Spa pools are mainly used for relaxation purposes and therefore it is common to have a heating system installed in them. Spa pool heaters not only provide a comfortable soothing experience that is perfect for unwinding after a long day, they also extend the season of the spa pool so that they can still be used during a cold weather.
The normal range to which a spa pool is heated is 97 to 102 degrees. This is considerably higher than the normal temperature of a swimming pool but spa pools are much smaller, typically not more than eight square feet and less than four feet deep. As a result the requirements for a heating system are less than those of a swimming pool.
There are four main types of spa pool heaters that are available today. These are:
Small gas heaters like the Hayward H100 or Pentair MasterTemp 125 which are designed for an above ground pool and/or spa. These are relatively cheap to buy and will be able to heat up a spa quickly. If you can use natural gas they are reasonably cost effective. Disadvantages are that they are not small and because of the need for ventilation and safety cannot be out of sight.
Direct Electric Heaters such as these made by Coates are small and effective. They can be installed out of sight and should offer trouble free operation for many years. However they cost more than a gas heater to buy and much more to run.
Lower capacity heat pumps like the Hayward HP50TA are another option. This model is designed specially for above ground pools and spas and has low running costs. You probably can’t hid it but there are less issues with installation than with a gas heater and it is the most environmentally friendly of these three options. The disadvantage is the purchase cost which is more than an electric heater and considerably more than a gas heater. Also a heat pump becomes less effective as the temperature goes down.
A solar heating system can also be considered. In the right location solar power is quite practical during the summer but is not much use on cold evenings at other times of year.
In the end it depends on how often you want to heat your spa. If it is only occasionally a gas heater is likely to be the best option but if it is used regularly it might be worth investing in a heat pump.