Duct Repair & Sealing in Norristown, PA

A lot of Norristown's older housing still moves air through ductwork that was never meant to be pushed. The original heat was a gravity warm-air furnace feeding enormous round trunks, and it worked because hot air rises, not because a fan drove it. When those houses were converted to forced air the furnace changed and most of the duct did not.

We repair and seal ductwork across the borough and the Norriton townships from the DeKalb Street office.

What is left of a gravity system

Those old trunks are oversized for the volume a modern blower actually delivers, so air travels through them slowly and gives up its heat to the basement on the way. The take-offs were commonly cut and fitted by hand, the joints were never sealed to any standard, and the original wrap has usually failed. The system is not broken exactly. It is doing a different job from the one it was built for, and it leaks and loses heat in proportion.

Damp basements are hard on sheet metal

Below-grade space near the river carries humidity, and old galvanised duct standing in it corrodes at the seams and along the bottom of horizontal runs. Boots pull away from floor openings, joints spring where the metal has thinned, and a return rusted through in a basement draws basement air, moisture and dust with it, straight into the blower and out into every room upstairs.

The party wall decides the route

In a rowhome or a twin there are no side walls to run duct through, so vertical runs were fitted into closets, chases alongside a chimney, or boxed-out corners. Anything feeding a third floor or converted attic therefore has the longest and most restricted path in the building, and it is nearly always the room people ring about. That run is where sealing and insulation pay back quickest, and it can usually be reached without cutting into finished rooms.

Return air is usually the missing half

Supply gets the attention because you can feel it. Return does not, and in converted houses it is often a single grille near the furnace serving an entire floor, with bedroom doors closing the rooms off from it. Shut the door and the room pressurises, the supply air has nowhere to go, and the room stops receiving air however the damper is set. Transfer grilles, jumper ducts or a properly sized second return solve it, and none of it is equipment work.

Measured before recommended

The reading that settles most of these arguments is total external static pressure, taken with a clean filter fitted. If the fan is working against a high number while the blower itself is healthy, the restriction lives in the distribution, and no new equipment will move it. Airflow and temperature rise across the furnace fill in the rest.

What the work involves

• ✓Seams, joints, plenum take-offs and register boots sealed with mastic, not covered in tape
• ✓Rusted-through sections of basement trunk and return cut out and replaced in new metal
• ✓Oversized gravity trunks reworked or reduced where the geometry allows
• ✓Boots dropped away from floor and ceiling openings refastened and sealed
• ✓Extra return capacity where a room takes supply air but cannot send it back
• ✓Runs through unheated basements, chases and attic space properly insulated