Wanted : Mathematician or Heating Engineer

The time has finally arrived to get out the Toad family paddling pool.
It's a bit of a whopper - 15' diameter and holds just over 12,000 litres of water when full - that's about 12 tonnes



All well and good on Sunday, but now I'm getting complaints from the junior toads that the water is too cold. I've tried getting them to wear 3/4 length wetsuits, but they're not impressed.

So I've looked at water heaters on eBay, and have seen several at either 3kw or 5kw.

The 5 sounds like it would make a better job, but i guess I'd have trouble powering it as it draws 23amps . . .

Would a 3kw heater have any effect on a pool that size ?

There must be some equation somewhere that would give the answer, eg. given a power input of x, initial temp of y, heat loss to the air/ground, etc.

Would the water get noticably any warmer, or would the only effect be to increase my electricity bill

Anyone have any ideas (sensible ones please )

cheers

S

It doesn't matter what power water heater you go for, it will still need the same amount of energy to heat the same amount of water - it will just heat it quicker....

To heat 12,000 litre of water by 1 degreee C will require a phenominal amount of electricity....
Have you thought about a solar water heater with a circulation pump? Something as simple as a radiator painted black with a solar PV fountain pump? Free electricity, and you can leave it running all day......
Just make sure that your inlet hose is not near you outlet hose in the pool....


Could go for the placaebo effect

extra few rashes of bacon at breakfast ought to do it

[SoulKiss]

Does it come with a cover?

Just let the Sun warm the water during the day and make sure you cover it at night to reduce amount of heat lost to the sky

Full solar solution

And tell the kids not to be wimps :P

[the_lone_wolf]

E = mC(delta T)

mass = 12000kg

C = specific heat capacity of water = 4200 (insert units here)

therefore for each degree you wish to heat the water by it will require 50400000 (12000 x 4200) Joules of energy - around 50 Megajoules

a watt is one joule per second, so to heat the pool by one degree with a 5kW heater would take 50,000,000 / 5000 = 10,000 seconds or 2.8 hours

that's assuming no loss of heat from the pool while you do it


tell them to get the wetsuits on...

bloody kids today dont know there born, when i was a lad................

Eeep! So that's where all the water went You could send them down our way for a paddle, just need to avoid anything brown and floating

Ok, random result off interweb:
"As 1 litre of water needs about 1.16 watts to raise it through 1°C in an hour, a 120 litre tank of cold mains water needs a total energy input of about 7800 watts-hours (120*1.16*56) to raise its temperature to the required level. With a 3 hour design reheat time, this means a power input of about 2600 watts."

Sooo.... using the same formula:
12,0000*1.16*20 (raising 20 degrees) = 278,400 watts to do the whole lot in one hour?!? So a 3kw heater would do it in.... about 93 hours....

Hmmm, that's 20 degrees though, may not need to be so much warmer, as it's unlikely to be coming out at 4 degrees to begin with, presumably closer to ten or so. Play around with the formula

Hope you're not on a water meter

heres a thought....

if you have a combi boiler fill it with some hot water.... cheaper than buying a pump etc etc ..

or if no combi boiler, fill the bath with hot water, coil the hose up in it the hot bath water symphen the water through the hose back into the pool,might require a smalll drill pump but it will work like a ground source heat pump..

ta da...

or go swimming...

Hmm, the bath idea is interesting. Just done some ropey maths.

Assumptions: You currently have 12000 litres of pool water at 10 degrees C.
Your bath is a very big 200 litre job.
Hot tap water is at 50 degrees C (I think the limit is 60 degrees, but call it 50 for cool down).

Empty a full 200 litre bath full of piping 50 degree water into your 12,000 litre 10 degree pool. You now have a 12200 litre pool at (if my maths is correct) 10.656 degrees.

I was swimming in the sea at 7.15am this morning, as I was yesterday and the day before and I bet the pool is comparatively quite warm already.