A boiler that stops working is often down to one of nine things: a thermostat issue, no power, low pressure, a failed pilot or ignition, a tripped breaker, a closed gas valve, a water leak, air in the system, or a frozen condensate pipe. You can check most of them yourself in a few minutes with a flashlight and a rag. Below, we walk through each one in a sensible order, and say when it's time to stop and call a technician.
Boston Boiler Repair Co is a free referral line that connects Boston callers with independent local boiler companies. If these checks don't get your heat back, call and we'll connect you. Here's how to run them.
Why is my boiler not working in Boston?
A boiler stops heating when it loses one of four things: fuel, ignition, water or electricity. Boston's many older homes make this more likely, with older pipes, older wiring, and boilers that have been repaired more often than replaced. Add a hard freeze in January and a brief power outage, and you've got the recipe for a cold morning.
Before you call anyone, run the nine checks below. They'll either fix the problem or give the technician a head start when you do call.
1. Check the thermostat and its batteries
A dead thermostat battery is one of the most common reasons a boiler that isn't broken at all seems to have stopped. That's especially likely in older homes with a battery-powered thermostat in a cold hallway.
Walk to the thermostat. If the display is blank, replace the batteries, usually two AA or AAA cells. If it has power, set it to Heat and push the temperature 5°F above the current room temperature. You should hear the boiler start within a minute or two. If nothing happens, move on to check two.
2. Confirm the boiler has power
Find the boiler and look for a power switch on or near the unit. It's usually a standard light switch on the wall within arm's reach. If it's off, flip it on. If it's on and the boiler still won't start, check the display or indicator light on the boiler. A blank panel with the switch on means the boiler isn't getting power, which points to a breaker or wiring issue.
If the boiler is totally dead, with no lights and no sounds, the problem is usually upstream of the boiler itself.
3. Look at the boiler pressure gauge
On a hot-water boiler, the pressure gauge typically reads about 12 to 15 PSI when the system is cold; check the label or manual for yours. Many boilers lock out when pressure drops too low, which is a safety feature, not a fault. Pressure near the relief valve setting (often 30 PSI) points to a different problem, often a failed pressure-reducing valve or expansion tank. Steam boilers run at very low pressure and use a different gauge.
If the gauge reads low on a hot-water system, you can top it up using the fill valve, a small lever or knob on the pipe near the boiler. Open it slowly, watch the gauge, and close it when you reach the normal cold pressure. If the pressure drops again within a day, you have a leak; see check seven.
4. Check the pilot light or ignition
Boiler pilot light problems Boston homeowners run into most often happen on older atmospheric boilers with a standing pilot. Look through the small sight glass on the front of the burner compartment. If you see a small blue flame, the pilot is fine. If you see nothing, the pilot is out.
On a standing-pilot boiler, the relight procedure is usually printed on a label inside the access panel. Follow it exactly. If the pilot won't stay lit after two attempts, the thermocouple has likely failed, which is usually an inexpensive part and a quick job for a technician. If you smell gas, don't try to relight it.
If your boiler has electronic ignition (no standing pilot), you'll hear a clicking sound when it tries to fire. No click means the ignition module or its power supply is the problem. Clicking with no flame means gas isn't reaching the burner - see check six.
5. Inspect the circuit breaker and emergency switch
Go to your electrical panel and find the breaker labeled for the boiler. If it's tripped (the switch sits between On and Off), reset it once. If it trips again immediately, stop - you have a short or a failing component, and resetting it repeatedly can damage the control board.
Also check the emergency shut-off switch, usually a red switch plate mounted at the top of the basement stairs or beside the boiler room door. If someone bumped it while carrying boxes, the boiler has no power no matter what the breaker says.
6. Check the gas supply and shut-off valve
Follow the gas line from the boiler back to the wall. There should be a shut-off valve - usually a lever-style ball valve. If the handle is perpendicular to the pipe, the valve is closed. Turn it parallel to the pipe and try firing the boiler again.
If you smell gas at any point during this check, stop immediately, leave the building, and call 911 or your gas utility's emergency line from outside. Don't flip switches, don't use your phone inside, and don't try to relight anything.
7. Look for water leaks and low water level
A leaking boiler is often a sign of a failed circulator pump gasket, a corroded section of pipe, or a bad pressure relief valve. Look for drips under the boiler, rust streaks on the floor, or water stains on the ceiling below the boiler room.
