Until fairly recently, if you wanted hot water you had to turn your heater on and wait around 30 minutes, or even longer if you used an immersion heater. Thanks to advances in technology, hot water can now be taken on demand via an instant hot water system.

Traditional Systems

To understand how these work, you need to understand how the traditional systems work. These systems use collection tanks where water is piped into them, stored and heated. When you need the hot water the tank empties; however, to have instant hot water the tank needs to be heated constantly to maintain temperature, even when you are not using the water, and although the tank is insulated, the water would eventually cool from natural heat loss. Because the tank needs to supply at least enough water for a substantial bath, a lot of space is taken up by it. Not only that — but if someone uses all the water from the tank before you, you will have to wait for the tank to be reheated again.

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Tankless Water Heaters

Instant hot water systems and water boilers from places like water boilers direct (for example) heat the water directly and don’t require a storage tank. Unlike the traditional system, cold water travels through the pipe when the HOT tap is turned on, where it travels into the heating unit. In here a gas burner or an electric element heats the water as it travels through. This results in a constant supply of hot water. Although no storage space is needed and you don’t have to wait for the water to be heated, a tankless heater’s output limits the flow rate.

Fast Water Delivery

Usually, instant hot water systems provide hot water at a rate of around 2–5 gallons per minute. If you are thinking of installing one, it’s good to know that the gas-fired heaters produce higher flow rates than the electric element variants. It’s also good to know that even the largest gas-fired systems can’t always supply enough hot water simultaneously for multiple uses throughout the bigger household. This can be easily overcome by installing more tankless heaters connected in parallel for simultaneous hot water. These new systems are very adaptable as you can install separate systems for appliances. For example, thirsty appliances such as a washing machine and dishwater can run off a single instant hot water system.

Because there is little to no waiting time for hot water nowadays, and the lack of having to constantly heat water in a tank makes these new heaters the most energy efficient solutions available on the market.