How do I set the superheat on a Sporlan thermostatic expansion valve?

Sporlan TXVs are factory set for 6-8°F (3-4°C) superheat. To adjust, turn the adjustment stem clockwise to increase superheat, counter-clockwise to decrease. Make small adjustments (1/4 turn) and wait 15 minutes for the system to stabilize before measuring superheat again. Access the adjustment stem through the removable cap on the valve body.

What causes a Sporlan TXV to hunt or oscillate?

TXV hunting (superheat oscillation) is caused by: incorrect valve sizing (oversized for the load), a frozen or contaminated power element, incorrect bulb charge for the refrigerant type, improper bulb location (not on horizontal suction pipe), or poor bulb contact with the suction pipe. Ensure the bulb is properly insulated and clamped tightly to the suction pipe.

How do I check if a Sporlan solenoid valve is opening?

Test a Sporlan solenoid valve by: (1) measuring coil resistance — typical coils are 8-30Ω at 25°C (OL indicates open winding); (2) applying power and listening for a click as the plunger opens; (3) checking for temperature differential across the valve when energized (inlet warm, outlet slightly cooler if flowing). A failed plunger tube causes valve to remain closed even when energized.

How often should I change a Sporlan filter-drier?

Replace Sporlan filter-driers whenever the system is opened for service, when moisture is detected (sight glass wet indicator changes color from green to yellow), when system contamination is suspected (acid test positive), or after a compressor burnout. After burnout, use a Sporlan Catch-All filter with activated alumina to remove acid from the system.

What Sporlan valve should I use for R448A retrofit?

For R448A (N-40) retrofit from R404A, Sporlan recommends using their Type T or Type Z expansion valves. Select the valve based on the new refrigerant capacity and operating conditions using the Sporlan selection guide. R448A may require a larger valve orifice than R404A for the same capacity — always verify the capacity rating at your specific operating conditions.

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By Octavian Ghindea

Co-founder & CTO · Reviewed May 2026

What error codes does Sporlan display?

Hunting

TXV oscillating superheat — check valve sizing and bulb installation

Flooded

Excess refrigerant — TXV too large or bulb charge failure

Starved

Insufficient flow — TXV stuck closed, ice, or contamination

Coil OL

Solenoid valve coil open — replace coil

Common questions about Sporlan equipment

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