Hi,

I've seen a number of 3kw pool heaters on ebay for about =A390. They're
for use in large paddling pools up to 15ft in diameter. e.g.:
http://cgi.ebay.co.uk/ws/eBayISAPI.d...&item=3D439 =
2981615&rd=3D1

My pool is a Bestway Fast Set 10ft circular pool with external pump and
filter, and the water height is approx 2ft.

So I'm wondering if anyone here has had experience of these heaters in
this type of pool, and whether its really going to heat a 10ft x 2ft
circular pool.

I've got a pool cover too, for what it's worth.

Boz

wrote:

I've seen a number of 3kw pool heaters on ebay for about £90. They're
for use in large paddling pools up to 15ft in diameter. e.g.:
http://cgi.ebay.co.uk/ws/eBayISAPI.d...2981 615&rd=1

My pool is a Bestway Fast Set 10ft circular pool with external pump and
filter, and the water height is approx 2ft.

So I'm wondering if anyone here has had experience of these heaters in
this type of pool, and whether its really going to heat a 10ft x 2ft
circular pool.

I've got a pool cover too, for what it's worth.


No experience necessary, just basic physics.

Your pool contains ~ 5m^3 of water, or 5000 litres. This has a mass of
5000kg.

A 3kW heater provides 3000J/s.

The specific heat capacity of water is about 4200 J/(kg.K)

So to raise the temperature of your 5000kg by 1 Celcius we need 21MJ.
Your 3kW heater would take just under 2 hours to deliver this. So if
you're aiming for a 5 Celcius rise, it'd take just under 10 hours.

And this is before you factor in conductive and evaporative losses.


--
Grunff

In article ,
Grunff writes:
No experience necessary, just basic physics.

Your pool contains ~ 5m^3 of water, or 5000 litres. This has a mass of
5000kg.

A 3kW heater provides 3000J/s.

The specific heat capacity of water is about 4200 J/(kg.K)

So to raise the temperature of your 5000kg by 1 Celcius we need 21MJ.
Your 3kW heater would take just under 2 hours to deliver this. So if
you're aiming for a 5 Celcius rise, it'd take just under 10 hours.

And this is before you factor in conductive and evaporative losses.

Not that I really approve of dumping large amounts of heat
outdoors, but this would be an ideal task for condensing boiler
with an extra zone, transfering the heat through a plate exchanger.
The temperatures involved will mean the condensing boiler will be
operating at peak efficiency (higher even than its published figures
for central heating use).

Cost wise, you should compare to running it overnight on cheap rate
electricity -- there may not be a lot in it. However, the electricity
option is nowhere near as environmentally clean, as electricity
generation efficiency is nowhere near as high as even the most
inefficient old gas boiler.

The other thing would be to ensure you have a very good pool cover
with regards to low thermal losses.

--
Andrew Gabriel

On 09 Jul 2005 12:30:17 GMT, Andrew Gabriel wrote:

Not that I really approve of dumping large amounts of heat
outdoors,

Neither do I. Maybe an option if the OP has the space is a small pump
(perhaps a solar powered) and lots of black hose pipe. On a day like
today there will be a considerable temperature rise in the water
flowing through the hose.

ISTR last year someone building a pool heating system using this
technique and been very happy with the results. Google?

--
Cheers
Dave. pam is missing e-mail

Dave Liquorice wrote:
On 09 Jul 2005 12:30:17 GMT, Andrew Gabriel wrote:

Not that I really approve of dumping large amounts of heat
outdoors,

Neither do I. Maybe an option if the OP has the space is a small pump
(perhaps a solar powered) and lots of black hose pipe. On a day like
today there will be a considerable temperature rise in the water
flowing through the hose.

ISTR last year someone building a pool heating system using this
technique and been very happy with the results. Google?


The OP could spend =A390 on an electric heater element (!), then pay to
run it every day, and not get much rise anyway.

Or the OP could buy =A390 worth of hosepipe, polythene & pump, and get
10kW with 1/10th the run cost of the 3kW heater.

Not a tough choice. Cheap pool solar heating is very easy to make btw,
probably easier than installing electric into the water.


