Listed in our heating and cooling services.
Short answer
The most expensive assumption in a boiler replacement is sizing the new unit from the label on the old one. Buildings change and the original was often oversized already. Ask whether sizing came from a heat-loss calculation, and whether existing radiation suits the lower water temperature a condensing boiler needs. Insulation, windows and air sealing all move the number, so matching the old nameplate perpetuates an error rather than reproducing a success.
The second question matters just as much: a condensing boiler only reaches its rated efficiency at return temperatures that some existing radiators cannot produce, which means the saving on the brochure never arrives. A proposal worth comparing states the calculated heat loss, the radiation it assessed, and what it assumes about the existing distribution.
Jobs this covers
- High-efficiency boiler replacement
- Gas, propane and oil systems
- Combi boiler installation
- Indirect water-heater integration
- Zone and control upgrades
- Boiler and heat pump hybrid planning
Signs a boiler is due for replacement
- The existing boiler fails repeatedly
- Fuel use is high
- The boiler is oversized or short cycles
- A chimney or venting change is needed
- Domestic hot water is inadequate
- A renovation changes heating loads
What service may include
Condensing boilers need low return temperatures. Real scope only shows up on the visit. A complete project may include heat-loss review, equipment selection, removal, piping and controls, venting or chimney work, fuel and electrical connections, startup, testing and permit coordination.
What affects the recommendation and price
An old chimney may need a new liner. Building heat loss, distribution water temperature, fuel, zones, chimney, condensate, electrical work, domestic hot water and code updates shape equipment and price.
What is different around Burlington
An oversized boiler short cycles, which wastes fuel and wears components. Ask what the runtime looks like on a mild day, because that is where oversizing shows.
What a written quote should tell you
- Whether sizing came from a heat-loss calculation on this building, or from the old unit's rating
- Whether the existing radiation was assessed against the new boiler's operating temperature
- Near-boiler piping, circulators, controls and zone work: included or additional
- Venting, combustion air and condensate disposal for a condensing unit
- Startup readings recorded, permits, and warranty registration
| Sizing method | Risk |
|---|---|
| Matches the old unit's rating | Perpetuates an oversizing error the building may never have needed |
| Heat-loss calculation on this building | Accounts for insulation, windows and air sealing done since the original install |
Common questions
Should a new boiler be the same size as the old one?
Not automatically. Older boilers are often oversized. A heat-loss review and radiation assessment support better sizing.
Can I keep existing baseboard?
Often. Its output at the proposed water temperature must match the home’s needs.
Should I install a heat pump instead?
Heat pumps, boilers and hybrid systems each fit different buildings and goals. Compare comfort, design temperature, electrical work, fuel cost and resilience.
What is a condensing boiler and does it work with my radiators?
A condensing boiler extracts extra heat by cooling its exhaust enough that water vapour in it condenses, which is where the higher efficiency comes from. The catch is that it only condenses when the water returning from the system is cool enough, generally below about 130°F, so it needs a system that can run at lower water temperatures. Radiant floors and generously sized radiators do this well. Undersized baseboard designed around 180°F water often does not, and installing a condensing boiler on such a system delivers much of the cost and little of the promised efficiency unless the emitters or the controls change too. Ask this question specifically before you buy one.
How do I know whether to repair or replace my boiler?
Weigh the repair against age, efficiency and the vessel's condition. A component failure on a sound twenty-year-old cast-iron boiler is often worth fixing, because the vessel may have a decade left. A cracked section, chronic leaks or a corroded heat exchanger is a replacement. Between those, the deciding factor is usually fuel: if you are on oil and considering a fuel change or heat pumps, replacing a failing boiler is the natural moment to make that decision, because doing it later means paying for the boiler twice.
Can I install a boiler myself?
No, for the same reasons as gas line work: fuel, venting and pressure vessels together. Boiler installation requires permits in Vermont, involves either fuel gas piping or oil piping, needs a correctly sized and correctly constructed vent, and produces carbon monoxide when done wrong instead of an obvious failure. It also has to be commissioned with combustion instruments to be running as designed. Where a homeowner genuinely adds value is upstream: insisting on a heat loss calculation, and comparing quotes on what they include rather than on the headline number.
What happens if a boiler is replaced without a heat loss calculation?
You get a boiler sized to the old boiler, which was probably oversized to begin with and is now oversized against a house that has been insulated and air-sealed since. The consequences are permanent: short cycling, lower seasonal efficiency than the rating on the box, more wear, and in a modulating condensing boiler, a unit that rarely gets to run in its efficient range. This is the most common and most expensive mistake in residential boiler replacement, and it is invisible because the house is warm. It just costs more every year for twenty years.
How long does a boiler installation take?
A straightforward like-for-like replacement is commonly one to three days. It extends when the fuel changes, when the venting has to change, as it usually does moving to a condensing unit, which needs sealed direct venting, not the existing chimney, when near-boiler piping has to be rebuilt, or when the existing system needs new controls and zoning. In Vermont the scheduling reality is that this work should be planned for spring or summer. A boiler replaced in January is being replaced under time pressure and at whatever price is available.
Do I need a permit and an inspection for a boiler replacement?
Usually. The requirement comes from more than one place, which is why it is worth asking instead of assuming. Vermont certifies the people who do the work: the Division of Fire Safety requires certification for anyone installing, inspecting or servicing natural gas or propane systems, and a Certification of Fitness for oil burner installation work.
Separately, the Vermont Plumbing Rules cover public buildings and any building connected to public water or sewer, and towns can have their own permit requirements on top. This is one of the inspections worth wanting: it checks the venting, the combustion air and the fuel connection, which are the three things that hurt people. Confirm what is in the quote, and get the closed permit and the combustion analysis readings at handover.
What does a new boiler's warranty require?
Boiler warranties commonly run 10 to 12 years on the heat exchanger and shorter on other components, but many manufacturers require professional installation and registration within a set window to keep the full term: a self-installed or unregistered unit can lose years of coverage without the owner realizing it.