Replace your boiler when the repair bills start arriving every season, when parts for your model go scarce, or when the heat exchanger shows corrosion or leaks, and for most boilers that window opens between year 15 and year 25. Age alone is not a verdict: a 20 year old cast iron boiler that has been maintained can be the healthiest thing in the basement. The real question is whether the next repair is buying you years or just buying the next repair. We run the repair-or-replace math below the way we run it in your basement, plus the scheduling truth nobody mentions: the swap you do in September costs you nothing in suffering, and the one you do in January does.
What are the signs a boiler is done?
- Repairs every season. One fix in a decade is maintenance; a fix every winter is a subscription to a failing machine.
- Scarce parts. When a circulator, gas valve, or control board takes weeks to source because the model is orphaned, every future breakdown is a long outage waiting to happen.
- Heat exchanger trouble: visible corrosion, weeping, or water where water should not be. Sections and exchangers are the boiler's heart, and replacing one in an old unit rarely pencils out.
- Short cycling, kettling noises, or rooms that heat unevenly no matter how the zones are balanced.
- A fuel bill drifting upward year over year at the same thermostat settings, which is efficiency leaving the building.
How do you run the repair-or-replace math?
Weigh the repair against the boiler's remaining life, not against its original price. A modest repair on a 12 year old boiler with a clean exchanger is easy money: pay it, and we will tell you so. If it can be fixed, we fix it. The math flips when a large repair lands on a unit already deep in the 15 to 25 year window, because you are spending real money to keep standing next to the same cliff. For scale, a typical seacoast gas boiler swap runs $8,800 to $23,400 installed, confirmed at your site visit, with straightforward swaps landing mid-band; the full cost breakdown lives in Boiler vs Furnace Replacement Cost in NH. When a repair quote reaches a meaningful fraction of that on an old unit, replacement stops being the expensive option and starts being the cheap one measured per year of heat.
Why does swapping in September beat swapping in January?
Because January takes away every choice you have. Boilers fail on the coldest nights, when they are working hardest, and a January failure means you are picking whichever contractor can come fastest, taking whatever equipment is on a truck that week, and paying emergency urgency instead of comparing quotes. A planned September swap inverts all of it: you choose the equipment, compare real numbers, schedule around your life, and walk into heating season with new equipment and a warranty instead of a 22 year old question mark. If your boiler showed the signs last winter, the week you are reading this is the right week to price it. That is a calendar fact, not a sales line.
What does a boiler swap actually involve?
Out with the old unit, then the work that separates a swap from an installation: near-boiler piping rebuilt in clean copper, zones and circulators sorted, proper venting, combustion setup, and a pressure-tested system commissioned before we leave. Gas swaps typically run one to two days; oil systems and boiler-plus-indirect-water-heater combos run longer because there is more system to build. If the water heater is also near its end, say so up front, because an indirect off the new boiler can solve both at once. The boiler page shows our actual installs, five-boiler commercial banks included, because copper work is our signature and stock photos are the industry's tell.
Should you replace it with a boiler at all?
Usually yes, and sometimes no, and you deserve both numbers. A baseboard or radiator house generally gets a new boiler, and a good one. But 2026's rebate programs pay people to at least look at the alternative: cold-climate heat pumps with the boiler kept as backup, or full conversions where the house suits it. There is no federal tax credit anymore, but NHSaves, income-qualified NH HEAR up to $8,000, Mass Save up to $8,500, and Efficiency Maine's tiers are all real, verified July 2026, and none of them pay a dime toward a boiler-for-boiler swap; the details are in the 2026 rebate guide. Our estimate engine prices the straight swap and the heat pump path side by side in 90 seconds, so the decision gets made with numbers instead of habits.
