Pools and spas
Pool and spa heating
An electric heater for a spa or pool works exactly the same way as a kettle. Electricity runs through
a metal element with high electrical resistance and most of the electrical energy is converted into
heat energy. This heat energy goes into the water to make it warmer.
The typical amount of power consumed by an electric spa heater is in the same range as an
average electric kettle, or a small portable electric heater. The difference is that you may only use
your kettle a few times a day – but a spa heater left on all the time is using that much power every
time the water temperature drops. And it’s trying to keep more than a thousand litres of water at a
high temperature during the coldest parts of the night as well as just when the spa’s in use.
The logical step is to turn the spa heater off, and only turn it on when it’s needed. But an electric spa
heater takes more than half a day to heat a spa from cold, which isn’t practical for most families.
Two alternatives are solar and gas heating.
Solar heating for a pool is simple, cheap and very environmentally friendly. Water circulates up and
through the black pipes on the roof, absorbing heat from the sun, and then circulates back into the
pool. A gas heater acts as a booster, but it’s only needed a few days a year – the sun does the rest.
The problem with solar heating for a spa is that the spa needs to sit at a higher temperature, and the
time it’s most used is at night. A solar spa heater would make a difference but wouldn’t be able to
fully replace the electric heater.
Gas heating can heat a spa from cold in approximately forty minutes, meaning it could be turned on
only as needed instead of running constantly. Changing from electric to gas would mean saving up
to five tonnes a year instantly. This was considered at the Lanes’, where they had a pool and spa
gas heater already installed. But it was poorly located, making connecting it to the spa problematic.
If electric heating is the only solution, then make sure your thermostat is set low. This saves energy
when the spa is idle, and it can be turned up again shortly before you want to use it.
If you have a pool or spa, check your local directories for a pool and spa specialist who can consult
with you and make sure your system is operating at its most efficient.
Pool blankets
Pool heating will be more effective if the pool has a blanket. And it will save water by reducing
evaporation as well. There are several types of blankets available.
Some act to warm a pool in the same way that greenhouse gases warm our planet. They let heat
from the sun through into the water, but then trap it inside so that it can’t leave easily. These are
good blankets to have when a pool is being heated by fossil fuels, as they reduce the amount of fuel
needed to maintain a given temperature.
If there’s already plenty of heat coming into a pool from a solar heater, as at the Barries and the
Lanes, what’s needed more is something to stop the heat leaving the water, particularly at night
time when the water isn’t being heated by the sun. An insulating thermal blanket will work best. The
thermal blanket is made of a wetsuit-like material that insulates the water from the air, making it hard
for heat to pass out of the water.
Suppliers of pool blankets can be found in your local directories.
| | Carbon Cops : Pools and spas
Pool pumps
Pool pumps are a major consumer of electricity. In some families the pool pump draws more
electricity than the kettle – and it usually runs for a lot longer than the kettle does in a day.
This means they’re a source of carbon emissions to watch for – producing as much as two
kilograms of carbon emissions for every hour that they run. Salt chlorinators can add an extra
half a kilogram. So finding the most effective way to use your pumps in each season can
save your carbon emissions, and add up to noticeable savings on your bills.
Spa pumps need to do two things – circulate the water to keep it evenly heated, and run the
jets. The second needs strong pumps, but the first only requires low-power pumping. Using
one very high-power pump to do both means using a lot more electricity than is needed
when the spa’s not in use. It’s overkill. Changing to a two-pump system means that the highpower pump is only running when the jets are on, not around the clock.
© ABC Copyright 2007
| | Carbon Cops : Pools and spas