Spas and hot tubs can use a tremendous amount of energy, the vast majority going to heating and filtering water. There are three major factors which affect these operating costs:
- Spa Size, and
- Operating Temperature.
The most important factor contributing to spa heating costs is the difference between the beginning water temperature and the final temperature. The larger the difference, the higher the costs. For example, to heat your spa from 70°F to 100°F and maintain that temperature for one hour costs about one dollar using gas or $2.23 using electricity; add $.20 per hour for the pump motor and another $.10 per hour for the aerator. (All figures based on a 6' x 6' spa of 500 gallons with a 2-hp filter pump and a 1-hp aerator. Energy costs used are 10 cents per kilowatt-hour and $1.40 per therm.)
To reduce your spa's operating costs, keep it covered with a tight-fitting insulated cover when not in use. When installing a spa, insulate it well around the sides and bottom.
Heat the spa only when you plan to use it, allowing time for warm-up, and keep its temperature at 102°F or lower. Check the accuracy of your spa's thermostat. An inaccurate thermostat can cost you hundreds of dollars each year.
Filtering is another major cost of owning a spa. Average spas have 2-hp filter pumps which cost about $.20 an hour to operate. These simple steps can help reduce filtering costs.
- Reduce the number of hours you filter. The average spa requires one-half to one hour of filtering each day.
- Filter enough to maintain water clarity. If you have a pool maintenance service, be sure to check with them before reducing filtration hours.
- Have your filter pump operation checked yearly by a qualified pool maintenance company. A malfunctioning filter pump costs more to operate.
- When it's not needed, switch off your aerator, the device that adds bubbles to the water jets. An average aerator is 1-hp and costs about $.10 an hour to use.
In some climates, a solar heating system is an alternative way to heat your spa. Solar covers are now available for pools to keep them warmer longer thus cutting down on the time it takes to heat up. Solar heaters that require solar panels need at least two times the surface area of the spa. You should consider several factors before deciding on a solar heating system for your spa:
- The initial cost of a solar heating system is generally higher than for a conventional heater.
- A back-up heating system is required.
- Solar heating systems work only during daylight hours and will not heat the spa at night.