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What Size Gas Hot Water System Do I Need?

Whether you’re constantly running out of hot water because your system isn’t large enough, facing sky-high gas bills, or dealing with an old hot water heater that no longer works, you can easily calculate the right size gas hot water system for your household.

Let’s have a look at the factors to consider when choosing the right size gas hot water system for your home.

What to Think About Before You Buy a New Gas Hot Water System

Bigger is not better when it comes to gas storage hot water systems. A hot water system with a greater storage capacity than you need will cost a fortune to run, as the system works to maintain the heat even when it’s not being used. This is why you need to find a system that can comfortably accommodate all of your home’s occupants and its appliances. Here are the factors to consider to help you determine your hot water usage and the best size gas hot water system for your family.

How big is your family?

In addition to the number of occupants, consider how often you run a washing machine or dishwasher and how often everyone showers or takes baths. A shower uses less water than a bath, particularly if you fill the bath to the top each time you use it.

How many appliances do you have?

A dishwasher can save on water compared to inefficient hand-washing habits like rinsing dishes with warm water. It’s also worth noting the water rating on appliances such as washing machines to help you calculate your hot water usage.

Do you wash in hot water?

If you have an older-style top-loading washing machine that takes in hot water instead of heating water internally, consider this in your hot water consumption calculation.

How many bathrooms do you have?

The more hot water taps you have to service, the bigger your storage system will need to be.

Do you have water-saving devices?

A water-saving shower head and water-saving discs installed on hot water taps will reduce the flow of water and slash the amount of hot water you use.

Should you Choose a System with a Storage Tank or an On-Demand Gas System?

A hot water system with a storage tank heats the water to ensure it’s always ready for use. When you turn on a tap, the system draws hot water from the top of the cylinder, which then refills from the bottom with cold water. The gas burner activates to heat the incoming cold water, which stays in the cylinder until needed again. However, the water tank can lose heat even during use, making it potentially less energy efficient than an instantaneous gas hot water system, especially for smaller households.

An instantaneous gas system, sometimes known as a continuous flow or on-demand system, heats water only when needed (once you turn on the hot tap). This method uses less gas than a storage tank system. Typically, installers mount these systems on a wall and position them as close as possible to the taps or appliances they supply to ensure efficiency and quick access to hot water.

Read more about the service demands of different systems in Signs your gas hot water system needs a service.

Other Factors to Consider for Your New Hot Water System

You consider both your tank size requirements and the water delivery capacity of your hot water system. For a storage unit, estimate that you’ll need 30 L per person at a minimum. Opt for brands that offer greater storage tank insulation so that your hot water service doesn’t have to work too hard to maintain the water temperature. Consider the units that offer the best energy efficiency rating you can afford.

With a continuous flow system, flow rate is one of the most important factors to consider. The litres per minute your system can deliver will determine how many hot water outlets it can supply with hot water at any one time. To calculate the flow rate you require, let your hot tap run into a bucket for a full minute and note down the total. Do the same on each of your outlets, and add up the total to calculate how many litres per minute you require at peak usage.

For more information about finding the best system for your home, read The best gas hot water heaters for your home.

Requirements for an Instantaneous Gas Hot Water System

Although instantaneous, or continuous flow, gas hot water systems are very energy efficient compared to storage tank systems, they consume more gas while in use. Therefore, if you install an instantaneous system to replace a gas storage system, your home may need a larger gas line installed from the meter to the hot water system. You may also have to change water supply values in order to install an instantaneous system.

Your new continuous flow system may also need to be connected to electricity to operate an internal computer and to prevent the pilot light from constantly running.

Are you asking the question, Why does my gas hot water heater keep going out? Read here to find out.

The Best Gas Water Heaters for Any Household Size

Before you decide which gas hot water heater to purchase, read our handy sizing guide below.

Small household of 1–3 people

Whether you live in a small house or unit, you should opt for a hot water system with a storage tank of at least 90 L. If you choose an instantaneous flow hot water system, a 16–21 L unit will meet your requirements.

The space-saving Bosch 16H is best for small households. This system does not require a power point because it uses HydroPower ignition. When you turn on the hot tap, the energy from the water flow ignites the system. You can use it with LPG or natural gas.

Medium-sized family of 2–4 people

A 26 L continuous-flow hot water system will meet the requirements of a medium-sized household, while a storage tank system should have a 135–170 L capacity.

The Dux Prodigy 135 L gas hot water heater is a great option for a medium-sized family. Its new burner technology makes it a market leader in hot water recovery. It operates on a standard-sized gas line and doesn’t require electricity to operate. It also offers an inline foam-filled tank for better insulation to help you save on your energy bills.

Large households of 3–5 people

A 170–260 L capacity storage tank or 32 L on-demand unit is best for households of 3–5 people.

The Rinnai Infinity 32 Enviro is designed for larger homes with 2–4 bathrooms. A 6-star unit, it uses less gas than a standard continuous flow system and features tough stainless steel internal construction.

Keep the Water Hot and the Family Happy

Choose a gas hot water system that comfortably meets your consumption needs to keep hot water flowing freely in your kitchen, bathroom, and laundry. Calculate your requirements by considering the number of bathrooms you have, the number of occupants in your home, and how many appliances rely on hot water.

For more information on buying the best gas hot water service for your home, call Same Day Hot Water Service on 1300 721 996. From gas hot water system servicing to emergency repairs and installation, we’re here for you at any hour of the day.

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