Boiler replacement cost

The same guide says a basic boiler can cost less than $3,500, a top-tier high-efficiency model can exceed $8,000, and labor can add around $2,000 depending on location and how complex the job is.

• Fuel. Gas, oil, propane and electric boilers are priced differently. Switching fuels adds work, such as a new gas line or removing an oil tank.
• Efficiency level. A standard boiler vents into a chimney. A high-efficiency condensing boiler needs new plastic vent piping through a wall or roof and a drain for condensate. The equipment costs more and the installation takes longer.
• Size. Boiler output should come from a heat loss calculation for your house. Copying the size of the old boiler often leads to an oversized unit that costs more and cycles too often.
• Hot water or steam. Steam systems need a steam boiler and an installer who knows near-boiler piping. Fewer contractors do this work well.
• Combination units. A combi boiler that also makes domestic hot water replaces a separate water heater but needs enough gas supply and more piping changes.
• What is around the boiler. A chimney liner, new circulator pumps, an expansion tank, zone valves, a backflow preventer or asbestos on old pipes can each add to the bill.
• Removal. Old cast-iron boilers are heavy. Hauling one out of a basement takes a crew.

• Boiler brand, model, output in BTU and efficiency rating.
• The heat loss calculation used to pick the size.
• Venting plan: existing chimney, new liner or new sidewall vent.
• Near-boiler piping, pumps, valves, expansion tank and controls, listed by item.
• Gas or oil line work, electrical work and the permit.
• Removal and disposal of the old boiler.
• Startup, combustion testing and system purge.
• Manufacturer's warranty and the installer's labor warranty.

Get at least two quotes on the same type of boiler. A standard boiler quote and a condensing boiler quote are not comparable until you account for venting and long-term fuel use.

Boilers have fewer moving parts than furnaces, and many problems are repairs: a circulator pump, an expansion tank, a zone valve, an igniter or a control. The boiler repair page covers those faults and what they involve.

Replacement is the sensible path when the boiler itself is leaking from the heat exchanger or cast-iron sections, when it has a cracked section, when parts are no longer made, or when repairs are frequent and the boiler is old. A leak from a fitting, valve or pump is different from a leak in the boiler body, so ask the technician to show you where the water is coming from.

If your quote is high mainly because of a move to high-efficiency equipment, ask for the standard-efficiency price as well. Other replacement prices are in the HVAC cost guides.