Quick Overview: This guide compares common resettable thermal switches and thermal cutoffs for water heaters and general heating equipment. The selected parts include OEM and aftermarket replacements for Bradford White units, KSD301 bimetal thermostats for appliances, and a pool heater rollout fuse. Use the summary table to find compatible part numbers, temperature ratings, and typical applications quickly.
| Product | Type / Temp | Compatibility / Use | Brand |
|---|---|---|---|
| 239-43676-03 Resettable Thermal Switch | 290°F Resettable | Bradford White water heaters (MI series) | Generic |
| Bradford White 239-43676-03 Thermal Switch | Resettable / OEM spec | Direct OEM replacement for Bradford White heaters | Bradford White |
| 2394367602 Water Heater Thermal Switch (Apobelor) | Resettable / 130°C (typical KSD301) | Bradford White direct replacement 239-43676-02 | Apobelor |
| 2394367602 Resettable Thermal Switch (MZCTD) | 130°C / 250V / 16A | Bradford White and similar residential/commercial units | MZCTD |
| Awozkcd KSD301 Shutoff Thermostat | 40°C On / 30°C Off (examples), KSD301 family | Appliances, fans, general thermostat control | Awozkcd |
239-43676-03 Resettable Thermal Switch 290F
This resettable thermal switch is listed as compatible with Bradford White part numbers 239-43676-03 and 415-43676-03. It is commonly used as an overheat protection device in MI-series water heaters and functions as a high-temperature cutoff. The switch is specified to open at approximately 290°F, interrupting power when the heater overheats. Its resettable design allows it to close again after cooling, restoring operation without replacing the component each time.
Features referenced include compatibility across multiple MI-series models and purpose as a replacement for worn thermal fuses. Suitable for technicians who need a like-for-like replacement for overheat protection in compatible Bradford White units.
Bradford White 239-43676-03 Thermal Switch
This listing is for a genuine OEM Bradford White replacement part, model number 239-43676-03. OEM parts are produced to match factory specifications and are typically supplied with assured fit and function for the designated water heater models.
Key product details emphasize OEM authenticity and direct interchangeability. For installations requiring factory-specified components—especially in warranty or code-sensitive situations—an OEM part may simplify verification of proper replacement.
2394367602 Water Heater Thermal Switch (Apobelor)
The Apobelor thermal switch is offered as a direct replacement for 239-43676-02 and monitors water heater temperature to prevent overheating. It functions as a resettable cutoff, restoring power once temperatures return to safe levels. The description notes compatibility with Bradford White water heaters and application in both residential and commercial installations.
Product features highlight automatic shutdown at preset thresholds and typical uses as a safety device to mitigate fire risk and equipment damage. Verify original part numbers and model compatibility prior to purchase.
2394367602 Resettable Thermal Switch For Bradford White
This MZCTD-branded switch is described as a direct replacement for part numbers 2394367602 and 415-43676-02. It cites a KSD301 temperature control rated at 130°C (266°F) with electrical ratings of 250V, 16A. The resettable characteristic is emphasized for repeated overheat protection cycles.
Detailed compatibility notes list several Bradford White model numbers. The product information suggests it can be used in residential and commercial units, but recommends verifying the heater model before installation to ensure correct fit and trip temperature.
Awozkcd UL/CUL KSD301 Shutoff Thermostat
The Awozkcd item is a KSD301-style bimetal snap thermostat intended for general appliance temperature control. The listed example has 40°C on / 30°C off action and is a Normally Open (N.O.) device, closing on temperature rise. The product carries UL/CUL approval and supports multiple voltage and current ratings including 125V 16A.
Unlike heater-specific resettable cutoffs, KSD301 thermostats are versatile for exhaust fans, small heaters, and motors. They provide precision switching via a bimetal disc and are used where repeatable temperature-controlled switch points are needed rather than a single-use fuse.
Buying Guide: How To Choose The Right Thermal Switch For Your Heater
Choosing the correct thermal switch requires comparing compatibility, temperature ratings, electrical specifications, reset behavior, and certification. This guide covers the main factors to evaluate before purchasing a thermal switch or thermal cutoff.
1. Confirm Model Compatibility And Part Number
Always cross-check the heater’s original part number or model plate. Many listings are labeled as direct replacements for specific Bradford White numbers like 239-43676-03 or 239-43676-02. Installing a part with a mismatched mounting, terminal layout, or trip temperature can lead to improper protection or operation.
2. Trip Temperature And Function
Thermal switches have specified trip temperatures. Resettable limit switches often open at higher temperatures (e.g., ~266°F–290°F) for overheat protection, while KSD301 thermostats offer lower control points (e.g., 40°C/30°C) for ambient or appliance-level control. Choose based on whether you need a safety cutoff or a temperature-control switch.
3. Resettable Vs. One-Time Cutoff
Resettable switches automatically close after cooling, reducing replacements when nuisance trips occur. One-time thermal fuses or fusible links must be replaced after they open and are typically used for critical safety where permanent intervention is required. Pick resettable units for maintenance-friendly setups and single-use fuses where mandated by design.
4. Electrical Ratings And Contact Type
Match voltage and current ratings to the heater circuit (examples: 125V, 250V, 16A). Also confirm contact action: Normally Open (N.O.) closes on rise; Normally Closed (N.C.) opens on rise. Incorrect contact type can prevent the heater from powering as intended.
5. Physical Fit And Terminal Configuration
Check mounting holes, bracket orientation, and terminal types. Even if temperature and electrical specs match, a different physical layout can complicate installation or require adaptors. OEM parts typically match the original form factor precisely.
6. Certifications And Quality Standards
UL or CUL listings indicate the device meets recognized safety standards. For appliances and home equipment, certified switches reduce risk and may be required for code compliance in some jurisdictions.
7. Application Specifics (Water Heater vs. Pool Heater vs. Appliance)
Pool heater rollout switches and water heater thermal cutoffs are designed for their respective environments and thermal dynamics. Pool heater fusible links often have higher rated temperatures (e.g., 152°C) and are sized for combustion areas, while water heater switches focus on tank and element temperatures. Select parts labeled for your specific application.
8. Longevity And Maintenance
Resettable designs can reduce spare parts inventory but may mask underlying faults if nuisance trips continue. When a switch trips repeatedly, diagnose tank components, thermostats, and element grounding rather than repeatedly resetting the device.
9. When To Choose OEM Vs. Aftermarket
OEM parts are beneficial when exact fit and factory specifications are required, such as during warranty or code-sensitive repairs. Aftermarket options can provide cost-effective replacements and broader availability but verify specs closely to ensure equivalence.
10. Troubleshooting Tips Before Replacement
- Confirm the heater model and original part number from the manufacturer’s plate.
- Measure supply voltage and inspect wiring and terminals for corrosion or loose connections.
- Check for signs of overheating or repeated trips that suggest component or control failure.
- Use a multimeter to test continuity of suspect switches when cool and after heating cycles per service manual procedures.
Comparing compatibility, trip temperature, reset behavior, electrical ratings, and physical fit will help select the most appropriate thermal switch for heater safety and reliable operation.