Help costing running of Lazy Spa hot tub with energy company

seaneylad

Good Morning

I am looking at a Lazy Spa Hawaii model

It says it uses 2050W (2.05kw) per hour and my energy company cost is Price £/kWh £0.120000 so approx. 0.24p for 2kw per hour.

Say approx. 30 days in a month which is 720 hours so 720 x .24p is £172.80 ... surely that cant be right?

Most websites states approx. £10 per week, and some people saying only a few pound change on their normal bill?

Is it because it doesn't use 2kw per hour all the time or?

Thanks all

spiro

Think of a pot of cold water on a gas cooker. To bring it to the boil you need the gas on high, once it's boiling you can turn the gas down and it will keep boiling. Same applies to the amount of elec you need to heat up and then maintain the heat in a hot tub. Obviously external influences will vary the amount of elec used, like it being outside and the weather turns cold.

Flt._Lt._Biggles

seaneylad wrote: »

Good Morning

I am looking at a Lazy Spa Hawaii model

It says it uses 2050W (2.05kw) per hour and my energy company cost is Price £/kWh £0.120000 so approx. 0.24p for 2kw per hour.

Say approx. 30 days in a month which is 720 hours so 720 x .24p is £172.80 ... surely that cant be right?

Most websites states approx. £10 per week, and some people saying only a few pound change on their normal bill?

Is it because it doesn't use 2kw per hour all the time or?

Thanks all

Think of an electric kettle - that has a 2kW heater in it. What happens to the water in that? What happens to the kettle then?

But a hot tub is obviously a lot bigger than your average kettle.

So think of an immersion heater. They are usually 3kW rated. But they act just like a kettle too. The tank is a lot bigger than a kettle, but a lot smaller than a hot tub. Can you think what stops the water from boiling with a correctly adjusted immersion heater?

I think most websites are correct - a hot tub will cost you about £500-£600 per year to run (if you want it running all year)
Not sure why some people tell you it's only a few pounds on their bill :huh:
£500-£600 would be about a 50% increase in the average home energy bill :eek:

Cardew

Surely nobody leaves a spa on 24/7 for a whole month??


Running costs will obviously depend on set temperature for water, & ambient temperature.



It is unlikely use all power 24/7 as the thermostat will cut in. However it is a large amount of water - equiv to aroun. 300 full kettles - and the spec states it will take 6 to 12 hours to heat to 40C on a typical 20C summer day.



Such an appliance would seem ideal for properties with solar PV on the roof and a device to divert excess generated power to the spa; or heat overnight on an Economy 7 tariff.

seaneylad

Thanks for quick replies

Yeah does seem a big jump in prices for energy bills, will have work a few more weekends lol!

I will probably only use it in 4 months of the year / summer so hoping £300/400 for them months maybe.. only one way to find out.

I just don't trust the people selling them ... its like mpg on a car in the sales pitch lol

Flt._Lt._Biggles

How much heat (i.e. electricity) you need to use will depend on how much heat is wasted.

You'll find hot tubs have a lid to help keep the heat from escaping when not in use (as well as to keep the muck out of the water), but then you cannot use the hot tub with the lid on. All that steam you often see escaping from a hot tub on a cold evening's use? Think of that as £1 notes floating away...

matelodave

The sums aren't really all that difficult, you just need to know how much water is in there and you can work out how much energy it will need to heat it from cold and then to maintain it's temperature

seaneylad

840L


average 700-900 per most of them

working out the maintaining cost isn't easy as it doesn't state anywhere

matelodave

850 litres raised to 35 degrees (25 degrees increase) from 10 degrees will take around 12 hours with a 2kw element = 24kwh. If you have it hotter then it'll take longer and cost more likewise it will cost less to keep it cooler.

If you assume that it will lose approx 10 degrees a day then you'll need another 10kwh a day to maintain it although the heat loss will depend on how often it's used and the outside temperature - you'll lose a lot more heat at night than you will during a hot summers day.

so 24 x £0.12 = £2.88 to get it hot and then another £1.20 a day to maintain the temperature.

You'll have to decide whether its better to keep it on all the time or just heat it when you want to use it, bearing in mind that it'll take the bset part of 12 hours to get it warm