Duct & Vent Installation & Repair

What duct and vent work actually involves

Duct work is the sheet metal, flexible duct, plenums, boots and registers that carry air between your furnace or air handler and the rooms you live in. Repair means finding where that system leaks, sags, collapses or has come apart, and fixing it. Sealing means closing every joint and seam with mastic so conditioned air reaches the room instead of the crawlspace. Replacement means new duct, sized for the equipment you actually own.

It matters more than most homeowners expect. Leakage in older residential duct systems commonly wastes 20 to 30 percent of the air the system produces. That air ends up in an attic or under the floor. You paid to heat it either way. A brand new furnace will still disappoint you if the duct behind it dumps a quarter of its output into a vented crawlspace.

Vent work covers the visible end: registers, return grilles, dampers and boots. Undersized or blocked returns are one of the most common reasons a system runs loud, runs long and never balances out.

Signs your ducts need attention

Duct problems show up as comfort complaints long before anyone looks in the attic. If several of these sound familiar, test the duct before spending on equipment.

• One or two rooms, usually the ones farthest from the furnace or over a garage, never reach the temperature the rest of the house does.
• Dust is back on the furniture a day after you cleaned, and the registers look grimy around the edges.
• You hear whistling, roaring or a metallic bang when the blower starts.
• Heating and cooling bills have climbed with no change in the weather or your habits.
• Air from a register smells like crawlspace, attic insulation, or something that got in there and died.
• You can see torn flex duct, duct hanging off its straps, or a boot pulled away from the register.

Weak airflow can also be a failing blower or a filter nobody has changed. A heating system repair visit rules that out. We check the equipment before we blame the duct.

How we handle a duct job

We do not quote duct work over the phone. What the duct is actually doing is rarely what the homeowner assumes.

1. Walk the system. We follow the duct from the equipment out to every register, through the attic or crawlspace, noting condition, sizing, supports and insulation. We count returns. We look at what it is connected to.

2. Measure instead of guessing. Static pressure readings show whether the system is fighting restriction. Where it applies, we test duct leakage rather than estimate it. Room-by-room airflow shows which runs are starved.

3. Show you what we found. Sometimes the answer is sealing what is already there. Sometimes one branch needs replacing and the rest is fine. Sometimes the system is past saving. We tell you which, and what changes if you choose the cheaper version.

4. Do the work. Sealing every joint, seam and boot. Replacing damaged runs. Re-hanging sagging duct so it stops kinking. Adding or resizing starved returns. Insulating anything in unconditioned space.

5. Verify. We retest, confirm the rooms that were short are now getting air, and handle the leakage testing and permit paperwork.

Your options: seal, repair or replace

There are a few paths, and the right one depends on the condition and design of what you have rather than on age alone.

Seal and repair. If the duct is correctly sized, properly supported and physically sound, sealing the joints and boots is the highest-value work available in this trade. It is unglamorous and it makes a large difference.

Partial replacement. Common where one section was chewed by rodents, crushed under stored boxes, or added badly during a remodel. We replace it and seal the rest.

Full replacement. Warranted when flex duct has gone brittle, when insulation has fallen off or gotten wet, when the layout fights the equipment, or when you are installing a system the old duct cannot feed. Residential work today typically uses insulated flexible duct for branch runs and sheet metal for trunks and plenums.

Redesign. Adding a return, resizing a trunk, splitting a long run so the far bedroom finally gets air, or adding dampers and zoning alongside a new thermostat installation. Where duct genuinely cannot reach a room, a ductless mini split beats forcing duct through a wall cavity that cannot hold it.

What affects the cost of duct work

Duct pricing comes down to how much duct there is, how hard it is to reach, and what the work has to achieve. What moves a quote:

• Access. A tall attic with a walkable floor is straightforward. A low crawlspace you have to belly through is not. Access drives labor more than anything else here.
• Scope. Sealing a dozen joints is a different job from replacing every branch in a four-bedroom house.
• Condition. Duct that is intact but leaky is cheap to improve. Duct that has been wet, chewed through or wrapped in deteriorating old material takes more.
• Design work. Adding returns, resizing trunks or re-routing runs takes more time and material than like-for-like replacement.
• Materials and insulation level. Higher insulation values and sheet metal trunk work cost more than minimum-spec flex.
• Permits and testing. California requires duct leakage testing by an independent HERS rater on most equipment changeouts and on substantial duct replacement.
• What we find along the way. A failing furnace, a bad thermostat, or a dirty evaporator coil restricting airflow all change the scope.

We put the number in writing after we have seen the system, never before.

Duct work in Santa Clara County

Local housing stock decides most of what we find. Much of the valley, including Santa Clara, Sunnyvale, Campbell and large parts of San Jose, is 1950s to 1970s tract housing, and plenty of it still runs original or first-replacement duct through vented crawlspaces and uninsulated attics. Flex duct from that era has often lost its insulation, gone brittle, or been crushed by stored boxes.

Slab-on-grade homes are their own category. Where duct was run under or inside the slab, moisture intrusion and collapse are the usual failure modes, and the honest answer is normally to abandon those runs and build a new attic system rather than try to rescue concrete.

On the regulatory side, California's Title 24 energy code requires duct leakage testing, verified by a third-party HERS rater, on most furnace and air handler changeouts and on significant duct replacement. Permits are pulled through the individual city, and San Jose, Morgan Hill, Gilroy, Los Gatos and Saratoga each run their own building department with their own timelines. We deal with that instead of handing it to you.

The move toward heat pumps matters here too. A heat pump supplies air at a lower temperature than a gas furnace, so it needs more airflow to deliver the same heat. Duct that was merely marginal behind an old furnace becomes the limiting factor behind a heat pump. If you are weighing a heating system installation or an air

conditioning installation, the duct belongs at the front of that conversation, not after the equipment is set. The same restriction shows up in summer, which is why plenty of A/C repair calls turn out to be duct calls.

Why homeowners choose Premium Heat and Air

We are a family-owned company with over 30 years in the trade, working out of 1724 Junction Ave in San Jose and serving homes across the South Bay. We are a proud Carrier dealer.

Day to day that means something plain. We look at the whole system before recommending anything, and we tell you when the cheaper fix is the right one. We will not sell you equipment to solve a duct problem, and we will not seal a duct system and call it finished when the real trouble is a failing blower.

Duct is also where we spend a lot of time cleaning up after other people's shortcuts, so we are careful with our own. Every run gets supported. Every joint gets sealed. Comfort isn't just a service here. It's personal, and your home deserves the same careful attention we give our own.

Where we work

We cover Santa Clara County and the surrounding South Bay, including Morgan Hill, Gilroy, Los Gatos and Saratoga, along with San Jose, Los Altos, Los Altos Hills, Palo Alto, Cupertino, Campbell, Santa Clara, Mountain View, Sunnyvale, Milpitas, Monte Sereno and Stanford.

If your ducts are leaking, noisy, or not reaching half the house, call (408) 612-6711 or get in touch. We will look at the system before anyone talks price.