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Thermocouples and RTDs
Using RTD temperature sensors
Using RTD temperature sensors

Prefer to use RTDs rather than thermocouples on your roaster - we've got a solution for you!

Linsey Fan avatar
Written by Linsey Fan
Updated over a week ago

The merits of thermocouples vs. RTDs (resistance temperature detectors) for coffee roasting applications is often debated.  The good news is that whether you lean towards thermocouples, or if you prefer RTDs, we've got you covered.

A little history...

Back when we started RoastLog, there weren't a lot of off-the-shelf hardware solutions for recording roast profiles. In fact, there were no software options specifically for commercial roasters.  So like any engineer worth their salt, we decided to build something!

As we set out to design our Data Bridge (our custom data logging device), we made the decision to use thermocouples for a litany of reasons.  For example, these handy temperature sensors were robust, reliable, and affordable - and remain so today. Since temperatures are dynamic over the course of the roast, we also wanted to be sure we chose a temperature sensor that would respond quickly enough to keep up during roasting.

While response times for thermocouples are more rapid than RTDs, one criticism of TCs is accuracy.  RTDs are generally considered more accurate (+/-0.1 deg C) than TCs (+/- 1.0 deg C).  There are a lot of factors that effect the accuracy of temperature readings. No matter which type of sensor you choose, our experience tells us that each has its pros and cons, and that there's no wrong choice.

Connecting your RTDs to RoastLog

We periodically review norms and standards across the RoastLog user base.  When it comes to the type of temperature sensors, thermocouples are still used by the vast majority of our users.  That said, RTDs have begun to grow in popularity.

Fast-forward a few years from the early days of RoastLog and a handful of companies have begun offering coffee roasters - large and small - data logging devices. One of the most popular of these are from the Canadian company, Phidgets.  Multiple versions of the Phidgets device have been introduced and we're happy to share that we are 100% compatible.

Phidgets VINT Hub connected to one RTD

Pairing the Phidgets device - we recommend the VINT Hub - with RoastLogger Web, makes for a very easy setup.  You'll need the following items:

  • VINT Hub Phidget

  • RTD Phidget VINT port adaptor

  • RTDs (two recommended) - bean temp & environmental air temp measurements

  • Phidgets cables

Once you're hardware setup is all done and you're ready to dive into RoastLog, check out our Getting Started collection of articles and don't miss the Getting Started with RoastLogger Web article, in particular

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