What are the specs for this Piston?

The correct replacement for Goodman model ANZ130181AC — 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 ANZ130181AC — 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.

IMAGE COMING SOON

Goodman

OEM Goodman Piston / Flowrator Kit for ANZ130181AC — B1789851

Name: OEM Goodman Piston / Flowrator Kit for ANZ130181AC — B1789851
Brand: Goodman
SKU: GOODMAN-15138
Price: 5.95 USD
Availability: InStock

SKU: GOODMAN-15138 Brand: Goodman

$5.95 $7.95

OEM Guaranteed

Same-Day Ship

30-Day Returns

Secure Checkout

Texas CMBL #19328542014

SAM.gov Registered

Govt POs Accepted

Goodman B1789851 Metering Piston (Flowrator) Kit

The B1789851 is the OEM metering piston, or flowrator, for the Goodman ANZ130181AC heat pump. This precision-drilled orifice sits inside the refrigerant line at the coil and controls how much liquid refrigerant feeds into the evaporator, setting the system's superheat and capacity. A worn, wrong-size, or debris-clogged piston shows up as poor cooling/heating, iced coils, or high head pressure. Because it is inexpensive and wear-prone, it is a common item to replace during a coil or compressor changeout.

Specifications

OEM Part Number: B1789851
Component: Fixed-orifice metering piston (flowrator)
Fits: Goodman ANZ130181AC heat pump
Bore: Factory-calibrated orifice for this model's tonnage
Body: Machined brass with sealing O-ring
Function: Meters refrigerant into the coil

OEM vs. Generic

Orifice size is everything with a piston. The OEM B1789851 is drilled to the exact bore the ANZ130181AC needs, so superheat and capacity land where the engineers intended. A generic piston with the wrong bore will starve or flood the coil and kill efficiency. For a few dollars, always match OEM.

Installation Difficulty: Professional

Replacing the piston opens the sealed refrigerant circuit. An EPA-608 certified technician should recover refrigerant, open the fitting, swap the piston and O-ring, then evacuate and recharge. Not a DIY repair. Estimated time: 45-90 minutes for a tech.

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 Piston / Flowrator K...

$5.95

Frequently Asked Questions

Does this Piston fit my Goodman ANZ130181AC — B1789851?

Yes. This is the factory-specified OEM piston for the Goodman ANZ130181AC — 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 ANZ130181AC — 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.

Menu