Navien combi boiler won't stop hydronic heating

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Have a Navien NCB 180E combi boiler installed. Its producing hydronic heat run to an air handler and DHW well. However, i realized that when i set my thermostate to "fan on" with the system set to "off" just to circulate some air, the Navien is kicking on and sending hot water to the blower to maintain its min temp of 140. Asked support and they said to make sure dipswitch #7 is set to down for zoned heating which it is. So i have 2 concerns:
1. When summer comes and i want to use my a/c (which uses the same air handler) will the navien continue to send 140 degree water to the air handler and fight my a/c? Its too cold now for me to turn my thermostat to cold and try it out to see what the navien will do, as i don't want to stress my condensor.
2. Is the navien supposed to hold water constantly at 140 in a sort of "standby" mode waiting for the thermostat to request hot water to the air handler, and does that mean i'm wasting fuel? When i do set the thermostat to "heat" the navien maintains the circulating water at 140 so this is its heat/operating temp.
Anyone know why my Navien seems to be set to "always on" hydronic heat and how to get it into a "standby" mode?

Thank you!


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Peace valley missouri
Circuit board in heater cn10 TT is the terminals for heat. Thermostat wiring fan in on position should only make R to G nothing else. In cooling when there's a call R to G is made to turn fan on usually on high speed. Heat fan speed is usually med or low. Controlled by a aqua stat. Have a wiring diagram from the air handler? Take a pic of it.
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