The Insulation
and Heating of Swimming Pools
The insulation
of a Swimming Pool
Ground Temperatures
The average ground
temperature anywhere in SW France lies normally between 10
and 15 degrees C depending on the time of year. Swimming pool
water temperature lies normally between 24 and 28 degrees
Centigrade - although some people prefer 30 degrees!
This results in
a temperature difference of about 15 degrees C. This is a
large temperature differential that will result in the loss
of substantial volumes of heat.
Heat Loss
from a Swimming Pool
Swimming pool heat
is lost from the water surface, walls and floor.
Heat loss is at
a maximimum when the pool is in use and the summer cover has
been removed. Most of this occurs because of the large amount
of heat energy that is taken out of the swimming pool water
when evaporation occurs from the pools surface.
The evaporation
rate is dependent on the pool’s initial temperature,
the surrounding air temperature and humidity, and the wind
speed at the pool surface. The higher the pool temperature
and wind speed and the lower the humidity, the greater the
evaporation rate. Though a windbreak— such as trees,
shrubs, or a fence—can reduce evaporation, it may shade
the pool from the sun, which is a strong natural heat source
for the pool.
But if the pool
is only used for 4 hours a day for 5 days a week on average
then this major heat loss from the pool surface will only
occur for about 12% of the time. If the pool is covered with
a solar cover then most of the heat loss then occurs through
the walls and floor of a conventional swimming pool.
Factors that
affect the Heat Loss
Heat lost through
the walls and floor is continuous and is dissipated into the
surrounding soil and is dependent on three basic factors:
- Area of the swimming pool
walls and floor
- Difference in temperature
between the soil and the swimming pool water
- The heat conducting properties
of the wall and floor construction.
The first factor
is fixed by the pool size and depth.
The second factor
can be affected by the heating of the pool water to increase
its temperature, by the presence of water in the surrounding
soil and by any water flow around the pool that can continually
remove heat from it.
The third factor
depends on the materials from which the pool is built.
If the water table
is high and the swimming pool construction materials can become
saturated this will cause a reduction in the thermal efficiency
and an increase in the heat lost.
How to reduce
Heat loss
Heat loss can
be reduced by well over 90% if the external surface of the
pool that is in contact with the soil is polystyrene. This
is because polystyrene consists essentially of miilions of
air bubbles encapsulated by a thin layer of hydocarbons. The
swimming pool water is then effectively encapsulated in a
“thermos flask”, which dramatically reduces heat
extraction into the ground.
Covering a pool
in-between periods of use is the single most effective means
of reducing pool heating costs. As much as 70% of heat loss
from a swimming pool is caused by evaporation. A pool cover
acts as a vapor barrier that dramatically cuts heat losses
from evaporation, resulting in significantly higher pool water
temperatures. A high performance solar cover can reduce the
water loss by evaporation by as much as 95%.
If there is static
water under the floor then convection comes in to play and
the water retains the heat like an insulator. If the water
is flowing however, then heat is extracted at an alarming
rate and insulation is a must. We can provide permanent pumped
drainage for your pool if we find that ground water will flow
around your pool when we are building it. Even if you do not
heat the pool this will increase the normal water temperature
quite significantly for a few centimes a day.
The Insulation
Benefits of a Bluepool
Our swimming pools
and swimming pool kits are all based on the use of hollow
polystyrene blocks for the construction of the pool walls.
These provide 100mm of dense 30kg / m2 polystyrene in the
walls and around the Roman Steps that reduces heat loss by
over 95%.
We can provide
a 50 mm or 100 mm thickness of similar polystyrene on the
floor of the swimming pool beneath the screed. The approximate
costs are shown in the following table. These may vary because
the cost of buying polystyrene fluctuates a lot because of
the direct connection with the cost of crude oil;
|
Pool
Size
|
50
mm without hopper (HT)
|
50
mm with hopper (HT)
|
100mm
without hopper (HT)
|
100mm
with hopper (HT)
|
|
8
x 4
|
825
|
875
|
1450
|
1585
|
|
10
x 5
|
1245
|
1375
|
2250
|
2475
|
|
12
x 6
|
1795
|
1975
|
3240
|
3565
|
If the pool floor
insulation is combined with a modern high performance solar
cover that combines a heat absorbing top surface and a heat
reflecting bottom surface the whole pool becomes in effect
a giant solar heater that should be comfortable to swim in
for nearly all the swimming season -
without
the need for any other form of heating!
What are the different types
of summer pool covers
Pool covers are designed using
UV-stabilized polyethylene, polypropylene, or vinyl to resist
deterioration. A cover lasts several years.
Solar covers are reminiscent
of bubble packing material, but using a thicker grade of plastic
with UV inhibitors. If you want to turn your pool into a giant
solar heater this is the type we recommend.
Vinyl covers consist of a heavier
material and have a longer life expectancy than bubble covers.
Insulated vinyl covers are also available with a thin layer
of flexible insulation sandwiched between two layers of vinyl.
Solar Swimming
Pool Covers
Solar covers heat a swimming
pool by converting the sun's light into heat like thousands
of tiny greenhouses, instead of reflecting it as water normally
does. This heat energy is efficiently conducted into the pool
water by the increased area of the covers underneath surface.
Tests have shown that 6 degrees of free heat can be gained
and the swimming season extended by a number of weeks!
