AM Chimney Sweep inspects, cleans and relines chimneys in Bloomfield. One situation comes up here again and again, and it rarely involves a fireplace at all: a heating upgrade that quietly changes what the chimney is being asked to do.
The “orphaned” water heater
In an older Bloomfield house, the chimney was usually built to carry the exhaust of a large boiler or furnace, with the water heater sharing the same flue. When that boiler is replaced with a high-efficiency unit, the new equipment normally vents through plastic pipe out the side of the house. The water heater is left behind as the only appliance on a flue that was sized for something many times larger.
A small gas flame cannot keep a big, cold masonry flue warm. The exhaust cools before it reaches the top, and the water vapor in it condenses on the flue walls. That moisture is mildly acidic. Over a few winters it eats at clay tile and mortar, and the weak draft makes it easier for exhaust to spill back into the basement instead of going up.
What it looks like
- White, chalky staining on the outside of the chimney, often strongest on one face
- Flakes of clay tile or sandy mortar collecting behind the clean-out door
- Damp patches on the chimney where it passes through the attic or an upstairs closet
- Rust on top of the water heater, or on the metal pipe that connects it to the chimney
- Moisture or a stale exhaust smell near the water heater when it has been running
Why this is common in Bloomfield
Census Bureau estimates show that close to four in ten Bloomfield homes were built before 1940, and more than a quarter are in two- to four-family buildings. That means a lot of tall, original masonry chimneys, and a lot of basements where two or three sets of heating equipment have been swapped out at different times by different owners. Each swap changes the load on the flue.
Source: U.S. Census Bureau, American Community Survey 2020–2024 five-year estimates.
How the problem is fixed
The usual answer is a chimney liner sized for the appliances that actually remain on the flue. A correctly sized liner stays warm enough to draft properly and keeps the acidic moisture off the masonry. Sizing is not a guess: it depends on the input rating of each connected appliance, the height of the chimney and how the appliances are connected.
Before a liner goes in, the flue should be looked at with a camera. If earlier condensation has already loosened tile or mortar, that debris has to come out first, and the inspection tells you whether the damage stops at the flue or has reached the brickwork outside.
Questions we hear from Bloomfield homeowners
My heating contractor did not mention the chimney. Is that unusual?
No. The chimney is often outside the scope of a boiler or furnace replacement. It is worth asking directly what will still be venting into the chimney once the job is done.
How do I tell what is connected to my chimney?
Look in the basement. A metal pipe running from an appliance into the base of the chimney means that appliance uses the flue. White plastic pipes leaving through the foundation wall mean that appliance does not.
Does a gas-only flue ever need cleaning?
Gas leaves little soot, but the flue can still be blocked by a nest, fallen tile or debris at the base. The Chimney Safety Institute of America recommends a yearly inspection for every chimney, including ones that serve only gas appliances.
Related chimney services in Bloomfield
- Liner installation and replacement
- Camera inspections before or after a heating upgrade
- Clay-tile flue repair where the tiles are still sound
- Chimney cleaning and removal of fallen debris
- Caps to keep rain out of a flue that is already running cool
Book an inspection
Call (862) 225-6529 or request a visit online. Tell us what heats the house and the water, and whether any of it was replaced recently. For an example of this kind of job, see our liner installation and crown repair project in Jersey City, or browse Our Work.