Spa Running Cost Calculator Coming Soon!

Most new portable and inground spas hold between 900 and 2000 litres of water. The Running costs of a spa has many variances and will change depending on 5 major factors.

1. Type Of Heater
2. Ambient Temperature
3. Heat Loss
4. What Temperature The Spa IsKept At
5. Cost Of Electricity Or Gas In Your Area

Basic Physics
The energy required to heat water is the same, regardless of what method is chosen. This is because the laws of physics dictate the energy requirement, not the type or brand of product. Every liquid has a "Specific Heat Capacity" value. In the case of water that value is 4.187kJ / kg K. This means that 4.187 Kilojoules of heat energy is required to raise the temperature of one kg mass (one litre) of water by one degree C at standard temperature and pressure. So taking worse case outdoor ambient temp of 13 Degrees C, using this rule, take 1000 litres of water X 4.187 Kilojoules = 4187 kilojoules to heat 1000 litres 1 degree C. So 4187Kj X 25 Degree C temperature rise = 104675KJ.

104675KJ = 104.657 Megajules

104.657 Megajules = 29.07639 Kilowatt-Hour

1. TYPE OF HEATER
Basically the biggest variance, where running costs are concerned using different types of heaters, will be if the heater is powered by gas or electricity. Mind you there are still some differences that make some electric heaters more efficient than other electric heaters and vica versa with gas, but these differences are very minimal in day to day running costs.

Gas Heater
We have taken, for example, the formula above to work out the amount of gas megajules needed to heat a spa from 13 degrees C (Celcius) to 38 degrees C which is the most common spa temperature. Using the formula above 104.657 Megajules X the rate we are invoiced at Box Hill South (Victoria 3128) for Natural Gas per Megajule is $0.007418 Cents per Megajule = $0.7763.

Electric Heater
We have again taken the formula above and used it to calculate what the cost it would be using electricity. Heating the water from 13 degrees C to 38 degrees C uses 104.657Megajuels.So 104.657 Megajules = 29.07639 kilowatt-hour. Electricity in Box Hill South (Victoria 3128) is costing $0.1287 per Kilowatt. So 29.07636 X $0.1287 = $3.74.

Solar Heating
Solar heating for spas is not commonly used, due to the fact that spa user temperature is around 38degC and it would be very hard to get a day with enough solar energy to maintain that for the whole day, unless of course you are in a hotter climate. Also a lot of people tend to use their spa during the night when there is no sun to heat the water. However we believe it is a great way of keeping your running costs down if it was done right. You still will need a heater but the solar would act as the main source and the other, (either gas or electric) as a booster, so it only comes on when the solar cannot maintain it. Ask us about a custom solar system.

DON'T FORGET ABOUT THE PUMP PUSHING WATER THROUGH THE HEATER $$$

Pump Driving Heater
The pump that is driving the heater is also drawing power. If it is a single speed 2 - 3.5 Hp (horse power) it will be drawing from 8 - 10 amps which if drawing 10 amps, it would be 2.4kw X $0.1287per Kilowatt = $0.3088 per hour. If a circulation pump or a two speed pump running on low speed was used the costs would be much lower.
For Example: A circulation pump drawing 88 watts X $0.1287 per Kilowatt = $0.01132 per hour.

Summary
Gas is cheaper than electricity for the same amount of megajules used and gas is also a far quicker way (up to 8 times faster) than electricity. If you have an electric heated portable spa and think it is costly, speak to us about converting yours to a gas heater and making your whole system more efficient. We can convert any electronic controller to run a gas heater safely and simply.

2. AMBIENT TEMPERATURE
The ambient temperature is the air temperature. If you have your spa situated in a sealed room the ambient temperature is obviously going to be a lot higher than having your spa outside with no protection or covering over it. So the higher the ambient temperature the less your heater has to be on, and the cheaper your running costs will be. Controlling outside temperature is impossible but there are some basic tips you can use to help lower your running costs. Our overnight ambient temperature is always lower than during the day, so your heater will have to be working harder and longer to maintain your set temperature. Some spa controllers have Sleep cycles, or economy cycles on them that can be programmed to come on at any time and they usually disable the heater. These cycles should be used during the night and early morning as you would be less likely to use your spa, so there is no need to keep it at the higher temperature.

