Tucson does not have a Midwest winter, and it is not a place where the heat never runs. At the official climate station the 1991–2020 normal low is 40.8°F in January and 40.5°F in December. The normal high those months is in the mid-60s. The same normals count about 12 days a year at or below 32°F. That is a heating season made of mornings, not of months of snow, and it is enough to find out whether the equipment that sat idle all summer still works. Sabino Creek Heating & Cooling repairs both gas furnaces and heat pumps here. This page is the choice between them when you are replacing, not the no-heat diagnostic. If the house is already cold, use furnace repair or heat pump repair first, and the homeowner checks on the fall checklist.
Two different ways to warm the same duct
A gas furnace burns fuel and heats a heat exchanger. The blower pushes house air across that exchanger. Supply air can feel quite hot at the register. The sequence has a draft inducer, a prove switch, an igniter, a gas valve, and a flame sensor. When it has sat from April until the first cold night, dust and an idle igniter are why it fails on the night you need it. That pattern is local. It is not a mystery of “furnaces in the desert.”
A heat pump is the air conditioner run in reverse. The outdoor unit pulls heat from outdoor air and the indoor coil gives that heat to the house. Supply air is milder. On many systems it lands in a range that feels lukewarm on your hand compared with furnace air, even while the room is warming. People who grew up with furnaces interpret that feel as “it’s not working.” Give it time on a cool morning before you decide the compressor is dead. Air that stays truly cold, or an outdoor unit that never starts while the indoor blower runs, is a fault. Electric resistance strips are the backup. They are supposed to help on the colder mornings. They are expensive to lean on all winter, and they are what you are using if the thermostat says Emergency Heat and the outdoor unit is silent.
Defrost is the part that looks wrong and often is not. On a damp morning the outdoor coil frosts, the system briefly reverses to melt it, and the supply air can feel cool for a few minutes. Steam at the outdoor unit during that cycle is normal. Ice that never clears is not. The repair page walks through that distinction. Do not chip ice off the fins to “help.”
The climate station is not your street
Those January numbers are the official Tucson station. They are not a promise about a lot up against the Catalinas or a house south of the city with no heat-island around it. Catalina Foothills nights drop faster than midtown. Oro Valley mornings run cooler than Broadway. Green Valley uses heat on winter mornings more than a central Tucson house that is empty all day, and frost is part of that valley’s winter. A heat pump that “keeps up” in Sam Hughes can spend a foothills January on strips if the compressor is weak, the charge is low, or defrost never quite finishes. The fix is still a diagnosis of the heat pump, not a speech about how mild Tucson is.
Shoulder season is the other local test. An October afternoon can still want cooling while the night wants heat. A heat pump is built for that swing when the reversing valve, the charge, and the controls are healthy. A furnace with a straight air conditioner simply does not run in the afternoon and does run at night. Both are valid. The house with the heat pump will disappoint you if you judge it at 3 p.m. in heat mode or at 7 a.m. after it was left in Emergency. Test on a morning that is actually cool. A 75°F afternoon makes every heating system look fine.
What the house already has is half the decision
Older central Tucson and a lot of Continental Ranch-era Marana houses have a gas furnace and a straight air conditioner. Newer tracts were often built with heat pumps and no gas furnace at all. Green Valley has plenty of package units that do one or the other. Replacing “the AC” in a heat-pump house with a cooling-only condenser leaves you without heat. Replacing a furnace and pretending the outdoor unit will heat is the mirror mistake. Look at the thermostat. Emergency Heat or Aux as a mode is a heat-pump clue. A gas pipe and a flue at the indoor cabinet are a furnace clue. If you are not sure, say so. The outdoor nameplate and one photo of the indoor cabinet usually settle it.
A switch from furnace to heat pump, or the other way, is not a thermostat setting. Gas means a flue, a gas line, and combustion air. A heat pump means an outdoor unit that can run in heat, a reversing valve, and a place for strips in the air handler if the design uses them. The electrical panel has to carry the strips or the new compressor. Ducts sized for very hot furnace air sometimes feel sluggish with the milder heat-pump supply, especially at the end of a long foothills run. That is a reason to look at the ducts, not a reason to condemn heat pumps as a category. The duct guide is ducts and attic heat. The load still has to be calculated for cooling, which in this climate is the bigger design day. See what size the cooling side needs.
