Pentair 77707-0234 Tube Sheet Coil Assembly Kit — 400K BTU MasterTemp & Max-E-Thermostat, Before 1/12/09 — Genuine OEM
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The Pentair 77707-0234 Tube Sheet Coil Assembly Kit is the genuine OEM heat exchanger for 400,000 BTU MasterTemp and Sta-Rite Max-E-Therm pool and spa heaters manufactured before 1/12/2009. It replaces a leaking, corroded or damaged tube sheet coil and restores proper heat transfer.
⚠️ Check Your Heater's Build Date First
This kit fits only heaters built before 1/12/09 (original tub design). For 400K heaters built after that date, the correct part is 474061. The two are not interchangeable — check the date on your heater's rating plate before ordering.
Key Features
- Genuine Pentair OEM: Correct fit and geometry for the pre-2009 tub design.
- 100% copper tube sheet: Used in models 460736, 460737, SR400NA and SR400LP.
- Complete service kit: Includes copper tube sheet assembly, ignitor, insulation kit, tube of silicone and the 77707-0119 o-ring kit (set of 12).
- Six coiled tubes: The distinctive round-coil design used across the 400K MasterTemp and Max-E-Therm range.
- Natural gas and propane: Fits both 400NA and 400LP configurations.
Specifications
- Part Number: 77707-0234
- Type: Tube sheet coil assembly kit (heat exchanger)
- Capacity: 400,000 BTU
- Material: 100% copper
- Fits: MasterTemp 400NA, 400LP; Sta-Rite Max-E-Therm SR400NA, SR400LP — built before 1/12/09
- Tube Sheet Plate: 5½" wide x 8½" tall; approx. 13" side to side; approx. 15" plate to coil end
- Includes: Tube sheet assembly, ignitor, insulation kit, silicone, 77707-0119 o-ring kit
- Post-2009 Equivalent: 474061
- Cupro-Nickel HD Version: 77707-0244
- Brand: Pentair / Sta-Rite (Genuine OEM)
Frequently Asked Questions
How do I know if my heater is before or after 1/12/09?
Check the manufacturing date on the rating plate. If it is on or after 12 January 2009, you need 474061 instead. Confirm before ordering, since this part cannot be returned once fitted.
Does this fit a 300K or 333K heater?
No. This is the 400K assembly. The pre-2009 300/333K version is 77707-0233.
What symptoms indicate a failed heat exchanger?
Water leaking into the combustion chamber, rising copper levels in your pool water, visible corrosion on the tubes, or a heater that fires but will not hold temperature.
Is this copper or cupro-nickel?
Copper. Salt pools and heavy chemical environments often specify the cupro-nickel HD version, 77707-0244.
Who should install it?
A qualified pool heater technician. The job involves gas and combustion components and requires the heater to be fully depressurised and disconnected.
Frequently asked questions
How do I size a pool heater?
Heater sizing follows pool surface area, the temperature rise you want and how exposed the pool is to wind. A larger BTU rating heats faster and cycles less; an undersized heater runs continuously and still struggles on cold nights. Gas heaters also need a gas line and meter capacity that can supply their rated input.
What is the part number for this heater component?
Pentair lists this heater component under part number 77707-0234. Quote 77707-0234 when you cross-reference against your equipment manual, an existing part, or a parts diagram, so you are comparing the same revision.
What routine maintenance does a pool heater need?
Keep water chemistry balanced, because low pH and high calcium hardness are the two most common causes of premature heat exchanger failure. Beyond that: keep the cabinet clear of debris, check for rodent nests before each season, and have the burner and gas train inspected periodically.
How do I confirm this fits my equipment?
Match the part number stamped on the component you are replacing, or look it up in the parts list for your Pentair equipment. If your model or serial number is not named on this page, send it to us before you order and we will confirm the fit.
Is this the complete heater or a replacement part?
Check the title and the specification section above. Heater listings and heater component listings share the same part-number format, so confirm whether you are buying a full appliance or a single serviceable component before ordering.
Is there a warranty on this heater component?
It carries the standard Pentair manufacturer warranty. The terms are set by Pentair, and on some equipment the coverage only applies when a licensed professional performs the installation. Keep the receipt and packaging until you have confirmed correct operation.