Pentair O-Ring Kit | MasterTemp & Max-E-Therm | 77707-0120
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- SKU:
- 77707-0120
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About This Item
The Pentair O-Ring Kit (77707-0120) is the OEM replacement seal kit for MasterTemp and Max-E-Therm gas heaters. This kit includes Item Nos. 3 and 5 from the heater's parts diagram.
IMPORTANT: KIT LISTING — MULTIPLE O-RINGS INCLUDED
This listing is a kit containing multiple O-rings — not a single O-ring. Confirm this kit number against your heater's parts diagram before ordering.
IMPORTANT: LUBRICATION REQUIRED — SOLD SEPARATELY
Always lubricate these O-rings with a silicone-based lubricant before installation. We carry the Pentair R172351 Lifeguard Silicone Lubricant — the OEM-matched product for Pentair equipment.
IMPORTANT: GAS HEATER COMPONENT — PROFESSIONAL SERVICE REQUIRED
Gas and electrical heater components must be serviced by a licensed pool professional or qualified HVAC technician. Do not attempt to service gas or high-voltage components without proper certification.
The O-rings in this kit form critical seals within the heater assembly. When these seals degrade, water can bypass or leak at the manifold connections, reducing heating efficiency and potentially causing water intrusion into the combustion chamber. Replacing this kit restores a leak-free seal during scheduled heater service or when a manifold leak is identified.
Specifications
| Pentair Part Number | 77707-0120 |
| Quantity Included | Kit (includes Item Nos. 3 and 5) |
Fits Into
| Brand | Equipment Line | Model / Part Number | Notes |
| Pentair | MasterTemp 175NA | 175NA | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 175LP | 175LP | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 200NA | 200NA | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 200LP | 200LP | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 250NA | 250NA | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 250LP | 250LP | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 300NA | 300NA | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 300LP | 300LP | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 400NA | 400NA | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | MasterTemp 400LP | 400LP | O-Ring Kit; includes Item Nos. 3 and 5 |
| Pentair | Max-E-Therm 200 (NA/LP Series) | MAX-E-THERM-200-NA | O-Ring Kit for ASME Max-E-Therm heaters. Includes Nos. 3, 5. Verify fitment before ordering. |
| Pentair | Max-E-Therm 333 (NA/LP Series) | MAX-E-THERM-333-NA | O-Ring Kit for ASME Max-E-Therm heaters. Includes Nos. 3, 5. Verify fitment before ordering. |
| Pentair | Max-E-Therm 400 (NA/LP Series) | MAX-E-THERM-400-NA | O-Ring Kit for ASME Max-E-Therm heaters. Includes Nos. 3, 5. Verify fitment before ordering. |
| Pentair | Max-E-Therm 200 (HD Series) | MAX-E-THERM-200-HD | O-Ring Kit for ASME Max-E-Therm heaters. Includes Nos. 3, 5. Verify fitment before ordering. |
| Pentair | Max-E-Therm 333 (HD Series) | MAX-E-THERM-333-HD | O-Ring Kit for ASME Max-E-Therm heaters. Includes Nos. 3, 5. Verify fitment before ordering. |
| Pentair | Max-E-Therm 400 (HD Series) | MAX-E-THERM-400-HD | O-Ring Kit for ASME Max-E-Therm heaters. Includes Nos. 3, 5. Verify fitment before ordering. |
Compatibility is based on Pentair parts documentation and available OEM records. This is not an exhaustive list. For certainty, verify the part number in your equipment's manual or on the original part itself before ordering.
Pro Tip
Replace this O-ring kit any time the manifold is removed for service — even if the existing O-rings appear undamaged. Heat cycling causes O-ring compression set over time, and reinstalling compressed seals is a leading cause of post-service manifold leaks. Before seating each O-ring, apply a thin, even coat of Pentair R172351 Lifeguard Silicone Lubricant to ensure proper seating without tearing. Have your licensed pool professional verify manifold torque specifications against the heater's service manual after reassembly.
