Cohasset · Boilers
Cold radiators, a leaking boiler, or an aging system in an older Cohasset home? Learn what to check and what to ask, then reach an independent local HVAC contractor.
Cohasset, Massachusetts
Cohasset grew outward from three early settlements, the village center, the harbor, and Beechwood, according to the town's master plan land use chapter (final draft, May 2019). Census estimates count 910 homes built in 1939 or earlier, about 28% of the housing stock. Many houses of that vintage were built around a boiler and cast iron radiators, and plenty still run on one.
Hydronic and steam systems are durable, but they have their own failure points: air trapped in the piping, a circulator that seizes, an expansion tank that loses its charge, a relief valve that drips, or sediment building up after decades of service. Knowing which symptoms point where helps you describe the problem clearly when you call.
This page covers the warning signs, the checks that are safe to do yourself, and what a repair or replacement in Cohasset involves. A call or online request connects you with an independent heating contractor who works in town.
That pattern usually means air in a hot water radiator. Bleeding it often helps, but if it keeps coming back, the system may be drawing in air somewhere.
In steam systems, water trapped in pitched-wrong piping causes hammering. In hot water systems, noise can point to a failing pump or trapped air.
A pressure relief valve that drips or discharges may be reacting to an expansion tank problem or excess pressure. Don't cap or plug it; call a technician.
Most residential hot water boilers run within a modest pressure range. A reading near zero or near the relief setting is worth a service call.
Water seeping from the boiler's sections or base can mean internal corrosion. On an older cast iron boiler, that often starts the replacement conversation.
Local knowledge
The age and origins of Cohasset's houses explain a lot about the systems inside them.
Prewar Housing
Older systems were often sized for drafty walls and single-pane windows. If your house has since been insulated or had windows replaced, a new boiler can frequently be smaller than the one it replaces, which is worth checking with a heat loss calculation.
Source: U.S. Census Bureau ACS
Summer Cottages
The draft master plan chapter says Jerusalem Road saw the town's first private summer cottages in the 19th century. If your house started as a seasonal home, ask the contractor to trace how heat was added later, since piping in those conversions can run through unheated spaces.
Code Oversight
As archived in February 2026, Cohasset's Building and Inspections page said the department administers the state building, electrical, and plumbing codes and handles gas inspections. A boiler replacement typically touches several of those, so expect a permit and an inspection.
Source: Town of Cohasset (archived page)
Right now
Start with safety, then a few checks that are within a homeowner's reach.
Take everyone outside and call 911 or National Grid's gas emergency number from there. Don't touch switches or the boiler on the way out.
Note the pressure and temperature reading on the boiler gauge. That number helps the technician narrow the cause before arriving.
With a radiator key and a rag, open the bleed valve until water replaces the hiss of air, then close it. Skip this on steam systems, which use automatic vents.
Don't open the boiler's fill valve, adjust the pressure reducing valve, or touch the burner. Those adjustments belong to the technician.
What to expect
A service visit usually covers the burner and combustion test, the circulator pump, expansion tank charge, relief valve, low-water cutoff on steam systems, and the venting. On older systems, the technician may also walk the house to see which radiators lag and why.
If replacement makes sense, the contractor files the permit with Cohasset's Building and Inspections department, which handles gas and plumbing inspections and, per its February 2026 archived page, takes permits online. Switching from oil to gas or a heat pump adds steps for the tank and possibly the chimney.
Prewar basements can be tight, with steep stairs and fieldstone walls, and an old cast iron boiler may need to be broken apart to remove. Ask how the contractor plans to get the old unit out and the new one in before the work date.
Hire smart
Massachusetts has no single HVAC license. Gas work needs a gas fitter license, oil burner work a Department of Fire Services certificate, ductwork a sheet metal license, and larger refrigeration systems a refrigeration technician license. Most heating and cooling installs need a town permit.
Gas boiler work needs a Massachusetts gas fitter license, which you can confirm on the state occupational license lookup. Oil boilers need a technician with a Department of Fire Services certificate, verified on that agency's site.
Steam systems behave differently from hot water. If your house has steam, ask how many steam systems the contractor has worked on and what they check first.
A new high-efficiency boiler can often reuse existing cast iron radiators. Ask how the contractor will protect the new boiler from sediment in old piping.
Have the estimate list the boiler model, near-boiler piping, venting changes, permit, removal, and any Mass Save offer the contractor expects.
Costs
On repairs, the part and its availability lead the way. A circulator or relief valve is a common swap, while a cracked cast iron section on an old boiler may not be repairable at all, and parts for discontinued models can take time to find.
Replacements in prewar Cohasset houses can involve chimney liners, new venting, removal through a tight basement, and repiping near the boiler. Fuel conversions add more. Get written estimates from more than one contractor, and ask each how the system was sized and which Mass Save offers through National Grid might apply.
More help in Cohasset
Every page below is written for Cohasset homes. Or start from the Cohasset hvac guide.
Questions
Still not sure? Send a short request and a local pro can answer the specifics.
Uneven heat often comes from air in the piping, a zone valve or circulator that isn't opening, or radiators that were never balanced. A technician can trace which zone is underperforming and why.
Usually, yes. Cast iron radiators hold heat well and pair nicely with modern boilers. The contractor should flush or filter the old piping so sediment doesn't foul the new equipment.
Yes, expect one. Cohasset's Building and Inspections department handles gas and plumbing inspections, and permits are filed online. Your contractor typically pulls the permit and arranges the inspection.
It can, if pipes run through crawl spaces, porches, or unheated additions added during a conversion. Ask a contractor to identify exposed runs and suggest insulation, rerouting, or antifreeze where appropriate.
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