Key takeaways
- Safety comes first. If you smell gas or a carbon monoxide alarm sounds, leave the house and call 911.
- Many no-heat calls come from simple causes: the thermostat, the power switch, a tripped breaker, an empty tank, or a dirty filter.
- Do not try to repair gas, oil, or electrical parts yourself.
- Protect your pipes. A house can freeze faster than you expect when the heat is off.
- If the checks do not work, call. We are open 24 hours a day, 7 days a week at (781) 353-8852.
Safety first: when not to troubleshoot at all
Before anything else, rule out danger. A few situations mean you should not try to fix anything yourself.
If none of that applies, you can work through the checks below. Stop whenever something looks unsafe, and call us at (781) 353-8852.
The checks, in order
- Check the thermostat. Make sure it is set to heat, the temperature is set above the current room temperature, and the display is on. If it uses batteries, replace them. Digital thermostats with a blank screen are often a dead battery.
- Check the furnace or boiler switch. Most have a switch that looks like a light switch on or near the unit. It sometimes gets switched off by accident. Make sure it is on.
- Check the breaker. Look at your electrical panel for a tripped breaker labeled furnace, boiler, or heat. Switch it fully off and then on once. If it trips again, leave it off and call us.
- Check the fuel. For oil, look at the tank gauge. If it is empty, you need a delivery, and the burner may need to be restarted by a technician. For propane, check the tank level. For gas, check that another gas appliance, such as the stove, works.
- Check the filter. A clogged filter can make a furnace overheat and shut off. Replace a dirty one.
- Check the vents and radiators. Make sure registers are open and not blocked by furniture. On hot water systems, check that radiator valves are open.
- Check the pressure on a boiler. The gauge usually reads around 12 pounds when the system is cold, though your boiler may differ. Very low pressure can shut a boiler down. Do not refill it unless you know how.
- Check the condensate line on a high efficiency furnace. A blocked drain can trip a safety switch. If you see water pooled around the furnace, call us.
- Look for error codes. Many furnaces have a small window with a blinking light. Note the pattern. It tells a technician a lot.
Do not remove covers from gas or electrical parts, and do not reset a furnace repeatedly. If it does not start after one or two tries, there is a reason. Repeated attempts can build up unburned fuel.
What the symptom tells us
| What you see | Common causes | What to do |
|---|---|---|
| Thermostat blank | Dead batteries, power issue, tripped breaker | Check batteries and breaker |
| Furnace clicks but does not light | Ignition parts, flame sensor, gas supply issue | Call us |
| Blower runs but air is cold | Igniter or flame sensor failure, or a lockout | Call us |
| Oil burner will not start | Empty tank, clogged filter or nozzle, tripped reset | Check oil, then call |
| Furnace starts and quits | Dirty filter, blocked vents, overheating | Replace filter, open vents, call if it persists |
| Boiler runs but radiators are cold | Air in the system, failed circulator, closed valves | Call us |
| Banging or loud noises | Delayed ignition, air in lines, failing parts | Shut off and call |
| Water leaking | Condensate drain, leak in boiler or piping | Call us |
Staying warm and safe while you wait
Warm and safe
- Gather everyone in one room, close the doors, and put towels at the base of the doors to cut drafts.
- Layer clothing and blankets, and keep young children and older family members warm first.
- Never use a gas stove or oven, a charcoal grill, or a generator indoors to heat the house. They can produce carbon monoxide.
- If you use an electric space heater, plug it directly into the wall, keep it away from anything flammable, and never leave it unattended.
- Check carbon monoxide alarms and make sure they have working batteries.
- If anyone in the home is very young, elderly, or has a medical condition, consider staying with friends or family while the heat is out.
Protect your pipes
A house without heat can reach freezing temperatures in a day or two in severe cold, faster if it is windy and the house is poorly insulated. Frozen pipes can burst and cause serious water damage. A few steps help.
- Let faucets on exterior walls drip slightly.
- Open cabinet doors under sinks to let warm air reach the pipes.
- Know where your main water shutoff is.
- Keep the garage door closed and seal drafts where you can.
- If the house will be empty and the heat stays off, ask us about draining the system.
When to call, and what to tell us
Call or text (781) 353-8852. We are open 24 hours a day, 7 days a week. It helps if you can tell us a few things, and you can send them in a text.
What to tell us
- Your name, address, and phone number
- The kind of heat you have, such as furnace, boiler, or heat pump, and the fuel if you know it
- What happened and when it stopped working
- What you have already checked
- Whether anyone in the home is vulnerable to cold
- Any error codes, noises, smells, or leaks
Read more on our emergency service page. If the repair turns out to be a bigger job, see furnace repair and boiler repair and installation.
How to avoid the next cold house
- Book a fall tune-up. Most winter breakdowns start as small problems that a tune-up finds. See maintenance and tune-ups.
- Change filters on schedule.
- Keep oil tanks above a quarter full and arrange regular deliveries.
- Test carbon monoxide alarms and replace them when they expire.
- Know how old your system is. If it is near 20 years, plan for replacement. See when to replace a furnace or boiler.
Questions homeowners ask
Why did my heat stop working in the middle of the night?
Systems run hardest in the coldest hours. A part that was marginal can fail, a filter that was almost clogged can shut the unit down, or a tank can run dry.
Can I reset my furnace myself?
Some units have a reset button, and one attempt is fine if the manual allows it. Do not repeat it. If it does not run, there is a cause that needs a technician.
How cold does it have to be for pipes to freeze?
Pipes can freeze when temperatures stay at or below freezing for a while, especially in exterior walls and unheated spaces. Dripping faucets and open cabinets help.
Is it safe to use an oven to warm the kitchen?
No. It is a fire and carbon monoxide risk. Use safe heating methods and layers.
Do you come out at night?
Yes. We are open 24 hours a day, 7 days a week at (781) 353-8852.
Related services
Sources and further reading
Written by the team at Home Heating and Cooling in Norwell, MA. We review our guides at least twice a year and update them when equipment, codes, or programs change. Last updated October 23, 2026.
