Getting your HVAC ready for winter

What does a pre-season heating check cover?

A pre-season heating check is a contractor's visit that inspects the parts you cannot see and adjusts the ones that drift. ENERGY STAR's maintenance checklist says the annual check should tighten electrical connections, lubricate moving parts, inspect the condensate drain, and, for heating, check the gas or oil connections, the gas pressure, the burner combustion, and the heat exchanger, because a dirty burner or a cracked heat exchanger causes improper burner operation. It says to do it in the fall, before the contractors get busy.

The annual HVAC tune-up guide explains what to ask for, what the technician should leave in writing, and what to record. If the house has a fireplace or a wood stove, the chimney gets its own annual inspection, and chimney and fireplace safety covers it. Book both in September; the point of the fall date is that the crew shows up before the cold does.

What can you do yourself before the first cold night?

Before the first cold night, do the homeowner's part: a new filter, a clear path around the equipment, open registers and returns, a look at the vent pipes, a thermostat check, and a test run on a mild day. None of it needs a tool beyond a screwdriver, and all of it catches the failures that turn into a no-heat call on the coldest night of the year.

1. Replace the filter and write the date on the frame. ENERGY STAR says to check it every month during heavy use months and to change it at a minimum every three months; the filter guide covers sizes, ratings, and airflow direction.
2. Clear three feet around the furnace, air handler, and water heater. Boxes, paint, and laundry migrate toward the utility closet over summer.
3. Open every supply register and return, and pull furniture and rugs off them. Leave them open; the system was sized with all of them open.
4. Look at the vent pipes on a gas furnace or water heater for rust, gaps, or sagging, and at the PVC intake and exhaust on a condensing furnace for blockages outside. Do not disassemble anything; note what you see for the technician.
5. Check the thermostat: fresh batteries if it takes them, and the mode switched to heat.
6. Run the heat on a mild day for fifteen minutes. Listen for new noises, smell for anything beyond the first-run dust smell, and feel for warm air at the farthest register. Done when: every room gets warm air and the system cycles off on its own.
7. Walk the ductwork you can see in the attic, crawlspace, or basement for disconnected runs or crushed flex duct; sealing and insulating ductwork is the follow-up if you find them.

Inspecting the furnace before heating season is the step-by-step for the equipment itself, including the point at which you stop and call.

What is different for a heat pump?

A heat pump is different because it heats by moving heat from outdoor air, it runs longer and gentler than a furnace, and it has an outdoor unit that needs to breathe in winter. ENERGY STAR's heat pump page says not to set the thermostat back when you are away or asleep, to set it to heat rather than auto so it does not switch modes on an unseasonable day, to use the auto fan setting, and to clean the filter when it is visibly dirty or the filter light says so.

ENERGY STAR also notes that certified cold climate units are tested down to 5 F and keep working below that, but a back-up heat source is most efficient at lower temperatures. Know which backup your system has (electric strips, a gas furnace in a dual-fuel setup) and confirm in fall that it works. Heat pump care in winter covers the outdoor unit, the defrost cycle, and what steam off the coil means.

How should you set the thermostat for winter?

Set the thermostat for the equipment and the weather, not for a number you read somewhere. With a furnace, the DOE's home energy checklist says a programmable thermostat that sets back automatically at night saves energy; with a heat pump, ENERGY STAR says to hold one temperature. On a hard-freeze night, the Red Cross rule overrides both: keep the thermostat at the same temperature day and night so the pipes in exterior walls stay above freezing.

That last rule is the one people miss. A setback that is fine in November can be the reason a kitchen supply line freezes in January, because the coldest hours of the night are the ones the thermostat was told to ignore. Freeze warning: what to do tonight is the short list for those nights, and setting a thermostat schedule covers the everyday program. When the house is empty in winter, the Red Cross says heat on and no lower than 55 F.

Which safety checks go with the heating season?

The heating season's safety checks are clearance, alarms, and the gas rule. The NFPA's heating tip sheet says to keep anything that can burn at least three feet from the furnace, fireplace, wood stove, or space heater, to test smoke alarms at least once a month, and never to use the oven to heat the home. Ready.gov's winter page repeats the oven rule and adds the carbon monoxide detectors with battery backups.

Test the smoke and CO detectors at the start of the season and monthly after that. If a portable heater will be part of the plan, space heater safety has the placement and cord rules, and the winter maintenance checklist keeps the monthly loop going once the season starts.