My hot tub uses 49% of my electricity per month...lets fix that.
- Thread starter tmprof
- Start date
400bird
Solar Wizard
I love the irony in the naming here!
yodamota
Solar Enthusiast
isn't polypropylene glycol found in ice cream these days?
I have a hot tub and have been thinking about how I could use it as "storage" to dump my excess solar energy during the day, instead of net metering or storing it in a battery.
I have an mpp lvx6048wp inverter and I've been thinking of adding some more solar panels and using the extra energy to heat the hot tub
basically the idea would be that I'd set the max temp a little hotter than "ideal" and power it off solar in the day so on a sunny day it gets up to max temp. but have it shut down at night when there is no solar. and have it be "ideal" most evenings when we get in. It seems like that would be more energy efficient than sending excess solar during the day into a battery and then trying to have the hot tub run of battery power at night.
I've heard it said that it is energy inefficient to let your hot tub cool down and then try to heat it up before using it, and that you should just leave it at a constant temperature. But it's gotta be more efficient than the loss you'd get going from solar to mppt to battery during the day then back from battery to inverter to heater at night, right?
has anyone done anything similar?
some of my main questions would be:
we love our hot tub too! use it almost every night.
I have an mpp lvx6048wp inverter and I've been thinking of adding some more solar panels and using the extra energy to heat the hot tub
basically the idea would be that I'd set the max temp a little hotter than "ideal" and power it off solar in the day so on a sunny day it gets up to max temp. but have it shut down at night when there is no solar. and have it be "ideal" most evenings when we get in. It seems like that would be more energy efficient than sending excess solar during the day into a battery and then trying to have the hot tub run of battery power at night.
I've heard it said that it is energy inefficient to let your hot tub cool down and then try to heat it up before using it, and that you should just leave it at a constant temperature. But it's gotta be more efficient than the loss you'd get going from solar to mppt to battery during the day then back from battery to inverter to heater at night, right?
has anyone done anything similar?
some of my main questions would be:
- is that going to be super hard on the hot tub's control board to cut power to it every night?
- if my lvx6048wp can handle the power draw of the heater? OP said his pulls 6.1kw, this inverter says "Grid-relay feature boosts max output up to 9KW", so based on that maybe it could? mine's a 500 gallon hot tub so I'd imagine it would be similar, but I've never measured the power draw of mine.
we love our hot tub too! use it almost every night.
I think that is a great idea! The only issue I see is if you want to get in the tub during a period where it's over heated, that might be uncomfortable. I live in Houston where it gets really hot during the summer. My hot tub rarely needs to heat even overnight during that time. Also, I lower the temp during the warm months so it feels more like a pool.
teal95
Solar Enthusiast
We paid "pro's" last year to winterize it. I could have done a better job. They didn't drain the ozonator/UV box so it froze and broke. Then they couldn't come up with replacement part, even though they're the ones who installed it (it was a replacement/upgrade when the original ozonator failed), and I wasn't even trying to make them pay for it.
All you need is a line blower and some antifreeze, both of which should cost about the same amount as a single opening or closing. It's really easy to close a spa yourself. You could probably get by with something smaller and cheaper if it's only for a spa as well. They also come up on eBay periodically, especially mid-season (middle of winter, or middle of summer).
There's a lot of "pro" pool guys that have almost no idea what they're doing, most states don't require licensing (beyond a business license) so anybody can do it, trained or not. One of the companies I used to work for hired this guy, he claimed to have been a welder on the Alaskan pipelines, I was a helper at the time, so they sent me with him. He literally had never even pulled a plug or skimmed before, and they were sending us on technical service calls. I quit when I found out he was being paid three times what I was and I was the one doing the work because I knew how, dude couldn't even hook up a pump. I work for myself now.
I would find a more reputable pool service. I offer a reasonable freeze protection guarantee, if my work fails, I will fix the busted pipe for free. I would have been out there with that part as fast as humanly possible. Even if they can't find the exact replacement part, you should be able to find one on eBay and have them install the part, I'm a reasonable guy, but if I paid somebody $3-400 to close my spa, I expect it to be properly done, and any issues that they caused, they should fix.
teal95
Solar Enthusiast
Wife keeps going back to the place she got it from. That's the third time I've went to their shop and they've been useless. I told her I'm not going in there again. There's a place that's much closer that doesn't sell the brand we have but every time I've been in their store they've been very helpful.
