When we last visited energy consumption for the pool, we'd just grabbed a beer after banking a $169 per year saving using Vera as a smart timer. If you're just joining us you can read that article here.
Now we can review the energy consumption being recorded by our Vera Home Automation Controller and definitively answer the question "Is an ECO Pool Pump worth the money?".
- The ability to adjust the RPM settings to any value.
- Option to run in 'manual mode' using an external timer (Vera in this case)
- Configurable startup priming, where the pump runs at one speed when turned on for up to 2 hours, then changes to a lower speed.
ECO pumps work by leveraging Pump Affinity Laws. That link is for the Engineers. For the rest of us, we're exploiting the fact that a small reduction in pump speed results in a much larger reduction in energy use. So we run the pump slower, for longer and end up moving the same amount of water for a lot less power. Using my previous 1.5hp pump I ran for between 4-8 hours depending on the season. For the ECO pump I need to increase that to 8-12 hours running on low speed. A quick adjustment to the PLEG schedule:
|sPool_Pump||Day of Week||+02:00:00r||1,2,3,4,5,6,7||None||Day of Week||-01:00:00t||1,2,3,4,5,6,7|
Gives me a 7-11.25 hour spread through the year based on sunrise/sunset. The reason it's a little lower is I'm planning to run the pump on a higher speed for an hour, to give the pool cleaner a chance to do its job before dropping to low speed. To begin with, I'm just going to set the pump for medium speed and see what the results are.
Results from Changing Pool Pump (Medium Speed)
It's clear from the Watts used that the maximum power draw has dropped (1143W down to 497W to be precise) and you can see the overall increased run time. In terms of kWh and therefore dollars the picture looks like this:
kWh per day dropped from 6.4 to 4.3. A 33% reduction in power consumption and at medium speed the pool cleaner continued to work normally and still had enough suction to climb the pool walls.
Nothing to sneeze at, but we're not done yet.
Results from Changing Pool Pump (1 hour Medium Speed then Low)
So the rationale here is we run the pump a little bit faster than medium for an hour, for the pool cleaner to get a chance to do some heaving lifting, before dropping down to a speed that minimises power use. A bit of fiddling with the Viron's settings resulted in this:
You can see the 1 hour increase in power for vacuuming, followed by the low speed for circulation and chlorination. We're now running at 250W of consumption for most of the day. This netted another reduction in daily kWh usage:
A further 45% reduction in daily use, from 4.9kWh (increased slightly with daylight) to 2.7kWh. Interestingly, the Zodiac MX6 still runs around the pool on the low speed setting. While it won't climb the walls it's still vacuuming and it may mean I have scope to lower the pump speed even more.
Return on Investment
Plugging all of this into my spreadsheet with the daily run hours for a calendar year, I get a new annual power cost of $225, a 71% reduction and $566 annual saving from where I started.
Money spent on the timer automation and ECO pump was around $1400 all up including installation, for a payback period of just under 2.5 years.
This compares very favourably with solar, having a faster payback and smaller up front cost. ECO pumps and Home Automation are definitely worth looking at if you have a pool at home and want to save some money.
Contact us if you've got questions about saving money on your pool costs.