Is Our Hot Tub Thermal Cover Worth The Cost?
Winter, of course, has been another matter. Not only is energy more expensive, but the lower ambient temperature means that the heater needs to kick in more frequently to help maintain even our "idle" temperature of 20°C (chosen to strike a balance between energy usage and warm up time).
The tub isn't just an inflatable rubber ring, it has a thermally lined outer layer (BestWay call the material EnergySense and claim that it increases efficiency by 40%). Similar material is used in the lid and the tub also sits on a sheet of interlocking foam tiles.
The catch though, is the price. Lay-z-spa, for example, want over £100 for even a small cover, though unbranded covers are cheaper.
Presumably, in order to actually achieve that level of improvement, you'd need to have been running an un-insulated tub, with no lid, out in the wind.
However, because I have the HomeAssistant integration set up, I do have a record of heater state, so it's possible to approximate energy usage by combining time active with the heater's rating (it has a single 2kW element):
