Review on ✨ BOKYWOX 3-Speed Hot Water Circulation Pump: Efficient Solution for Domestic Water Heating with Solar Heaters/Faucets (RS15/6R) by Tony Miller

I bought this pump for an under counter pump to get hot water without wasting a lot of water down the drain. It replaces a cheaper pump I had that was starting to leak. I ran it from hot to cold water under the bathroom sink. The positive thing is that the pump is very quiet. Almost inaudible. Disappointing: 1) It doesn't prevent leakage if it doesn't work. Therefore, without a check valve, hot and cold water will mix through the pump, heating cold water and cooling hot water. I installed a spring loaded check valve that closes on the hot water side because I figured it would shut off the hot water when cold water comes out of the faucet and the spring keeps it from being siphoned off. This works up to a point. When I have the hot water line fully open (under the sink when shut off) there seems to be enough hot pressure to force the cold line to pump something through the check valve when I run cold tap water, causing it to warm up. If I partially close the hot water shut-off valve, the cold water faucet can work properly and not pump hot water. However, this reduces the flow of hot water to the faucet and limits the flow the pump pumps when it's on, increasing the time it takes for hot water to get there. So not a perfect solution for my use case.