PT100 Thermocouple for Boilers in Nairobi | Wisdo Merchants

PT100 Thermocouple for Steam and Hot Water Boilers

A boiler depends on knowing its own temperature. If the sensor reads wrong, the burner overfires and wastes diesel, or the boiler runs short of hot water and steam just when you need it. In the worst case, overheating damages the boiler itself. A PT100 thermocouple gives the boiler controller an accurate reading, so it fires the burner at the right time and holds the temperature steady. At Wisdo Merchants, we supply PT100 thermocouples for boilers to boiler technicians, hotels, hospitals, laundries, schools and factories across Nairobi and Kenya.

Strictly speaking, a PT100 is a resistance thermometer, not a true thermocouple. Inside the probe is a platinum element that measures exactly 100 ohms at 0 °C. As the boiler water heats up, the resistance rises in a precise, predictable way. The controller reads it and starts or stops the burner to keep the water at the set temperature.

Features and Benefits of the PT100 Thermocouple

• Steady boiler temperature. The burner fires and stops at your exact set point, so hot water and steam stay consistent.
• Saves fuel. It stops the burner overfiring, which cuts diesel use.
• Protects the boiler. Accurate control prevents overheating of the boiler shell and heat exchanger.
• Stable for years. Platinum drifts very little, so readings stay reliable over time.
• Rugged industrial build. A stainless steel sheath protects the element, and the screw-cap head keeps the wiring dry and secure.
• Industry standard. Most boiler controllers and PLCs accept a PT100 input.

For boiler technicians, this means dependable repairs and fewer callbacks. Meanwhile, owners get reliable hot water and steam with lower fuel bills.

Technical Specifications

Applications of the PT100 Thermocouple and How to Use It

• Hot water boilers in hotels, hospitals and schools
• Steam boilers in laundries, food factories and dairies
• Calorifiers and hot water storage tanks
• Thermal oil boilers and heaters
• Flue gas temperature monitoring for efficiency checks

Replacing a Faulty Boiler Sensor

Picture a technician called to a hotel whose boiler keeps overheating at night. First, they switch off the burner, isolate the power and let the boiler cool. Next, they note how the old sensor is wired to the controller, then remove it from its sensor pocket. After that, they fit the new PT100 thermocouple fully into the pocket and connect it to the controller’s PT100 terminals. Finally, they power up, check the controller is set for a PT100 input, and fire the boiler while comparing the reading with the boiler’s thermometer.

Burners and Spares for Your Boiler

The PT100 tells the controller when to fire the burner, whatever brand you use. It suits boilers fired by the Riello G5 for small boilers, the Riello G20 for bigger heating loads and the two-stage Riello RL 34 MZ. While servicing, replace worn fuel lines with our braided hose for burner fuel lines.

Safety and Handling

• Isolate the power first. Switch off the burner and controller before wiring.
• Let the boiler cool. Boiler water, steam and pipes stay dangerously hot after shutdown.
• Never open a pressurised fitting. Fit the sensor in a dry pocket, or depressurise and drain the boiler first.
• Handle the probe gently. Bending or dropping it can damage the platinum element inside.
• Keep the safety devices. The PT100 controls temperature, but it never replaces the boiler’s high-limit thermostat or safety valve.

Frequently Asked Questions

Where is the sensor fitted on a boiler?

Usually in a sensor pocket (thermowell) on the boiler shell or flow pipe. The pocket lets you change the sensor without draining the boiler.

Is a PT100 really a thermocouple?

Technically no, though it’s widely called one. A thermocouple produces a small voltage, while a PT100 changes its resistance with temperature. For boilers, a PT100 gives accurate, stable control.

How do I know the boiler sensor has failed?

Common signs are wrong or jumping readings, a sensor error on the controller, or a boiler that overheats or won’t fire.

Can I use it with any boiler controller?

Only with controllers that have a PT100 (RTD) input. Check the controller’s label or manual, or call us to confirm.

Do you deliver outside Nairobi?

We offer same-day delivery once your order is confirmed, subject to stock availability. Call or email our sales team to confirm stock and arrange delivery to your site.

Order a PT100 Thermocouple from Wisdo Merchants

Accurate sensing keeps boilers efficient, safe and reliable. Our PT100 thermocouple helps your boiler hold the right temperature while saving fuel. Furthermore, you can browse our burners range for burners and boiler spares.

Visit us: Dar es Salaam Road, Off Enterprise Road, Industrial Area, Nairobi
Call: +254 795 938305
Email: sales@wisdomerchants.com