Hayward HAXBPK1931 Bypass Kit (Old Style Header) — H-Series / ED1 (Pre-10/28/2000)
The Hayward HAXBPK1931 is an OEM heater bypass kit designed for Hayward H-Series gas pool heaters that use the old style header. The bypass assembly helps regulate internal water flow through the heater’s heat exchanger, supporting stable operation and helping protect the exchanger under varying flow conditions.
Fits / Compatibility
- Hayward H-Series Millivolt & Electronic Ignition (ED1 style) heaters made before 10/28/2000
- Common compatible ED1 models include: H1501, H2001, H2501 (verify heater data plate)
- Also commonly referenced for select H-Series Induced Draft heater applications that use the old style header
Fit tip: Hayward has different bypass kits depending on heater generation/header style. Confirm your heater manufacture date and header style before ordering (this kit is for the older style configuration).
What’s Included
- Black plastic bypass baffle
- Round bypass end (brass)
- Bypass shaft and plug (brass)
- Bypass spring
- Header O-ring (commonly referenced as HAXHOR1930)
Common Reasons to Replace
- Heater header service where the bypass parts are worn, damaged, or missing
- Recurring header leaks traced to a flattened or damaged header O-ring
- Flow-related heater issues where inspection shows a stuck or deteriorated bypass assembly
- Preventive rebuild on older H-Series heaters to restore proper internal flow control
Specs (Quick Reference)
- Part Number: HAXBPK1931
- Part Type: Heater Bypass Kit (Old Style Header)
- Pool Type: In-Ground
- Approx. Shipping Weight: 14.4 lb
Installation Notes
- Turn off power to the heater and pump, and allow the heater to cool before servicing.
- Relieve system pressure before opening the header/union area.
- Clean header sealing surfaces and O-ring grooves before installing new components.
- Use a light coat of silicone-based lubricant on O-rings only (never petroleum-based).
- If the header is cracked/warped or sealing surfaces are damaged, replacing the bypass kit alone may not stop leaks.
Related Products
- Hayward HAXBPK1931 Bypass Kit (search)
- Hayward HAXHOR1930 Header O-Ring (search)
- Hayward HAXNNO1930 Heater Union/Nipple Kit (search)
- Hayward HAXPSA1930 Water Pressure Switch Assembly (search)
- Hayward H-Series Heater Parts (search)
- Silicone O-Ring & Gasket Lubricant (search)
Maintenance Tips
- Keep filter pressure under control—dirty filters and restricted flow can cause heater issues that look like bypass problems.
- Maintain balanced water chemistry to reduce scale in the heat exchanger and header area.
- After any header service, run the system and check carefully for slow drips; small leaks can quickly leave mineral deposits and worsen sealing.
- Support nearby plumbing so the heater header/unions aren’t under constant stress from misaligned pipes.
