Hi there,

I have a Noritz NRC711-DV tankless water heater. There are two buttons (one in my master bedroom and one in the kitchen) which I can press and have the cold water circulated to get warm. Recently I replaced a cartridge for the shower in my master bath: I turned off the main water switch and turned on all faucets to let water run out before the replacement. I did not turn off the power for the Noritz tank and the recirculation system. After I finished my work, I re-opened the main water switch. But now I could not get the warm water quickly as before after I press the buttons. I can hear the noise from the pumper but there is no temperature display on the Noritz panel. I have to let the water run for a long time to get the warm water. It seems that the recirculation system does not work (gas heater not on?). How can I fix this issue?

The circulation pump might be air bound and needs to be bled. Is the pump built into the heater or a separate pump?

Thank you, Steve. The pumper is a separate one from the heater.

if the pump is connected by flanges, loosen the bolts a little to let some water leak out. if there is any air that will get any air out. then retighten the bolts
same thing if the pump is connected by unions. loosen them

If the pump has a screw like in the linked video, loosen the screw a little until water comes out , then tighten the screw back up.

[www.youtube.com]

Sorry guys, I bled the pumper but it did not help. I still have the cold water after I press the "hot button" for pre-heating. I can hear the pumper is circulating the water insider. But it seems that gas is not burning to heat the water. The temperature display does not show anything such as "120". When I only turn on the hot water faucet, I can see the temperature display shows "120".

Any other thoughts? Thanks!