If you work in industrial automation, chances are you’ve relied on Honeywell temperature transmitters at some point. As someone who’s been supplying these units for over eight years, I get asked a lot of the same questions—most of them pretty straightforward, but one that always pops up when customers are calibrating systems or troubleshooting drift is: “What’s the temperature coefficient of a Honeywell temperature transmitter?” It’s not a one-word answer, I’ll admit, so let me break this down like I would over a coffee at a trade show, no fancy jargon that makes your eyes cross. Honeywell Temperature Transmitter
First, let’s start with the basics, because a lot of folks mix up “temperature coefficient” with something like accuracy. Put simply, the temperature coefficient (we shorten it to TC around the warehouse) is how much a transmitter’s output drifts when the ambient temperature around it changes. Every electronic component has a TC—resistors, sensors, even the microchips that run the transmitter—so it’s impossible to get a unit that’s 100% immune to temperature shifts. The key is how well Honeywell engineers design those effects out, right?
I deal with two main lines of Honeywell temperature transmitters day to day: the THT3000 series, which is workhorse stuff for oil and gas, chemical plants, and wastewater treatment, and the TSTR8300, a smaller, more compact unit used in food and beverage processing and pharmaceutical facilities where space is tight. Their TCs aren’t the same, and that’s intentional—each is built for a specific use case, so you don’t pay for specs you don’t need, and vice versa.
For the THT3000, the TC is rated at ±0.015% of the calibrated range per °C. Wait, let me make that real for you. If you’ve got a unit calibrated to measure 0°C to 100°C, that’s a 100°C range. So a 1°C change in ambient temp would shift the output by 0.015% of 100°C, which is 0.015°C. That’s tiny—like a single blip on a thermometer. The catch here is that’s the TC for the ambient temperature; there’s also the process temperature, right? Because the transmitter is reading the process medium (water, oil, whatever) so the difference between process temp and ambient is a factor too. Honeywell accounts for that in their design, so the process-related drift is even lower—±0.01% of range per °C. Most of the customers who go for THT3000 are in heavy industries where the plant floor can swing from 10°C to 50°C in a single day, so this TC keeps their readings stable even when the AC acts up or a door gets left open.
Now the TSTR8300, the compact one. It’s not as overbuilt as the THT3000, so its TC is a bit higher, at ±0.025% of range per °C. That’s still really good—way better than generic no-name units you’d find online. The difference is because it’s smaller, so the components are packed a bit tighter, and the power draw is lower, which means the self-heating effect is minimal (that’s when the transmitter warms itself, adding to the ambient temp shift). For the TSTR8300, self-heating contributes about 0.005°C per mW, which is negligible for most applications. I had a customer last year in a craft brewery using these for fermenting tanks—they run their plant at a steady 20°C, so even with small process temp swings, this TC didn’t cause any issues with their fermentation consistency.
I should also mention that Honeywell lists TCs in two ways: some are per “full scale range” (FSR), others per “span” of the measurement. For industrial transmitters, span is more common, so that’s what I quoted. A mistake I see a lot of new integrators make is mixing that up—they see a TC in per FSR and it looks better, but if your span is smaller, that doesn’t translate the same. For example, a transmitter with a ±0.01%/°C TC per FSR on a 0-100°C range is the same as 0.01%/°C span for that range, so it all lines up. Honeywell’s datasheets spell this out clearly, and I always make sure to send my customers the exact datasheet for their specific model so they don’t get tripped up.
Another thing that affects TC is how the transmitter is mounted. I’ve seen customers get a unit that should have a TC of ±0.015%/°C end up with drift three times that, just because they mounted it near a hot pipe or a ventilation fan blowing directly on the electronics. The transmitter’s sensor is isolated from the process, but the electronics module is exposed to ambient temp, so if the ambient temp isn’t stable, the TC becomes a bigger factor than it needs to be. Honeywell recommends mounting the transmitter in a weatherproof enclosure if the plant has large temp swings, and that’s a tip I pass on to every customer—saves them headaches later when they’re calibrating their system quarterly instead of monthly.
Now, why does this matter? If you’re running a critical process, like refining gasoline or manufacturing injectable drugs, a small drift in temperature can lead to big problems. A refinery I supply to had an issue a few years ago where they were using a cheap temperature transmitter from a competitor; their TC was ±0.1%/°C, so when the plant temp dropped 10°C, the temperature reading shifted by 1°C. That made their control system adjust the heating too much, wasting thousands in fuel every month. When they switched to Honeywell THT3000, their drift was 0.15°C for that same 10°C swing, so their control system was spot on, and their utility bills dropped a ton. That’s the kind of real-world impact TC has, and Honeywell’s numbers are designed to keep that drift as low as possible without jacking up the price unnecessarily.
