Boiler flue pressure high altitude

martin ce jarrell

Takagi 310 combi new heater 8600' altitude, vertical flue oversize, roof 12/12 pitch, flue is 10' from peak, combustion air in the basement. 991 failure 5 times ignition failure. Old heater did the same.

GGross

Can you link to the unit? my understanding is Takagi doesn't make a combi just a tankless water heater.

you need to run through the steps that come with the unit, there isn't a shortcut. confirm that all of this is within spec write it down and then come back if it doesn't work