NT

On 9 Jul 2005 03:46:00 -0700, wrote:


So I'm wondering if anyone here has had experience of these heaters in
this type of pool, and whether its really going to heat a 10ft x 2ft
circular pool.

Given enough time it will warm it up a bit, I know someone who ran
one continuously on a larger pool for several months last year with
the thermostat set to 28deg. The major heating came at the end of
the season when they got their electricity bill. The heater isn't on
this year.

Also bear in mind that it isn't something you can just plug into an
extension lead and forget. Electrical installations near pools are,
quite sensibly, governed by quite strict installation rules as the
risk of accident is high. Electricity and water don't mix.

--
Peter Parry.
http://www.wpp.ltd.uk/

wrote:
Dave Liquorice wrote:
On 09 Jul 2005 12:30:17 GMT, Andrew Gabriel wrote:

Not that I really approve of dumping large amounts of heat
outdoors,

Neither do I. Maybe an option if the OP has the space is a small pump
(perhaps a solar powered) and lots of black hose pipe. On a day like
today there will be a considerable temperature rise in the water
flowing through the hose.
snip
Or the OP could buy ?90 worth of hosepipe, polythene & pump, and get
10kW with 1/10th the run cost of the 3kW heater.

Not a tough choice. Cheap pool solar heating is very easy to make btw,
probably easier than installing electric into the water.


Details?
10m^2 collector area, how does it work?
Polythene over hosepipe?

Ian Stirling wrote:
wrote:

Or the OP could buy ?90 worth of hosepipe, polythene & pump, and get
10kW with 1/10th the run cost of the 3kW heater.

Not a tough choice. Cheap pool solar heating is very easy to make btw,
probably easier than installing electric into the water.

Details?
10m^2 collector area, how does it work?
Polythene over hosepipe?


ok... firstly I would not use an open roof surface for collection, as
a) it will also collect bird**** and other assorted bacteria
b) it will leak water onto the roof structure underneath the covering
and rot it.

Buy a =A350 pump, checking it can run continuously and has a type of
motor that can be slowed down eaily.

Spend the rest of the money on hosepipe, the more the better. Avoid
orange, white or light grey. Wind it in a huge flat spiral pancake.
You'll get a lot more heat if you space each turn out by one pipe
width, but that requires wire or similar to hold it togther/apart. Aim
for 10 square metres or more.

Cover the pipe with polythene, add the pump on an RCD, and run it at
lowest speed setting.

You now have a fairly efficient low cost 10kW heater.


NT

Ok, many ideas given so far, and I've thought about the cost and
environmental aspect and decided not to go for an electric heater.

The pool cover I have is bright blue polythene and gets very hot in the
sun.

Would it be best to pull the cover taught over the pool so that it does
not touch the surface (i.e. a 6 inch gap between water and cover), or
let the cover sag so that it touches the water?

Or, is it better to let sunlight penetrate the water direct and remove
the cover during the sunshine?

I A-level physics, and we never covered swimming pool thermodynamics
;-) I got an E anyway, so even if we did I'd probably get it wrong !

Boz

On 10 Jul 2005 04:42:42 -0700, wrote:

The pool cover I have is bright blue polythene and gets very hot in
the sun.

Would it be best to pull the cover taught over the pool so that it
does not touch the surface (i.e. a 6 inch gap between water and
cover), or let the cover sag so that it touches the water?

Is the cover just a sheet of polythene or does it have any insulation
properties?

If it's just sheet I'd let it sag onto the water during the day so
that you transfer as much heat as possible into the water but lift it
clear at night so you get the insulation of a layer of air.

--
Cheers
Dave. pam is missing e-mail

wrote:
Ian Stirling wrote:
wrote:

Or the OP could buy ?90 worth of hosepipe, polythene & pump, and get
10kW with 1/10th the run cost of the 3kW heater.

Not a tough choice. Cheap pool solar heating is very easy to make btw,
probably easier than installing electric into the water.