I also get asked about the “long-term” TC, which is different from the short-term ambient TC. Honeywell’s transmitters have a stability rating of ±0.05% of range per year, which means over time, as components age, the TC doesn’t change much. You won’t have to recalibrate your transmitter every six months just because the electronics are wearing out. For customers in continuous operation—like paper mills that run 24/7—this is a huge deal because it means less downtime for calibration, which translates to more production and more money for their business.
Wait, let’s clear up a common myth: some people think temperature coefficient is the same as accuracy. No way. Accuracy is how close the reading is to the actual process temperature at a specific moment, while TC is how much that reading changes when temp changes. A transmitter can have great accuracy but a bad TC, or vice versa—Honeywell’s units nail both. For example, the THT3000 has an accuracy of ±0.025% of range, so even when the ambient temp shifts, it’s still within that accuracy window because the TC is low enough.
What about special applications? If someone needs a transmitter for extreme environments—like arctic drilling or high-temperature furnaces—Honeywell has models for that too. Their extreme temp transmitters have TCs as low as ±0.008% of range per °C, because they use better, more stable components (like ceramic resistors instead of plastic ones) that can handle -40°C to 125°C without drifting. I sold a few of those to a mining company up in northern Canada last year, and they said the readings were still stable after a harsh winter where temps dropped to -35°C for weeks on end.
Now, let’s talk about how this plays into supply, because I’m a supplier, so that’s my lane. A lot of the time, customers come to me looking for a transmitter with a specific TC, and I don’t just pull a unit off the shelf. I ask them about their process: what’s the temp range they’re measuring? How stable is their plant’s ambient temp? What’s the criticality of the process? If it’s a simple application, like heating water for a building, the TSTR8300’s TC is more than enough, and it’s cheaper. If it’s a critical process, I steer them to the THT3000, because the lower TC will save them money in the long run on calibration and utility costs. I never push a more expensive unit than they need—partly because I want repeat business, but mostly because I know overengineering a solution just wastes money.
I also test every Honeywell transmitter I get before shipping it out, just to make sure the TC matches the datasheet. Sometimes a unit might have a small drift out of spec, and I send it back to Honeywell for replacement—their quality control is good, but mistakes happen. Last quarter, I had three THT3000s come in with a TC that was a tiny bit higher than rated, so I sent them back and got new ones within a week, no questions asked. That’s the kind of support you don’t get with no-name brands, which is why my customers keep coming back.
Another question I get: do TCs change over the life of the transmitter? I mentioned stability earlier, but generally, no—Honeywell’s components are chosen to minimize drift over time. I’ve had customers tell me they’ve had Honeywell transmitters running for 10 years, and when they recalibrate them, the TC is still within spec. The only time you’d see a change is if the transmitter gets damaged—like if it’s hit with chemicals or dropped during installation, but that’s not a TC issue, that’s a handling issue.
Let me wrap this up so it makes sense for someone who’s not an electrical engineer. The temperature coefficient of a Honeywell temperature transmitter isn’t a random number—it’s a spec tailored to the model, designed to keep your temperature readings stable even when things get hot, cold, or swing around. For most industrial uses, you’re looking at ±0.015% to ±0.025% of range per °C, which is way better than the average transmitter on the market. Mounting matters, understanding the difference between ambient and process temp helps, and picking the right model for your application means you don’t pay for specs you don’t need.
If you’re in the market for a Honeywell temperature transmitter and you want to talk through which model’s TC is right for your process, or if you need a quote, feel free to reach out. I’ve got stock of both the THT3000 and TSTR8300, and I can get special models for extreme environments too. No hard sell, just honest advice from someone who’s worked with these units for years and knows how they perform in real plants, not just on a datasheet.
Yokogawa Pressure Transmitter References
- Honeywell, “THT3000 Temperature Transmitter Datasheet,” Honeywell Process Solutions, 2022.
- Honeywell, “TSTR8300 Compact Temperature Transmitter Specification Guide,” Honeywell Industrial Automation, 2023.
- ASTM International, “Standard Test Method for Temperature Coefficient of Electronic Components,” ASTM B117-21, 2021.
- Honeywell, “Extreme Environment Temperature Transmitter Product Bulletin,” Honeywell Advanced Technologies, 2022.
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