Everything you need to know about your hot tub’s rest mode

Get to know your hot tub’s modes and you could cut down its running costs.

Most spas have three modes: standard, economy, and rest (although their names vary across different models). 

Here’s your guide to what each mode does and when you should use each one to shave the most off your electricity bills (without ever ending up with a tepid hot tub when you want a luxurious soak).

Standard 

Set your hot tub to 38°C in standard mode and it will climb to that temperature and then stay there. Every hour or so, it will filter the water to check its temperature and run the heater until it gets back to the temperature you’ve set.

If you use your hot tub most days, the most effective way to run it is actually to just leave it in standard mode. That’s because the kind of spa you’ll pick up from a WhatSpa?-recommended dealer will be so well insulated that very little heat will escape from it. The heater will only have to come on a touch every few hours to keep it up to temperature – which means it will be running a lot less time in total than if you kept letting the temperature drop and then heated it back up again.

Economy 

By default, most hot tubs run through a two-hour filter cycle in the morning and another in the evening. Switch your spa to economy mode (often called eco mode) and its heater will only run during these filter cycles.

Economy mode can certainly save you a bit of money during a spell of good weather during the summer, when the ambient temperature is a lot higher. But, with the weather we have in the UK, it will often increase your hot tub running costs, as your hot tub’s temperature will drop so low between filter cycles that your heater will end up running longer than it would have in standard mode to heat it back up again.

So, while it’s worth flicking your spa’s eco mode on when we have a spell of great weather, it’s probably not going to be very economical at all here in the UK any other time of year.

Rest

Your hot tub’s rest mode (often called sleep mode) works the same as its economy mode. The only difference is that the heater will only kick in once the temperature is 10°C lower than the temperature you’ve set. 

So, if your hot tub’s temperature is set at 38°C, the heaters will only kick on during the filter cycle when the water has dropped to 28°C or below. The heater will then cut off when the temperature hits 38°C or after or an hour – whichever comes first.

This is a great way to reduce your energy bills if you won’t be using your hot tub for a while. If your spa has a rest mode, it’s a good idea to add switching that on to your checklist of things to do to your hot tub before you head off on holiday. Just bear in mind you’ll need to wait a few hours for your hot tub to heat up again when you get back and turn it back on to standard mode.

The final verdict

You can certainly shave a bit off your energy bills by switching your spa to rest mode before you head off on holiday. You can also cut your hot tub’s running costs by turning economy mode on during the height of summer, when the ambient temperature will be high enough that your spa won’t get too cold between filter cycles.

But you’ll actually save the most money if you leave your hot tub on standard mode during everyday use, as it takes a lot less energy to keep your hot tub at a temperature than to heat it back up once it’s dropped down. 

For more expert advice on buying, installing, and maintaining a hot tub – as well as a shortlist of the most energy-efficient models on the market – pick up your free copy of WhatSpa? magazine.

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