Pentair 77707-0253 Air Combustion Blower Kit — MasterTemp 400NA & Max-E-Thermostat SR400NA, Natural Gas — Genuine OEM
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The Pentair 77707-0253 Air Combustion Blower Kit is the genuine OEM blower assembly for natural gas MasterTemp 400 and Sta-Rite Max-E-Therm 400 pool and spa heaters. The blower drives the forced-draft combustion system — without it the heater will not fire.
⚠️ Natural Gas Only
This kit is for natural gas 400NA models. Propane units take a different blower kit. Check your heater's fuel type before ordering.
Key Features
- Genuine Pentair OEM: Correct blower speed and housing for the 400K natural gas combustion system.
- Restores combustion performance: Addresses no-ignition, lockout and airflow-related fault codes traced to a failed blower.
- Complete kit: Supplied as an assembly rather than a bare motor.
- Forced-draft design: The blower is what makes the MasterTemp's sealed combustion and high efficiency possible.
Specifications
- Part Number: 77707-0253
- Type: Air combustion blower kit
- Fuel: Natural gas only
- Capacity: 400,000 BTU models
- Fits: Pentair MasterTemp 400NA; Sta-Rite Max-E-Therm SR400NA
- Heater Model: 460736
- Propane Equivalent: Different part — confirm fuel type before ordering
- Brand: Pentair / Sta-Rite (Genuine OEM)
Frequently Asked Questions
Will this fit my propane heater?
No. The 77707-0253 is the natural gas kit. Propane models use a different blower assembly — 77707-0254 covers the 175LP and 200LP, and larger propane models have their own part numbers.
What symptoms point to a failed blower?
The heater not firing at all, repeated ignition lockouts, unusual noise from the blower housing, or airflow and pressure-switch fault codes once the switch itself has been ruled out.
Does it fit smaller MasterTemp heaters?
No. This is the 400K assembly. The 175K, 200K, 250K, 300K and 333K models each use different blower kits.
Is the motor sold separately?
This is supplied as a complete kit. Pentair does not generally sell the blower motor as a standalone component for this model.
Who should install it?
A qualified pool heater technician. The blower sits within the sealed combustion system and correct reassembly matters for safe operation.
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 77707-0253. Quote 77707-0253 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.