Description
1. Unboxing & Physical Snapshot
- Model & Brand: Honeywell / Commercial Controls — Remote Bulb Temperature Controller (
T678A1437). - Physical Dimensions: Approximately 143mm x 51mm x 67mm (5-5/8 in. high x 2 in. wide x 2-5/8 in. deep compact housing envelope).
- Estimated Shipping Weight: 1.4 kg (robust die-cast housing and liquid-filled copper capillary sensing bulb assembly).
- What’s in the Box: Temperature controller chassis, remote copper capillary bulb, mounting bracket hardware pack, and multi-language installation sheet.
2. Product Introduction
Environmental hook: Governing fluid and air temperatures within severe HVAC duct networks or industrial boiler loops demands reliable mechanical sensing hardware capable of enduring chronic vibration and thermal shock. The ruggedized case protects internal snap-acting microswitches from aggressive mechanical stress and ambient dust.
Mounting securely directly onto control panel surfaces or remote equipment bulkheads, this unit interfaces fluid lines or air ducts via a flexible capillary tube. Reliability engineers depend on its dual sequential switching architecture to sequence multi-stage heating or cooling loads safely, which is critical for maintaining precise environmental compliance.
3. Core Technical Specifications
| Parameter | Value |
| Setpoint Temperature Range | 0°F to 100°F (-18°C to +38°C) |
| Switching Output | Two SPDT (Single-Pole Double-Throw) snap-acting switches operating in sequence |
| Electrical Rating | Maximum connected load of 2000 VA (120 Vac / 240/277 Vac) |
| Sensing Element | Liquid-filled copper remote bulb with capillary line |
| Interstage Differential | Fixed low-differential configuration for staged activation |
| Enclosure Protection | Open-frame industrial controller housing with Norel cover |
4. Global Compliance & Industry Certifications
- Regulatory Approvals: UL Listed (UL File E4436 Vol. ), CSA Certified, and CE Mark compliance for commercial electrical equipment.
- Safety Directives: Complies with applicable low-voltage electrical safety and thermal control device standards.
- Compliance Significance: The UL Listed certification guarantees that internal electrical spacing and heavy-duty switch contacts prevent electrical breakdown or contact welding under full 2000 VA connected loads.
- Audit Note: Verify specific lot certifications with OEM documentation prior to final mechanical loop commissioning.
5. Long-Term Storage & Asset Preservation Guide
When storing mechanical capillary controllers in warehouse inventory, prioritize physical protection of the thin copper capillary tube. Avoid sharp bends, kinks, or crushing forces along the flexible line, which would fracture the liquid fill and permanently ruin thermal calibration.
Keep the unit stored in a dry environment with relative humidity below 60% to prevent oxidation on the terminal screw blocks. Store the main housing upright inside its original protective carton to protect the external setpoint adjustment knob from mechanical impact damage.
6. Physical Installation Prerequisites
- Clearance Requirements: Leave adequate front clearance to allow unhindered access to the setpoint adjustment dial and manual verification of internal switch operations.
- Capillary Routing: Route the copper capillary tubing with gentle, sweeping radii (minimum 2-inch bend radius) to prevent internal stress points or fluid flow restrictions.
- Sensing Bulb Placement: Mount the remote sensing bulb directly in the median flow stream using an approved immersion well or compression fitting to ensure accurate thermal tracking.
7. Buyer’s FAQ (Logistics & Compliance Focus)
- Q: What Harmonized System (HS) Tariff Code applies to international shipments of this temperature controller?
- A: Typically classified under HS code 9032.10 (Automatic thermostats for regulating temperature); verify exact rulings with your customs broker.
- Q: Does this mechanical controller require external control power to operate?
- A: No; it operates as a self-contained electromechanical switching device driven directly by thermal expansion within the liquid-filled capillary bulb system.
- Q: How does the Country of Origin (COO) documentation affect cross-border import tariffs?
- A: Manufactured primarily in North American or designated global production facilities, the COO document determines eligibility for preferential trade terms; request paperwork prior to dispatch.
- Q: What transit insurance protections are mandatory for shipping this device?
- A: Procure standard “Fragile Electronics” logistics insurance, ensuring the capillary spool is heavily cushioned against heavy shock vibrations during freight handling.
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- A: Procure standard “Fragile Electronics” logistics insurance, ensuring the capillary spool is heavily cushioned against heavy shock vibrations during freight handling.
