Pentair Tubesheet/Coil Kit 400K Pool | 77707-0234
Pentair
SKU: 77707-0234
Pentair MasterTemp / Sta-Rite Max-E-Therm 400 Tube Sheet Coil Assembly Kit (Old Tub Design) | 77707-0234
The Pentair 77707-0234 is a factory replacement tube sheet coil (heat exchanger) assembly kit for select 400,000 BTU pool and spa heaters. It is used to restore heating performance when the existing coil is leaking, scaled, or internally damaged. This kit is intended for MasterTemp 400 (models 400NA and 400LP) and compatible Sta-Rite Max-E-Therm 400 applications where this part number is specified.
Compatibility
- Fits: Pentair MasterTemp 400 heaters, models 400NA and 400LP (where 77707-0234 is specified)
- Also used on: Sta-Rite Max-E-Therm 400 heaters (where 77707-0234 is specified)
- Design note: Commonly associated with heaters manufactured before January 12, 2009 (old tub design). Verify your heater’s parts list to confirm.
What This Kit Does
- Replaces the heater’s tube sheet/coil assembly (heat exchanger section) that transfers heat to pool water
- Helps correct internal leaks, reduced heat output, and performance loss caused by coil damage or heavy scaling
- Provides the required sealing components for proper reassembly (kit contents vary by heater design revision)
What’s Included
- Tube sheet coil (heat exchanger) assembly for MasterTemp/Max-E-Therm 400 applications
- Required O-rings for sealing the coil/tube sheet connection points (as supplied with the kit)
- Insulation components (as supplied with the kit)
- Igniter (as supplied with the kit)
- Blower gaskets (as supplied with the kit)
Common Signs You Need a New Coil Assembly
- Water leaking from the heater cabinet or evidence of internal water damage
- Poor heating performance after confirming proper gas supply, airflow, and clean filter flow
- Repeated “sooting” or overheating symptoms related to restricted heat transfer (often from scaling)
- Visible corrosion or damage to the existing coil/tube sheet assembly during service
Installation Notes
- This is a major heater repair. Installation is best handled by a qualified pool heater technician.
- Verify your exact heater model and manufacturing/design revision before ordering.
- After replacement, confirm proper water flow, combustion airflow, and venting to prevent repeat damage.
- Address the root cause of coil failure (water chemistry, scale, low flow, freeze damage) before restarting the heater.
Related Products
- Coil/Tubesheet Sealing O-Ring Kit (400NA/400LP) - 77707-0119
- Manifold Kit (400NA/400LP) - 77707-0016
- Thermal Regulator Kit - 77707-0010
- Water Pressure Switch - 42001-0060S
- Drain Plug - U178-920P
- Pentair MasterTemp 400 replacement parts
- Sta-Rite Max-E-Therm 400 replacement parts
Maintenance Tips
- Maintain balanced water chemistry (especially pH and alkalinity) to reduce scaling and corrosion inside the heat exchanger.
- Keep flow in spec: clean the filter, baskets, and pump strainer to avoid low-flow overheating and coil stress.
- If you operate in hard-water areas, consider periodic scale prevention practices and monitor heater outlet temperature.
- Winterize properly in freeze-prone areas—freeze damage is a common cause of coil and header failures.
Questions about returns? View our return policy.
Hours Of Operation:
Monday - Friday: 7:00 am to 5:00 pm Phoenix Time
Saturday: 8:00 am to 2:00 pm
Sunday: Closed
- We do not ship on Saturday or Sunday.
- Orders totaling more than $300 will require signature confirmation upon delivery.
- We process and prepare orders for shipment within 1 business day. Please note that many other pool supply retailers require 3–5 days of handling time before shipping.
- Orders placed after 1:00 pm Phoenix Time may not be eligible for same-day shipment.
- Expedited shipping options are available at checkout.
Return Policy:
- Products that are received damaged will receive a refund in store credit.
- Most products are eligible for return within 30 days of receipt, except where noted below.
- To initiate a return, please complete an RMA form prior to sending your item back.
- Original shipping costs are non-refundable and will be deducted from the return credit.
- Items returned missing accessories or original packaging, or that are not in the same condition as received, may be subject to a restocking fee of up to 100% depending on the condition of the item upon return.
- Some returns will be charged an automatic 15% restocking fee.
- We are unable to issue refunds for items that have been damaged or rendered inoperable due to installer error.
- Please complete the return form to receive your RMA number and return shipping label.
- Chemical products are not eligible for return under any circumstances.
- The Pentair Colorsync 618031 is not eligible for return.
- Pool cleaners are not eligible for return.
- Opened seals and o-rings are not eligible for return.
- Capacitors are not eligible for return.
- Plastic popup tools are not eligible for return.
- Automation components and circuit boards are not eligible for return.
- If a light is returned due to a reported malfunction and is found to be fully operational upon testing, return shipping costs and a restocking fee will be deducted from the refund.
- Orders refused at the time of delivery will be subject to the original shipping costs being deducted from the refund.
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