3. HEAT LOSS
Having a Hard cover on your spa is a necessity. A good insulated hard cover will more than halve your running costs and provide your spa with protection from the elements, leaves, debri and animals. A hardcover can be made for any shape or size spa including swim spas, just have a look in our products section. You unfortunately do not only lose heat through the top of the spa you also lose it through the sides and the base. If you have a portable spa in a cedar or plastic cabinet, there is a good chance you have already got some type of foam
installation. This will help in keeping some of the heat in the pipe work and body of spa. One of the best insulators, just like in most of our roofs and walls, is pink batts or fibreglass batts. These can be added in and around your spa and surrounding pipework. Keep in mind that it will retain the heat but not prevent it from escaping, so just like the roof, Sizalation or builders Foil can be used to retain the heat.

Caution: When doing this DO NOT put the batts anywhere near the motors or blowers, as they suck air and could suck up the fibres. It would also be a good idea to separate the insulation from the pumps and equipment using a heavy duty heat resistant plastic sheet or even foil (sizalation). That is why a lot of manufacturers have what they call engine bays, or equiptment compartments. Some manufacturers also use the heat generated from the pumps and have ducts going back into the surrounds of the spa, which is a great idea. Insulation can save you a fortune in running costs, in fact I have seen some portable spas that actually hold 25 to 30 degrees, just with the circ pump running and heater has not been on for days.

If you have an inground spa it is very hard to do your own insulation unless its in a deck and there is access underneath. When you purchase your inground spa you should request it to be either flo-coated or foamed to help with insulation. Flo - coating also helps prevent moisture penetrating the fibreglass which helps in the prevention of blistering and bubbles forming. Where as foam is also great for protecting the pipework and a good insulator.

Your blower and air controls are also often forgotten as big heat loss items. Your air controls which are usually round turning knobs on the top of your spa, let air into the jets and create a turbulence causing better pressure out of the jet. The controls suck in cold or colder air from under the lip of the spa and just make the heating process harder! So turn them off when you are not in the spa, you should see no white bubbles coming out from the water jets at all! Unless it is an ozone jet, in which case should be the only jet to have white bubbles coming out from it! Your blower is basically a big hair dryer that blows, once again cold or colder air sucked in from the cabinet or outside. As you could imagine continuos use of the blower will cause the water to cool down considerably, especially in an electric heated portable spa! Quite quickly too. The gas heated spas will cool down as well but will bring the temperature back up very quick with no problem at all! There are heated blowers available that heat the air that is sucked into them, which work quite well. But a good practice is to only put your blower on for short periods at a time, like 5 or 10 minutes or you will cool the water down considerably!

4. WHAT TEMPERATURE THE SPA IS HEATED TOO
AND HOW MUCH THE PUMPS ARE USED
The Hotter your spa is kept the longer and more frequent your heater will be on to maintain the temperature you have set it at. If you have a gas heater the best way to run it is to set your time clock twice a day for filtering and heating, and leave the temperature at about 25 to 30 degrees. You will find that the heater wont be on for long to maintain that, and then when you wish to have a spa go and bump the temp up 15mins before you hope in. It should reach 38 in no time. If you have an electric heater it is a good idea to do the same thing only you will have to wait longer for it to reach 38, you may wish to keep it at 30 so it doesn't take as long to reach 38. Note: It is not a good idea if you have a electric portable spa to turn it off at night and then turn it on the next day again. The best thing is to lower the temperature, not turn it off! How much you use your spa will also play a big factor on your running costs! If you for interest sake if you use it twice a day with all pumps and blowers running for an hour, compared to once a day with everything running for 20mins with all pumps and blowers running, you will take off about a ¼ of the cost! Or more! But simple things, like if it is only you in it, don't run all the pumps! Only run the pump for your seat!

5.THE COST OF ELECTRICITY OR GAS IN YOUR AREA

The cost of electricity varies depending on where you live. A smart thing to think about is getting a serperate off peak meter put into your switch board.Then you could hook up your spa and your hot water and any other appliance to this and save a fair bit of money because the rate is much cheaper.Ask your power company provider for more info.

The cost of gas also varies and unfortunately, natural gas is not available in every suburb. But even when LPG or bottle gas is used it can still work out cheaper than electricity.