Instructor urges use of cold‑climate heat‑pump specs for Flagstaff homes

Steve Hansen, an HVAC instructor at Coconino Community College, told a public meeting in Flagstaff that cold‑climate performance and elevation adjustments should guide selection of heat‑producing equipment. “Efficiency and understanding the equipment has always been important to me,” Hansen said, noting experience in the industry and in teaching HVAC, electrical and plumbing.

Hansen said heating loads in Flagstaff are the primary design driver because local cooling needs are much smaller than in lower‑elevation Arizona cities. “Now the cooling side is also important, but it's not as important at this elevation or our because our cooling loads are much smaller than, say, that in Phoenix,” he said.

The instructor described two technical points he said contractors and buyers should consider. First, manufacturers publish performance charts that show how units perform at different temperatures; Hansen urged checking those charts for operation at lower temperatures typical in Flagstaff. “So when we look at the things, we we have all these charts that tell us what they do that are produced by the manufacturer so that we know what they'll what to expect from the equipment,” he said.

Second, Hansen said units must be derated for elevation because lower atmospheric pressure reduces heat transfer. “We have to derate for elevation because we have less atmospheric pressure and less to absorb heat from,” he said, adding that recent industry awareness of elevation effects has increased.

Hansen also compared cold‑climate and non‑cold‑climate equipment. He said some manufacturers now make units that maintain capacity at much lower temperatures — “some of them as low as, 17 below and full capacity,” he said — whereas equipment meant for milder climates can lose effectiveness when temperatures drop “about 23 or 30 degrees.”

Hansen summarized why those factors matter for local installations: because Flagstaff’s lower overnight temperatures and larger day‑to‑night swings increase heating demand, designers should verify both low‑temperature performance and elevation derating when sizing equipment. “We look at them specifically to make sure that at the lower temperatures like we have here in Flagstaff, that it actually will maintain the amount of heat that we're looking for on the heating side,” he said.

Hansen said he passes those considerations on to his students at Coconino Community College so they can specify and install systems appropriate to cold, high‑elevation environments.