How long does it take to heat a spa? (Heating Time, Key Factors, & Quick-Heat Tips)

How Long Will It Take to Heat Up a Spa?

As a general rule, an average-sized portable spa will take about 12-16 hours to heat up.

A few variables will affect the heating time, including the starting temperature of the water, ambient temperature outside, the desired temperature you want the water to heat up to, the volume of water in your spa, the size of your heater and if you have a heat pump or not.

Keep reading to learn more about these factors that affect heating your spa.

How Long Does It Take to Heat a Swim Spa?

Heating a swim spa generally takes between 48 to 72 hours. Similar to spa pools, this duration varies depending on factors such as starting water temperature, the heater’s power, and outdoor temperatures.

Swim spas, due to their larger volume, naturally take longer to heat than standard-sized spas.

Below, we break down the factors that impact heating time in detail.

What Factors Affect Spa Heating Time?

Heating a spa is influenced by multiple factors. Understanding these helps you better predict heating durations and optimise for shorter heat-up times.

Ambient Temperature

Cold outdoor air temperatures can slow down heating, as more energy is required to raise the water’s temperature. Conversely, warm weather allows for faster heating times.

Cover and Insulation Quality

A well-insulated spa cover helps retain heat, allowing the water to warm up faster.

Covers prevent heat loss and trap warm air, reducing the heater’s workload. Ensure your cover is in good condition and fits securely over the spa.

Spa Heater Power

A more powerful heater can significantly reduce heating time. Spa heaters vary in capacity, commonly ranging from 3 kW to 5.5 kW. For larger spas or those intended for cold-weather use, opting for a higher-capacity heater and/or a hybrid heat pump is beneficial.

Heat Pumps

If your spa pool or swim spa has a heat pump, it can heat the water to your desired temperature more quickly, as there’s no need to wait for the spa heater element to warm up. Heat pumps are also ideal for maintaining temperature once the spa is warm, helping to keep operating costs low over time.

If you’re seeking guidance on choosing the best heat pump for your spa, our detailed article below is a valuable resource.

Water Starting Temperature

If the spa has recently been emptied and refilled, the water may be quite cool, resulting in longer heating times.

Wind Exposure and Location

Spas exposed to wind or in open areas may lose heat more quickly. For lower energy consumption and quicker heating, consider situating your spa in a sheltered area or using windbreaks to minimise cooling.

Spa Size and Water Volume

Naturally, larger spas with greater water volumes take longer to heat. For a typical home spa with average capacity, heating times will be shorter than for swim spas, which are designed for both relaxation and exercise.

Water Circulation System

Some spa models circulate water while heating, which can help distribute warmth evenly and speed up the process. Systems with higher circulation rates may heat the water slightly faster, ensuring that warm water is consistently spread throughout the spa.

Does a spa pool heater run all the time?

Your spa heater does not run all the time. It only operates in heating mode when the water temperature in your spa drops below your set temperature.

When this happens, in modern spa systems, the controller can automatically sense that your water temperature has dropped below the set temperature, and the heater will turn on again and run until your water reaches your set temperature again.

When your water temperature is reached, the heater will turn off.

In Summary

Heating up a spa requires consideration of various factors, from water volume and heater capacity to environmental conditions.

Understanding the average heating time for your spa, along with efficiency tips, allows you to plan a warm and relaxing spa experience whenever you like.

Got more questions? We’re here to help!