Kegerator Temperature Sensor Types: Thermistor or Bulb

What the sensor type means on a listing

When you read a kegerator listing, the temperature control section may name the sensor type: thermistor, capillary bulb, or simply “thermostat.” These words describe how the unit senses the air temperature inside the cabinet and tells the compressor when to run. The sensor is one part of the control system, and the listing may pair it with a digital display or a mechanical dial.

A listing that names the sensor gives you a clue about the control design, but the sensor type alone does not tell you how the unit performs. The same kegerator may appear in several listings with slightly different wording, so the sensor description may vary from one listing to the next. Read the bullet list for the control type and the display type as well.

If a listing does not name the sensor type, that is not a fault. Many listings say only “thermostat” or “temperature control.” Reading the control type and the display type is often more useful than looking for the sensor word. You can compare two units on those stated details even when neither names the sensor. See the kegerator temperature control types guide for the control words listings use.

• The control is electronic or mechanical
• The display is likely digital or a dial
• The adjustment is stepped or continuous

Thermistor sensors explained

A thermistor is an electronic component whose electrical resistance changes as the temperature around it changes. The control board reads that resistance and compares it to the set point you choose. Because the reading is electronic, a thermistor-based control can show the temperature on a digital display and adjust in small steps.

In listings, the thermistor word usually appears next to “digital display,” “electronic thermostat,” or “thermostat control.” When you see those words together, the unit reads temperature electronically and adjusts through a control board. The listing may also specify a temperature range that the control can hold, but it rarely states how closely the unit holds the set point. For more on how a digital display pairs with a thermistor, read the digital display features article.

What a thermistor listing can and cannot tell you: it tells you the sensing method and the likely control style. It does not tell you how quickly the cabinet responds, how evenly the temperature is held, or how accurate the reading is. Those details are usually “not stated by the seller.”

Capillary bulb sensors explained

A capillary bulb sensor is a mechanical device: a small bulb filled with a gas or liquid, connected by a thin tube to a switch. As the temperature in the cabinet changes, the gas or liquid expands or contracts and moves a diaphragm, which opens or closes the switch that runs the compressor.

In listings, a capillary bulb sensor usually appears with a mechanical dial control. The dial may be labeled with numbers or with a range, and the user turns it to choose a colder or warmer setting. Some listings call it a “capillary thermostat” or simply “mechanical thermostat.”

What a capillary bulb listing can tell you: the sensing method is mechanical, and the control is a dial. What it cannot tell you: how evenly the temperature is held or whether the dial position matches a specific temperature. Those details depend on the cabinet, not on the sensor alone.

Reading accuracy in listings

Accuracy is rarely stated in a kegerator listing. A listing may say the thermostat holds a temperature range, or it may say nothing about accuracy at all. The phrase “not stated by the seller” is common for sensor accuracy because accuracy is not a specification that sellers publish consistently. The thermostat differential article explains what the difference between the on and off points means.

What you can compare across listings: the control type (digital or dial), the display type, and the stated temperature range. A digital display with a thermistor sensor shows the current reading, so you can see the temperature at a glance. A mechanical dial with a capillary bulb does not show a reading, so you set it by turning the dial. For how to read a stated temperature range, see the temperature range spec article.

For a buying decision, the sensor type matters less than whether the listing gives you a way to see and adjust the temperature. A listing that states a control type and a display type gives you more to compare than a listing that names only the sensor.

Matching the sensor type to your setup

For a first kegerator, either sensor type can work. The practical difference is how you set the temperature: a digital display with a thermistor lets you read and adjust in numbers, while a dial with a capillary bulb lets you turn to a position. Choose the control style you prefer to use. The best kegerator guide shows how the control type appears across current models.

For a home bar where you want a quick read, a digital display paired with a thermistor sensor gives you a number on the cabinet. For a garage or a shared space where a simple dial is enough, a capillary bulb control may be all you need. The best undercounter kegerators guide and the best commercial kegerators guide list the stated control details for different cabinet types.

The sensor type appears across home and commercial listings. A commercial listing may state a mechanical thermostat, while a home listing may state a digital display for convenience. Match the control style to the space, not to the word “commercial” or “home.”

Questions to ask the seller

Before you buy, read the listing for the control type and the display type. If the listing names the sensor but not the control, ask the seller how the temperature is adjusted.

These questions help you compare two listings that both say “thermostat” without naming the sensor. A listing that answers the control and display questions gives you a clearer picture than one that only repeats the sensor word.

For more on how the thermostat reads the cabinet, read the temperature probe placement article, the thermostat differential article, and the temperature control types article.

• Is the temperature reading shown on a display or a dial?
• Is the control electronic or mechanical?
• Does the listing state a temperature range for the thermostat?
• Is the sensor included with the unit or listed as a separate part?

What to pick for your situation

Questions

What is a thermistor sensor on a kegerator?

A thermistor is an electronic component that changes resistance as the temperature around it changes. The control board reads that resistance and adjusts the compressor. Listings that mention a thermistor usually pair it with a digital display.

What is a capillary bulb sensor?

A capillary bulb sensor is a mechanical device: a small bulb filled with gas or liquid connects through a thin tube to a switch. As the temperature changes, the gas or liquid expands or contracts and moves the switch. Listings that mention it usually pair it with a dial control.

Which sensor type is more accurate?

Accuracy is not usually stated in listings, so there is no published basis to compare the two. The practical difference is the control style: a digital display with a thermistor versus a dial with a capillary bulb. Compare what each listing states about the control and display.

Do I need a specific sensor type on a kegerator?

No. Either sensor type can appear on a kegerator. Choose based on the control style you prefer and what the listing states about the display. See the best single tap kegerators guide for single tap models.

What if the listing does not state the sensor type?

“Not stated by the seller” is common for the sensor type. Read the control type and display type in the bullet list instead.

Are thermistor sensors only on home kegerators?

No. Sensor types are not limited by the home or commercial label. Read the listing for the control and display details. The best dual tap kegerators guide shows how control details appear across dual tap models.