Model # DTR900

Internet #202835804

General Tools Indoor/Outdoor Thermometer with Min/Max Memory

Discontinued General Tools

Indoor/Outdoor Thermometer with Min/Max Memory

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Product Overview

Since 1910, General Tools has grown to become the recognized industry leader for specialty hand tools and instruments. The General Tools DTR900 Inside/Outside Thermometer with Min/Max Memory can display inside and outside temperatures simultaneously, along with the time and date. It is ideal for walk-in refrigerators, reach-inn boxes, greenhouses and household and lab applications.

California residents: see   Proposition 65 information

  • Simultaneously displays the time and indoor and remote probe temperatures or the time and date and the remote probe temperature
  • Stores and recalls minimum and maximum indoor and remote probe temperatures with time and date stamps
  • Measurement ranges: 14° to 122°F indoor, -40° to 176°F outdoor
  • Measurement accuracy\resolution: ±1.8°F / 0.1°
  • Display size: 2.53 in. x 0.91 in.
  • Fast response
  • 6.5 ft. long waterproof exterior sensor cable is thin enough to fit under a window
  • 1 switch selects °F or °C temperature unit and time and date format
  • Mounts on a wall or a flat surface

Info & Guides

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Product Depth (in.)
Product Height (in.)
Product Width (in.)


Outdoor Living Product Type
Other Weather Monitoring Device
Product Weight (lb.)

Warranty / Certifications

Manufacturer Warranty
90 Days

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Customer Questions & Answers

Min/Max History

Most of these reset min/max daily. Looking for a unit that will record and retain all-time min/max (inside and out) until reset manually. Want to use over the winter in an unoccupied off-grid cabin to see how well the insulation and passive solar are working.
Asked by: Steve
Thank you for your recent inquiry with The Home Depot. This unit will hold the minimum and max temperature since the time the battery was installed or it has been reset. This item is currently in stock online. For any other questions, please call us at Customer Service 800-430-3376. Thank you for shopping Home Depot.
Answered by: THDSupport
Date published: 2015-09-20
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Customer Reviews

Indoor/Outdoor Thermometer with Min/Max Memory is rated 4.0 out of 5 by 12.
Rated 4 out of 5 by from Gets the job done I bought this for monitoring temperature ranges in my company's network server room. It's been installed about a week now, and it gets the job done, allowing me to determine the highest and lowest temperatures for the room and the rack.
Date published: 2011-07-10
Rated 4 out of 5 by from Adaptable to monitor solar hot water heating. Great for monitoring solar hot water heating system temperatures. With it, I can tell at what time all warm water in the storage tank has been used up. I can also see the maximum temperature reached during the day.
Date published: 2012-10-04
Rated 4 out of 5 by from good product Easy to set up and use. Like that you can look back a few dates to trend templs
Date published: 2014-08-20
Rated 4 out of 5 by from Looks good and it works I use it to measure the temperature of a chase that contains water pipes and tends to drop below 32 degrees when the outside temperature gets below 12 degrees. I really like the feature that stores the minimum temperature with the time because that lets me know when there might be a problem with freezing. The controls are minimal and not obvious so read the instructions carefully. It works well for my application.
Date published: 2013-02-12
Rated 5 out of 5 by from Perfect for use in our small pharmacy refrigerator We must keep a log of the refrigerator and the room temperature for compliance purposes. This machine must also be capable of recording the last 24 - 74 hours. This is the perfect thermometer at a VERY reasonable price.
Date published: 2014-04-10
Rated 5 out of 5 by from Bought this to see the temperature inside a room walled off from my forced air heater's thermostat. works great. I am able to view the temperature inside a room that I don't have access to just by drilling a small hole through the interior wall and setting the thermostat sensor inside the room and mounting the thermostat inside my family room so I can adjust my heater up or down depending on what that room's sensor shows. Wonderful product!
Date published: 2012-01-03
Rated 1 out of 5 by from Small display, inflexible settings The characters on the display are small and not clear when viewed from an angle. The unit can be set to C or F, but with C you also must get 24 hour time and - all US or all European (which may be okay for most people). I returned the unit.
Date published: 2011-11-22
Rated 4 out of 5 by from General Indoor/Outdoor Thermometer Using to monitor temp in an air space between a stove pipe and the wall, and the wired remote sensor works well for me. Thermometer Inside and Outside have 1/10 temp readings, thats kind of nice and this Thermometer serves its purpose! It also has a table top stand or wall mount! Cons: a little pricey for what it is, no back light and to reset time/date you have to pull the battery! I have not had any problems with it and would recommend it to others.
Date published: 2014-11-12
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