Sad saga but good in the end (I hope!) Our hot water has always been on a recirculation loop. When we first got the combo boiler I bought a hot water recirculation pump on eBay. It had an internal temperature gauge and shut off at 120 degrees. We used an infrared trigger/timer to turn it on a few minutes before we needed hot water and it ran for 15 minutes or until the water temperature reached 120 degrees on the return.
Unfortunately, the pump stopped working (about 12 years) so I had to find a replacement. I started with a nice looking, functional Amazon off brand and it worked on install but stopped working after about 6 months. Cheap internals? Then I tried another off brand pump. This time a little stronger. However the unit arrived broken. They replaced it but I decided not to open the replacement and just return it too. I actually ordered this one twice as the first box was empty!
I decided to bite the bullet and order a brand name pump. I ordered a Grundfos COMFORT 10-16 TA BU/LC hot water recirculation pump. This model has an internal temp sensor and would have worked like our original pump but after I installed it I could not get it to pump water. I assumed it was not strong enough at a peak of 2.2 gallons per minute. Had I ordered it through Amazon I could have repackaged it and returned it but my supplier denied the return because it had been installed. Bummer. I ordered the Taco 006e Smart Recirculating pump. About $100 more expensive, its specs say maximum 11 gallons per minute. But I installed it in the old spot and it wouldn’t turn on the water heater. Not enough pressure? I removed the water pressure regulator and it still didn’t pump enough to turn on the heaters! I thought maybe too much pipe, too much rise? So I lowered it to the floor. Didn’t work to turn on the water heater which only needs .5 gallons per minute flow according to the documentation. I was flummoxed. So I asked Chat GPT. WAS THIS PUMP STRONG ENOUGH for about 150 ft of pex? Answer it is almost ideal. Do you want to know more? Yes. More general info. Do you want to know a common mistake? Yes. This pump needs a check valve after the pump because it can’t work against the incoming cold water for our nearby kitchen that is not on the loop. Well darn. After three months with these two pumps this hint finally solved it. Bought a spring check valve, installed it in place of the pressure regulator and voila! It works and turns on the hot water.
But the Smart plug has two modes. On for 5 off for 10 which is constant hot water circulating or learning our use patterns. It’s currently learning but seems to be on every time we need hot water. The temp sensor is external and zip tied to the pipe after the pump and at least 18 inches from the water heater. I think our first pump had an internal check valve and maybe the off brand pump wore out because it didn’t. I was persistent and finally got this one figured out.
