I just picked up a used '99 Hotspring Sovereign and I'm in the process of getting it setup at my house. The friends I got it from had it plugged in, at 110. It seems that was also the factory preset. It's a pretty big tub, and I'm in a fairly cold climate (MI), so I'm wondering if 110 is really adequate. The upside of going 110 is it wouldn't cost me much to setup, in fact I'd probably do it myself with the GFCI outlet they had. But I'm thinking 220 would be better for heating and so everything can run at the same time. Is 110 significantly cheaper on my electic bill? Anyone have strong opinions either way?

I'm leaning toward 220, unless somebody talks me into 110. What would be a good ballpark estimate on having somebody setup the 220 subpanel for me and hook it up to the tub? Any secondary market for the parts (couldn't find much on eBay, but I may be searching wrong)?

Many times you can switch your tub over to 240V, but in your spa's case, it will only be the heater you will convert. It will be advantageous with respect that it won't take as long to heat, and will run less during the winter, thus potentially saving you plenty. Typically your spa will heat 4 degrees an hour on a good day as it is, using around 1200 watts for the heater. With 240V you could expect up to 16 degrees an hour, but at the cost of around 4000 watts for the heater. Over all, 240 would be cheaper to run.

Well, for your tub, the only potential savings going 220v would be, well, there wouldn't be any...

220v is no more efficient in terms of electrical bill, but you can pull twice as many amps with with wire 1/2 the size. That's why it may be considered "more efficient" but efficiency stops there.

Sure, the heater will run less hours per day 220v, but, it will pull about 4x as much electricity when it is running. The amount of energy consumed to heat the spa will identical for 110v and 220v spas.

If you're in a cold climate, 220v buys convience, the ability to heat faster, and heat while the jets are running.

Talk to you friends, and see if it was an issue for them.


A 1999 Sovereign is convertable, but it does it a little different. You'll need a 30amp220v service, as well as a 20 amp, 110v service. A total of 5 wires (3 hots, N, and G). The size of the wire is dependant on legnth of the run, typically, the 30 amp, 10guage braided, and the 20 amp, 12g braided, and a 10 g ground.

Good luck,

~Swine

Here's some interesting math:

figure a 30 degree temperature rise

figure a 5500KW heater at 240V, which is the same heater as a 1440W heater at 120V

Average rise with 1440 watts on 300 gallons of water is 4 degrees per hour

Average rise with 5500 watts on 300 gallons of water is 16 degrees per hour

Total wattage used to obtain the 30 degree rise at 120V 1440W is 7.5 hours using a total of 10800 watts.

Total wattage used to obtain the 30 degree rise at 240V 5500W is 1.875 hours using a total of 10312.5 watts.

Difference of 500 (give or take) watts. Doesn't seem like much, but if you figure the usage over a year's time, figuring the average tub will heat 10 degrees a day average over the year

That makes for a difference of 59.3125 kilowats in the year, and at 9.2 cents per kilowatt, that is an annual savings of a whopping 5.46 bucks a year.

Now that may not seem like much, but if you want to do more math, that savings will pay for the water you use in the tub! Also keep in mind that the whole time your heater is running, so is your pump. I didn't account for the energy savings in running the pump just one quarter the time using the 240 heater setup.

If you calculate a 4hp pump, running on low speed for heating, you will run the pump 3 hours less a day, and over a year's time that will save an additional 44.73 a year!

So, what is about 50 bucks a year in savings? Enough for me to do the switch!

...Not to mention, this member has a 24 hour circ pump, it's running regardless of his heat concerns.

Heating 10degrees/day?? Not in a Hot Spring Spa...His little mag drive circ pump is heating the spa as well, generating a constant 60Watts of heat.

We can deduce his savings going to 220v less than $3/yr.

That little circulation pump, if running 24/7, is costing 75 bucks a year to operate. Why does HS do this? That 60 watts of power will only generate 0.16 degrees of temperature rise in an hour. I wouldn't count on that for heating the spa in a 20 degree day with a 15 mile an hour wind, unless it's in the house. Granted, the HS uses the circ pump so the pump's energy savings can't be included, the truth still remains that if you want to get down to counting beans, it's still cheaper to run 240V.... even if it's not much of a savings.

If it was set up where the low speed pump ran for heating, for an average of an hour a day just to heat, it would only cost 14.91 to run the pump to heat for a year. If you figure in filter cycles, I would imagine everything about balances out.

Just a note, after all this calculating, and my mind smoking from numbers.... it would appear that my Sundance with it's circ pump for heating, and low speed for filtration, actually costs less to operate than a HS with a 24 hour circ pump for the filtration and heat. HS uses the 24 circ pump to be able to claim 24 hour filtration, yes?

I'm now leaning toward keeping the 110V, and I'll see what I think after a year or so. I have a 70-80 foot run, to get electric cable back to the tub, from my panel. I just priced 8-3 wire at Home Depot yesterday, along with the additional 50 A breaker in my main box and 2 GFCI breakers in the subpanel and I think I'm looking at $2-300 just for parts. I've had a few quotes of nearly $800 to do this conversion for me, and I'm not 100% comfortable doing it myself.

Look with that run and the cost of a hotsprings gfci sub panel you may never make up what you spent through energy savings, but I did it to my 97 sovereign and the main plus is that now it stays at a more constant temp. Even while in it mine now stays right where I set it even open for extended periods of time w/ a party in the tub. I imagine this would be even better in winter for you, i'm in coastal california, and w the 110 setup the tub temp would really drop in 1/2 hours time, so i kept it at a higher temp than i really enjoyed so i could stay in longer.
remember if you do convert you need a pretty specific sub panel w 20/110 and 30/220 breakers and 6 or 7 wires of different guages going to the tub.If you dont have 220 at your main, and you hire an electrician you could be easily spend a grand on parts and labor. But hell that tub cost somebody like 7 grand at one time.