MCK-301-61 & MCK-301-85 Digital Temperature Controllers for Cold Chain & HVAC

When a Mechanical Thermostat Fails at 3 AM — And Your Cold Chain Cannot Afford It

Imagine a refrigerated warehouse storing temperature-sensitive biologics. The ambient summer temperature outside is pushing 45°C. Inside the compressor room, the control panel houses a 15-year-old bimetallic thermostat — its calibration drifted by ±4°C over the years, its contacts pitted from years of inductive switching. At some point in the early hours, it fails to actuate the compressor correctly. By morning, the storage zone has crept 6°C above the validated upper limit. The product is compromised. The audit trail shows no alarm was triggered, no defrost cycle was logged, and no corrective action was recorded.

This is not a hypothetical. It is the precise failure mode that microcontroller-based digital temperature controllers were engineered to prevent. In cold chain logistics, pharmaceutical cold rooms, food processing, and HVAC chiller plants, the thermostat is not a passive convenience device — it is the primary protective element in the refrigeration control loop. When it drifts, fails to switch, or lacks defrost intelligence, the consequences cascade rapidly.

Novatek Electro India's MCK-301-61 and MCK-301-85 digital temperature controllers are purpose-engineered for exactly these environments. Designed, manufactured, and quality-audited at our Delhi facility under ISO 9001:2015 and CE certification, they bring microcontroller intelligence to refrigeration and HVAC control loops that previously depended on mechanical or basic electronic thermostats.

MCK-301-61 — HVAC & Room Temperature Controller

MCK-301-85 — Refrigeration & Cold Chain Temperature Controller

Why Mechanical and Basic Electronic Thermostats Fail in Industrial Refrigeration

To understand why digital microcontroller-based controllers matter, you need to understand what actually goes wrong with legacy thermostats in industrial refrigeration duty:

1. Contact Degradation from Inductive Load Switching

Compressor contactors and fan motors are inductive loads. Every switching event generates an arc across the thermostat contacts. Over thousands of cycles, contact resistance rises, switching becomes unreliable, and setpoint hysteresis effectively shifts — sometimes by several degrees Celsius. In a pharmaceutical cold room or a food processing chiller, a 3°C drift in effective switching threshold is the difference between a compliant storage environment and a product loss event.

2. Sensor Calibration Drift

Bimetallic and capillary thermostats rely on mechanical deflection for temperature sensing. These mechanisms drift over time, especially in environments with vibration (compressor rooms) or thermal cycling. Unlike PTC/NTC thermistor-based digital sensors, they offer no self-diagnostic capability and no way to verify calibration in the field without a reference thermometer and a recalibration procedure.

3. No Defrost Intelligence

In refrigeration systems operating below 5°C, frost accumulation on evaporator coils is inevitable. Without a programmed defrost cycle, frost buildup progressively reduces heat transfer efficiency, increases compressor discharge pressure, raises power consumption, and eventually causes the evaporator to ice over completely. Legacy thermostats have no defrost scheduling capability whatsoever — defrost timers are added as separate electromechanical modules, introducing additional points of failure.

4. Absence of Alarm and Logging

Regulatory frameworks for pharmaceutical cold chain (Schedule M, WHO PQ guidelines) and food safety (FSSAI, HACCP) increasingly mandate continuous temperature monitoring with alarm records. A mechanical thermostat generates no digital record, no time-stamped alarm, and no audit trail. This alone disqualifies it from compliant cold chain deployments.

Introducing the MCK-301-61 and MCK-301-85: Microcontroller Intelligence for Refrigeration Control

Both the MCK-301-61 and MCK-301-85 are members of Novatek Electro's MCK-301 family — microcontroller-based intelligent temperature controllers designed for HVAC room temperature control and refrigeration duty respectively. They accept PTC and NTC thermistor inputs, operate across a supply voltage range of 220V–415V AC, and provide digital setpoint programming with configurable hysteresis, alarm thresholds, and operational modes.

Key Technical Specifications

Operational Modes That Match Real Refrigeration Control Requirements

What distinguishes these controllers from basic digital thermostats is the structured set of operational modes programmed into the microcontroller logic. The MCK-301-61 is designed for HVAC room temperature and climate device control, including both electric heater thermostat duty and air conditioning zone control. The MCK-301-85 extends this to refrigeration plant duty with compressor cycling and defrost control.

