Chimney Services in Randolph, NJ

What the numbers suggest for chimneys in Randolph

Census estimates put utility gas at about 73% of Randolph's occupied homes, fuel oil at 14%, electricity at 11% and propane at 1%. With gas this dominant, the chimney in many houses serves a furnace, boiler or water heater as well as, or instead of, a fireplace.

The 9,349 housing units are concentrated in two eras: about 36% from the 1960s and 1970s and 34% from 1980 to 1999, with 15% from 1940 to 1959 and 11% since 2000. Over that span, both the appliances and the ways they vent have changed, and a house may have had its heating equipment replaced more than once. Homes from the later decades may also include factory-built fireplaces.

About 74% of units are detached houses, 7% are attached and 19% are in buildings of two or more units. The figures describe Randolph overall, not any single home.

Three ways a gas appliance gets rid of its exhaust

Building science guidance from Pacific Northwest National Laboratory, drawing on the national fuel gas code's appliance categories, sorts household gas equipment roughly like this:

• Natural draft (atmospheric). The burner draws air from the room, and the heat of the exhaust carries it up a metal vent or a chimney flue. A Nebraska state fact sheet notes that most fuel-fired water heaters and some furnaces work this way.
• Induced draft (fan-assisted). A small fan helps the burner, but the exhaust still relies on the flue's draft, so these units usually still connect to a chimney or a metal vent.
• Sealed combustion (direct vent). Outside air comes in through one sealed pipe and exhaust leaves through another, typically on high-efficiency condensing furnaces. These do not use the chimney at all.

The U.S. Department of Energy notes that direct-vent appliances installed in conditioned space eliminate the possibility of backdrafting, the reversal that pulls combustion products, including carbon monoxide, back into the house.

Reading your own basement, and what it means for the chimney

From the floor, without touching anything, you can usually see where each appliance's exhaust pipe goes. A pipe that runs into the chimney wall means that appliance depends on the flue. Two pipes running to the outside, one bringing in air and one carrying exhaust, point to sealed combustion.

That picture tells you what needs attention:

• If any appliance still vents into the chimney, the flue, connector and cleanout belong on the yearly inspection. Furnace and boiler flue cleaning covers that work.
• If the furnace was switched to direct vent but the water heater still uses the chimney, the flue may now be oversized for a single small appliance. Our guide to the orphaned water heater explains why.
• Natural-draft appliances are the ones exposed to house pressure. The same Nebraska fact sheet lists clothes dryers, kitchen and bath fans and leaky supply ducts among the things that can depressurize a house enough for exhaust to spill in.

When an appliance is about to change

CSIA's inspection guidance lists replacing an appliance with one of different specifications, or changing fuel type, among the reasons for a Level 2 inspection. If you are swapping a natural-draft furnace for a direct-vent model, or the reverse, an inspection before a new appliance records what the chimney looks like before the installer plans the venting.

The same split applies to gas fireplaces; our guide to direct-vent and B-vent fireplaces covers it.

Local questions

Sources

1. U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates (tables B25034, B25040, B25024), via Census Reporter
2. Pacific Northwest National Laboratory, Building America Solution Center: Pre-Retrofit Assessment of Combustion Appliances
3. U.S. Department of Energy, Building Science Education Solution Center: HVAC Direct Vent Equipment
4. Nebraska Department of Water, Energy, and Environment: Combustion Safety Facts
5. CSIA: The Three Levels of Chimney Inspections