Putting a 10 ton unit in Santa Fe, New Mexico. Altitude 7,000 feet. Lennox LGA120 with high heat.
The Lennox specs have a "high altitude derate" table, and they list the gas manifold pressure. 3.6" in w.g. for 2,000-3,000 ft. 3.1" in w.g. for 7000-8000 ft.
How do I translate this into decreased output btuh?
I've been in Texas for 5 years now (lived in Salt Lake City previously, 4200 feet) and haven't derated anything since arriving. I used to just discount 4% per 1,000 feet because that was the recommendation in the literature. (Carrier's, I think.)
I haven't used a gas manifold pressure chart to derate output before, and could use some pointers.