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    Hot Tub Running Costs
    • #1
    • 26th Feb 06, 2:52 PM
    Hot Tub Running Costs 26th Feb 06 at 2:52 PM
    Hi. This is my first post so please be gentle.

    I admit that a hot tub in our garden is not the best money saving idea, but I am hoping that someone will be able to advise the best way forward in dealing with the company we purchased it from.

    Our tub was purchased in late September, delivererd early November. £1750 was paid on credit card and the balance (another £1750) on debit card. Prior to purchase we looked around and ultimately decided on a specific tub. The ad on the website indicated that "the approximate electrical running costs WILL BE £9 per month" (note: not should be)

    Our electricity bill landed (with a thud) two weeks ago. Looking at our bill for the same period last year, the tub is costing us £60 per month to run ontop of our normal usage.

    On speaking to the company, they state that they estimate between £9 and £15 per month. Being on the cautious side, we budgeted £20 per month.

    I was on the 'phone to the tub company within 30 minutes of the bill landing. After many tense 'phone calls, we finally had two engineers come out on Friday to install a further insulation layer. During the week, prior to the further insultation, we took a 24 hr meter reading which showed 40 units of consumption. Following the further insulation, we took another 24 hr reading which still shows a 40 unit consumption over a 24hr period.

    Please could anyone advise where to go from here. What redress can we get from the company. How are we coverered re credit card protection?

    At the end of the day, when we decided to purchase a tub, we knew that it would hike our electricity bill. I thought £20 per month would have been sufficient bearing in mind the £9 advertised. We are now in the position that no matter how much we like our tub, we cannot afford to run it! Had we known that it would cost £60 per month we would never have purchased it. It would be like buying a Hummer to drive and being told it would do 40mpg!

    Any advice gratefully received!

Page 1
    • boogiemaster
    • By boogiemaster 26th Feb 06, 6:33 PM
    • 900 Posts
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    • #2
    • 26th Feb 06, 6:33 PM
    • #2
    • 26th Feb 06, 6:33 PM
    You should always look at the specs of an item before buying it, if its 4.7 kilowatt then itís going to use some power.
    They could say that the £9 per month was just an estimate suing it once a week not every day.
    You could also call trading standards and see if they can do something under false advertising.
    Does the £9 a month say using it every day for so many hours a day? If it doesnít then where do they get their estimates from?
    Get in touch with trading standards and the citizen advice bureau
    The hummer is heavy and wonít do that much to the gallon; I doubt it will even do 40mpg more like 15-20 if youíre lucky
    • gavinp
    • By gavinp 26th Feb 06, 7:08 PM
    • 468 Posts
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    • #3
    • 26th Feb 06, 7:08 PM
    • #3
    • 26th Feb 06, 7:08 PM
    Is the tub on a timed switch or on 24 hours a day ?

    Is it possible to use cheap rate "Economy 7" overnight electricity to heat it ?

    How long does it take to heat up from cold ?


    • jfdi
    • By jfdi 26th Feb 06, 11:20 PM
    • 1,003 Posts
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    • #4
    • 26th Feb 06, 11:20 PM
    • #4
    • 26th Feb 06, 11:20 PM
    Ours costs about £25 to £30 a month (at current prices!, not Economy 7) to run - not a lot of difference between summer & winter.

    It's a 3kw heater, and we have 37 degrees as our preferred temp. However, there is a 'stand-by' function where it cools off a bit (down to about 30 degrees) - we just have to remember to put it back to normal about 1hr before use!

    Ours is a Spa-form, locally made - is yours British? I know a lot are imported.

    • Nile
    • By Nile 27th Feb 06, 8:47 AM
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    • #5
    • 27th Feb 06, 8:47 AM
    • #5
    • 27th Feb 06, 8:47 AM
    Hello f1owers

    Welcome to the MSE site.
    Hi, I'm the Board Guide on the In my home (includes DIY) and the I wanna buy-it or do-it boards which means I volunteer to help get your forum questions answered and keep the forum running smoothly. However, do remember that Board Guides don't read every post. If you spot an inappropriate or illegal post then please report it to It is not part of my role to deal with reportable posts. Any views are mine and are not the official line of

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    • lisyloo
    • By lisyloo 27th Feb 06, 9:01 AM
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    • #6
    • 27th Feb 06, 9:01 AM
    • #6
    • 27th Feb 06, 9:01 AM
    Hi F1owers,

    I am not a lawyer but I do think you have a strong legal case because
    a) you have evidence of what they said (do you have that in writing?) or can you prove it's advertise (if it's on a web site print it out before it's removed).
    b) you have evidence of what it's using.

