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Information Guides

Calculating Required Heating Time

The time it takes to initially warm your pool or spa depends on several factors:

  • Determine how many gallons of water are to be heated. Knowing this, you can then compute the equivalent pounds of water involved, and the BTUs necessary to heat the volume of water to the desired temperature.
  • Next, find the approximate BTU output of your heat pump at the current ambient air temperature (see specifications table in heater manual).
  • Finally, decide upon the temperature at which you plan to maintain your pool or spa.

Sounds complicated, but it’s not! The following worksheets ( standard and metric) can be used to calculate approximately how long it will take your heater to bring your pool or spa up to temperature. Keep in mind that heating times will vary somewhat due to weather conditions during the period that the heater is in use.

When you start your AquaCal heat pump for the first time, the heat pump must be permitted to operate, continuously, until the desired water temperature is attained.

  • This may take several hours, to several days, depending upon the time of the year and weather conditions.
  • If a time clock or similar device controls the operating time of the circulation pump, temporarily override the time clock or controlling device to allow for 24-hour, continuous water pump operation.

Once the body of water is up to temperature, the time clock can be reset.

  • A heat pump is a maintainer of heat, and thus is sized to overcome heat losses. However, during the colder months, when heat losses are at their greatest, and in order to keep up with increased heat losses, water pump run times may need to be extended.
  • Since air is generally at its warmest during the daytime, it is best to operate heat pumps during the daytime when there is more heat to transfer. Whenever possible, set system run times for daylight hours.

NOTE: An optional Call Flex Time Clock Manager (AquaCal part #0030S) can eliminate the need to change water pump run times as heat losses change with weather conditions. Please contact your installing dealer for details. Contact our Customer Service department for Dealer Locator information.

Pool/Spa Blankets

Purpose of Pool Blankets:

A pool blanket will assist the heat pump to maintain water temperature, while significantly reducing heating costs.  Blanketed pools will typically lose only 3 – 4° of heat per night versus 8 – 10° overnight with an un-blanketed pool. Un-blanketed pools typically loose 50% of the heat placed in the pool by the heat pump and/or sunlight.

Owners should check with the installing dealer to see if their heat pump was sized to be used in conjunction with or without a blanket.

Conventional Blankets:

Conventional blankets, commonly referred to as “Solar Blankets“, consist of a thin plastic-like membrane that floats on the water surface. To be effective, solar blankets, whenever the pool is not in use,  must be physically placed (most typically by hand) over the water surface.

A conventionally blanketed pool loses only 20% of its heat gain, overnight.

WARNING: Improperly used, Pool-Spa solar blankets can become a drowning risk to people and pets.  Solar blankets are not safety covers. They are not designed to support the weight of a person or pet.  Never enter a pool until the solar cover is completely removed (under no circumstances should anyone swim under the blanket).  Follow all safety recommendations of the blanket manufacturer.

Liquid Blankets:

For those who want to save on heating costs, but do not want the bother and potential dangers of a conventional blanket, liquid blankets offer a viable alternative to conventional, plastic membrane solar blankets.

A liquid-blanketed pool, on average, loses only 30% of its heat gain, overnight.

We recommend searching these key terms on Google: Pool Blankets, Solar Blankets, Liquid Blankets.

Disclaimer: AquaCal disclaims any responsibility for or liability related to the performance or safety of any swimming pool blanket(s).

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