Best hot tubs for cold climates
Short answer
The Nordic Hot Tubs Crown holds heat on the least power of the 167 six- and seven-seat hot tubs with a California standby filing: 131 W, against a 209 W median. Standby is the power a covered tub draws to stay hot, so it measures heat lost through the shell, cabinet and cover.
Picked on published facts only. How we picked
No manufacturer pays us. How we make money
Lowest standby, 2 to 3 seats
Caldera Spas Aventine
Vacanza Series · 2 seats
The lowest standby draw of the 47 tubs with 2 to 3 seats that have a California filing, 30% under the median. Insulation, as the maker lists it: FiberCor, fully insulated.
Second brand, 2 to 3 seats
Sundance Spas Dover
780 Series · 3 seats
The lowest standby draw from a second brand in this size, 29% under the median.
Lowest standby, 4 to 5 seats
Hot Spring Aptos
Freeflow · 5 seats
The lowest standby draw of the 78 tubs with 4 to 5 seats that have a California filing, 35% under the median. Insulation, as the maker lists it: Spray-In Full Foam.
Second brand, 4 to 5 seats
Jacuzzi J404L
J4 Collection · 4 seats
The lowest standby draw from a second brand in this size, 34% under the median. Insulation, as the maker lists it: Multi-layer insulation.
Lowest standby, 6 to 7 seats
Nordic Hot Tubs Crown
Classic Series · 6 seats
The lowest standby draw of the 167 tubs with 6 to 7 seats that have a California filing, 37% under the median. Insulation, as the maker lists it: Full foam.
Second brand, 6 to 7 seats
Master Spas S6
LH Series · 7 seats
The lowest standby draw from a second brand in this size, 36% under the median. Insulation, as the maker lists it: full foam.
Lowest standby, 8 or more seats
Jacuzzi J509
J5 Collection · 9 seats
The lowest standby draw of the 21 tubs with 8 or more seats that have a California filing, 38% under the median.
Second brand, 8 or more seats
Bullfrog Spas X7
X Series · 8 seats
The lowest standby draw from a second brand in this size, 28% under the median. Insulation, as the maker lists it: High-density full-foam.
How we picked
We ranked every hot tub with a matched California standby filing and a published seat count, 313 of the 390 in our data, by standby watts within its size: 2 to 3, 4 to 5, 6 to 7 and 8 or more seats. On a tie, the tub holding more water ranks higher. We show the lowest in each size and the lowest from a second brand.
Nothing else feeds the ranking: not the build checks, not price, not anyone's opinion. The yearly figure is standby watts held for 8,760 hours; it leaves out heating fresh water and running the jets.
Why is standby power the cold-climate test?
Standby power is the closest thing to a heat-loss rating that every brand selling in California has to file. The test behind the figure runs with the cover on, the water held hot and the air around the tub at 63°F or colder. With nobody in it, the tub's power goes to filtering the water and replacing heat that leaks out through the shell, the cabinet, the floor and the cover.
The filing reports power at a fixed gap between water and air temperature, which is what lets a 6-seater from one maker be compared with a 6-seater from another. A colder yard widens the gap, so every tub draws more at home than on paper.
| Caldera Spas AventineVacanza Series · 2 seats | 107 W | 937 kWh |
|---|---|---|
| Sundance Spas Dover780 Series · 3 seats | 108 W | 946 kWh |
| Nordic Hot Tubs D'Amour MSModern Series · 2 seats | 108 W | 946 kWh |
| Hot Spring MiniFreeflow · 2 seats | 112 W | 981 kWh |
| Nordic Hot Tubs D'Amour SESport Edition · 2 seats | 114 W | 999 kWh |
| Hot Spring AptosFreeflow · 5 seats | 120 W | 1,051 kWh |
| Jacuzzi J404LJ4 Collection · 4 seats | 122 W | 1,069 kWh |
| Sundance Spas Montclair780 Series · 5 seats | 131 W | 1,148 kWh |
| Sundance Spas Marin880 Series · 5 seats | 136 W | 1,191 kWh |
| Nordic Hot Tubs Impulse DPClassic Series · 5 seats | 140 W | 1,226 kWh |
| Nordic Hot Tubs CrownClassic Series · 6 seats | 131 W | 1,148 kWh |
| Master Spas S6LH Series · 7 seats | 134 W | 1,174 kWh |
| Bullfrog Spas Calm6Calm · 6 seats | 142 W | 1,244 kWh |
| Jacuzzi J408J4 Collection · 7 seats | 147 W | 1,288 kWh |
| Sundance Spas Altamar880 Series · 6 seats | 148 W | 1,296 kWh |
| Jacuzzi J509J5 Collection · 9 seats | 151 W | 1,323 kWh |
| Jacuzzi J508J5 Collection · 8 seats | 172 W | 1,507 kWh |
| Bullfrog Spas X7X Series · 8 seats | 177 W | 1,551 kWh |
| Sundance Spas Aspen880 Series · 8 seats | 193 W | 1,691 kWh |
| Bullfrog Spas A8A Series · 8 seats | 208 W | 1,822 kWh |
Does the type of insulation matter?
The lowest-standby tubs here use different methods: the Caldera Spas Aventine (FiberCor, fully insulated), the Hot Spring Aptos (Spray-In Full Foam), the Jacuzzi J404L (Multi-layer insulation) and the Nordic Hot Tubs Crown (Full foam). The filing measures the whole package, so compare watts rather than insulation names. Hot tub insulation types explains the methods.
What should I check in the showroom?
- Ask for the model's California standby figure and compare it with the tables here and on the standby power ranking.
- Lift the cover. Feel how heavy it is and look at how well it seals along the hinge.
- Ask whether the heater is 4 kW or 5.5 kW at 240 volts. Of the 266 tubs that publish it, 147 have 4 kW and 114 have 5.5 kW. A bigger heater brings the water back up to temperature faster after a long soak.
For what that power costs where you live, see hot tub running cost. For picks on build checks and warranty, see the best hot tubs.
Common questions
What is the best hot tub for a cold climate?
On the one measure taken the same way for every brand, the tub that loses the least heat for its size. Among six-seaters that is the Nordic Hot Tubs Crown at 131 W on standby, against a 209 W median. The picks above give the lowest for each size.
Does a California test tell me anything about a cold climate?
Yes. The test measures the tub, not California weather. It runs with the cover on, the water held hot and the room at 63°F or colder, and reports power at a fixed gap between water and air so tubs compare fairly. In a colder yard every tub draws more than its filing, because the gap is bigger.
How much power does a hot tub use on standby?
Across the 317 tubs we matched to a California filing, standby runs from 107 W to 350 W, with a median of 197 W. Held all year, 197 W is about 1,726 kWh. Heating fresh water and running the jets is on top.
Sources
3
- California Energy Commission, Modernized Appliance Efficiency Database (portable electric spas)Standby watts and test fill volume for 317 hot tubs
- US Department of Energy, proposed test procedure for portable electric spas, 87 FR 63356 (October 18, 2022)Test conditions: cover on, ambient air 63°F or lower, power normalized to a fixed water-to-air temperature gap
- California Energy Commission, portable electric spas FAQSpas sold in California must be certified to the CEC