If your HVAC system were a body, the furnace or heat pump would be the heart…

…and the ductwork would be the veins and arteries.

Most homeowners focus on the “heart” (the equipment) and totally ignore the ducts:

• Leaky joints
• Crushed or undersized runs
• Old metal or flex duct in rough shape
• Rooms that never get enough air

Then they wonder:

“Why is my brand-new system still loud / uneven / expensive to run?”

In a lot of Bay Area homes, the ductwork is the real problem—and sometimes the real hero when it’s fixed.

This guide from Galaxy Heating & Air Conditioning covers when it makes sense to:

• Repair your existing ducts
• Seal them for better efficiency
• Or replace them completely

📍 Serving Contra Costa, Alameda & San Francisco counties

📞 Want a professional duct evaluation? Call or text (925) 578-3293.

Why Ducts Matter So Much (Especially in the Bay Area)

Your furnace, heat pump, or AC can only deliver comfort through one path:

the duct system.

If that system is:

• Leaky
• Poorly designed
• Undersized or badly installed

…you’ll see things like:

• Hot and cold rooms
• Noisy vents
• Long run times
• Higher PG&E bills
• Dust and air quality issues

And here’s the kicker: you can install the best equipment money can buy, but if the ducts are bad, the system will never live up to its potential.

In older Bay Area homes—especially with additions, converted garages, pop-tops, and ADUs—ductwork is often a patchwork of different eras and “creative” solutions.

Common Duct Problems We See in Bay Area Homes

Here’s what we regularly find when we get into attics and crawlspaces:

1. Leaky Ducts

• Joints that were never sealed properly
• Old duct tape (now dried up and useless)
• Gaps where ducts connect to the plenum or registers
• Return ducts sucking air from attics, crawlspaces, or garages

Leaky ducts = you’re paying to heat/cool places you don’t live in.

2. Undersized or Poorly Designed Runs

• Long duct runs feeding distant rooms with tiny diameter
• Too few return ducts, especially in two-story homes
• “Octopus” style manifolds that were never engineered
• Flex duct with too many bends, sags, or kinks

Result:

• Weak airflow
• Noisy vents
• Rooms that never feel quite right

3. Old, Degraded, or Damaged Ducts

• Insulation falling off or missing
• Rodent damage or chewed insulation
• Collapsed sections of flex duct
• Old duct board or duct systems from decades ago that simply aren’t up to modern standards

Sometimes ducts are so old or hacked together that repair is like trying to patch a sinking ship.

4. Ducts in the Wrong Places

• Ducts running through unconditioned attics with poor insulation
• Returns pulling air from dirty spaces
• Supply ducts with long, exposed runs baking in the sun

Bad placement increases heat loss/gain and makes your system work harder.

Signs You Might Have a Duct Problem

You don’t need to climb into the attic to know something is off. Common symptoms:

• Certain rooms always too hot or too cold
• Very loud airflow at some registers, weak at others
• Dust, smells, or allergies worse when the system runs
• Your system runs a lot but home still feels uneven
• Big difference between upstairs and downstairs comfort
• High utility bills despite a “decent” system

If you’ve already upgraded equipment but comfort didn’t improve much, it’s almost always a duct issue (or several).

Repair, Seal or Replace? How to Decide

Let’s break down the three main paths and when each makes sense.

Option 1: Duct Repair – Fixing Specific Problems

Sometimes the duct system is basically okay, but there are a few problem spots:

• A run that’s crushed or kinked
• A disconnected duct in the attic
• A couple of badly located or undersized vents
• A return that needs to be enlarged or relocated

In these cases, targeted repairs or modifications can make a big difference.

When Duct Repair Makes Sense

Duct repair is a great option when:

• Most of the ductwork is in decent condition
• You’re mostly happy with the overall comfort, except for a few bad rooms
• The ducts are relatively newer or already at least somewhat properly sized and insulated
• You’re not ready for a full replacement but want real improvement

Examples of smart repair moves:

• Re-routing or upsizing a run to a problem room
• Fixing disconnected or crushed sections
• Adding a return vent to a starved area (like upstairs)
• Adjusting or adding balancing dampers

Repair is about surgical fixes, not a full gut job.

Option 2: Duct Sealing – Stop Conditioning the Attic

Duct sealing focuses on:

• Closing gaps, cracks, and loose joints
• Sealing around the plenum and boot connections
• Using proper mastic, tapes, and materials designed for ducts (not basic hardware-store “duct tape”)

Leaky ducts are one of the biggest sources of energy waste in many homes. In Bay Area attics and crawlspaces, that means:

• Heating and cooling air you never enjoy
• Pulling in dusty, musty, or polluted air from places you don’t want it

When Duct Sealing Makes Sense

Sealing is a great move if:

• The layout and size of your ducts are basically okay
• The ducts are not ancient or falling apart
• You’re planning to keep the existing system for a while
• You’re trying to improve efficiency and comfort without a full replacement

Sealing can:

• Reduce energy waste
• Improve comfort room-to-room
• Help systems run quieter and more evenly

Many homeowners feel a noticeable difference after a good sealing and balancing job.

Note: If ducts are very old, poorly designed, or damaged, sealing alone is like putting new tires on a car with a bent frame. Helpful, but not the full solution.

