The cost of luxury in our home is killing our bottom line. We're starting to look at ways to cut our gas and electric costs. One of our big drains is our hot tub. Between the 4 of us, someone uses the tub each day of the week.
I'm wondering what the best plan of attack might be for keeping the hot tub ready to go and bringing the cost down.
Right now it's set at 103 24/7. Would it make any difference in cost if I kept it at 100 and turned it up to
103 each afternoon in time for my wife and kids to enjoy the tub each evening and turned it back to 100 each morning? It seems like I would be spending as much reheating the tub each day as I would to keep it at 103 24/7.
What do think and what strategies do you use to keep your hot tub ready to go while keeping the cost of heating down?
Lowering the temperature will reduce the cost, at least some. Lets say you keep it set at 103º for 20 hours a day and at 100º for four hours. Further lets say it takes one hour to cool or reheat. The cost of cooling and reheating will be a close offset (actually it will benefit you a little.) During the remaining 18 hours you will be loosing less heat less fast at 100º then at 103º and that will be all savings. It does not cost more to heat than you saved when you were not heating as it cooled.
I don't own one, so I've obviously never experimented with temps. Does it need to be at 103 degrees? If you dropped it to 98, would it still be fabulous, or just kinda OK?
Is it physically outside? Its best kept indoors and either way you can cover it with more insulation which will save you more than chillin it.....
Its great your using it a lot, many are bought and drained after awhile, for a wide variety of reasons. its like exercise machines, well maybe not quite that bad but still not good
My first comment is that 103F is too hot. It doesn't need to be more than 100F for a pleasant soak. Regardless, here is how it comes out for us. We have a 350-gallon Jacuzzi brand tub. The heater is 1,500 watts. We are also on a timed meter which is available at our power company. Power is 12-cents/KW hour during prime time (9:00 A.M. to
9:00 P.M. weekdays) and 4-cents/KW hour the rest of the time.
Because we don't use the hot tub every day, we run our filter cycle only one hour twice a day. Normally, it would be two hours twice a day. We run the filter/heater at 8:00 A.M. and 9:00 P.M. each day to keep in the 4-cents/KW hour window. So it takes 12-cents of electricity per day during the filter cycles (assuming the heater has to run the entire time) and let's say another 10-cents per day to keep it at 100F while being used. That comes out to $6.60 cents per month worst case. Our nighttime temperatures have been running mostly in the 20's all winter. A few mornings in the teens.
It's outside next to the deck. It has an insulated cover on it.
I was worried about it not being used after the novelty wore off, but my worries proved unfounded. It gets used between sunset and bedtime on a regular basis and I use it in the middle of the night whenever insomnia rears it's ugly head. Daytime use is rare except when my daughter has friends over.
I've tried 102, 101, and 100. It's not unpleasant, but, for me, 104 is the magic number, and for my family 103 is the magic number.
I'll drop my filter frequency to the greatest time interval available. I'll look into a timer. That would be much easier than remembering to turn down the temp each morning and to turn it up each afternoon.
The Solar Option has been mentioned. If you can rig a way to use gas to preheat the water, you will probably find that less expensive than electricity.
One hundred years ago in Japan they used wood heaters to heat their bathwater. It was a good idea then and it can be an economical choice today. Several wood stove manufactuers ofter a hot-water heating option.
Indoors is better than outdoors for a hot tub location. With an indoor tub, all the waste heat will at least contribute something to heating your house in the winter. The heat loss from the outdoor tubs goes straight into the air.
Inside is a lot better primarily because the amount of heat needing to go in it is a fraction of what it is outside. If it's 20 degrees outside with it set at 104 you have an 84 degree delta. Inside, at 70, the delta drops to 50. That's about 40% less. Having it inside isn't much of a benefit for most as far as having the heat go into the house instead of outside. During heating season this is a plus, but during cooling, it switches to a negative. Overall, it's probably a small plus.
I would definitely set the unit on a timer, so the temp gets setback during hours when it's not gonna be used, then raised prior to periods when use can be expected. I have one outside here in NJ and I keep it lowered to around 60 during the coldest winter months, cause I only use it a couple times a week. Prior to using it, I raise the temp back up far enough in advance. Setting it back is exactly like lowering the thermostat in the house at night.
I would make sure it's as well insulated as possible. Is the cover in good shape, not water logged, and has no gaps? Is the spa located so that its as sheltered as possible?
BTW, I agree that anything below about 104 is less desirable. I like mine more like 106. And fiddling with a few degrees at the expense of enjoying it the way you like is not gonna make much difference. Again, if the delta is 104-20, thats 84. If you set it at 100, thats
80, which is less than a 5% difference in energy use. I guess you could have the timer take it to 100 prior to use, then turn it up the rest of the way manually, just prior to use.
I just thought of something. What temperature is recommended for safety? I understand that water temperatures play a big role in keeping the water sanitary.
Everything I have read says that 15-minutes at 104F is the maximum exposure for a person in good health. Someone who is pregnant, has diabetes or heart problems should not be exposed to even that much. The problem, apparently, is that when you get the body to that high a temperature, the body loses its ability to shed heat. You can find a lot of information on the large spa equipment websites.
I am curious as to what sort of heating system your hot tub uses? I have connected power over the years for two types that use electricity for heating. One uses a 20 amp 120 volt circuit and heats the water only when the jets are not in use. This unit takes a longer time to heat the water from cold. The other type uses a 40 or 50 amp 220 volt line and heats the water up much quicker than the previous one that I mentioned. The heater can work with the jets going. Of course this type also consumes considerably more power. Or do you have a gas heater?
If you have the 220 volt model, I don't think it would be necessary to run the heater 24/7 although you may need to run the pump frequently for filtration purposes. You could try calling the manufacturer or distributor to ask them how long it takes for the water to get to your ideal temperature.
A couple of manufacturers used to make timers just for hot tubs, but I haven't seen any lately. I think solid state controls are taking over. Try doing a search for pool or hot tub time clocks. You could also check
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or contact an electrical supply house. Take a look at
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and look up models 1100D and 1100FM under Special Purpose Controls.
I always amazes me that people spend a fortune insulating their homes to save energy, then they get these things and put them outside in freezing weather and wonder why their electric bill is beyond belief.
The OP needs to build a structure around it, attached to the house. There is no other way to cut the cost by anything significant, when the thing is outdoors in winter. Insulate the structure well, and you will see big savings in power usage. For summer use, make some of the walls of this structure removable, maybe even part of the roof.
Myself, I'll stick to a hot bath in my bathtub !!!
Insulate it better. There is a spray for the underside of the tub itself. Another cover for the tip is in order. Then keep it at 95, find out how long it takes to go from 95 to 103 and educate everyone on the fact they will have to turn it up ahead of time (and back down). The exact numbers here are hypothetical, but the cooler you keep it the more energy you will save.
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