navien ncb-240

Hey all, My home has a Navien NCB-240E NG tankless water hater. After not having the system serviced or cleaned for a solid 5 years (I know -- not good), we recently had it done per recommendation of our plumber. They replaced the ignitor, cleaned the air inlet screen, replaced the filter, and...

I have a Navien NCB-240 piped Primary / Secondary. The secondary loop is feeding a couple of manifolds that split off the flow to half inch PEX-AL_PEX home runs to 12 cast iron radiators. The boiler is set to run on reset curve with max temp of 140 at 5 degrees outdoor temperature and 104 at 60...