The Best Fall Thermostat Settings for Michigan Homes

Forty-five degrees at six in the morning and seventy-four by three in the afternoon. That's a West Michigan September, and it's why the thermostat in a lot of houses gets touched four separate times before dinner — heat in the morning because the kitchen floor is cold, off by ten, AC by two because the west-facing rooms are baking, back to heat before bed.

Most people ask me what the perfect number is. I'd rather answer a more useful question, which is how to set the thing once in September so it stops needing a referee every afternoon. So: the numbers I'd start from, what a setback is really worth, the mistake that has the furnace and the AC both running on the same October day, and the one system type where most of this advice flips around backward.

The Numbers to Start From

Three settings cover the day for most families. These are starting points, not commandments:

Sixty-eight is where nearly every energy guide points, and it's a fair place to begin. It's the mirror image of the seventy-eight we suggest for summer settings, and it's the same bargain in reverse. It is not where everybody ends up. A house with a lot of glass, a slab floor, or forty-year-old windows will feel colder at sixty-eight than a tight build will at sixty-five, because you're feeling the cold surfaces around you as much as the air. Older folks and small kids generally want more. Sit with the number for a week before you decide it's wrong.

What I care about more than your daytime number is whether you're setting back at all. Somebody holding seventy-two around the clock is spending real money on an empty house every weekday. Somebody at seventy while they're home who drops to sixty-two for the ten hours they're asleep or gone will beat them on the bill without ever being uncomfortable.

How Much a Setback Is Actually Worth

The number that gets repeated is roughly one percent off your heating cost per degree of setback, held for about eight hours. So eight degrees back overnight lands somewhere near eight percent.

Take that as a rule of thumb, because that's all it is. The real figure depends on how leaky your house is, how cold it gets outside, how well insulated your ducts are, and how long the setback runs. A tight house holds its heat so well that a setback saves less than the rule suggests. A drafty one can beat it.

It's worth knowing why, because it's also why the "hold one temperature" advice is wrong for a furnace. Your house loses heat in proportion to the difference between inside and outside. At sixty-two inside and thirty outside, it's bleeding heat more slowly than it would at seventy inside. Fewer BTUs escape during those hours, so fewer have to be replaced. The morning recovery doesn't cancel that out — it's just paying back the smaller amount you actually lost.

Two limits on how far to take it. Don't go so deep that pipes in exterior walls or a crawlspace get near freezing, especially if you're leaving town. And don't set back radiant floor heat much at all, because concrete takes half a day to come back.

Heat Pumps Play by Different Rules

This is the part that trips people up, and it matters more every year as heat pumps get more common around here.

A gas furnace has one speed: full blast. Asking it to bring the house from sixty-two to sixty-eight costs the same per BTU as holding sixty-eight would have. A heat pump doesn't work that way. It's efficient when it's running steadily against a small load, and when you ask it for a big fast recovery, most thermostats respond by turning on the auxiliary electric resistance heat — strips that are, roughly speaking, the same technology as a toaster, and the most expensive heat in the house by a wide margin.

Set a heat pump back five degrees overnight and there's a good chance you're paying for electric strip heat every morning to recover. That can wipe out the savings and then some.

So for a heat pump:

• Keep the swing to about two degrees, or skip the setback entirely and hold one number.
• Use a thermostat that knows it's driving a heat pump. Models with adaptive or intelligent recovery start warming early and slowly so the compressor does the work instead of the strips.
• Don't jump the setpoint by hand. Bumping it four degrees because you're cold right now is the single most reliable way to fire the backup heat.
• Leave emergency heat alone unless the compressor has actually failed. It's a limp-home mode, not a cold-snap mode.

Not sure which you have? Look at the outdoor unit in January. If it runs, it's a heat pump. If it sits dead until April, a furnace is doing your heating. We compared the two in heat pump versus furnace if you're weighing a change.

The Dead Band Question

If your thermostat is set to AUTO changeover — free to pick heating or cooling on its own — the gap between your heat setpoint and your cool setpoint is doing a lot of work in the fall. That gap is the dead band.

