How to heat up an inflatable hot tub faster?

Heating an inflatable hot tub to the highest temperature setting (104F - law limited) can take up to 48 hours depending on the outside temperature and insulation quality. Is there anything you can do to make it heat up faster?

Well, heating such a large amount of water takes a lot of energy, and how much electrical energy you can use is limited. We'll have to take a look at other options for speeding-up the heating process.

How to speed up the heating?

1. Insulate the hot tub (cover it!)

There's not much you can do about the insulation of your inflatable hot tub walls (air acts as an insulator there), but you can definitely use an insulating cover!

A typical choice for an inflatable hot tub is an inflatable cover, creating an insulating air pocket. If you feel crafty, you can make your own polystyrene cover for even better insulation.

The insulating cover will dramatically reduce heat losses, both by radiation and by evaporation.

Of course, the bigger the temperature difference between the water and the outside air, the more important this is.

When setting up the hot tub, use an insulating layer under the hot tub. A wooden deck will insulate much better than concrete. Even an old rug will reduce the heat losses through the bottom of the spa.

2. Fill it with hot water (But be careful!)

This can drastically reduce the heating time, or even make it non-existent. However, be super careful to not exceed the maximum hot tub temperature (usually 104° Fahrenheit) as it might damage it. If you pour boiling water onto the vinyl, it might melt. 

Never fill your hot tub with boiling water, unless there's already enough colder water to dissipate the heat. In that case, make sure to not pour the hot water near the inflatable hot tub walls.

3. Use a solar heater

During hot summer days, a solar heater connected to your hot tub filtration system can rapidly speed up the heating - for free! Disadvantage - requires the sun.

4. Use a wood-burning or gas water heater

This might be more expensive to set-up, but can save you some money in the long run, if the wood or gas is cheap in your area. A normal inflatable hot tub heater runs on electricity and is limited in how much power it can take. You can bypass this with your own heater in the circuit.

Check out how did this guy improved his lay-z-spa:

Anything else?

Unfortunately, speeding up the heating process means dumping a lot of energy at once into the water, which is no easy feat. Your options are limited. My advice? Plan ahead! ;-)