What are the specs for this Piston?

The correct replacement for Goodman model ASZ130181AF Heat Pump — B1789851 is this exact part. It is the factory-specified replacement with exact OEM specifications. Using a part with different specifications can cause equipment damage or void your warranty. You can verify this by checking the data plate on your Goodman equipment which lists the model number ASZ130181AF Heat Pump — B1789851.

What symptoms indicate I need a new piston?

Common symptoms that indicate you need a new piston include unusual noises, intermittent operation, complete failure to operate, or visible damage. For specific diagnostic guidance, visit nationalhvacparts.com/pages/hvac-diagnostic.

Is this piston compatible with Bryant or Payne systems too?

Many Goodman parts are cross-compatible with Bryant and Payne systems since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across multiple brand labels with different model numbers. To verify cross-compatibility, check your Bryant or Payne equipment service manual for cross-compatible part numbers, or contact info@nationalhvacparts.com with your model number for confirmation.

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Goodman

OEM Goodman Metering Piston Kit for ASZ130181AF Heat Pump — B1789851

Name: OEM Goodman Metering Piston Kit for ASZ130181AF Heat Pump — B1789851
Brand: Goodman
SKU: GOODMAN-16138
Price: 5.95 USD
Availability: InStock

SKU: GOODMAN-16138 Brand: Goodman

$5.95 $7.95

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Genuine Goodman Metering Piston Kit — B1789851

The Goodman B1789851 metering piston (flow-rator) is the fixed-orifice refrigerant metering device used in the ASZ130181AF 1.5-ton heat pump system. It regulates the flow of liquid refrigerant into the coil, controlling superheat and subcooling for correct capacity and efficiency. A worn, clogged, or incorrectly sized piston causes poor cooling, iced coils, and high energy bills. This OEM kit ensures the exact orifice bore your system was engineered for.

Specifications

OEM Part Number: B1789851
Component: Fixed-orifice metering piston / flow-rator
Fits: Goodman ASZ130181AF heat pump (1.5 ton / 18,000 BTU / 13 SEER)
Function: Meters liquid refrigerant flow into the evaporator/condenser coil
Kit includes: Precision-drilled piston insert

OEM vs. Generic

Piston performance depends entirely on precise orifice diameter matched to system tonnage. The genuine Goodman piston is bored to factory tolerance for the ASZ130181AF; generic pistons with the wrong bore will mis-charge the system and hurt efficiency. At this low price, always use the OEM-specified orifice.

Installation Difficulty

Professional (4/5). Installing the piston requires opening the refrigerant circuit — recover the charge, replace the piston in the liquid-line body, then evacuate and recharge. Must be handled by an EPA 608-certified technician for proper superheat/subcooling verification.

Shipping Information

Orders placed before 3PM CST ship same business day
Standard delivery: 2-5 business days
Express shipping available at checkout
Free shipping on orders over $75
Tracking number emailed upon shipment

Return Policy

30-day returns on unused parts in original packaging
Electrical parts (capacitors, contactors, control boards) are final sale once installed
Email info@nationalhvacparts.com to initiate a return
Refunds processed within 5-7 business days

OEM Goodman Metering Piston Kit ...

$5.95

Frequently Asked Questions

Does this Piston fit my Goodman ASZ130181AF Heat Pump — B1789851?

Yes. This is the factory-specified OEM piston for the Goodman ASZ130181AF Heat Pump — B1789851. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.

How do I replace the piston on my Goodman ASZ130181AF Heat Pump — B1789851?

Refer to your equipment service manual for model-specific steps. General approach: turn off power, photograph connections, remove old part, install new part, restore power and test. For gas components, hire a licensed technician. Email info@nationalhvacparts.com for guidance.

What symptoms mean I need a new piston?

Common symptoms: unusual noises, intermittent operation, complete failure, or visible damage. Visit our diagnostic hub for symptom-based troubleshooting.

Is this piston compatible with Bryant or Payne too?

Many Goodman parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.

Should I use OEM or aftermarket for my Goodman piston?

OEM recommended for reliability and warranty compatibility. OEM parts match exact factory specifications for proper fit, performance, and safety. While aftermarket alternatives cost less upfront, the risk of improper fit and reduced lifespan usually makes OEM the better value long-term.

How fast does National HVAC Parts ship?

Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.

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