MASTER SPAS Auxiliary Slave Heater Pack 5.5kW - X300939

MASTER SPAS Auxiliary Slave Heater Pack 5.5kW - X300939

Auxiliary Slave Heater Pack 5.5 kW

What our Experts Think

• Reliable supplemental heating: The 5.5kW output provides strong, consistent heat support for maintaining ideal spa water temperature even in colder conditions.
• Improves system efficiency: Works as an auxiliary/slave unit to reduce strain on the primary heater, helping extend overall system lifespan.
• Fast temperature recovery: Helps hot tubs recover heat more quickly after use or water top-ups.
• Designed for compatibility: Engineered specifically for Master Spas systems, ensuring proper integration and stable performance.
• Energy-smart support role: Activates as needed to assist heating demand, helping balance performance and energy usage.
• Durable spa-grade construction: Built to withstand continuous water exposure and long operating cycles in demanding spa environments.

Q&A

Q: What is the MASTER SPAS Auxiliary Slave Heater Pack 5.5kW – X300939 used for?
A: It is a 5.5kW auxiliary (slave) flow-through heater system designed to help maintain and boost water temperature in compatible Master Spas hot tubs and swim spas.

Q: Is this a direct OEM replacement part?
A: Yes. The X300939 is an OEM Master Spas control/heater pack component made for compatible spa systems.

Q: What power requirements does it need?
A: It operates on 240V and typically requires a dedicated 30A GFCI electrical circuit for safe installation.

Q: What does a “slave heater” mean?
A: It works alongside the primary heating system to improve heating efficiency and help maintain stable spa water temperature under load.

Q: Is it suitable for all Master Spas models?
A: No. It is model-specific and must match your spa’s electrical and plumbing configuration—always verify compatibility before purchase.

Q: Does it include installation hardware?
A: It is typically supplied as a heater/control pack assembly, but installation fittings and wiring may vary depending on spa model.

Q: What are the benefits of this heater pack?
A: It helps maintain faster heat recovery, stable water temperature, and reliable spa performance during use in colder conditions.

Maintenance Tips

• Keep the heater pack area dry, ventilated, and free of chemical vapors to protect internal relays and sensors from corrosion.
• Ensure proper water flow at all times—clean filters regularly and check for restrictions that can cause overheating or “no flow” shutdowns.
• Maintain balanced water chemistry (pH, alkalinity, calcium hardness) to prevent scale buildup on the 5.5kW heating element and extend lifespan.
• Never run the heater dry or allow airlocks in the plumbing—bleed air after refills or service to avoid dry-fire damage.
• Inspect electrical connections, sensors, and terminals periodically for tightness, corrosion, or heat discoloration.
• Use a properly rated 30A GFCI supply and protect the system from voltage spikes or unstable power.
• After servicing, confirm correct mode/settings so the auxiliary heater engages properly during demand cycles.