Pentair
Pentair Drain Cap/Thermal Regulator O-Ring U9-371 – for Filters & Heaters
Pentair Drain Cap / Thermal Regulator O-Ring
Replacement O-ring for compatible Pentair MasterTemp and Sta-Rite Max-E-Therm heaters, plus select Waterford and Cristal-Flo filter applications.
Warranty Information
1-Year Manufacturer Warranty
Ultimate Pools is your first point of contact for compatibility verification, installation guidance, and warranty support.
The Pentair Drain Cap / Thermal Regulator O-Ring (U9-371) is a replacement sealing component used in compatible Pentair and Sta-Rite pool equipment. It is also referenced by former part number 35505-1313.
This O-ring is used to help seal supported thermal regulator cap and filter drain cap applications, helping block water from escaping between mating components. This part has been discontinued.
Key Features
Used as a sealing O-ring in compatible MasterTemp and Max-E-Therm heater applications.
Also specified for compatible Waterford and Cristal-Flo T-BP filter applications.
Designed to block water escape between compatible mating surfaces.
Fits the listed Pentair MasterTemp heater models.
Fits the listed Sta-Rite Max-E-Therm heater models.
U9-371 has been discontinued and was formerly identified as 35505-1313.
Compatibility & Fitment
Compatible with the following Pentair and Sta-Rite equipment:
- Pentair MasterTemp Heaters: 460792, 460793, 460730, 460731, 460732, 460733, 460734, 460735, 460736, 460737, 460805, 460806
- Sta-Rite Max-E-Therm Heaters: SR200NA, SR200HD, SR200LP, SR333NA, SR333HD, SR333LP, SR400NA, SR400HD, SR400LP
- Waterford Systems Sand Filters: Compatible applications using U9-371
- Cristal-Flo T-BP High Rate Sand Filters: Compatible applications using U9-371
Compatibility may vary by production year, configuration and installation. Verify your exact model and part number before ordering.
Applications
- Thermal regulator cap sealing on compatible heaters
- Drain cap sealing on compatible filters
- Replacement of a worn or damaged O-ring
- MasterTemp heater servicing
- Max-E-Therm heater servicing
Because this part has been discontinued, verify the exact application and part number before ordering or sourcing a replacement.
Specifications
| SKU | U9-371 |
| Former Part Number | 35505-1313 |
| Brand | Pentair / Sta-Rite |
| Product Type | O-Ring |
| Application | Thermal regulator cap and filter drain cap sealing |
| Compatibility | Listed Pentair MasterTemp and Sta-Rite Max-E-Therm heaters; compatible Waterford Systems and Cristal-Flo T-BP sand filter applications |
| Status | Discontinued |
| Warranty | 1-Year Manufacturer Warranty |
| Final Sale | Yes |
Frequently Asked Questions
It is used as an O-ring seal in compatible thermal regulator cap and filter drain cap applications.
Yes. It is compatible with the listed MasterTemp heater models.
Yes. It is listed for the specified SR200, SR333 and SR400 Max-E-Therm heater models.
U9-371 was formerly identified as part number 35505-1313.
Yes. The supplied product information identifies this part as discontinued. It is also final sale.
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