Hot water recirc system not working

pump

Issue: Hot water slow (90-120 secs) to come to distant fixtures
Recirc system: 2 dedicated returns, merged to single pipe, feeding a 103258LF Bell & Gossett (NBF-9U/LW Pump 1/40 HP Motor) pump installed at the “Space Heating Return” inlet (where drain valve is) on our 50gal Bradford White water heater.
House: built in 2014, 3600sf, 2-story, 10 foot ceilings, upstairs bathrooms on opposite sides of the house, water heater on ground floor roughly centered. Kitchen about 25 feet from water heater. 2nd story bathrooms roughly 20-30 feet horizontally, & 12-15 feet vertically removed from water heater.

Pump seems to be oriented correctly (arrow pointing down toward the water heater) and it gets quite hot when it runs. It seems to be running normally, gently vibrating and very quiet. This system has never worked—no change in time to hot water whether pump is running or not. I don’t know where the 2 return lines come from—upstairs & kitchen (or maybe both upstairs)?

Is this pump sized right for our home? What else could be wrong?

Recirc Pump, return lines

Best Answer

When the pump is running the pump and piping around the pump will get hot even if there is no water flow. Check the spring loaded check valve, that brass thing between the pump and the water heater to make sure that it's arrow is pointing down also. more possible problems; 1) The pump may not have enough "head" to push water through that spring loaded check. If that is the case, remove it and replace it with a standard swing check in the horizontal piping above the pump. 2) The pump may be air bound and will require that a vent valve be installed in the horizontal piping above the pump to purge the air. That type pump will not push any trapped air in the pipe. The air stays trapped and the pump will not pump. The installation looks OK except for the spring loaded check and the pipe above the pump not having a vent valve. I have the same pump on my hot water recirculating lines that handles 3 bathrooms and it works great. I set my timer to run the pump 15 minutes each hour and for 2 hours in the morning and evening when we normally take showers. my 2 cents