Pentair Coil/Tubesheet Sealing O-Ring Kit | Max-E-Therm 400 & MasterTemp 400 Heaters | 77707-0119
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- SKU:
- 77707-0119
-
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About This Item
The Pentair Coil/Tubesheet Sealing O-Ring Kit (77707-0119) is the OEM replacement O-ring set for the water system coil and tubesheet sealing points in the Max-E-Therm 400 and MasterTemp 400 series heaters. This kit contains 12 O-rings — the complete set required to service all coil/tubesheet sealing positions in the 400-model heat exchanger assembly.
⚠️ IMPORTANT: KIT OF 12 O-RINGS — NOT A SINGLE PIECE
This listing is a kit of 12 O-rings. All 12 are required to fully service the coil/tubesheet sealing positions in the 400-model heater water system. Do not order a single unit expecting to service the full assembly.
⚠️ IMPORTANT: HEATER COMPONENT — PROFESSIONAL INSTALLATION 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.
These O-rings seal the coil and tubesheet interface within the heater's water system heat exchanger. When these seals degrade, water can bypass the intended flow path or leak internally, reducing heating efficiency and potentially causing damage to the heat exchanger assembly. Replacing the full set of 12 O-rings restores a proper water-tight seal across all coil/tubesheet contact points. Match the part number 77707-0119 against your existing parts or your heater's service documentation before ordering.
Specifications
| Pentair Part Number | 77707-0119 |
| Part Name | Coil/Tubesheet Sealing O-Ring Kit |
| Quantity Included | Kit of 12 O-rings |
Fits Into
| Brand | Equipment Line | Model / Part Number | Notes |
| Pentair | MasterTemp 400 Series | 400NA | 12 O-rings included; for Models 400NA, 400LP. Kit quantity = 1 (all 12 O-rings included). |
| Pentair | MasterTemp 400 Series | 400LP | 12 O-rings included; for Models 400NA, 400LP. Kit quantity = 1 (all 12 O-rings included). |
| Pentair | Max-E-Therm 400 (NA/LP Series) | MAX-E-THERM-400-NA | Coil/Tubesheet Sealing O-Ring Kit for 400 Model. 12 O-rings per kit. |
| Pentair | Max-E-Therm 400 (HD Series) | MAX-E-THERM-400-HD | Coil/Tubesheet Sealing O-Ring Kit for 400 Model. 12 O-rings per kit. |
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
When servicing the heat exchanger, replace the full set of 12 O-rings — not just the ones showing visible wear. Partial replacement leaves aged seals in place that are likely to fail shortly after reassembly, requiring a repeat disassembly. Before installation, apply a thin coat of Pentair R172351 Lifeguard® Silicone Lubricant to each O-ring to help seat it evenly, prevent tearing during assembly, and extend service life. Never use petroleum-based lubricants — they will degrade rubber O-rings and accelerate seal failure.