Details?
10m^2 collector area, how does it work?
Polythene over hosepipe?


ok... firstly I would not use an open roof surface for collection, as
a) it will also collect bird**** and other assorted bacteria
b) it will leak water onto the roof structure underneath the covering
and rot it.

Buy a ?50 pump, checking it can run continuously and has a type of
motor that can be slowed down eaily.

Spend the rest of the money on hosepipe, the more the better. Avoid
orange, white or light grey. Wind it in a huge flat spiral pancake.
You'll get a lot more heat if you space each turn out by one pipe
width, but that requires wire or similar to hold it togther/apart. Aim
for 10 square metres or more.

Cover the pipe with polythene, add the pump on an RCD, and run it at
lowest speed setting.

You now have a fairly efficient low cost 10kW heater.


Hmm.
10m^2/4cm = 250m.
Best price for 30m I can find seems to be about 12 quid.
Call it a hundred quids worth of hose.
Without the space, it's more like 250 quid.
I've wondered in the past about twinwall sheet.
If only there was a nice leak-proof way to seal hose to the ends, it'd be
ideal.
One sheet of clear twinwall on top of one sheet of black.

Ian Stirling wrote:
wrote:
Ian Stirling wrote:
wrote:

Or the OP could buy ?90 worth of hosepipe, polythene & pump, and get
10kW with 1/10th the run cost of the 3kW heater.

Not a tough choice. Cheap pool solar heating is very easy to make btw,
probably easier than installing electric into the water.

Details?
10m^2 collector area, how does it work?
Polythene over hosepipe?


ok... firstly I would not use an open roof surface for collection, as
a) it will also collect bird**** and other assorted bacteria
b) it will leak water onto the roof structure underneath the covering
and rot it.

Buy a ?50 pump, checking it can run continuously and has a type of
motor that can be slowed down eaily.

Spend the rest of the money on hosepipe, the more the better. Avoid
orange, white or light grey. Wind it in a huge flat spiral pancake.
You'll get a lot more heat if you space each turn out by one pipe
width, but that requires wire or similar to hold it togther/apart. Aim
for 10 square metres or more.

Cover the pipe with polythene, add the pump on an RCD, and run it at
lowest speed setting.

You now have a fairly efficient low cost 10kW heater.


Hmm.
10m^2/4cm = 250m.
Best price for 30m I can find seems to be about 12 quid.
Call it a hundred quids worth of hose.
Without the space, it's more like 250 quid.
I've wondered in the past about twinwall sheet.
If only there was a nice leak-proof way to seal hose to the ends, it'd be
ideal.
One sheet of clear twinwall on top of one sheet of black.


The design I gave last night is not in fact the design I would use.
There are many improvements that would, erm, improve it, including cut
cost. I was just too tired to go over em all then.

1. The main one that cuts cost is to use reflective plastic to reflect
more sun onto the collector, enabling a smaller collector to be used.
This can halve the amount of hose needed.

2. connect several pipe runs in parallel, now much less pumping power
is needed.

3. As well as using a hose collector, dont forget the cheaper option of
a reflective mylar sheet on a frame to shine sun direct into the pool.

4. Its quite possible to space the pipes out further, this improves
cost per kW at the expense of more space. More spaced out pipe panels
are more efficient financially, and less efficient thermally.


NT

In article . com,
writes
Ok, many ideas given so far, and I've thought about the cost and
environmental aspect and decided not to go for an electric heater.

The pool cover I have is bright blue polythene and gets very hot in the
sun.

Would it be best to pull the cover taught over the pool so that it does
not touch the surface (i.e. a 6 inch gap between water and cover), or
let the cover sag so that it touches the water?

Or, is it better to let sunlight penetrate the water direct and remove
the cover during the sunshine?

I A-level physics, and we never covered swimming pool thermodynamics
;-) I got an E anyway, so even if we did I'd probably get it wrong !

