By Cliff Dennis, Owner of Vassars Service of Richmond - Published October 6, 2026
The Original Request
We were originally called to Mr. Bob's home to provide an estimate for installing a ductless mini-split system in the master bedroom.
The home was only about six years old and already had a central heating and air-conditioning system serving the space. The homeowner explained that the master bedroom had never been comfortable, and they were considering adding a separate mini-split specifically to solve that problem.
The original HVAC installing contractor had been back to the home several times to look at the existing system. The homeowners had been told that the system was installed according to specifications.
Asking Permission to Look Deeper
While I was at the home evaluating the requested mini-split installation, I noticed the existing central HVAC system and ductwork.
Before recommending another piece of equipment, I asked the homeowner if he would mind if I took a look at the existing system.
My reasoning was simple: in a six-year-old home with an existing central system, that equipment should potentially have been capable of keeping the master bedroom comfortable. Before adding another system, I wanted to understand why the existing system wasn't doing the job.
During my initial visual inspection of the duct system, several fittings caught my attention. Based on their configuration and size, they appeared overly restrictive. From experience, I suspected these restrictions could be creating excessive resistance to airflow and preventing the equipment from delivering its intended performance.
But rather than relying on experience and observation alone, I recommended that we test it.
Test, Don't Guess
I explained to the homeowner that, for a modest diagnostic fee, we could measure the system's airflow and total external static pressure.
One way I explain static pressure to homeowners is to compare it to blood pressure. When you visit a doctor, one of the basic measurements they take is your blood pressure because it provides important information about what is happening inside your body.
We can do something similar with an HVAC system.
Static-pressure testing allows us to measure the resistance the blower is working against. Combined with airflow measurements, it helps us determine how well the equipment and duct system are actually performing - not simply whether the equipment turns on and runs.
I also recommended performing a load calculation to determine how much heating and cooling the home actually required. That would allow us to verify whether the existing equipment was properly matched to the home before recommending additional equipment.
The homeowner agreed.
What the Testing Revealed
The load calculation confirmed something important:
The existing HVAC equipment was capable of serving the home.
The bigger problem was how the conditioned air was being delivered.
Our testing showed static-pressure readings approaching twice the equipment's rated pressure, indicating excessive resistance within the air-distribution system.
Much of that resistance appeared to be associated with the design and configuration of the fittings connecting the equipment to the duct system. We also identified a section of ductwork that appeared to be undersized.
The homeowner didn't necessarily need another heating and cooling system.
The existing system needed the opportunity to perform the way it was intended to.
Designing the Correction
Based on our testing, the homeowners authorized us to develop a duct-system renovation plan.
Instead of simply replacing pieces of ductwork and hoping for an improvement, we developed a plan specifically intended to reduce resistance and improve airflow to the areas of the home that weren't receiving adequate conditioning - particularly the master bedroom.
We then presented the homeowners with a proposal for the corrective work and explained the improvement we expected based on the testing and design.
They decided to move forward.
The Result
Our team completed the duct renovations over the course of several days. Afterward, we scheduled a final test-out so that we could measure the system again and verify the results.
Something happened before we even returned to perform that testing.
The homeowner told us that for the first time in the six years they had lived in the house, their master bedroom was comfortable.
They also noticed that the entire HVAC system was quieter.
When we completed our final testing, the measurements confirmed what the homeowners were already experiencing.
We measured approximately a 100% improvement in airflow performance along with a substantial reduction in static-pressure resistance.
The improved airflow didn't just address the bedroom comfort problem. Reducing excessive system resistance also allows the HVAC equipment to operate under better conditions, which can improve system performance, support efficiency and help reduce unnecessary stress on components.
The Bigger Lesson
This project started as a request for a price on a mini-split.
Had we simply provided exactly what was requested, the homeowners might have ended up purchasing another piece of HVAC equipment while the underlying problem with their existing system remained.
Instead, we asked a few more questions.
We inspected. We measured. We calculated. We designed a correction based on what the testing told us. And then we tested again to verify the results.
That's the difference between assuming what a comfort problem is and measuring the system to determine what's actually causing it.
At Vassars Service of Richmond, our goal isn't simply to install more equipment. It's to understand how the entire comfort system is performing and provide solutions based on testing, measurement and verified results.
If you're not testing, you're guessing.
