Furnace Installation in Princeton, NJ

Furnace Installation in Princeton

Much of Princeton's housing was built before central cooling was normal and often before ductwork was, so heating and cooling arrived separately and at different times. That is why so many houses here run a boiler for heat and something entirely different for cooling.

About 22% of homes in Princeton were built before 1940 — old enough to have been built with radiators and no ductwork at all; 74% of them heat with natural gas, so furnace and boiler work is the bulk of what comes up here. (US Census ACS 2022)

The venting change nobody mentions until afterwards

A furnace above about 90% efficiency is a condensing appliance. It extracts so much heat that the exhaust is cool and wet, and cool wet gases will not rise up a masonry chimney. They vent instead through PVC pipe out a side wall.

That is fine for the furnace. The problem is what it leaves behind.

The orphaned water heater

In a great many New Jersey houses the furnace and the gas water heater share one flue, sized for both. Take the furnace off it and the water heater is alone in a passage far too large for it. Its exhaust travels slowly, cools, and condenses against the masonry — acidic moisture that deteriorates the chimney from the inside and can stop the flue drafting properly. That is a combustion safety issue, not a cosmetic one.

What the fix costs

Usually a correctly sized liner for the water heater, sometimes moving it to a power-vented or condensing model instead. Either way it is real money and it belongs on the quote. A replacement quote that says nothing about the flue on a house with a shared chimney is incomplete rather than competitive.

Where the PVC comes out matters

Clearances to windows, doors, soffits, gas meters and the property line are all specified. On the attached and semi-attached housing common across Hudson, Essex and the older river towns, finding a compliant termination point is genuinely constraining and should be settled before equipment is ordered.

Sizing, efficiency and what to actually buy

Two decisions matter and one of them is usually made badly.

Capacity

From a load calculation on your house. Furnaces are routinely oversized, and an oversized one short-cycles: it satisfies the thermostat quickly, shuts off, and starts again — which is the hardest thing you can ask of the equipment and produces uneven temperatures. A correctly sized replacement is often smaller than what came out.

Efficiency, measured as AFUE

The percentage of the fuel that becomes usable heat. An 80% furnace is the conventional-vent option; 90%-plus is condensing, and that is what triggers the venting change above. In New Jersey's heating season the running-cost difference is real, but so is the venting cost — price both configurations rather than assuming higher is automatically better.

Single stage, two stage or modulating

A single-stage furnace is either full-on or off. Two-stage and modulating units run longer at lower output, which holds temperature more evenly and is noticeably more comfortable. They cost more and they are worth it in a house with rooms that never quite match.

The full guide: everything about furnace installation — how the job works, what decides the price, and the questions worth asking before you book — is on the service page. This page covers what is different about it in Princeton.

Areas we cover in Princeton

We work throughout Princeton, including the areas around Downtown Princeton, Historic Littlebrook, Historic Princeton University and Institute for Advanced Study.