    Do you have legal cover on your house insurance?
    Do you have a legal helpline?

    If so use them.
    If not then you will pobably find that you need to make a small claim in the county court.
    I think you have a very strong case.
    You can find plenty of info on this by googling but you will need to write to them and ask for a refund if they cannot fix the hot tub in X days (make it reasonable), otherwise you will recoup the costs in the county court.

    For those that don't know about hot tubs, they stay on ALL the time.
    They are heavily insulated.
    They also run a filter cycle at certain invtervals.
    You cannot switch then off (or bacterial will multilply).
    I would say that £60 per month is excessive.
    Mine costs about £15-£20 per month which I think is more usual (although it was more expensive to begin with).
    • kittie
    • By kittie 27th Feb 06, 9:10 AM
    • 12,444 Posts
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    • #7
    • 27th Feb 06, 9:10 AM
    • #7
    • 27th Feb 06, 9:10 AM
    Cost obviously depends on Kw per hour ie the number of Ww x the number of hours used. Don`t forget the heating up time. No legal case here as the wattage will be displayed on the unit. No doubt the insulation level is mentioned somewhere on the literature. A case of buyer beware
    • lisyloo
    • By lisyloo 27th Feb 06, 9:57 AM
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    • #8
    • 27th Feb 06, 9:57 AM
    • #8
    • 27th Feb 06, 9:57 AM
    Cost obviously depends on Kw per hour ie the number of Ww x the number of hours used.
    I don't think it's a simple multiplication.

    A hot tub is like a fridge, freezer or central heating system (or any other device controlled by a thermostat).

    Once it's reached the correct temperature then the heating side of it will switch off (although filtering may still be going).

    I can't see how it's a simple multiplication as most of the time it's off.
    I think some people don't understand how hot tubs work (no offence intended to anyone).
    You don't just switch them on when you use them - they are on ALL the time but heating goes on and off like it does in a centrally heated room.

    Obviously if you use it a lot then it will require more heat (because whe you're in it and the lids off then the water cools faster) but in my experience (had one for 2 years) this doesn't make a great deal of difference.

    I think there is a case here, but if free legal advice if available via a free helpline (on house ins or possibly car insurance) then this should be the first port of call as we are not lawyers.
    I have a car insurance policy once (with a company called DAS) where the legal advice covered ANY matter not jsut motoring.
    Get checking those plicies for free professional advice.
  • f1owers
    • #9
    • 27th Feb 06, 5:12 PM
    • #9
    • 27th Feb 06, 5:12 PM
    Hi and many thanks for the replies I have received.

    Apart from still taking regular meter readings, we have had lengthy discussions with a family friend who works for one of the large firms of credit cards, and who has advised on where to go and how we are coverered re Sale of Goods Act, mis-selling, misrepresentation, goods not as described

    Running costs today are slightly down - 34 units for 24hrs use instead of 40 units (that is for the whole house!). Perhaps the new layer of insulation needed to get up to temperature to be effective?? Only time will tell. I have also had tips about setting the temperature slightly lower and then upping it prior to use.

    Ideally I want our running costs down to a maximum of £20 per month during the winter. Should we have no joy with the company concerned, we shall go down the legal road, return the tub, and shop around for another one.

    Again, many thanks!