In addition to significant energy
savings, solar pool covers do the following:
- Conserve water by reducing
the amount of make-up water needed by 30%–50%
- Reduce the pool's chemical
consumption by 35%–60%
- Reduce cleaning time by keeping
dirt and other debris out of the pool
The high heat absorption covers
look this;
The aluminium surface
that projects down into the water maximises the contact area
available to transmit the heat from the sun into the water
and the aluminium colour reflects the light and heat coming
up from the pool water back down into it.
Heating of
a new or existing pool
Is it possible
to add heating to an existing pool?
If you have a pool
without heating and would like to extend your pool swimming
season by 2 to 3 months each year then it is probably quite
easy to add a pool heating system.
The pool heating
options
Options Available
The options for pool heating
include solar, heat exchanger using an existing oil or gas
boiler, direct electric heating, heat pump using the ambient
air as a heat sink, heat pump using the ground as a heat sink
and finally a heat pump using ground water as a heat sink.
Selection
Criteria
In our opinion the criteria
that are most important in terms of assessing the relative
merit of pool heating systems are the following with the most
important ones first:-
- Reliability - It is no good
having a pool where the temperature varies wildly from week
to week - you just end up not using it
- Running cost - If the heating
is going to increase your energy bill by several hundred
per cent - you will end up turning it off
- Maintenance cost - This goes
hand in hand with reliability - if the heating system is
always leaking water you will end turning it off
- Capital cost
Solar
Solar is very unreliable and
if the system quality is not absolutely first class it can
soon become very costly and irksome to maintain. After a few
years of frost even the best system will start to leak - and
emptying the system in winter does not really help because
there will always be back-falling areas in the pipework that
you cannot drain down. If you want to take advantage of solar
power it is better to insulate the pool walls and floor and
install a high performance energy absorbing summer cover all
as described above.
Heat exchangers
and direct electric heaters
Heat exchangers
and direct electric heaters will only cost about 30% of the
cost of a heat pump but can use 10 x as much electricity or
fuel costs. They are very reliable and cheap to maintain but
can cost as much as 12 - 15 euros per day to run.
Heat pumps
using the air as a heat sink
Heat pumps of this type will
use about a euro a day in power - depending on pool size and
water temperature. They are very reliable and should last
at least 5 - 7 years before requiring renewal and all the
parts are replaceable.
Other types
of heat pump
Other types of heat pump will
be economical to run but much more expensive to install and
so we are not considering them further at this point in time
Heat Pumps
Costs
A heat pump will cost somewhere
in the 5 to 8,000 euros range depending on pool size and you
should recoup the capital cost in terms of reduced energy
bills compared with gas, oil or electric heating after 2 -
3 years.
So in our opinion if you are
going to heat your pool - install a heat pump using air as
the heat sink. If you cannot afford it you cannot really afford
to heat your pool so it is probably best left until you can
afford one.
If you want us to see if it
is possible to install a heat pump to heat your pool just
fill in the contact form at the top of the page and type heating
in the last box and then click on "Please contact me"
Heat Pump
Details
Bluepools installs Gamme Eden
Pac heat pumps with the characteristics shown in the following
table.We use Gamme because they are very quiet at a noise
level of 65.5 dBa.
They look like this and are
about 600 mm high by 700 wide and 300 mm deep
Single phase
heat pumps
|
Model
|
Power
output (kW)
|
Power
used (kW)
|
Max.
pool volume (m3)
|
Pool
size
|
Price
(HT) euros
|
|
EDEN11
|
8.5
|
1.8
|
0 to
55
|
8 x
4
|
4351
|
|
EDEN21
|
10
|
2.04
|
45
to 70
|
10
x 5
|
5459
|
|
EDEN31
|
12
|
2.42
|
60
to 85
|
12
x 6
|
5689
|
|
EDEN41
|
15
|
3.15
|
75
to 110
|
>12
x 6
|
6266
|
Three phase
heat pumps
|
Model
|
Power
output (kW)
|
Power
used (kW)
|
Max.
pool volume (m3)
|
Pool
size
|
Price
(HT) euros
|
|
EDEN33
|
12
|
2.42
|
60
to 85
|
12
x 6
|
5920
|
|
EDEN53
|
16
|
3.22
|
75
to 110
|
>12
x 6
|
6554
|
|
EDEN63
|
21
|
4.02
|
90
to 150
|
>12
x 6
|
8130
|
Installation
Charges
Our installation charges are
as shown in the following table. We only provide a temporary
power connection to commission the heat pump.
You will need to get your own
electrician to provide the permanent power connection. If
the power connection is installed before we arrive to fit
the heat pump we will use the permanent power supply. We will
provide the specification for the electrical connection with
our invoice for the supply of the heat pump.
The installation charges are
shown in the following table:-
|
Basic
charge
|
Distance
from Jonzac
|
Total
Charge (euros HT)
|
|
500
|
0 to
100 kms
|
650
|
|
500
|
100
to 200 kms
|
725
|
|
500
|
200
to 300 kms
|
875
|
|
500
|
>
250 kms
|
500
+ 1.25 euros per km
|
If you would
like a quotation for a heat pump please fill in the Contact
Form at the head of the page - just type HEAT in the box for
pool size - thank you
|
