Replacing a Boiler or Furnace? Check the Chimney First

When an old boiler or furnace comes out and a modern one goes in, the existing masonry flue is frequently wrong for the new appliance. It can be oversized, unlined, or already damaged by decades of acid condensate from the old unit. Finding that out before install day keeps the project on schedule.

WHY THE FLUE HAS TO MATCH THE APPLIANCE

A flue is sized for the appliance it serves. An old atmospheric boiler sends a large volume of hot gas up the chimney. A modern unit runs cooler and produces less, so the same flue can be far too big for it. Gases that cool too much on the way up condense, and gas and oil condensate is acidic.

That acid eats mortar joints, flue tile and masonry from the inside, where nobody is looking. By the time it shows on the outside of the building, the flue has been leaking for a long time.

THE APPLIANCE LEFT BEHIND

A common version of this happens at home. A high-efficiency furnace or boiler often vents out the side of the house through its own pipe. The water heater that shared the chimney with the old unit is then left alone in a flue sized for two. Draft weakens and condensation builds, and the flue usually needs a liner sized for what is still connected to it.

NOT THE MECHANICAL CONTRACTOR'S TRADE

The flue problem usually gets discovered mid-project, and the flue is not the mechanical contractor's trade. We handle that part, and we work alongside the contractor installing the new equipment. Call us before the old unit comes out, not after it stalls the schedule.

HOW WE RELINE A BOILER FLUE

FuranFlex FF1 is a composite liner that goes in soft through the existing openings, then cures hard into one seamless piece. It retains nearly the full area of the flue, follows offsets around structure, and needs no demolition. Most jobs are one day on site, and it carries a 25-year warranty.

UL 1777 — Listed for venting Category I gas and oil fired appliances.

FOR COMMERCIAL BUILDINGS

Masonry boiler stacks in older buildings are almost always deteriorating from the inside. Hotels, lodges, condominium buildings, schools and offices tend to discover it during a sale, a code inspection or a CO complaint. We reline those flues without shutting the building down, and your tenants and guests never know we were there.

WHAT AN ASSESSMENT GIVES YOU

A camera inspection of the flue, measurements, photographs and a firm price. If the flue is sound, we will tell you that. After the assessment is complete, you will be provided a multi-page industry standard report, the kind you can hand a fire marshal, an insurer or a buyer.

BOOK A FLUE ASSESSMENT

Call or text (406) 629-2936. Serving Southwest Montana and Jackson Hole, Wyoming. See commercial boiler flue lining.