Am I Under-firing my Furnace?
Last month I installed a GMV series 95%, 2-stage Goodman furnace in my own home. The manifold pressure the Goodman specs recommend are a range (Low: 1.6-2.2, High: 3.2-3.8). The temp rise for each stage is specified as 30-60F. I set the manifold pressure to the minimum recommended. I have a temp rise of about 35F for both stages. Clocking the gas meter, I get inputs of 39K BTU and 58K BTU. This furnace is specified as a 70K BTU input furnace. I realize that I am within the specs for manifold pressure and temp rise, but I still worry that I might be under fired. I don't want to have any primary heat exchanger condensation happening.
Can any of you guys give me any reassurance to leave the furnace as it is, or reasons to increase the firing rate?