September and October in Southwest Michigan produce some of the most awkward weather of the year for a heating system. A 76-degree afternoon followed by a 41-degree night is normal, and it happens repeatedly.
Most thermostats are set for summer or for winter. Fall needs its own approach, and it is the shoulder-season counterpart to the best thermostat settings for summer.
Quick answer: The best fall thermostat settings for Michigan start with switching the mode from Cool to Heat, then following a schedule: warm the house before you wake up, set it back while the house is empty and set it back again overnight. Avoid Auto changeover with close setpoints, and make sure the thermostat location gives your fall thermostat settings an accurate reading.
If your thermostat is still on Cool, switch it to Heat. Leaving it on Cool means nothing happens on the first cold morning.
Be careful with Auto changeover. Auto switches between heating and cooling based on which setpoint gets crossed, and if the two setpoints sit close together you can end up cooling in the afternoon and heating that night, on the same day. That is expensive and hard on the equipment.
If you do want Auto during shoulder season, set a wide deadband. Heat at 66 and cool at 76 gives the house ten degrees to float without either system engaging, which in fall is usually enough.
The point of a schedule is to avoid conditioning an empty house and to let temperature drift when nobody notices.
Morning. Start warming about half an hour before the alarm, so it reaches comfortable at wake-up rather than starting then.
Daytime, empty house. Set back several degrees. Fall is forgiving here because outdoor temperatures are mild enough that the house does not lose heat quickly, so a larger setback costs nothing in recovery time.
Evening. Back to comfortable before you get home.
Overnight. Set back again. Most people sleep better cooler, and this is the longest stretch of the day.
Weekends. A separate program. Most thermostats support it and most people never set it up.
Many people believe that letting a house cool and reheating it costs more than keeping it steady. For a conventional furnace, that’s not true.
Heat loss depends on the temperature difference between inside and outside. A cooler house loses heat more slowly, so during setback you lose less energy than you would have. Reheating costs something, but less than you saved.
Two exceptions matter.
Heat pumps. Deep setbacks work differently. Recovering from a large drop can trigger auxiliary electric resistance heat, which is expensive and can erase the savings. With a heat pump, use modest setbacks of a few degrees, or a thermostat with adaptive recovery that starts early enough to recover on the heat pump alone.
Very cold weather. Do not go below 55 degrees in freezing weather because of pipe risk. If you travel during a cold snap, keep it higher than you might think and open cabinet doors under sinks on exterior walls.
A thermostat measures one spot. If that spot is not representative, the schedule you set is not the schedule you get.
Problem locations: direct sunlight at some point in the day, an exterior wall, directly above or below a supply register, near a kitchen, in a hallway with no airflow, or beside a lamp or television.
If your house is consistently warmer or cooler than the thermostat says, location may be the cause, and relocating it can solve a comfort problem no amount of programming will fix. It is also a common contributor to uneven heating.
Auto. The blower runs only when heating or cooling. Standard.
On. Continuous. Better filtration and better mixing between floors, at the cost of more blower energy. Modest on a variable-speed blower.
Circulate or timed. Runs the blower a set number of minutes per hour regardless. For fall this is often the best of both, especially with air filtration or a two-story house.
Replace the batteries, even if it seems fine. Many models fail without warning, and a thermostat that dies in December is a no-heat call.
Reprogram after a power outage. Some thermostats revert to factory defaults, and factory defaults are not your schedule.
Check the changeover setting on a dual fuel system. The temperature where control passes from heat pump to furnace should be set for your actual rates, not left where it shipped. More in dual fuel systems explained.
Confirm it is level if it is an old mercury bulb unit.
If your thermostat has no schedule, has a mercury bulb, does not match your equipment type, or is more than about fifteen years old, replacing it is one of the least expensive HVAC improvements available.
Compatibility is the important part, and we cover it in smart thermostat compatibility. Thermostat service is straightforward work, and getting the right one for your system matters more than the feature list.
J&J has served Southwest Michigan for over 50 years.
No. For a conventional furnace, setting back while you are asleep or away saves energy, because a cooler house loses heat more slowly. Heat pumps are the exception and do better with smaller setbacks.
Once overnight lows are consistently dropping into the 40s and 50s. Switch the mode over rather than relying on Auto with narrow setpoints.
Whatever you sleep well at, and not below 55 degrees in freezing weather because of pipe risk. Many people are comfortable in the low to mid 60s overnight.
If your fall thermostat settings still leave the house too warm or too cold, J&J can check the thermostat and the system behind it.
Schedule service online or get in touch at (269) 965-1627 today! Prefer to pick a time yourself? Book your visit online.
9000 M-66 South • East Leroy, MI 49051
(269) 965-1627
Monday - Friday: 8:00am - 5:00pm
