The short answer
The things that hurt a furnace in Northern Virginia are mostly small habits: pressing the reset button over and over, running it without a filter, boxing it into a closet and storing paint beside it. None of them costs anything to stop. Here’s the list we’d give a neighbor, and what to do instead.
Filters
Don’t run it without one. Dust that gets past the filter ends up on the blower wheel and the heat exchanger. That wheel in the photo is what it looks like. Don’t wash a disposable one. It comes back with less filter and more holes. Don’t buy the highest MERV on the shelf because it sounds better. A thick, tight filter can choke a system built for something looser. Which filter your furnace actually wants.
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
Press it once. If the furnace trips again, stop. The reset is telling you a safety shut it down for a reason, like overheating or a flame it couldn’t read, and pressing it again doesn’t fix the reason. Go through this list when the heat is out, then call.
While you’re in there: don’t tape down the door switch or run it with the panel off. That switch is there so the blower doesn’t run while the burner compartment is open.
Where it lives
Don’t store things against it. The National Fire Protection Association says three feet from anything that burns. Paint, gas cans and solvents shouldn’t be in the room at all, since a gas furnace has a flame in it. Don’t seal up its closet either. A gas furnace pulls air to burn. If your closet door has louvers, they’re there on purpose, so don’t replace it with a solid door. Don’t block the returns or close vents to save money. It breathes through those. We covered that one in our list for keeping the house warm.
What not to ignore
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Swipe to see all columns →
| If you notice | Don’t | Do |
|---|---|---|
| It runs a few minutes, shuts off, starts again | Don’t call it normal | Find out why it short cycles. It’s hard on the parts. |
| A burning smell | Don’t assume it’s always dust | Dust on the first run is normal and fades fast. Here is when it isn’t. |
| Water around the base in winter | Don’t mop and forget it | A high-efficiency furnace makes water and drains it. A clogged drain can shut the heat off. |
| A carbon monoxide alarm | Don’t pull the battery | Get everyone outside and call 911, then read this. |
| A tech shuts it off for a cracked heat exchanger | Don’t turn it back on | Ask to see the crack, and get a second look if you want one. What that crack means. |
Timing
Don’t let the coldest night be its first run. Everyone’s calling that night. Run this test while you can still get an appointment. Don’t turn it up to 85 to warm up faster, because heat comes out at the same rate. What to set it to instead. Don’t run a space heater all season to avoid looking at the furnace. The space heater rules are here, and a room that’s always cold has its own real fixes.
And when it’s getting old, don’t let it pick the day for you. How long a furnace really lasts tells you when to start thinking about it, on your schedule and not at 2 am in January.
Questions people ask
Once. If it trips again, something is making it shut down, and pressing it more only hides that. Leave it off and call.
Can I run my furnace without a filter?
Not for long. Without one, dust coats the blower wheel and the heat exchanger, and that’s a much bigger cleaning than a new filter. If you’re out, buy one today.
Is it safe to store things next to a furnace?
The National Fire Protection Association says to keep anything that can burn at least three feet from heating equipment. Paint, gas cans and solvents shouldn’t be in that room at all.
Should I run a furnace after a technician shuts it off for a cracked heat exchanger?
No. Leave it off until someone’s confirmed it, and it’s fine to ask a second company to look. Have them show you the crack.
Book it
Want somebody to go through it before the cold gets here? The heating check is $67 per system through December 31, on a furnace, heat pump or boiler. Book it from goswiftpro.com/cookiesoffer and free MOLTN cookies come with the visit. Or call (703) 997-9757. SwiftPro is rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