• Heater Thermostat Mode: Controls electric heating elements in temperature-conditioned spaces, with configurable ON/OFF hysteresis to prevent short-cycling.
• Air Conditioning Zone Control Mode: Manages fan coil units or split AC contactors in multi-zone HVAC installations with deadband control.
• Refrigeration / Compressor Control Mode: Drives compressor contactors based on zone temperature feedback, incorporating anti-short-cycle timers to protect compressor motors from rapid restart stress.
• Defrost Scheduling Mode: Initiates timed defrost cycles at programmable intervals, suspends compressor operation during the defrost period, and returns to cooling duty upon defrost termination — either by time or by temperature.
• Alarm Mode: Activates a relay output when measured temperature exceeds the configured high-temperature or low-temperature alarm threshold. Suitable for driving audible alarms, remote notification modules, or BMS input signals.
• Test Mode: Enables forced actuation of output relays for commissioning and fault-finding without requiring thermal stimulus — a critical capability for panel builders during factory acceptance testing.

Where These Controllers Are Applied

Pharmaceutical and Vaccine Cold Chain

Regulatory-grade cold rooms and refrigerated storage for biological products, vaccines, blood products, and API storage require continuous temperature monitoring with alarm capability and documented setpoint integrity. The MCK-301-61 and MCK-301-85 provide the monitoring, switching, and alarm functions required in these environments, complementing data loggers and validation thermometers in the instrumentation stack.

Food Processing and Cold Storage Facilities

Multi-chamber cold stores, blast freezers, and chilled distribution warehouses require independent zone temperature control with defrost scheduling tuned to the specific product load and ambient conditions. The configurable defrost intervals and termination logic in the MCK-301-85 match the operational patterns of these facilities without requiring PLC programming.

HVAC Chiller Plants in Commercial and Industrial Buildings

Chilled water plants serving large office complexes, hospitals, data centres, and manufacturing facilities use multiple compressors staged against varying cooling loads. The MCK-301-61 provides zone-level temperature control logic for air handling units and fan coil circuits, ensuring that compressor staging is driven by real zone conditions rather than a central setpoint alone.

Water and Wastewater Utility Infrastructure

Pump stations, treatment works, and electrical switchgear rooms in water utility infrastructure frequently require temperature-controlled ventilation and cooling. In tropical climates, switchgear room temperatures exceeding 45°C accelerate insulation ageing and relay maloperation. The MCK-301-61 provides automatic control of cooling fans, exhaust ventilators, and split AC units in these unmanned environments.

Industrial Process Cooling

Process chillers serving injection moulding machines, hydraulic power packs, CNC machining centres, and transformer cooling circuits require tight temperature regulation to maintain product quality and equipment life. The configurable hysteresis and anti-short-cycle protection in the MCK-301-85 are directly applicable to these process cooling loops.

Quick Selection Guide

* All prices exclusive of GST. GST @ 18% applicable extra. Prices effective from 01.04.2026 as per Novatek Electro India Price List 2026-27.

Why Novatek Electro?

• ISO 9001:2015 Certified Manufacturing: Every MCK-301 series unit is produced and tested under a documented quality management system. Traceability, process control, and inspection records are maintained for every production batch.
• CE Certified Product Range: The MCK-301-XX family carries CE marking, confirming compliance with EU electromagnetic compatibility and low voltage directives — a prerequisite for export-oriented OEM panel builders and multinational facility operators.
• Made in India, Engineered for Indian Conditions: Wide input voltage range (220V–415V AC) addresses the voltage fluctuation reality of Indian industrial power supplies. Products are tested under Indian ambient temperature and humidity conditions, not European laboratory norms.
• 30+ Years of Electrical Protection Expertise: Novatek Electro India brings over three decades of experience in electrical protection and control devices, with a product range spanning motor protection relays, multifunction timers, power quality analysers, and HVAC controllers.
• After-Sales Support and Distributor Network: Technical support is available through our sales team and authorised distributor network across India. Panel builders and OEMs can access application engineering guidance, wiring diagrams, and commissioning support.

Frequently Asked Questions