Heating a hot tub on Economy 7 and off-peak tariffs

Why timing beats the tariff

Economy 7 gives you roughly seven hours overnight at a low rate and a higher rate through the day. Time-of-use and spot tariffs do the same in a more granular way. The problem is that a hot tub does not care about the clock: it reheats whenever the water drifts below your set temperature, which is mostly during the expensive daytime and evening hours. So the cheap overnight window sits unused while the tub buys its heat at peak price.

Move that heating into the cheap window and the same warmth costs a fraction. That is the whole opportunity, and it is why simply switching to Economy 7 without changing when your tub heats often changes very little.

How Spapilot puts the heat on the cheap hours

Spapilot heats your tub during the cheapest hours and coasts through the expensive ones, while still hitting the temperature you set for the baths you have planned. You set the warmth and the times, it only decides when to heat, never whether to. The water stores the heat, so it can buy energy hours earlier, in the cheap window, and stay warm through the peak.

• Works with Economy 7, time-of-use and spot tariffs, no special plan required.
• Fits the Balboa or Gecko system your tub already has. No new tub, no rewiring.
• Fitted in about half an hour, with no electrician needed.

What off-peak heating saves

The saving falls on the heating component of your running cost, the largest and only easily movable part. Up to 80 percent is possible on the most volatile days with the Planner active, and 40 to 60 percent is typical across a season on a spot plan. On a flat tariff, where there is no price gap to exploit, only the standby saving remains.

How these figures are derived, and the assumptions behind them, is documented on the dated savings methodology page. To see what it would look like on your tub and tariff, try the running-cost calculator.

Common questions

Is a hot tub cheaper to run on Economy 7?

It can be, but only if the heating actually happens during the cheap overnight window. Economy 7 gives you roughly seven off-peak hours at a much lower rate. A tub left to reheat around the clock pays the expensive day rate for most of its heat, so the tariff alone does not save money. The saving comes from concentrating the heating into the cheap hours.

What is Economy 7 and how does it apply to a hot tub?

Economy 7 is a UK electricity tariff with two rates: a low rate for about seven hours overnight and a higher rate during the day. Heating a hot tub is the single biggest and most movable running cost, so it is an ideal load to shift into the cheap overnight window.

How do I heat my hot tub only during off-peak hours?

You need a controller that decides when to heat, not just how warm to keep the water. Spapilot heats your tub during the cheapest hours and coasts through the expensive ones, while still hitting the temperature you set for the times you want to bathe. You set the warmth and the schedule, it handles the timing.

Does off-peak heating work on any electricity plan?

It works on any plan where the price changes through the day, Economy 7, time-of-use, or a spot tariff. The wider the gap between cheap and expensive hours, the larger the saving. On a flat tariff there is no price gap to exploit, so only the standby saving remains.

How much can off-peak heating save on a hot tub?

The saving falls on the heating component of your running cost. Up to 80 percent is possible on the most volatile days with the Planner active, and 40 to 60 percent is typical across a season on a spot plan. How these figures are derived is set out on our dated methodology page.