    • jennifernil
    • By jennifernil 27th Feb 06, 6:14 PM
    • 5,105 Posts
    • 2,131 Thanks
    If you are using 34 units for the whole house that is £2.55 per day at the price we pay today. Remember electricity costs have risen a lot lately so you need to compare units not price with what you used before you got the tub.
    If you use £2.55 every day that is about £930 per annum.
    We have 2 heated greenhouses , run 3 fridges and 3 freezers, ( we have a "granny flat") and use the tumble drier a lot. We spend over £1050 per annum on electricity. If you want to run a lot of stuff you must expect it to cost a bit.
    • totalguitar
    • By totalguitar 1st Mar 06, 4:06 PM
    • 159 Posts
    • 28 Thanks
    Spa Bath

    This one on Ebay claims £6pm running costs if kept at a constant temp. How does yours compare in specification ?
    • gromituk
    • By gromituk 1st Mar 06, 5:54 PM
    • 3,031 Posts
    • 540 Thanks
    Erm, you do have the lid on all the time it's not in use, don't you?

    As others have said, the rating in kW has rather little to do with the ENERGY consumption (in units) as opposed to the POWER consumption (how fast the meter spins) when the element is on, because the element is controlled by a thermostat. The bigger the element, the less time it will have to be on to maintain a certain temperature. What matters is the insulation - how fast the heat escapes. So adding an extra layer was a good thing to do.

    The hotter the water is above ambient temperature, the more rapidly heat will escape - in direct proportion. So, if the outside temp. is 10 degrees and the water is at 20 degrees, the difference is 10 degrees, a certain amount of heat will escape, and it will cost a certain amount to run. If the water is at 30 degrees, the difference is 20 degrees, and it will cost twice as much to run. If the water is at 20 degrees and the night time temp drops to 0, it will again cost twice as much to run.

    So, to save money, keep the temperature down - the same happens with central heating systems (it is a myth that it takes less energy to keep the house warm all the time because the heating doesn't have to work so hard to heat it up if you do). But of course, the disadvantage is that you need to anticipate using the hot tub to heat it up first.

    Water has a calorific value of 4200J/kgK. What this means is that you need 4200 joules of energy to heat each kg (i.e. litre) of water by one degree celcius. 4200J is almost exactly what your 4.7kW element gives off every second, so, if you had 1l of water in the tub, it would heat up by a degree a second. If you have 1000l in the tub, it will take 1000 seconds (about 15 minutes) to heat up by 1 degree. The time it takes to warm up, in seconds, is approx. the temperature difference multiplied by the number of litres in the tub.

    Notice I am making approximate calculations here, because there are other factors involved. The water will take longer to heat up in practice because of the heat constantly being lost through the insulation of the tub. You will lose a large amount more with the lid off, because the water will evaporate much more rapidly, and it takes a lot of energy to evaporate water. If you are blowing air through it, you are causing more evaporation by agitation, and cooling it down with the air, so your costs rocket again. Environmental nightmare.

    For something as energy hungry as this, heating from a condensing gas boiler would be a much better idea. Not only would you be able to heat up more rapidly when required (20kW or more) thereby allowing you to save energy by keeping the water cooler the rest of the time, but gas is about 1/4 of the price per unit, and the conversion to hot water would be very efficient (as the boiler would always be in condensing mode).

    It might be a good idea to see if your meter is calibrated properly. If the element is running for an hour, little else is on in the house, and the meter goes up by more than 5 units, suspect it. (By the way, units are in kWh [kilowatt-hours], not kilowatts per hour - it is a multiplication, not a division.)
    Time is an illusion - lunch time doubly so.
    • gromituk
    • By gromituk 1st Mar 06, 6:07 PM
    • 3,031 Posts
    • 540 Thanks
    Spa Bath

    This one on Ebay claims £6pm running costs if kept at a constant temp. How does yours compare in specification ?
    by totalguitar
    Ugh - legalised lying. It goes on about how the water pump only consumes less than 100W, but fails to mention that the 1hp air pump is 700W and doesn't even mention the power of the heating element, which dwarfs both of these!

    But we can calculate it, from "425 gallon-degrees per hour". Assuming this is UK gallons, and degrees Farenheit, that is approx. equivalent to 425x4.5/(2*3600) = 0.26 degrees C per litre (kg) per second. Multiplying this by the calorific value of water gives you about a 1.1kW element - pretty tiny. It couldn't be more than 2kW anyway, or it couldn't plug into a 13A socket (when pump and blower are taken into account) so could no longer be described as portable. That's going to take you more than four times longer to heat up the water than with the built-in spa, assuming the same amount of water.
    Time is an illusion - lunch time doubly so.
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