Furnace replacement in Gibbstown, NJ

Signs the furnace is near the end

The repair is to the body of the furnace, not a part on it. A cracked heat exchanger is the classic case. The gas utility can shut the appliance off when it finds one, and on an older furnace the repair costs a large share of a new unit.

The same furnace keeps needing visits. Two or three calls in one heating season usually mean the next failure is already lined up behind this one.

Parts are scarce. Control boards and inducer assemblies for discontinued models can take days to arrive, and a house without heat in January cannot wait days.

It runs on oil and the burner needs constant attention. Soot buildup, repeated lockouts and a smoke reading that will not come down are all reasons to price a new oil furnace, or to ask whether gas is available on the street.

Why the old size is the wrong starting point

ZIP 08027 has a median build year of 1962 according to the Census Bureau's American Community Survey, and 83% of its homes went up before 1980. Since then many have gained insulation, replacement windows, finished basements or additions. A furnace sized for the house in 1975 is often too big for the same house today.

An oversized furnace heats in short bursts, cycles often and leaves rooms uneven. The fix is a load calculation: room dimensions, window area, insulation and air leakage, worked out before a size is chosen. Ask the contractor what the proposed size is based on. "The old one was 100,000 BTU" is not a measurement.

The ductwork matters just as much. Return air that is too small, or a supply trunk with open joints in the basement, will hold a new furnace back no matter what its efficiency label says.

Gas or oil, and the chimney

A new high-efficiency gas furnace condenses its exhaust and vents through plastic pipe out a side wall, not up the chimney. When a lower-efficiency furnace or a water heater still shares the old chimney, the chimney may need a liner sized to what is left on it. A contractor checks this at the survey visit, not on changeout day.

On oil, a replacement oil furnace still uses the chimney. If gas runs past the house, this is the moment to ask whether conversion makes sense. See oil-to-gas conversion.

Changeout day

A like-for-like furnace changeout usually takes one working day: shut off fuel and power, remove the old unit, set the new one, reconnect gas or oil, venting, wiring and the duct plenums, then start up and test. If an air conditioner coil sits on top of the furnace, the contractor will say whether it stays or comes out with the furnace.

Under the state construction code a like-for-like furnace replacement is "minor work": the township construction office is notified before work starts, a permit application follows within five business days, and the job is inspected. Ask who gives the notice and when the inspection is expected.

Questions for the contractor

• What size is proposed, and what measurement of the house is it based on?
• Does the quote include venting changes, a chimney liner, or a new return?
• On a gas furnace, what combustion readings will be recorded at start-up?
• Who applies for the permit, and who meets the inspector?
• What warranty comes from the manufacturer, what comes from the installer, and how long does each run?

What to say when you call

• Gas or oil, and roughly what year the furnace went in
• Whether it is still running, and what it does when it fails
• Whether a central air conditioner shares the ductwork
• Whether a repair figure or a replacement quote is already on the table
• The address and ZIP code, and where the furnace sits