Is It More Efficient To Leave My Water Heater On? - Discussion

This is one of the most frequently asked questions we get here at Electrical Deals Direct, there are several schools of thought and a constantly evolving discussion around the question 'Should I turn my water heater off?', indeed there might be too many factors to conclude the right answer honestly, however, we aim to try and offer the reader a sense of the main talking points to assist whether they can come to a quality answer on this. We would like to note that this topic is still developing, so the understanding and overall estimative solutions that this article may discuss or prompt could change over time and based on the reader's situation and understanding.

Potential Variables

So there are a fair few variables that we would like to note before getting to some arguments for or against. In an article from I News

"A study of over 21 million homes revealed the majority of properties across England and Wales only meet the insulation standards of 1976 or older"

This could have a massive bearing on the worth of you turning the heater on or off. A shocking third of homes in the country don't have proper or modern loft insulation, this could form a massive impact on the outcome of this question. Another thing to consider is the size of the unit, running costs being higher for larger quantities of water and the kW total of the elements inside the heater. Furthermore, the length of time away may influence your decision, f.e. Turning a heater on or off can yield varying levels of monetary savings and efficiency, especially when comparing the impact of a 6-hour pause versus a 6-day shutdown.

Arguments For Turning The Water Heater Off

Considering heat loss basics, one argument clearly favours the water heater being turned off. A hot coffee cools faster at a room temperature of 0°C than at a room temperature of 20°C. Thermodynamics implies it's usually better to switch off water heaters while away, as heat loss daily can cost less than reheating once. You really have to weigh up the hassle of turning your unit off, for a simple 'plug and play' unit the benefit financially you may stand to gain by switching it off may be worth the hassle (in plug and play's case simply pulling the plug/turning the switch off). The costs of re-heating water will largely depend on your gas/electrical rates, in the example of a month away from the home, it's more than likely that you should want to switch the unit off, even if you have to flush out a complicated system for safety reasons, the cost saved not using the water heaters electricity to constantly maintain a hot water supply might well prove beneficial.

Arguments Against Turning The Water Heater Off

One core argument that would suggest leaving the unit on would be a safety concern. The average property owner may not have the know-how to drain a water system, so turning off the unit without doing this is not feasible. This is because a reserve of water may accrue dangerous bacteria when not at a certain temperature, namely legionella. The idea that this could occur in stagnant water pipes if the heater was turned off, would likely cause many concerns.

The counterargument to our basic thermodynamics argument above is this. Over a given length of time, the cost to "top-up" heat from 59 degrees to 60 each time the temperature dips, may in some cases actually be less expensive than heating that given amount of water from room temperature back up to 60 degrees. Naturally, one should consider that these two points may contradict each other. When evaluating which side of this coin holds true in a specific scenario, it becomes essential to factor in the volume of water and the duration the unit remains unused or switched off. Regarding electrical expenses, it's evident that heating a volume of water by a single degree would incur a lower cost than heating the same volume by, for instance, 40 degrees to restore it to a boiler's standard 60-degree mark.

Conclusion

As discussed in the opening statement, the true answer for your specific needs may well be dependent on your personal situation. If you were to leave a property for months at a time the answer is more than likely going to be to turn off your Water Boiler, Cylinder or other Water Heater. But many alternate or varying factors may influence the outcome of this question. Luckily, we have a whole team on hand that can easily help deduce your needs and warrant the best course of action for efficiency and money saving. Please don't hesitate to contact us on 01934 253600 with your conundrum and we shall do our best to advise and assist. Many thanks for reading.