by Craig Lauridsen
I recently installed a hot water recirculating system at my home. I did this to save water and time. There are a couple different types of these systems available but I will focus on the one that I used. Here’s how it works: A small pump is installed on top of the water heater and a thermal bypass valve is installed under the sink that’s furthest from the water heater. That’s it!
The average household wastes thousands of gallons of water per year waiting for hot water. It used to take about 2 minutes and 15 seconds before my shower was hot enough to get in, now it takes 25 seconds. This is an 80% reduction in time and water (about 3 gallons per shower based on my 1.8 GPM showerhead). I experienced similar savings at the bathroom faucet. Between the shower and faucet I calculated an annual water savings of about 2,000 gallons for two adults. I will personally save over 10 hours per year not waiting for hot water—maybe I’ll use that time to think of other ways I can save water!
Overall, I am very happy with my hot water recirculating system. If you are considering installing one of your own, here are a few things to consider:
- Your energy use will go up slightly because you’re heating the same water twice. These recirculating systems move hot water in the pipes (that has already been heated once) back to the water heater to be heated again. If you don’t want to increase your energy usage and you’re willing to wait for hot water, you can forgo the recirculating system and “shower with a bucket.” The water you capture in the bucket can be used to flush toilets or water plants.
- Most of these pumps have a timer that you set for certain times of the day (when you’re most likely to shower, wash your face, etc.). If you do these activities when the pump is off then you’ll have to wait for hot water (just like you used to).
- Most of these systems use your cold water pipes as a return line back to the water heater. This means that when the pump is running you’ll get several seconds of warm water when you turn on the cold handle. This also means that you are putting water that has passed through the water heater into your cold pipes. Some research has shown that you shouldn’t drink water that has passed through the water heater because it can contain higher concentrations of lead. I filter my drinking water so I’m not too concerned about this.
- To maximize efficiency you should consider insulating all of your hot water pipes.
- Some recirculating systems won’t work with tankless water heaters. So keep this in mind if you have, or plan on installing, a tankless water heater.
For detailed research about recirculating systems, check out this helpful webpage from the Alliance for Water Efficiency.