Navien NFC 250/200H DHW recirculation

[caterpillar]

I have a NFC combi boiler that I added a Grundfos UPS15-58 FC external recirculation pump. I have 3/4 pex with a designated return line that runs about 45' one way and 45' back. Im activating the pump with a smart plug and an app controller. When I turn on the pump should the combi boiler start making hot water and recirculate it until it reaches the set temperature? When I start the pump it will not start making any hot water until I open a faucet. Is there a setting that needs to be set in order for the boiler to start making hot water when the pump comes on without a faucet being opened? Here is how it is plumbed. Thanks.

 

[Breplum]

Have you set DHW recirculation to External Recirculation in section 9 of the set-up wizard adjustments?

 

[Sponsor]

 

[caterpillar]

Have you set DHW recirculation to External Recirculation in section 9 of the set-up wizard adjustments?

Yes, Just don't understand why you turn on the faucet and it makes hot water, turn on the pump to circulate flow through a closed loop system and it doesn't turn the boiler on to make hot water. I don't want the boiler running when we are not there as this is a lake house

 

[John Gayewski]

Yes, Just don't understand why you turn on the faucet and it makes hot water, turn on the pump to circulate flow through a closed loop system and it doesn't turn the boiler on to make hot water. I don't want the boiler running when we are not there as this is a lake house

They make hot water based on their own logic. They decide when to fire and when not to. All it should care about is keeping the internal tank warm.

 

[Breplum]

Sorry, I am not trained on the combi. Would have to call Navien, and unfortunately, they don't like to talk to non-plumbers. maybe try anyway. Can you get a domestic HW gpm reading when the pump turns on? My suspicion would be air-locked pump. I have seen plenty of Grundfos circulators that are 'running' but have trapped air in the impeller so not actually moving water. For those situations we add tee and hose bibb to each side of the pump.