If you find an active leak, shut off the boiler at the emergency switch and close the water feed valve, then call. A boiler that runs short of water can overheat and crack its heat exchanger, turning a repair into a replacement.
8. Listen for unusual noises
A noisy boiler is usually telling you one of three things. Banging or hammering, especially on steam systems, often means water trapped in the pipes. Gurgling means air in the system that needs to be bled. Whistling or screeching can mean the pressure is too high or a circulator pump bearing is failing.
For gurgling on a hot-water system, you can bleed the radiators yourself with a radiator key. Many technicians start on the top floor and work down. Open the bleed valve until water dribbles out steadily, then close it, and check the pressure afterwards. Steam radiators don't bleed this way; they have air vents that can stick. If the noise continues, have a technician look at it.
9. Check the condensate pipe (high-efficiency boilers)
If you have a high-efficiency condensing boiler, it produces condensate that drains through a plastic pipe, sometimes out through an exterior wall. On a very cold night, that pipe can freeze, the boiler senses a blocked drain, and it locks out.
Find the plastic condensate pipe leaving the house near the boiler. If it's iced at the end, pour warm (not boiling) water over it until the ice clears, then reset the boiler once. If it locks out again, the pipe may be pitched wrong or exposed, and a technician should reroute or insulate it.
Common mistakes to avoid
The biggest mistake is resetting a boiler over and over without fixing the underlying cause. A lockout is the boiler protecting itself. Reset it once. If it locks out again, stop and call.
Other mistakes worth avoiding:
- Adding water without checking pressure. Overfilling stresses every gasket and the relief valve. Fill to the normal cold pressure for your boiler and stop.
- Ignoring a slow drip. A slow drip adds up to gallons over a few days, which is enough to drop pressure and let the boiler run short of water.
- Bleeding radiators with the system running. Shut the boiler off first, or you'll pull air into the system instead of pushing it out.
- Using the wrong reset procedure. Every boiler brand has its own reset sequence. Check the label on the unit, not a YouTube video for a different model.
If you've run all nine checks and the boiler still won't fire, you've likely narrowed it down to a component failure: control board, gas valve, circulator or heat exchanger. That's the point where a technician with the right test equipment saves you money.
When to call a professional
Call a professional the moment you smell gas, see water actively leaking from the boiler, or find the breaker tripping repeatedly. Those three situations are not DIY territory - they're safety issues.
For everything else, the rule of thumb is simple: if you've run the nine checks above and the boiler still won't fire, the next step is a diagnostic visit. Call to be connected with a local company for boiler repair in Boston, and tell them your boiler's brand so they can bring common parts such as thermocouples, igniters and circulator pumps.
Ask the company about any diagnostic or trip fee before they come out, and whether it's credited toward the repair.
Frequently Asked Questions
Why is my boiler not working in Boston?
Common causes include low system pressure, a tripped breaker after a power outage, a dead thermostat battery, and a frozen condensate pipe on a high-efficiency boiler during a cold snap. All of these are quick to check.
What should I check before calling a boiler repair in Boston?
Check the thermostat batteries, the boiler power switch, the pressure gauge on a hot-water system, the pilot or ignition, the breaker, the gas shut-off valve, and the condensate pipe.
How do I reset my boiler in Boston MA?
Find the reset button on the boiler or burner, often marked "Reset." Press it once and listen for the boiler to start. If it locks out again, don't keep resetting it; call (617) 691-5446 to be connected with a local boiler company.
Can I fix my boiler myself in Boston?
You can safely handle thermostat batteries, a single breaker reset, pressure top-ups, radiator bleeding and thawing a condensate pipe. Gas work in Massachusetts has to be done by a licensed plumber or gas fitter, and oil burner work by a licensed oil burner technician.
When should I call a professional for boiler repair in Boston?
If you smell gas, leave the building and call your gas utility or 911 from outside. Call a technician if water is leaking from the boiler or the breaker trips more than once. For no heat, call after you've run the nine checks.
Get help with boiler repair in Boston
If your boiler still won't fire after these nine checks, call to be connected with an independent local company. For no heat on a cold night, see emergency boiler repair in Boston.
Call Boston Boiler Repair Co at (617) 691-5446 to be connected with a local boiler company.