Dual fuel, without the brochure fog
Dual fuel means a heat pump handles the mild hours and a gas furnace takes the colder ones. You need both machines and controls that switch them. It fits houses that already have gas and want the heat pump for the long shoulder season without giving up a furnace on the mornings that actually frost. It is a real scope of work: two heat sources, a coil match, and a control strategy someone has to explain in a sentence you can repeat. It is not “hybrid” as a sticker on a furnace that has no outdoor heat pump. If a proposal uses the word and does not say when the furnace takes over, ask.
We will not invent a heating-bill comparison. Electricity prices, gas prices, how often strips run, and how leaky the house is all move the answer, and a percentage from a national ad is not your January. What we can settle on site is whether the house has gas, whether the panel has room, whether the ducts will carry the airflow, and whether the equipment you have is worth repairing through another summer. Cooling season is long here. A heat pump and a straight air conditioner both have to survive June. The heating choice does not get you out of a proper cooling installation. Efficiency ratings on new equipment are SEER2 and, for heat pumps, HSPF2. They are not a one-to-one match with the SEER number on a ten-year-old nameplate.
Comfort details people notice in the first week
Furnace air arrives hotter and in shorter cycles once the house is up to temperature. Heat-pump air arrives milder and the system may run longer. Longer is not failure if the room is getting warmer. Strip heat kicking on during every mild evening is failure, or a thermostat left in the wrong mode. Learn what Aux looks like on your thermostat before a cold snap, not during one.
Filters matter to both. A packed filter trips a furnace limit and makes a heat pump ice up or lean on strips. After monsoon season the filter is guilty until proven otherwise. Rooms with closed doors and no return path heat slowly on either system. That is airflow, and it will be blamed on the new equipment if nobody mentions it.
Noise is different. A furnace’s inducer and burner light-off are indoor sounds. A heat pump’s outdoor unit runs in January, which surprises people who were used to a silent condenser all winter. If the outdoor unit is under a bedroom window, say so before the replacement location is copied from the old pad out of habit. HOA screens in Oro Valley still have to let air move. A heat pump buried in a walled pocket defrosts poorly and cools poorly.
Repair what you have, or replace the type
An igniter, a flame sensor, a defrost board, or a reversing valve is a repair. It does not require you to change religions about gas versus electric. A compressor failure on an old heat pump, or a heat exchanger problem on an old furnace, is the moment the type becomes a choice. Price the repair. Price the replacement you actually want, with the scope written down. The decision framework, separate from the heating physics, is repair or replace. TEP lists heat-pump installation rebates on the Efficient Home Program page; the current “up to” amounts and the participating-contractor rule are summarized on the replacement cost page. Do not pick a heat pump because a rebate exists, and do not reject one because a neighbor prefers the feel of furnace air. Pick it because the house, the ducts, and the winter you actually have line up.
What to send, and when to stop experimenting
If heat is already down, say that, and do not keep cycling a furnace that smells like gas. Leave and call 911 or the gas utility. The form is not that line. A short dusty smell on the first fire of the fall can be normal and should fade. A rotten-egg smell is not.
If you are planning a replacement before anything has failed, use the form with “just planning” or “this week,” the ZIP, and what heats the house today. Mention foothill mornings or a Green Valley package unit if that is you. We follow up the same business day. A heating tune-up is the better request when the equipment still runs and you want it proven before a cold stretch, rather than replaced on a hunch. Test heat on a cool morning either way. A system that only gets judged in July will lie to you about January.
Sources for the figures on this page
- National Weather Service Tucson 1991–2020 normals: January high 66.5°F and low 40.8°F, December high 65.5°F and low 40.5°F, about 12 days a year at or below 32°F. weather.gov/twc/TucsonMonthlyNormalExtremes.
- Tucson Electric Power Efficient Home Program: tep.com/efficient-home-program.
Supply-air “feel” is a comparison, not a diagnosis. Cold air that never warms, a gas smell, or ice that does not clear means stop and request service.