Your Heat Just Went Out. Do These Things First.

It is cold, the house is getting colder, and you want to know whether this is a phone call or something you can sort out.

Work through this in order. It takes ten minutes and it solves a real percentage of the calls I go out on.

Stop first if any of these are true

• You smell gas or oil. Leave the house. Call from outside, and call the gas company or the fire department, not us first.
• A carbon monoxide alarm is sounding. Everyone outside. Call 911.
• You see or smell smoke, or anything is scorched. Same.
• Water is actively leaking from the boiler or furnace. Shut the system off and shut the water off if it is coming from the heating loop.

None of that? Continue.

1. The switch

There is a switch that controls the heating appliance. It looks like an ordinary light switch, usually red or labeled, mounted at the top of the basement stairs or on a wall near the equipment.

People flip it thinking it is a light. Cleaners flip it. Kids flip it. Check it.

2. The breaker

Go to the panel and find the breaker for the furnace, boiler, or air handler. A tripped breaker sits between on and off, and it can be subtle.

To reset properly, push it all the way to OFF first, then back to ON. Halfway does not reset it.

Reset it once. If it trips again, stop. Something is faulting and repeatedly resetting a breaker onto a fault is genuinely dangerous.

3. The thermostat

Set it to HEAT and push the setpoint well above the current room temperature. Ten degrees, so there is no question it is calling.

Change the batteries if it takes them. Low batteries produce weird intermittent behavior and this is a very common find.

If it is a smart thermostat, check that it is not stuck offline, on a schedule somebody set, or in a mode like ECO or AWAY that somebody enabled and forgot about.

4. Fuel

Oil: look at the tank gauge. If it reads empty or near it, that is your answer. Running an oil system dry means it needs to be primed and bled after refilling, which is a service call.

Propane: check the tank percentage. Same story.

Natural gas: confirm other gas appliances work. If the stove lights, you have gas.

5. The reset button

Oil burners have a reset button on the primary control, usually a small red button.

Press it once. If it fires and runs, good. Note that it locked out and mention it when you get it serviced, because a lockout is a symptom of something.

Do not press it repeatedly. Each attempt sprays unburned oil into the combustion chamber. Enough of that and you have a real hazard when it finally does light. Once. That is it.

Gas furnaces generally do not have a manual reset like this, though many will attempt ignition a few times and then lock out. Cycling power at the breaker will usually clear a lockout for one more attempt.

6. Outside, if you have a sidewall vent

High efficiency furnaces and boilers vent through PVC pipes out the side of the house. If those are blocked by drifted snow or ice off the roof, the pressure switch shuts the appliance down.

This is a very common call after a storm and it is a five minute fix. Go look. Clear them carefully. Do not chip at ice against the pipe, and if it is packed hard, warm water works.

Same for the intake pipe if you have two.

While you wait

Protect the house.

Close off unused rooms. Concentrate what heat you have.

Let a faucet drip, the one farthest from where water enters the house. Moving water resists freezing and it relieves pressure so ice does not split a pipe.

Open cabinet doors under sinks on exterior walls so room air reaches the plumbing.

Space heaters, carefully. Directly into a wall outlet, never an extension cord or a power strip. Three feet of clearance from anything. Never unattended, never overnight, never in a room where someone is sleeping. More house fires start this way every winter than from anything a furnace does.

Do not use a gas oven or a grill to heat the house. Every year somebody does this and it kills people. Carbon monoxide has no smell.

If the house is going to sit cold for a while, shut the water off at the main and open the faucets to drain the system. A cold house is a problem. A flooded house is a much bigger one.

When to call

If you went through all six and still have no heat, call. Tell whoever answers what you already checked, because it saves real diagnostic time and you will get a better answer faster.

Give us the fuel type, roughly how old the equipment is, and any noise or error code you saw. Many furnaces flash a diagnostic code on a small LED behind the access panel. If you can read that code off to us, we may show up with the part already on the truck.