Six checks before you pay a call-out fee
- Thermostat — set to HEAT, and set above the current room temperature. Obvious, frequently the answer.
- Thermostat batteries — a dying thermostat displays fine and stops calling for heat. Swap them.
- The furnace switch — there’s a switch that looks exactly like a light switch on or beside the furnace. People flip it while carrying laundry and never connect the two events.
- The breaker — even gas furnaces need electricity for the blower and controls.
- The filter — a clogged filter restricts airflow, overheats the exchanger, and trips the safety limit. If it’s grey, replace it and try again.
- The door panel — the front panel has an interlock switch. If it isn’t seated properly, the furnace will not ignite, by design.
These six account for a meaningful share of “my furnace is dead” calls, and they cost nothing to rule out.
Then call the right trade — route by what’s in the basement, not by “no heat”
“No heat” is the single most useless thing you can say when booking, because it fits five different trades. Go and look at the appliance first, then call.
Metal box, blows air through vents, gas line into it → forced-air furnace. HVAC technician.
Outdoor unit that also runs in summer → heat pump. HVAC technician. Note that heat pumps blow air noticeably cooler than a furnace does and go briefly cold in defrost cycle; if the house is holding its temperature, it is probably working.
Radiators or baseboard pipes, and a tank-like unit with pipes and a pump → boiler. This is where people get bounced. In much of the US boiler work sits under a plumbing licence, and plenty of forced-air HVAC companies decline it. Ask “do you service hot water boilers” before dispatch, not after.
Radiators that hiss and clank, one pipe per radiator → steam. A specialist, and there are not many. A general HVAC tech will often make it worse.
Oil tank in the basement or beside the house → your oil supplier’s service department, not a gas HVAC company. Service is frequently bundled with your delivery contract. Check the tank gauge first: a meaningful share of oil “no heat” calls are an empty tank and a delivery, not a repair.
Electric baseboard heaters, or an electric furnace with no gas line → electrician. There is no combustion appliance to diagnose.
No gas at any appliance in the house → the utility, free. The test takes ten seconds: try to light a gas stove burner. Lights normally means you have gas and the fault is the heating appliance. Won’t light means the problem is upstream and an HVAC diagnostic fee would be wasted. Check your account for a non-payment shutoff while you’re at it.
And the override on all of it: if you smell gas, leave the house first and call from outside. No heat is an inconvenience; a gas leak is not.
Calling in the right order
If you rent, the landlord comes before any contractor. Not after, and not in parallel. Book your own technician first and you will very likely eat the bill — most leases require written notice and an opportunity to repair before you can charge anything back, and a landlord who was never given the chance owes you nothing. Report it in writing with a timestamp first. Details on the deadlines are further down this page.
If you own, run the six checks, then the burner test, then call. The order matters because the first two are free and the third has a call-out fee attached. A dead thermostat battery diagnosed at 11pm on a Sunday costs the same as a failed inducer motor diagnosed at 11pm on a Sunday.
Emergency versus morning. If the house is above freezing, you have space heaters, and nobody in the house is elderly, very young, or unwell, the after-hours premium usually buys you nothing that waiting until 8am wouldn’t. If pipes are at risk or someone vulnerable is in the house, pay it.
Before you buy a furnace on the coldest night of the year
Cold snaps are when the heating trade does its highest-pressure selling, and the sequence is consistent: a diagnostic visit, a cracked heat exchanger or a failed control board, the unit declared unsafe or uneconomical, and a replacement quoted on the spot with a discount that expires if you think about it overnight.
Sometimes that is all true. Verify it anyway:
- Ask for photographs of the fault. A crack, a burnt board, a seized motor — every technician has a phone.
- Ask for the combustion analyzer reading in parts per million, if carbon monoxide is being cited.
- Ask for the red tag. A genuinely unsafe appliance gets condemned in writing. No paperwork, no condemnation.
- Ask what the repair would cost, separately from the replacement. If the answer is “we don’t repair units that age”, that is a business policy, not a diagnosis.
Then check the arithmetic. Fixr puts a full furnace replacement at $2,800 to $7,500, national average $4,800. HomeAdvisor puts a typical furnace repair at $133 to $505, with an ignitor at $150 to $500 and a flame sensor at $150 to $250. The gap between those is why the pressure exists.
The other thing that gets attached to emergency heating calls is duct cleaning. It does not restore heat, it is rarely urgent, and Fixr prices it at $300 to $700, national average $500 for a 2,000-square-foot home. Sold at four figures at midnight in January, it is being priced against your circumstances rather than the work. Decline it and book it in spring if you want it.
And if the answer really is a new furnace, it does not have to be tonight, and it does not have to be financed on the doorstep. Space heaters and one night buy you a second quote in daylight.
Staying safe while you wait
Space heaters are fine when used properly: three feet of clearance from anything that burns, plugged directly into a wall outlet rather than an extension cord, and switched off when you sleep or leave. Close doors to unused rooms and concentrate heat where people are. Open cabinet doors under sinks on exterior walls so pipes don’t freeze — a no-heat night in a cold snap turns into a burst-pipe morning surprisingly often.
What to never do: heat the house with a gas oven, or run a generator or charcoal grill anywhere indoors, in a garage, or near a window. That’s the sequence that turns a cold night into carbon monoxide poisoning.
If you rent
Heat is not optional. Most jurisdictions treat loss of heat in winter as a habitability emergency with a defined response window, often 24 hours. Report it in writing with the time, keep a log of indoor temperatures, and if the landlord misses the deadline, contact code enforcement. In many places you also have remedies like repair-and-deduct — but only if you documented the notice properly first.
If cost is the barrier rather than a landlord, LIHEAP (the federal Low Income Home Energy Assistance Program) and local 211 services exist precisely for this, including emergency furnace repair in some states.