Old Town Fort Collins has the oldest housing in the city. The median single-family home here was built in 1927 and measures about 1,163 square feet (Larimer County assessor data via the Coloradoan, April 2022), and only 217 of the area’s 3,506 single-family homes were built less than 50 years ago. These houses — brick Victorians, Craftsman bungalows and Prairie Style homes — were built before central air conditioning existed. Their ductwork was squeezed in decades later, through framing that was never designed for it, and the results are still visible in the comfort complaints we hear: the upstairs is hot, the back bedroom is cold, and the system runs constantly without ever catching up.
That is not a furnace problem or an air conditioner problem. It is a duct problem, and no filter change will fix it.
The common duct problems in Old Town homes are:
- Retrofitted ducts squeezed into old framing
- Disconnected and leaking runs
- Undersized returns and unbalanced airflow
Common duct problems: retrofitted ducts squeezed into old framing
The defining Old Town duct problem is geometry. Pre-1930 stud spacing is often thin and non-standard, so installers ran flex duct through whatever path existed — tight joist bays, low crawlspaces, and attic corners. Flex duct that is pinched, kinked or sagging between supports chokes airflow, and every kink costs the rooms at the end of the run. We regularly find runs that were crushed during a later remodel, or a bathroom or kitchen renovation that cut a duct and never reconnected it properly.
Basements and crawlspaces add a second constraint. Many Old Town homes have tight, low basements that make it hard to vent a modern condensing furnace — PVC venting and a condensate drain need room that a 1927 basement does not always offer — and the ductwork down there is often the original installation, now 40 or 50 years old. If your home still has its first set of ducts, assume they leak.
Disconnected and leaking runs
Duct leakage is the most common defect we find in older Fort Collins homes, and it is invisible from the living room. Joints separate in attics and crawlspaces, collars pull loose, and flex duct tears where it meets the plenum. The furnace or AC is producing conditioned air, but a share of it never reaches a register — it heats or cools the attic instead. Nationally, Angi puts duct sealing at $375–$6,000, averaging about $2,250 (2026), and the spread reflects how much of the system is accessible and how bad the leakage is. A duct leakage test, done with the system running, tells you whether sealing is worth doing before you spend anything.
The symptoms are specific: one or two rooms that are always 5–8 degrees off from the thermostat, dust that returns days after cleaning, and a system that runs long cycles. If the air at the far register feels weak even when the system is running hard, the run is either disconnected, crushed, or undersized for the room it serves.
Undersized returns and unbalanced airflow
Many Old Town retrofits were sized by guesswork. A single central return in the hallway, with bedroom doors closed, starves the system of air and pressurises the bedrooms — air gets in but cannot get back. The fix is usually a return in each bedroom or a properly sized transfer grille, not a bigger furnace. Oversizing the equipment to compensate is the classic mistake: at 5,003 feet a furnace already derates about 12% and an AC roughly 10–20%, so a system sized from sea-level ratings is effectively undersized here, and a bigger box on leaky, undersized ducts just makes the imbalance louder and more expensive.
Swamp coolers and homes with no ducts at all
Some Old Town and Sheely-area homes still run evaporative (swamp) coolers, which work in dry June, fail in humid August, and admit wildfire smoke through open windows. Others have no ductwork worth saving at all. For those homes the standard answer is a ductless mini-split: wall-mounted heads served by a small outdoor unit, with no ducts to leak and no framing to fight. It is the retrofit that fits the house as it actually is, rather than forcing the house to fit a ducted system.
Historic rules: what they do — and do not — say
Homeowners often worry that Old Town’s historic status blocks HVAC work. It does not, in the way people fear. The Old Town design guidelines are voluntary, and the Landmark Preservation Commission treats exterior HVAC as a visibility issue — place equipment toward the rear, keep it low and out of the prominent view. There is no blanket ban on AC condensers in Old Town, and no specific condenser-placement code section to cite. Buildings 50 years or older do need Historic Preservation review for exterior alterations, so a visible new condenser or a rooftop unit is worth a call to the City’s preservation staff at 970-224-6078 before you install — but a duct repair inside the house is not an exterior alteration at all. Our Old Town Fort Collins HVAC page covers the neighbourhood’s housing stock and retrofit options in more detail.
What fixing it looks like
A proper Old Town duct job starts with an inspection and a leakage test, not a quote for new equipment. Sealing accessible joints with mastic, replacing crushed flex runs, adding returns where rooms are starved, and insulating ducts that run through unconditioned attics will usually recover more comfort than a new furnace on the same leaky system. Duct cleaning is a separate job — nationally it runs about $343–$398 per 1,200 square feet in Fort Collins (HomeYou, 24 October 2026) — and it is worth doing after sealing, not before, so you are not cleaning ducts that are about to be opened up again.
Get help with HVAC in Fort Collins
If your Old Town home has rooms that never heat or cool properly, the ducts are the first place to look. DNA Refrigeration Heating & Cooling handles duct sealing, duct repair and duct cleaning across Fort Collins — call us at (970) 932-2324. We are open 24 hours, 7 days a week.