Set heat to sixty-eight and cool to seventy, and on a day that starts at forty-five and hits seventy-four, you have given the system permission to run the furnace at breakfast and the air conditioner in the afternoon. Same house, same day. People call that a broken thermostat, and it almost never is. It's the dead band being too narrow for a shoulder season with a thirty-degree daily swing.

Give it at least four degrees of separation, and five or six is better in September and October. Sixty-seven and seventy-three, say. The house sits at seventy-one for a stretch of the afternoon and neither system does anything, which is exactly what you want.

Why Sixty-Eight Feels Different in October Than in January

Humidity works the other direction in winter than it does in summer, and fall is where you notice the handoff.

Cold outside air holds almost no moisture. Heat it up to sixty-eight indoors and the relative humidity falls through the floor — a house that was sticky in August can be desert-dry by Thanksgiving. Dry air pulls heat off your skin faster through evaporation, so the same sixty-eight that felt fine in October feels drafty in January, and people compensate by pushing the thermostat up a couple degrees.

In September and early October you get a short window where the air is still reasonably moist and sixty-eight feels genuinely comfortable. Enjoy it. When the dry stretch hits and you catch yourself creeping toward seventy-two, the thermostat usually isn't the thing that needs adjusting. Putting moisture back in the air is cheaper than heating the whole house two degrees hotter all winter.

The other thing that makes sixty-eight feel colder than it should is air that isn't moving where it needs to. A crushed duct, a closed damper, a filter that's been in since spring — the thermostat reads sixty-eight in the hallway while the back bedroom sits at sixty-two. No setting fixes that. A furnace maintenance visit will find it.

Is a Smart Thermostat Worth It Here?

It depends almost entirely on whether you'd follow a schedule without one.

The savings in all of this come from the setbacks, not from the hardware. If you're already programming a basic thermostat and living with what you programmed, a smart one is a modest upgrade. You get geofencing that notices when the house empties out, remote access so you can warm the place up on the drive back from the cottage, and reports showing what the system actually did all month. Those are conveniences worth paying for. They aren't a new source of savings.

If you're the household that never programmed the old one and just bumps it by hand, that's different. A smart thermostat saves you real money because it finally does the setbacks nobody was doing. Same for anyone with a heat pump, where adaptive recovery is worth having on its own.

Figure a few hundred dollars installed for a good one in the Grand Rapids market, more if your system needs a common wire pulled. We went deeper on the payback in do smart thermostats actually save money, and we install and set up smart thermostats if you'd rather not fight with the wiring and the app.

One caution I'll repeat to anybody with a heat pump: buy one that supports heat pumps properly and set it up as a heat pump during install. A smart thermostat configured as a conventional furnace will happily run your backup strips all winter and report cheerfully that it's saving you money.

Making the Switch Without a Service Call

The other fall thermostat question is when to give up on cooling entirely. There's no calendar date. When you've gone a week without wanting the AC and the overnight lows are consistently in the forties, you're done.

Before the furnace carries a full week of work, run it deliberately on a mild afternoon — set it above room temperature, let it run half an hour with the windows open, and see what happens. You want to find a problem in September when the schedule is open, not on the first hard freeze. We walked through the whole changeover in switching from AC to heat, including the parts people skip.

I was in a house in Grandville a few falls ago where the family had been fighting their thermostat for weeks and were convinced the furnace was short cycling. AUTO changeover, heat at seventy, cool at seventy-two. The system wasn't broken and neither was the thermostat. We spread the setpoints, put in a schedule with an overnight setback, and that was the whole visit. I've never felt great charging for a diagnostic that turns into a two-minute settings change, which is part of why I'd rather put this in a blog post than in an invoice.

If the settings are right and the house still won't hold temperature, that's a different conversation and worth having. Uneven rooms, a furnace that runs constantly, or a bill that jumped without a weather explanation all point at the equipment. Comfort Plan members get priority scheduling, 15% off repairs, and no overtime charges when something goes sideways at a bad hour — the details are on the Comfort Plan page.