- Categories: Pool Fixing
How Long Does It Take to Heat a Pool?
You’ve got the pool, the sunshine, and the perfect day for a swim, but the water’s still chilly. So, how long does it take to heat a pool? The answer depends on more than just switching on your heat pump. In this guide, we’ll look at average heating times for different pool sizes, the key factors that speed things up or slow them down, and practical tips to get your pool ready for swimming faster, without wasting energy.
Average Heating Times for Common Pool Sizes
While no two pools heat exactly the same way, here are some ballpark figures based on standard heat pump performance:
- Small pools or spas (under 10,000 L): These can warm up surprisingly quickly. If you’re raising the water temperature by 5 °C, expect it to take around 45–60 minutes.
- Medium residential pools (20,000–40,000 L): To increase the temperature by 10–11 °C, you’ll likely need 24–48 hours of continuous heating.
- Large pools (50,000+ L): For the same 10–11 °C rise, the process can stretch to 48–72 hours.
These are averages, not guarantees. Plenty of factors can influence the result.
Pool Size & Volume
The larger the pool, the more water your heat pump has to warm. It’s simple physics, heating 70,000 litres takes more time and energy than heating 20,000 litres. Knowing your exact pool volume helps match the right size heat pump to your needs.
Heat Pump Capacity & Efficiency
Heat pumps are rated by their kilowatt (kW) or BTU output. A larger, more efficient unit will heat faster, especially if it has a high COP (Coefficient of Performance). COP tells you how much heat you get per unit of electricity; the higher the number, the better.
Temperature Difference
The greater the gap between your current water temperature and your target temperature, the longer it will take to heat. For example, raising your pool from 18 °C to 28 °C will take roughly twice as long as a 5 °C boost.
Ambient & Water Temperatures
Because heat pumps draw warmth from the air, they work best in milder conditions. Heating times will be quicker in late spring and summer than in early spring or autumn. In cooler months, expect slower performance and plan accordingly.
Pool Cover Usage
A quality pool cover can dramatically reduce heating time. It prevents overnight heat loss, cuts evaporation, and holds onto the warmth you’ve already paid for. Without one, you could lose up to 3–4 °C overnight, meaning your heat pump starts each day at a disadvantage.
How to Maximise Heating Efficiency
If you want to get swimming sooner without blowing out your power bill, a few simple strategies can make a big difference.
Choose a High-Efficiency Heat Pump
Models with a higher COP are more efficient, delivering more heat for the same electricity cost. For NZ conditions, aim for a COP of at least 5.0 or higher. An efficient heat pump like our Hayward range means you’ll get more warmth for every kilowatt of electricity, making it a smart long-term investment for both performance and savings.
Heat During the Warmest Part of the Day
Running your heat pump when the air temperature is at its highest (usually midday to late afternoon) boosts efficiency and shortens heating time. Warmer ambient air allows the heat pump to work less hard, which also helps extend the lifespan of its components.
Always Use a Pool Cover
It’s the single most effective way to keep heat in and reduce energy use. Even a basic solar blanket can save hours of heating time. Plus, covers minimise evaporation, which is a major source of heat loss, especially on windy days.
Keep Your Pool Circulation in Top Shape
Clean filters and good water flow help your heat pump work at its best. Poor circulation means uneven heating and longer run times. Regular maintenance ensures heated water is evenly distributed, so there are no cold spots lingering in the pool.
Size with a Buffer
When buying a new unit, consider going slightly larger than the bare minimum. That extra capacity, 20–30% more than your base calculation, gives you flexibility for cooler nights or unexpected swim days. It also ensures your heat pump isn’t constantly running at maximum capacity, which can reduce wear and tear.
Warm Faster, Swim Sooner
By understanding these factors and following a few efficiency tips, you can cut down heating time, save on running costs, and enjoy more comfortable swims. If you’re ready to time your pool heating just right, Dolphin Pacific can help. Find your local dealer and they’ll match you with the perfect heat pump for your pool and give you the advice you need to warm it quickly and efficiently.
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Hey! I'm Adrian, founder and pool expert here at Dolphin Pacific. I love spending time with family, fishing, and have been known to brew my own beer.
