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Has your shower just gone cold and you need to replace your old hot water system? Has your family grown over the last few years and you keep running out of water?

If you’ve decided whether to go for gas or electric, solar or heat pump, instantaneous or ‘continuous flow’, the next question you’ll need to ask yourself is: “What size hot water system do I need?” Here at Gold Coast Plumbing Experts, our hot water experts are here to help.

Just about every single day, we advise, supply and install all technology types, brands, makes and models of storage-style hot water systems – and once you start looking into it, you’ll notice there are plenty of different system sizes to choose between. Depending on the brand, the ‘normal’ selection of tanks typically range from itty-bitty 80-litre units to monster 400L tanks and beyond – and that’s a big difference indeed. And if you’re getting an instantaneous system, these differ in capacity too, with 7L, 14L and 21L per minute units among the most common.

So is there a hot water system size calculator that can help you out here? What hot water tank sizes and capacities are there, anyway, and how on earth will you get it right for your lifestyle, family size, space requirements and budget?

Hot water system sizes – Here’s how to choose

The first thing to understand is that, if you have the space for the whopping great variety of hot water tank and capacity sizes, choosing a system that is too big or powerful is simply a waste of money – not only up-front but also with respect to those ongoing running costs. What you’re aiming for is that perfect balance between never running out of water, and keeping your costs down.

Now, bear these factors in mind:

1. Family size

If your house has 7 people living in it, it’s obvious that you’ll need more hot water on tap than a couple. But also think about whether your family is likely to expand and the water heater lifespan given that many hot water warranties these days are as long as 10 or 12 years.

2. Number of bathrooms

Most modern houses have more than two showers as well as a bath, and you’ll also use hot water in the kitchen, too. And the more bathrooms and kitchens you have, and whether your washing machine uses hot water, will significantly alter your hot water system size choice.

3. Hot water usage

As most families do most of their hot water usage in the evening, you can place such an immediate demand on your system that you want to guard against running out at these times. If your usage is more evenly spread throughout the day, you can probably opt for a smaller unit.

4. Off-peak tariffs?

If your electric system is on an off-peak tariff that is cheaper to heat at night, you’ll want a tank big enough to heat a full tank overnight that can then be used throughout the day and evening without needing to do a more expensive top-up. If you’re only on peak power, you can get away with a much smaller unit. With tankless hot water systems the number of outlets used at the same time is more important than the number of people residing in your home.

With those considerations in mind, here are some handy numbers to use as a rough guide:

Electric tank storage hot water system (off-peak)

  • 1-3 people – 250L
  • 3-5 people – 315L
  • 5-8 people – 400L

Electric tank storage hot water system (peak)

  • 1 person – 25L
  • 1-2 people – 50L
  • 2-3 people – 80L
  • 3-5 people – 125L

Reference: https://www.ergon.com.au/retail/residential/tariffs-and-prices/economy-tariffs/hot-water-tank-sizes

Instantaneous (tankless) gas hot water systems

  • 1 outlet – 9L
  • 2 outlets – 18L
  • 2-3 outlets – 27L
  • Over 3 outlets – 36L

Reference: https://www.elgas.com.au/blog/494-what-size-hot-water-system-do-i-need

What size hot water system – Are you ready to choose?

At the end of the day, the only real way to determine the perfect system for your home, family, usage and lifestyle is to talk to a true expert – just like the guys at Gold Coast Plumbing Experts! We don’t just repair and replace hot water systems Gold Coast wide with guaranteed workmanship and fast, friendly service, we’re more than happy to go the extra mile to make you happy. Get in touch today!