My AC Guy Says I Don’t Have Enough Return Air
Your AC guy says:
“You don’t have enough return air.”
He might be absolutely right.
Undersized return ductwork is something we find all the time.
But how do we know?
Preferably not because somebody stared at your return grille for six seconds and said:
“Yeah, that looks small.”
We can measure this stuff.
What Does “Not Enough Return Air” Mean?
Your blower has to move air through the HVAC system.
Air leaves through the supply ducts.
And that air has to make its way back to the equipment through the return side.
If the return ductwork, filter, grille or other components create too much restriction, the blower may have trouble moving the airflow the equipment needs.
Think about trying to drink through a tiny straw.
You can still move liquid.
You’re just working considerably harder to do it.
How Do We Know the Return Is Restrictive?
One of our best tools is static pressure.
We can measure the pressure the blower is working against and look at what’s happening on the return and supply sides of the system.
We can also evaluate:
- return duct size
- return grille size
- filter size and pressure drop
- duct configuration
- blower settings
- equipment airflow requirements
- condition of the ductwork
- actual system airflow
Sometimes the problem isn’t technically that the house needs another return grille.
Maybe the existing return duct is crushed.
Maybe somebody installed an extremely restrictive filter.
Maybe the filter rack itself is undersized.
Maybe the return plenum is tiny.
Find the restriction first.
Why Does Return Air Matter?
Poor airflow can cause all sorts of problems.
It can reduce system performance.
It can affect temperatures and refrigerant readings.
It can contribute to coil freezing.
It can increase blower workload.
It can make rooms uncomfortable.
And it can make perfectly good HVAC equipment look like it has a refrigeration problem when the real problem is:
The thing can’t breathe.
Does Adding Another Return Always Fix It?
No.
That’s why we diagnose before cutting giant holes in your house.
If the restriction is somewhere else, adding another grille may accomplish very little.
We want to know where the pressure drop is occurring and correct the actual problem.
Sometimes that means adding return capacity.
Sometimes it means increasing duct size.
Sometimes it’s a filter issue.
Sometimes the duct system needs more substantial correction.
What Should You Ask?
Ask:
“How did you determine I don’t have enough return air?”
If the answer includes actual measurements and an explanation of where the restriction is?
Great.
Your AC guy may be doing exactly what he should be doing.
The Klein Answer
Yes, your AC may genuinely need more return air.
We find undersized and restrictive return systems regularly.
But airflow isn’t something we need to diagnose by eyeball alone.
Measure the system.
Find the restriction.
Then fix the part that’s actually restricting it.
Because sometimes your AC doesn’t need refrigerant, a TXV or a new system.
Sometimes it just needs to breathe.