The usual suspects
Starved airflow
A loaded filter or closed vents mean plenty of heat, no delivery. The furnace may also be overheat-cycling.
Duct leaks into attic or crawlspace
Heated air pouring into unheated spaces — far rooms run cold while the crawlspace stays cozy.
A furnace losing capacity
Weak blower, dirty burners, or a failing component — the "it kept up last winter" signature.
Extreme-cold design limits
On rare single-digit nights, running continuously a few degrees short is a right-sized system at its limit — not a defect.
Get the heat you’re already paying for.
Duct leaks and airflow faults waste heat into the crawlspace — we find where it’s going and fix the path.
Book My Same-Day Visit60 seconds online · or call (206) 486-6373
Worth trying first (5 minutes, free)
- 1
Fresh filter, every vent open, returns clear of furniture.
- 2
Feel the supply air: hot at the closest vent but cool far away points at ducts.
- 3
Compare rooms and write down cold ones — the map speeds the visit.
Still not working? Then it’s a technician job — and the sooner it’s booked, the sooner the house is comfortable again. Book the visit →
Stop and book a pro if…
- Supply air is barely warm at the closest register — that’s the furnace, book it.
- The furnace overheat-cycles while the house stays cold.
- Rooms over crawlspaces went cold after pest or cable work — a duct is likely open.
- CO alarm or any gas smell — the usual rules: out first.
Why homeowners hand it to us
- You approve the price first. Upfront quote before a single screw turns.
- Same-day service. Book in a minute, hear from a tech within 1 business hour.
- 500+ jobs done by 4.9★ rated, professional technicians.
- Fixed right, guaranteed. If it’s not right, we make it right.
Quick answers
Is it normal to run constantly in a cold snap?
On design-limit nights, yes — steady running slightly below setpoint is normal and efficient. Failing on ordinary 40°F days is the real flag, and that’s diagnosable.
Ducts or furnace — how do you tell?
Temperature drop across the furnace tells us what it makes; register temperatures tell us what arrives. The gap locates the loss — measured, not guessed, and priced upfront to fix.
Would a bigger furnace help?
Usually the most expensive wrong answer — most "too small" furnaces are actually leaking or choked. We check the cheap causes first, always.
Done guessing?
Running non-stop and still cold means every hour is wasted gas. Book the diagnosis today.
Book My Same-Day Visit60 seconds online · or call (206) 486-6373
More: all problems · heating service · AC service · 24/7 emergency