Review on Highly Efficient 110V NPT3/4'' Domestic Water Circulation Pump With 3-Speeds For Hot Water Recirculation And Solar Heater/Faucet Applications (RS15/6G) by Johnathan Stoner

I hooked it from electric hot water boiler to heat exchange radiator in furnace duct-work. It runs great but even at lowest speed it moves water too fast. I'm wondering if I can slow flow by partly closing vales without damaging the motor. Works to heat my home but moving that much water keeps boiler element on too long and no savings to heat bill. Saw some concerns about threaded connections but you can get a flex hose that will screw on no problem.