Introduction
As a pool owner, you’ll want to understand the electricity usage of your pool pump and chlorinator, in order to manage it effectively. As they say, you can’t manage what you don’t measure.
At Together Energy, we help you save 25-40% on the electricity cost of your pool.
This short guide will help you estimate the monthly electricity consumption of your pool pump and chlorinator. Be prepared to fall off your chair.
We hope this information will empower you to make informed decisions about your pool's operation and maintenance, and most importantly, join the waiting list for TED.
Step 1: Identify Your Equipment's Wattage
The first step in estimating your pool equipment's electricity usage is to identify the wattage of your pool pump and chlorinator. This information is usually found on the device's label or in the manufacturer's documentation - it will be written in watts, abbreviated W, or kilowatts (kw). In this context, the term wattage and power are interchangeable and basically measure the capacity to do work in a set period of time.
Pool Pumps
Pool pumps typically range from 750 to 2,500 watts. The higher the wattage, all else being equal, the higher the flow rate and pressure of your pump.
Just like a kilogram is 1000 grams, a kilowatt (kW) is 1,000 watts. So the label on the pool pump may say 1,000 W or 1.0kW - same thing. Another measure of power, especially in the US, is horsepower. If by any chance, all you can find is hp or horsepower, 1 hp = 745W, 1.5hp therefore is 1120W.
It’s important to appreciate that higher flow rate and pressure is not necessarily better. Remember the main function of your pump is to move water through your filter to remove debris. Now imagine what happens if you double the flow and pressure – the filter actually less effective because more small particles get pushed through. Obviously, the higher the wattage the more electricity you'll consume too, so all else being equal more powerful pumps cost more per hour of operation.
What about dual-speed or variable speed pool pumps? We will cover these in more detail in future posts, but for the time being, if you have a variable speed or dual speed pump, you should mostly be running it at its lowest speed setting for filtration, so use that wattage for calculations.
Chlorinators
Many of us think of salt water pools as free sanitation, you just add salt and no longer need to buy chlorine. Well that's partly true, but what you're effectively doing is replacing that trip to the pool shop to buy chlorine with a higher electricity bill, albeit a lot less expensive overall.
Chlorinators work by passing a low-voltage current in your salt water through two electrodes in an electrolytic cell to produce chlorine (it does get a bit more complicated than that but for the purpose of this discussion, that’s what we need to know).
A chlorinator’s power determines its ability to produce chlorine, in grams per hour. A small pool can work well with a 20g/hr chlorinator, but a 100,000 litre pool in the tropics may need a more powerful 40g/hr unit to cope with summer.
Chlorinators will tend to consume 200-400W (or 0.2-0.4kW), depending on their cell size, salt water levels, water temperature and power setting.
If you can’t see a wattage figure for your chlorinator, you may guestimate 200W for a smaller pool / chlorinator combination, and 400W for a larger pool / chlorinator.
Step 2: Calculate Daily and Monthly Usage
Back to our pool, once you know the wattage, you can calculate the daily and monthly electricity usage. This calculation is relatively straightforward:
Daily Usage: Multiply the wattage of the device (in watts) by the number of hours it runs per day. For example, if your pool pump is 1,000 watts and it runs for 8 hours a day, the daily usage is 8,000 watt-hours (or 8.0 kilowatt hours, kWh for short).
Monthly Usage: Multiply the daily usage by the number of days in the month. Using our example, if you run the pump every day, the monthly usage would be 8.0kWh/day x 30 days, or 240.0 kWh.
So a typical pool with a 900W (0.9kW) pump and 200W (0.2kW) chlorinator, running 10 hours in summer is therefore using 11.0kWh of energy per day ((0.9+0.2)x10), or 330kWh/month.
Step 3: Understanding Electricity Bills
On your electricity bill, the electricity you use is billed in kilowatt hours, or kWhs. It is the sum of all the energy that has passed through your meter over the billing period, usually a month or quarter.
Energy is power multiplied by time, so while the toaster and kettle may all be high-powered (1kW each), they tend not to run for very long. A fridge on the other hand, may appear be relatively low powered, but it runs 24/7 all year round.
So for example, a typical electricity bill for a small household may have a total consumption of 720kWh over 30 days, or 24kWh/day (720/30).
Step 4: Estimating The Cost
To calculate the cost of running an appliance, like your pool equipment, you simply need to multiply the power of your equipment (in kW) by the time it runs (in hours) by the electricity rate, which is typically measured in cents per kilowatt-hour (¢/kWh). You can find this information on your electricity bill or by contacting your utility provider.
A typical electricity rate for a Sydney homeowner today is 38¢/kWh. So returning to our typical 1.1kW pool / chlorinator combination above, which is running 10 hours in summer. If we multiply 11kWh / day by 38¢/kWh, the result is $4.18/day, or $125/month, or $1,526/yr.
What??? $1,500/yr to run the pool?
What about Variable Tariff?
Now things get slightly more complicated if you have a smart-meter and what’s called a variable or “time of use” tariff, where your electricity usage is split into off-peak, shoulder, and peak periods.
Basically, your energy retailer charges you different rates at different times of the day, to incentivise you to run your appliances when there is less demand, and the energy is cheapest.
While the bill clearly displays the different rates for peak, off-peak and shoulder rates, I must say I have always found it difficult to find out what hours of the day these relate to. It turns out the hours are determined by your electricity distributor (runs the poles and wires), with whom you do not have a direct customer relationship. You can find out who your distributor is at the Australian Energy Regulator website. Then if you search for “time of use tariff” and the name of your distributor, you will hopefully be taken to a page that makes it clear when your different rates apply.
Sydney for example, is in the Ausgrid distribution network, and the tariffs are determined as follows:
If you have a solar PV system on your roof connected to the grid, you may also notice an extra line for the amount of energy you have fed back into the grid under the solar feed-in tariff. It’s usually much lower, like 5¢/kWh. We will dedicate entire posts on how to run your pool with solar PV shortly.
So to estimate your pool’s daily running cost on a time-of-use tariff, you need to determine how your daily run time (say 10 per day) is split between the three tariff zones – it could be 4 hours off-peak, 4 hours shoulder, 2 hours peak for example, multiply each by the total power of the pool pump and chlorinator, and then multiply that by the electricity rate. The following table shows an example.
Understanding the cost of your pool’s electricity usage is the first step to significant savings with TED.
Join our waiting list today to secure your TED, and tell your friends to do the same. We’ll send you loads of tips on how to better manage your pool and save money.
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