You have a 20,000-gallon pool and use a 125,000 BTU heater. Your water is currently 70 degrees F but you would like it to be a minimum of 80 degrees F. How long will it take before the pool water reaches 80 degrees F? 10 x 1.33= 13.34 hours of heating before the pool reaches 80 degrees F.
It depends on a few things to determine how long it takes a heat pump to heat a pool. However, overall a heat pump generally heats a pool after 24 to 72 hours by 20-degrees Fahrenheit. For smaller pools like a spa pool, the heat pump can heat a pool between 45 and 60 minutes.
For inground pools less than 20,000 gallons, small gas heaters like the Raypak 206K BTU output are suitable. Pools up to 30,000 gallons should look at the Pentair 300K BTU or higher, and pools over 50,000 gallons should look at the Hayward 500K BTU.
Overall, a heat pump usually requires between 24 and 72 hours to heat a swimming pool by 20°F (11°C) and between 45 and 60 minutes to heat a spa by 20°F (11°C).
A pool that is uncovered can lose up to 5 degrees F overnight; a good cover can cut that loss by half. Used at night or whenever your pool is not in use, the pool cover can help save fuel costs by cutting heat loss regardless of the type of heating you utilize.
If you want to get as much time as possible out of your pool, however, a heater is a good investment. With a pool heater, you can easily be swimming May through mid-October, giving you a good five months of use out of your pool. That's literally double the amount of time you'd get without one.
According to the World Health Organization, water temperatures ranging from 78 to 86 degrees Fahrenheit are generally comfortable and safe for those engaging in moderate physical activity in a pool.
It is not advisable to heat your pool at night because of the time and energy it will consume. You're advised to heat your pool during the day for more efficiency, and if you can, buy a solar blanket to retain the temperature of your pool.
A pool heat pump should not be left running all the time. For one, you are wasting electricity by keeping it on when your pool is already warm enough. Also, this will lead to an increase in energy costs month after month.
While adding a pool heater requires an upfront investment, it helps you maximize your investment by being able to use your pool for much more of the year. Between setup and operating costs, a pool heater costs between $300 and $5,000, with the average cost around $2,000.
On average, natural gas burns about 1 therm per 100,000 BTUs per hour (British Thermal Units). Meaning, an average pool heater between 300,000 and 400,000 BTUs will cost anywhere from $3.30 to $4.40 per hour to heat your pool.
Efficiency and Installation
By nature, gas heaters have a greater environmental impact than electric. However, electric takes longer to heat up your pool water and is less efficient in colder temperatures. This is because they rely on outside heat to warm up the pool water.
Natural Gas – Pool heaters using natural gas will heat your pool in just a few hours compared to solar and electric heating which can take up to a day or two.
The fastest way to heat your pool is to use a gas pool heater and a solar cover. It's like heating up your coffee in the microwave and putting a lid on it. No matter how you plan to heat your pool, you should at least have a solar cover (or liquid solar cover) to help you retain the heat.
The best time to heat your pool is during the day at least several hours before you plan on using it. The risk of running your pool pump overnight is that the outdoor temperature might be too low for the pump to efficiently warm your swimming pool.
If you are trying to save money or energy, run your heater only when the pool water temperature dips below 78. If the water is sufficiently warm, the air temperature will be less important. Temperatures in the 50s, and even 40s, can be tolerated if the heater is keeping the pool water warm.
Water temperatures are slow to heat up, and just as slow to cool down. Water is very "stubborn" to change temperature. It takes 4 times the energy to heat up water than to heat air. Water also "feels" colder because water is a more efficent medium than air to cool our body down.
Air bubbles in the pool cover act as an insulator in a similar way that your thermos would keep water warm. A pool cover will, therefore, keep your pool water warmer for longer.
According to the American Red Cross and the National Pool and Spa Institute, the recommended minimum swimming pool temperature for most aquatic activities should be between 83 and 86 degrees Fahrenheit.
Heat pump pool heaters work efficiently as long as the outside temperature remains above the 45ºF–50ºF range. The cooler the outside air they draw in, the less efficient they are, resulting in higher energy bills. However, since most people use outdoor pools during warm and mild weather, this usually isn't an issue.
No matter where you're swimming, avoiding water below 70 degrees Fahrenheit is a good rule of thumb for the average swimmer. The truth of the matter, though, is that 70 degrees is still pretty chilly. You'll probably have a better time if you wait for warmer water. In fact, you'll be safer, too.
Heat transfer efficiency is higher with higher flow rates. However, you have to look at total efficiency and cost. It may be worth the extra heat loss to run the pump at lower speeds.
Cost of Running a Propane vs.
The size of your pool also matters, with larger pools costing more to heat than smaller ones. On average, however, a gas heater costs around $200 to $400 a month to run. Electric heat pumps cost less, coming in at about $100 to $200 a month.