Option 3: Full Duct Replacement – When It’s Time to Start Over

Sometimes the most honest, long-term solution is:

“These ducts have had their time. Let’s design and install a proper system.”

Full replacement becomes a serious consideration when:

• Ducts are 30+ years old, degraded, or full of patches on patches
• Airflow is terrible throughout the home, not just in one or two rooms
• You’re planning a major equipment upgrade (new heat pump, high-efficiency system, dual fuel, etc.)
• There’s significant rodent, moisture, or insulation damage
• The existing layout is clearly guesswork, not design

Benefits of Full Duct Replacement

When we replace ducts, we’re not just swapping old for new—we’re redesigning:

• Proper sizing for each room (based on loads, not just “close enough”)
• Shorter, more efficient duct runs where possible
• Correct number and placement of supply and return vents
• New, insulated ducting with proper sealing from day one
• Quieter, smoother airflow

Paired with a new heat pump, furnace, or dual fuel system, new ducts can feel like an entirely different house:

• More even temps
• Less noise
• Better indoor air quality
• Lower stress on the equipment

Yes, it’s a bigger investment up front. But if your current ducts are a mess, this is often where the real magic happens.

How Galaxy Decides: Repair vs Seal vs Replace

We don’t walk in assuming “replace everything.” We start by actually assessing your duct system.

A typical Galaxy duct evaluation may include:

1. Visual Inspection

• Condition of ducts in attic/crawlspace
• Insulation and sealing quality
• Signs of damage, age, or rodent issues
• Layout and obvious problem areas

2. Airflow & Comfort Checks

• Room-by-room airflow and temperature feedback
• Noting hot/cold rooms, noise, and balance issues

3. Static Pressure & System Testing

• Measuring how hard your system is working to move air
• Seeing if the duct system is choking the equipment

4. Discussion of Your Plans

• Are you keeping your current system for a while?
• Planning to upgrade to a heat pump soon?
• Any remodels or additions in the works?

Then we lay out options, usually along these lines:

• Good: Targeted repairs + sealing + balancing
• Better: More extensive modifications or partial duct replacement where needed
• Best: Full duct redesign and replacement (often paired with equipment upgrade)

You get the pros, cons, and ballpark costs for each, and we help you decide what fits your comfort, budget, and timeline.

Bay Area-Specific Duct Challenges

A few things that are especially common in our region:

1. Older Homes with Add-Ons

• Original ducts may have been sized for just the original footprint
• Later additions got “whatever we could tie in” ductwork
• Result: new rooms never quite feel right, and original rooms suffer too

Replacement or a serious redesign is often the only way to truly fix this—not just bigger equipment.

2. Two-Story Comfort Issues

• Heat rises, second floor bakes
• Ducts feeding upstairs may be undersized or too few
• Returns often missing upstairs entirely

Solutions can include:

• Duct modifications
• Added returns
• Zoning
• Or adding ductless mini splits upstairs while the main system handles downstairs

3. Wildfire Smoke & Air Quality

If your return ducts are leaky or pulling air from attics or crawlspaces, smoke days will:

• Push more polluted air into your system
• Overwhelm filters faster
• Make the home feel more irritated even with windows closed

Properly sealed and well-designed ducts + good filtration (MERV 11–13) are key here.

FAQ – Duct Repair, Sealing & Replacement

Q: Is duct sealing really worth it if my equipment is old?

A: In many cases, yes. Sealing can:

• Reduce waste
• Improve comfort
• Protect new equipment if you upgrade later

But if ducts are in terrible shape, we’ll be honest if sealing is just putting lipstick on a pig.

Q: Can you just add one or two ducts to fix a hot/cold room?

A: Sometimes. Other times, the whole system is already maxed out and adding more runs makes everything worse. That’s why we look at static pressure and overall design before adding branches.

Q: How long do new ducts last?

A: Properly installed, insulated, and sealed ducts can last decades. It’s not something you should have to redo every 10 years if it’s done right.

Q: Will new ducts lower my energy bills?

A: Very often, yes—especially if the old ones were leaky or poorly insulated. The biggest wins are usually:

• Better comfort at lower runtime
• Less wasted heating/cooling of attics or crawlspaces
• Systems that don’t have to work as hard

Q: Do I have to replace ducts if I’m installing a new heat pump?

A: Not always—but it’s the ideal time to evaluate them. If the ducts are undersized, leaky, or in bad shape, your new heat pump won’t perform the way it should. Sometimes partial upgrades are enough; sometimes full replacement is the smart call.

Not Sure If Your Bay Area Ducts Need Repair, Sealing or Replacement?

You don’t have to guess from the attic ladder.

If you’re in Contra Costa, Alameda, or San Francisco counties, Galaxy Heating & Air Conditioning can:

• Inspect your ductwork, equipment, and airflow
• Tell you honestly if repairs and sealing will do the trick, or if it’s time to replace
• Design a duct system that actually matches your home, comfort needs, and new equipment
• Pair proper ducts with heat pumps, furnaces, dual fuel systems, or ductless mini splits for a full comfort upgrade

📞 Call or text (925) 578-3293

💬 Or contact us through our website to schedule a no-pressure duct evaluation

We’ll help you decide whether your Bay Area ductwork just needs a little TLC—or a full fresh start—to give you the comfort and efficiency you’ve been missing.