Replaced the igniter. Still nothing. So next step new Gas regulator maybe? I just replaced in March
I have no clue if the pressure changes when the heater tries to fire. I do not have tools to test that.What is the gas pressure before you start the heater?
Does the pressure change when the heater tries to fire?
What is the exact model number of the heater? (Part number p/n from the sticker).
Maybe remove one of the bottom manifold bolts to see if water comes out.
Check the voltage and current going to the igniter when the heater tries to fire.
Maybe some pictures would be helpful.
Unless the problem is that there is no gas pressure getting to the heater.Not much to go wrong when buying a new one.