Boz

I have the 15' version and am looking at the same issue, you can get
solar covers for these pools which heat the pool and insulate (its
coated bubble wrap by the look of it) BUT this isn't enough to get the
water up to a usable temp for the wife but every little helps. I am
working on a solution using the central heating perhaps an extra
cylinder with the pool water circulated through it or what about turning
the whole pool into a giant open cylinder by having a coil of hep2o
running around the bottom :-) I will probably end up with a solar
solution using black sheets under perspex with water running down them

--
David

On 10 Jul 2005 04:42:42 -0700, wrote:

Ok, many ideas given so far, and I've thought about the cost and
environmental aspect and decided not to go for an electric heater.

The pool cover I have is bright blue polythene and gets very hot in the
sun.

Would it be best to pull the cover taught over the pool so that it does
not touch the surface (i.e. a 6 inch gap between water and cover), or
let the cover sag so that it touches the water?

Or, is it better to let sunlight penetrate the water direct and remove
the cover during the sunshine?

I A-level physics, and we never covered swimming pool thermodynamics
;-) I got an E anyway, so even if we did I'd probably get it wrong !

Hi,

Look for a solar pool cover:

http://www.google.co.uk/search?hl=en&c2coff=1&q=solar+pool+cover&btnG=Sear ch&meta=cr%3DcountryUK%7CcountryGB

Something else that could help is to have a shower, gradually turning
the water cooler before getting in the pool to acclimatise yourself.

cheers,
Pete.

Heh, I have exactly the same issue as you regarding the wife.

Anyway, the ideas seem to be getting too far fetched for me, the
average Jo at home, simply wanting to put the pool up for the kids over
summer. Solar heating sounds the best, but of course that only works
now the weather's perked up. For the last week I've had a pool staying
cold in the grey weather!!

Actually, I might dig up the garden and install under-garden heating
using a coal-fuelled furnace pumping hot air round sub-terranean
chambers. Them Romans wrote the book on environmental heating
solutions, surely...

Boz

On 11 Jul 2005 01:22:01 -0700, wrote:

For the last week I've had a pool staying cold in the grey weather!!

Is that with solar heating? Even on dull overcast days at this time
of year you should be able to get several hundred watts per square
metre. Brillant bright sunshine like today and you'll be over a kW/m^2

Actually, I might dig up the garden and install under-garden heating
using a coal-fuelled furnace pumping hot air round sub-terranean
chambers. Them Romans wrote the book on environmental heating
solutions, surely...

Be better to burn wood, carbon neutral.

--
Cheers
Dave. pam is missing e-mail

In article .com,
writes
Heh, I have exactly the same issue as you regarding the wife.

Anyway, the ideas seem to be getting too far fetched for me, the
average Jo at home, simply wanting to put the pool up for the kids over
summer. Solar heating sounds the best, but of course that only works
now the weather's perked up. For the last week I've had a pool staying
cold in the grey weather!!

Actually, I might dig up the garden and install under-garden heating
using a coal-fuelled furnace pumping hot air round sub-terranean
chambers. Them Romans wrote the book on environmental heating
solutions, surely...

Boz

Another idea... a bank of radiators painted black with water circulating
through them, not very pleasing on the eye though, for full efficiency
they would need to track the sun across the sky on a revolving mount.
--
David

Actually, I might dig up the garden and install under-garden heating
using a coal-fuelled furnace pumping hot air round sub-terranean
chambers. Them Romans wrote the book on environmental heating
solutions, surely...

Be better to burn wood, carbon neutral.

If I burned all my household rubbish instead of recycling it, that
would be even better wouldn't it It'd save the faff of putting out the
boxes every fortnight *and* heat my pool. Brilliant. Just need a tall
chimney to get those smelly fumes away from my property.

Think it'll catch on?

Boz

David wrote:

I am working on a solution using the central heating perhaps an extra
cylinder with the pool water circulated through it.

I have seen this done, on an in ground pool. The central heating pump
was diverted to feed hot water to a heat exchanger. Worked quite well,
but obviously the running costs were significant.

Regards
Capitol

On 11 Jul 2005 09:07:59 -0700, wrote:

Be better to burn wood, carbon neutral.

If I burned all my household rubbish instead of recycling it, that
would be even better wouldn't it

Unlikely as most of your flammable waste is probably plastic, derived
from oil, thus fossil carbon.

--
Cheers
Dave. pam is missing e-mail