It's a swim spa, so it's huge. But yes, it still has the same places that need drained.
It's a swim spa, so it's huge. But yes, it still has the same places that need drained.
That'll help a lot. I've been adding 2 inch pink panther FOAMULAR board foam.
Also rigged up being able to use firewood to heat the tub. I still want to use electric instead of gas though ideally during the day.
Also solar water heater is on my list
I came to the same conclusion in my testing. mine is ~1200 watts but I consider it more "supplemental power" kinda keeping it the same temp it already is at
This is an interesting topic. I've been thinking about building a hot tub heater control for mine with an ESP32, a high voltage/high current DPDT relay, plus a couple Dallas 1-wire temp sensors. I'm already using ESPHome and Home Assistant for various DIY controls and monitoring. While this won't do anything to reduce the total electrical consumption, I'd use it to shift when the heater runs to avoid importing from the grid during peak rates and make better use of our grid-tied solar as export tariffs continue to drop. Setting up the relays normally closed will be a fail safe so things run factory-normal if my project goes offline, as well as using the temp sensors to prevent temps from going too low. In addition to monitoring, this would allow some additional automation opportunities too. If I get around to this project I'll try and remember to post up a thread here.
Osmethne
Solar Enthusiast
I would definitely use a heat exchanger to separate the hot tub water from heater water.
Osmethne
Solar Enthusiast
And this idea of draining it for the winter I don't get. I think winter is the best time to use a hot tub.
yes please do! I would be very interested to see how that goes for you and what your final setup looks like
James Getman
New Member
I think the coldest I used the hot tub was 17 Fahrenheit, your hair would freeze if you were not wearing a hat. Putting dish soap in there was fun, 2 to 3 feet of frozen suds. Getting too old for that adventure.
My favorite is when my hair is frozen and I'm in the hot tub.
yep I love that, also jumping in the snow and then running back in the hot tubs.
Up in vail / steamboat springs in colorado there are places we go out at 0F/-17C many of the hotels keep them running all year outside.
k490
Solar Enthusiast
I have had a hot tub for 10 years now bought it used from a friend who lost their house to foreclosure and divorce. Didn't pay much for it since then I have gone through 3 control modules and a new pump from Acura Spa in Riverside, CA. It's a power hog put a amp meter on the wire watch it pull 50 amps at 240V. Even my hot water heater doesn't pull more then 20 amps. I turn it down to 80F we heat it up on the days we want to use it. Sometimes the clock gets flipped so it's heating during peak hours I'm getting a demand charge now in the winter.
We haven't even filed it yet this year been so warm here in AZ we still hitting 80's. I might fill it we do like using it when it gets down into the 40F degrees. Most of the year it stays drained spa store told me it might cause it to crack not keeping it filled if that happens ill just trash it. We been draining it for at least 5 years now I open the connection to the pump drain the water out of the lines.
We haven't even filed it yet this year been so warm here in AZ we still hitting 80's. I might fill it we do like using it when it gets down into the 40F degrees. Most of the year it stays drained spa store told me it might cause it to crack not keeping it filled if that happens ill just trash it. We been draining it for at least 5 years now I open the connection to the pump drain the water out of the lines.
crack just from being empty? that's a new one, what commission percentage do the sales guys get there?
It'd crack from your extreme temps etc way before just magically sitting empty
k490
Solar Enthusiast
That is what he was saying because summer gets to 119F here it being drained might cause it to leak because dries out. I haven't had that issue with it we had a pump go out and the control board died 3 times. I'm not sinking any more money into it if it dies give it away first who hauls it away. Lots of them in FB marketplace, or CL for free all the time here. People buy them don't realize how much work it is keeping the chemicals perfect and draining refilling. They leave them full of nasty water all summer turn green eventually just want it gone. The cost to have it wired into the house is also not cheap I did it myself I know a co-worker who spent $2500 for a contractor to run wire underground. He put in a 16-person hot tub cost him almost $20k I told him he was nuts in AZ just sit in the pool 92F water in the summer.
