Calculating Hot Tub Energy Usage:

There is a simple formula to help you estimate energy usage and cost.

Watts = Volts X Amps

So if you know the volts (115 or 230) and motor's amps (listed on the label) you can figure out the watts.

Once you know the watts and the cost per KWH (look at your electric bill to see what you pay) you can use the next formula to figure the costs.

On the island of Oahu in Hawaii electricity costs $0.18 per Kilowatt Hour (KWH).

P.S. a KWH = 1000 watts for 1 hour.

Cost per KWH X total KWH = cost of electricity

This is simple for those who are mathematically minded. However, many people are not math minded! Don't feel bad. Go to the bottom of this page for the summary.

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So here is an example: Full Foam "poor value spa"

ONE. An "Iron Might" pump is 115 volts and has a 1.3 amp rating. The Iron Might is a commonly used 24 hr. a day circulation pump used on full foam "poor value spas".

So 115 volts X 1.3 Amps = 149 watts.
Therefore 149 watts X 24 hrs = 3725 watt hours or 3.725 KWH
3.725 KWH X $.18 = $.675 per day for this circ pump.
$.675 X 30 days = $20.12 month for the circ pump

TWO. Next we will estimate Large Jet Pump costs. Lets say the spa is used 4 days a week with the pumps on for 30 minutes a day. You have a large 4 HP pump at 230V rated at 13 AMPS. 230 X 13 = 2990 watts. If you estimate that the pump is on for 30 min 4 days a week, then you can figure that the pump is run for 2 hrs per week at 2990 watts or 5980 watt hours. 5.980 KWH X .18 = $1.076 week X 4 = $4.30 month.

Three. Next we will estimate electric heater usage in a full foam spa. The 5,500 watt electric heater is the only source of heat in a full foam spa. Assuming that the spa is used 4 days a week for an hour each day...
As soon as the cover is lifted off heat starts escaping from the water. Assuming the heater comes on 30 min after the cover is removed and stays on for 1 HR to reheat the water. So 5,500 watts at 16 hrs a month equals 88,000 watt hours or 88 KWH. 88 KWH X $.18 = $15.84

Summary: Full Foam "poor value spa"
Circ pump = $20.12 (poor value small pump: 8gal/min)
Jet Pump: = $4.30
Spa Heater: $15.24 (16 hrs per month)
Total: $39.66 (full foam)

Summary of a Haven Spa: Thermally sealed design.
Circ pump = $18.77 (.63amp x230v)(high quality/high flow 30gal/min)
Jet pump= $4.30 (kept the same for comparison)
Spa Heater: $3.96 (4 hrs a month 22 KWH x .18)
Total: $27.03 ( Haven Thermally Sealed design)

Conclusion: As you can see a major cost item is the electric 5,500 watt heater. This is where the Haven Spa will save you money. This is because of the heat capturing design of the Haven Spa. Haven uses pump waste heat as the primary heating source for the water. The expensive to run heater rarely has to switch on to heat the water. That is the difference in the 2 examples. This is based on estimating usage. Your usage patterns will vary of course. Use the big jet pump much more than the example and this will increase your electric costs also.