A-103 · Distribution
The equipment gets the credit. The duct does the work.
A correctly sized system on bad duct performs worse than an average system on good duct. It is the least glamorous half of the trade and it is where most of the comfort lives.
What a leaky attic duct costs you
A typical unsealed system in this parish loses between a fifth and a third of its conditioned air into the attic. In July that air is being replaced by 130° attic air pulled in through the return side, which is why the hallway smells like insulation when the system starts.
Sealing is measurable work. We test the system before and after with a duct blaster and give you both numbers. If the improvement is not worth what we charged, that is visible on the page and we would rather you saw it.
Typical result A 1990s Gonzales house we sealed last spring went from 31% leakage to 6%, and the back bedroom came within two degrees of the thermostat for the first time. No equipment was changed.
Symptoms
When the duct is the problem
If you recognise three or more of these, a duct assessment will tell you more than a new condenser will.
- One room is always five to ten degrees off the rest of the house.
- The system runs constantly in August and still cannot hold the setpoint.
- Registers in the far rooms barely move a tissue held up to them.
- The filter loads up in three weeks instead of three months.
- You can hear the return whistling from another room.
- Closing interior doors makes a noticeable difference to how a room feels.
- Bills climbed year on year with no change in how you use the house.
- The last contractor solved it by turning the blower up.
Fig. 5 — what we are aiming for
Short straight trunk, take-offs on calculated centres, no branch longer than it has to be, and nothing crushed under a walkway board.
Assessment
What we do first
Measure static pressure
Across the air handler, with the filter in place as you actually run it. Most systems we test are running at nearly double what the equipment was designed for.
Measure leakage
Duct blaster on the system, pressurised to a standard, leakage recorded as a percentage of system airflow. A number, not an opinion.
Measure room airflow
At every register with a flow hood, compared against what that room's load says it needs. This is where the eight-degree bedroom gets explained.
Price the fix in order of value
Sealing first, then the branches that are undersized, then the trunk if it comes to that. You are welcome to stop after step one and see how it feels.
One room that never gets there?
A duct assessment is $195 and takes about ninety minutes. It comes off the price of any work that follows from it.