I have a mini max nt low nox heater. I replaced the hot surface ignitor and the ignition control module. The heater comes on run strong for about 6 seconds then turns off it does this 3 times and then goes into ignition module lockout
You will need to check the flame sensor and make sure it's clean, check the burner tray and look for soot, plugged or corroded burners, and last check your gas pressure and make sure the water column is within range.
propane / natural gas
Maximum inlet gas pressure 10 in. WC 14 in. WC
Minimum inlet gas pressure **5 in. WC 12 in. WC
Normal manifold pressure 4 in. WC 11 in. WC
*All Readings are taken with the heater fired. Any adjustments
or readings made with heater off will give incorrect readings.
** 6 in. WC for 400 model
Correction, natural gas 10in. wc maximum / 5-6" minimum
propane 14" max /12" min.
Richard thank you for your response what if the model heater I have does not have a flame sensor supposably it's built into the hot surface ignitor. Heater was working fine until hot surface ignitor blew out replace that then it wouldn't Heat replace the ignition module then the hot surface ignitor would actually heat up and it would start and then stop after three to five seconds