How can firing rate affect heat exchanger longevity?
If the firing rate is too low, its that same as having low return air temperatures (RAT). Condensation will form, mix with the flue gas and cause corrosion.
A high firing rate is the same as low air flow; the heat exchanger will run hotter than designed, and will eventually crack.
How do you check the firing rate?
Firing rate is determined by manifold pressure, BTU content of the fuel, and orifice size. We’ll be covering those topics in another post.