.

Where Dux wins

Dux is the value all-rounder. If you are replacing an electric or gas storage tank like for like and want a dependable Australian-made unit without paying a premium, Dux does the job well. A fitted electric storage tank sits around $1,500 to $2,500 and a gas storage tank around $1,800 to $3,000.

Dux also makes the Airoheat heat pump, which is where the real savings live. A heat pump moves heat instead of making it, so it uses about a third of the power of a standard electric element. It costs more up front, roughly $3,500 to $5,500 before rebates, but the running cost is the lowest of any electric option and it is rebate eligible in NSW, which can bring the price down close to a tank. For a family watching power bills, the Airoheat is a genuinely smart pick.

Terry's verdict

There is no single winner, and any plumber who tells you otherwise is selling something. If you are gas connected and want endless hot water with easy future repairs, Terry leans Rinnai Infinity. If you want value on a straight tank swap, or you want to cut running costs with a heat pump and claim the rebate, Dux is excellent. Both are reliable, both have good parts backup, and both will last their expected life if they are sized and installed properly.

The bigger mistakes Terry sees are undersizing a continuous flow unit for a growing family, or sticking with electric storage on a full tariff when a heat pump would pay for itself. He will look at your gas connection, your hot water habits, and your roof and switchboard, then give you a fixed price before any work starts. No upsell, no call centre.

If you are weighing up Rinnai against Dux for a Berala, Auburn or Lidcombe home, give Terry a call on 0415 274 542 and he will tell you straight which one suits your place.