Boiler Repair & Replacement in New Haven, CT

New Haven’s housing stock skews older than most of Connecticut, and older homes heat with water, not air. Steam radiators in pre-war buildings and hot-water baseboards in mid-century homes both trace back to one boiler in the basement. That concentration is why boiler expertise matters here more than in newer suburbs: a tech who mostly installs furnaces can misdiagnose a steam system badly.

The two systems behave differently. Steam systems run at higher temperatures, need proper venting at every radiator, and punish low water levels. Hot-water systems depend on circulator pumps, zone valves, and expansion tanks. A quote that does not name which system you have is not a real quote.

Oil-fired boilers need an annual tune-up — nozzle, filter, electrodes, and combustion check — and skipping it is the most common cause of mid-winter no-heat calls. Gas boilers are more forgiving but still benefit from an annual check of the burner, venting, and safety controls. A maintenance visit typically runs $150–$300 and pays for itself the first time it prevents a January failure.

• Circulator pump failure. One zone goes cold while the rest heat. Pumps run $400–$700 installed.
• Zone valve or thermostat faults. A zone that will not call for heat or will not shut off. Usually a $150–$400 repair.
• Expansion tank failure. Pressure relief valve dripping or pressure swings. A straightforward $150–$350 fix.
• Burner or ignition failure. On oil systems, a clogged nozzle or failed electrodes; on gas, an igniter or gas valve. Typically $150–$400, more if the burner itself is failing.
• Leaking sections or a cracked block. On an old cast-iron boiler, this is usually the end: section replacement approaches replacement cost, and replacement is the honest recommendation.

Boiler replacement typically runs $6,000–$10,000 installed, with steam systems and oil conversions at the higher end. The choice that matters most is fuel: stay with oil, convert to gas where the street has it, or move to a heat pump with radiators replaced or supplemented by ductless heads. Each path has different upfront costs and different fuel bills, and the right answer depends on your street’s gas availability, your radiator layout, and how long you plan to stay. Ask every bidder to price the conversion scope — gas line, chimney liner, oil tank removal at $1,500–$3,000 — as separate lines, not buried in the unit price.