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Red handheld CO2 temperature humidity monitor with display

TENMARS ELECTRONICS

TENMARS ELECTRONICS ST-501 CO2 temperature RH monitor electrician tool

SKU CH-0FGF-V8595 MPN ST-501

Measures CO₂, temperature and humidity with NDIR sensor, user calibration, 50,000-record USB datalogging and audible alarm

  • Labor warranty1 Year
  • Product typeTest Equipment
  • Color and finishRed
  • Number of items1 pack
  • Sold asBox
  • Parts warranty3 Years
  • Monitors CO₂, temperature and humidity with three independent sensors
  • NDIR sensing measures carbon dioxide from 0 to 9999 ppm
  • Accuracy within ±60 ppm or ±5 % of reading up to 2000 ppm
  • Stores 17,000 records internally and transfers 50,000 via USB
  • Built-in CO₂ alarm buzzer and PC software for data analysis

Indoor air quality monitor

The Tenmars ST-501 measures carbon dioxide, temperature and relative humidity using three independent sensors. It is built for HVAC technicians, facility managers and electricians who need verified indoor air quality data during commissioning or troubleshooting. The instrument logs up to 17,000 records internally and transfers up to 50,000 records via USB in under ten seconds.

Build integration and data workflow

The unit runs on an internal backup battery that preserves date and time settings while a power-management IC extends operating life. USB connectivity lets you download logs to the supplied PC software for parameter changes and trend analysis without additional adapters. No external power supply or specialised mounting hardware is required for typical handheld or benchtop use.

Thermals noise and power draw

The monitor operates silently with no moving parts, so it adds no audible noise to occupied spaces. Its low-power design allows extended monitoring sessions on the internal battery, and the CO₂ alarm buzzer activates only when concentrations exceed the set threshold. The NDIR sensor maintains the stated accuracy of ±60 ppm or ±5 % of reading up to 2,000 ppm without active cooling.

How it compares

Measured against everything we stock in Electrical Trade Tools & Kits, at today’s prices. Recalculated every night.

Price $364.99
Pricier than about 90% of the 5,006 comparable items (median $95.99).

Specifications

Product
Brand nameTENMARS
Model nameST-501
Product typeTest Equipment
Color and finishRed
In the box
Number of items1 pack

Questions about this item

What is the CO2 measurement ceiling before the ST-501 goes over range?

The ST-501 reads up to 9999 ppm; readings above 2000 ppm are flagged as over range.

Does the ST-501 generate noticeable heat or fan noise during all-day logging?

The ST-501 has no fan and its low-power IC keeps heat minimal during continuous operation.

What computer connection is needed to download the 50,000 stored records?

A standard USB port and the supplied PC software are required to pull the logged data.

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