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Hot Tub Efficiency

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You make an excellent point. I am not yet an owner. Hence my ignorance. I am currently on a fact finding mission.

i would spend upfront to maximize cost efficiency over time. for instance, I recently bought a variable speed pump for my pool.

Would you be able to give a guess on both 110 and 220? Assume a timer is used and heat/ circulation is done at night when my TOU energy is cheapest. Used 4 times a week? And lets assume a high quality cover as I was told that in itself was a money saver over time.

I hope this is enough for you to venture a guess, just a guess is ok

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How many miles per gallon does a car get?

How much does a house cost?

Can you see that there's a few variable involved? Just a few ;-)

There are a few things you can do to reduce your heating costs (120v vs. 240v isn't it). Insulation, insulation, insulation. The better the spa is insulated the less it will cost to heat. DON'T forget the cover! There are varying thickness with varying insulating abilities. And, Protect your spa from wind. Most people don't realize it, but wind, even a slight breeze, can draw quite a bit of heat from the spa.

Average cost? Based on 20 years on message boards... Most people pay between $30 - $200 a month....remember though, PG&E is some of THE most expensive electricity in the country. And if you try to figure it out, remember, you're probably already paying in the top tier (over 27 a kWh) and the spa will just add to it.

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Dr. Spa...

Thanks for the reply. Yes, I am aware of PG&E's astronomical rates. However, I recently installed PV solar. I did so knowing (planning?) on a hot tub, and therefore oversized the solar by just a bit. Hence my question should be more specifically, what is the Kwh' draw of a typical new 300 gal, quality cover, wind blocked tub?

Yes, I understand variables matter. Therefore, I'm asking for nothing more than a semi-educated guess.


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I live in southern Vermont and my 350 gal. tub costs an average of $360/yr. for electricity.

My electricity costs @ $.15/kwh

The tub is outdoors next to the house (no wind break on 3 sides), has full insulation (not just spray on the shell), and is covered when not in use. It gets used 2-4 hours per week. My circulator pump runs continuously.

My friends report similar avg. cost per month.

Perhaps you can extrapolate from that info. to get an idea what yours might cost.

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  • 2 weeks later...

I estimate my CalSpa from 1988 costs me $15 per month in electricity and chemicals to run. Mine is 220 VAC, but now I know that 120 VAC would work fine for me. I have it on the No Freeze/Thermostat setting so it only switches on when the temperature drops, and have been amazed for last few years how few minutes (not hours) a day it requires for heating. Yes, always keep covered when not using.

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I don't know for sure what POCO is, but I'm in Phoenix, AZ and have Arizona Public service as my electricity provider. My rates are less on weekends and from 9pm to 9am.

For the first 20 years I had this spa I was on a "demand" rate, where I had a surcharge each month based upon the one-hour of highest demand for the entire month. So when the spa was installed the 220 VAC wiring was part of the APS no-interest loan for the load controller, they had to run wires through the attic to the spa. The load controller prevented it, the dryer, AC etc. from running like one-hour straight, would break it up into separate sections so the hour demand would be under my pre-set limit.

When the load controller went out after 20 years and I changed to the current price APS structure (my previous program had been grandfathered but was soon to be closed out), I was surprised that the spa actually ran so few minutes a day to heat the water (like 400 gallons). So I now don't worry too much about what time it actually kicks on, want it ready when I want to use it. So moving the filter unit outside of the partially-insulated redwood "box" didn't seem to affect things appreciably, except to make filter cartridge R&R for cleaning tons easier; plus those giant "nuts" to retain the original filter cover kept breaking and were like $22, and the O-ring there also oftentimes leaked, was not good design.


However, when I drain/exchange with new water, I would generally schedule that for a weekend or wait until 9pm to switch on to heat, as then I'd be heating 400 gallons of water from like 70F to 104F. In comparison, my electric water heater (no natural gas here, home built during fear of natural gas shortages, pushed by the electric companies, surprise !!!) is 50 gallons 220 VAC and heats to maybe 130F every day.

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