Coated sheet metal
- Takes very high heat near burners without concern
- Rusts once the coating is scratched
- Sloped floors and drain spouts need extra forming and sealing
Industry
Injection Molding for HVAC
Inside a furnace, air handler, or heat pump, plastic parts spin in fast air, sit in dripping condensate, and ride through years of on and off vibration. Each of those wears a part out in a different way.
Inside the unit
What each HVAC part is up against
Air, water, heat, and vibration rarely hit the same part equally.
| Part | Main threat | Common resin |
|---|---|---|
| Fan blades and blower wheels | Imbalance, creep at speed, and noise | Glass filled PP or nylon |
| Condensate drain pans | Standing water, cleaning chemicals, and growth in corners | Flame rated PP or ABS |
| Louvers, grilles, and registers | Sun on outdoor units, sagging on long slats | ASA outdoors, ABS or PP indoors |
| Control and thermostat housings | Heat from boards, a clean look on the wall | Flame rated PC/ABS |
| Damper parts and linkages | Wear at pivots after years of cycling | Acetal or nylon |
Moving air
Fans that stay balanced and quiet
A fan that is slightly out of balance is a noise complaint for the life of the unit.
- Every blade has to fill and cool the same way, so the gate usually sits at the hub center for even flow outward
- Glass fibers line up with flow and change how blades shrink, which shows up as blades that sit at slightly different angles
- Blades held at speed in warm air slowly creep outward, so the resin is chosen for its long term stiffness, not its first day strength
- The bore that fits the motor shaft often gets a metal insert or a molded flat so the wheel cannot slip
Drain pans
Molded drain pan or sheet metal pan
Many equipment makers have already moved. The ones who have not usually have a reason.
Molded plastic
- Does not rust, and the slope to the drain is molded in
- Drain spouts, mounting tabs, and sensor pockets come in one part
- Needs a flame rated grade and distance from the hottest parts of the unit
FAQ
Questions from HVAC equipment teams
Why do some drain pans grow slime and others do not?
Water left standing in corners and flat spots is the cause. Pans that slope continuously to the drain and avoid pockets stay cleaner. Some resins also come with antimicrobial additives, which help but do not replace good drainage.
Can outdoor unit grilles be plastic?
Yes. ASA or UV stabilized PP handles sun on condenser tops and side grilles. Long slats need support along their length so they do not sag in summer heat.
Does the flame rating come from the molder?
It comes from the resin grade and the equipment listing. The molder runs the grade named on the drawing and keeps it for every order.
Is there a minimum order for replacement parts?
No. There is no minimum order quantity, which suits service parts that are ordered in small, irregular batches from the same tool.
Keep reading
Related guides
Parts that move and guide air, and the resins inside heating and cooling equipment.
Fan blades
Balance, pitch, and stiffness.
Fan bladesAir vents
Louvers and registers.
Air ventsImpellers
Blower wheels and pump rotors.
ImpellersPolypropylene
Drain pans and wet parts.
PolypropyleneASA
Outdoor grilles that hold color.
ASAWarpage
Why long slats and pans bow.
WarpageIndustries hub
Every sector page in one index.
Industries hubNext step
Tell us where the part sits in the unit
Upload CAD with the part's location, the air temperature it sees, and whether it stays wet. DFM checks balance on rotating parts and drainage on pans. NetProto manufacturing is ISO 9001 certified.