HTC-1 Clock / Humidity & Temperature Digital LCD Instructions

HTC-1 Thermometer

Here are instructions for the HTC-1 clock / humidity and temperature digital LCD.

HTC-1 Thermometer

I own two HTC-1 devices and it has helped me monitor my indoor surroundings. A while ago I lost the instructions, so I sat down and worked out most of the basics, which I’ve provided below:

How to switch between Celsius (°C) and Fahrenheit (°F)

  1. On the back of the device, lift up the stand (support legs).
  2. Press the black button to switch between the different temperature scales.

HTC-1 Thermometer Rear Button

How to set the time and date

  1. Press the MODE button for two seconds until the seconds are blinking.
  2. Press the ADJ button to adjust, and then when ready press MODE again to switch to the next option.
  3. Once the time and date are set, press MODE to finish.

How to set the alarm

  1. Press the MODE button to switch to the alarm time.
  2. Hold the MODE button until the minutes flash and use the ADJ button to select the minutes you require.
  3. Then press MODE again to select the hour option and use the ADJ button to choose the hour.
  4. When finished, press MODE to finalise.

How to enable and disable the alarm
Press the adjust button until both the audio symbol and ‘Alarm’ are shown above the time, and repeat the action to disable the alarm.

HTC-1 Thermometer Alarm Function

How to turn the alarm off when it’s sounding
When the alarm makes a sound, press the MODE button once.

HTC-1 Thermometer Rear

I really like the HTC-1 and my devices are currently being used in a bedroom and lounge. I am able to monitor the effectiveness of my actions, such as opening a window, closing a door and adjusting the boiler. I don’t use the alarm function, but I do find the clock feature useful.

I own a digital thermostat, which is in my hallway. I live in a flat and it’s interesting to see the temperature differences between a bedroom, hallway and lounge.

A cheap device, but it has made a huge difference.


      • No. It’s “Celcius” or “Centigrade”, which is equivalent. There is no such unit as Celsium – that’s a product name. The device does not add 2 degrees to the “total” – I bought two of these units and they differ by up to 2.4 degrees when placed side-by-side. In warm locations, they differ by 1.9 degrees and in temperatures below 10C they differ by 2.4 degrees C.
        In any event, the temperature defaults to C at startup after inserting the battery. It can be changed to F – but that is not simply adding 2 degrees!

  1. Thanks so much for these easy to read, easy to follow instructions.
    The instruction pdf file online – a copy of the instructions on the packaging – is almost incomprehensible.
    This is easy to follow. I sincerely hope that my device (purchased used) will no longer wake me up in the middle of the night with random alarms.

    • Hi Philipp,

      You’re welcome. I’m glad you’ve found the instructions helpful. I really like this device and I find it so useful.

      Best Regards


  2. Thanks for taking the time to post these instructions – I have four of these and lost the User Manuals a long time ago. They’re all set up again now!

    Incidentally, mine are all within 0.5 degrees Celsius of my main lounge thermostat (I left them all next to it for three days), and also my work air conditioning thermostat (same test). I guess it’s just the luck of the draw. But totally worth the cheap price in my opinion.

    • Hi Bumper,

      Thank you for taking the time to leave a comment. Much appreciated. It’s great to receive feedback and to receive an opinion about the device.

      I agree, I think the device is worth the cheap price. Recently I placed the device in the bathroom to monitor the temperature and humidity. I find it so helpful.

      Best Regards


      • I appreciate what you have done with the instructions. Easy to follo. I assume there is no way to make adjustments. The temperature part is 2.4 degrees F higher than my mercury thermometer and 5.5 higher than my digital hermostat.

  3. Thanks a lot for these simple to follow instructions. Have now been able to switch the alarm off which was driving me crazy!

  4. Thanks for the instructions.
    My wall clock just broke so they’ve helped to get the time adjusted on the HTC-1.
    I only used it for checking the temperature up to now. I’m going to get a lot more use out of my HTC-1 now.
    Stay safe.

  5. Thank you!!! I just got mine and the alarm was driving me crazy and the directions that came with it didn’t say how to change from Celsius to Fahrenheit so thank so much for your easy to read directions.

  6. this is gonna sound stupid but i got my grow light and control so do i have to use the control box to make light burn or can i manually turn light off and on

    • Hi Gregory,

      Thank you for leaving a comment. I think you’re writing about a different product or model. Sorry I’m unable to help you, but I hope you find a solution.

      Best Regards


  7. Thanks, I successfully used these instructions to reset the time and date after changing the battery. However the humidity reading has now disappeared from the display. How do i make it display the humidity again? Cheers, Cliff

    • Hi Cliff,

      I’m sorry to read your humidity display has disappeared and unfortunately I don’t know how to solve your issue. In your position, I would remove the battery for a few minutes and see if that solves the problem. Sorry I couldn’t help you.

      Best Regards


  8. Thanks for these instructions. Like everybody else I find the paper manual impossible to understand. Yours are easy peasy.

  9. I have two HTC-1 devices…bought in 2012 and 2016…

    #1…shows the time continuously…and has the Black Button on the back…
    #2…is 1/4 inch wider and 1/4 inch taller…rotates (5 seconds) time/date…and has “C/F” and “Reset” Buttons on the back…

    BOTH can reveal MAXIMUM and MINIMUM Temperature/Humidity over any period…NEITHER has an Alarm…

    THANX for the Instructions!!!

  10. Hello, temperature and humidity readings have disappeared from the display.
    How do I make them display again?
    Best regards

    • Hi Leon,

      Sorry I don’t know what the problem is. If I had that problem, I would remove the batteries for a minute or two and then see if those readings displayed again.

      Best regards


    • Have you tried pressing the “memory” button?

      Max and min are memory readings, the highest and lowest since the battery was in or reset. Press it twice to cycle back to current temp/humidity

  11. Thanks. I saved these instructions since last year but forgot how to deploy them in the interim. Great stuff. Thanks lots. -Writer
    PS: it works quite well and there are no problems with the current temperature. The seconds tend to run faster annually and the instructions are an AC Doyle mystery. -w.

  12. Thanks for the instructions. I got one of these as a freebie with a grow light, but with no instructions. I was completely mystified until I read this.

  13. Thank you so much. These instructions have really helped me out. Somehow when I bought this device, I figured out how to set the time and temp. in F. The battery needed to be replaced and although I mgd to set the time and date, I cldn’t remember how to get the temp. to F. Also, previously my attempts were hit or miss. Your instructions have saved me a lot of time and frustration. Also, good to read that some people found the temp off by a few degrees. I guess I need to use another devide to see whether it is my home thermostat or this device.

  14. If I understand correctly, you just long-press the ADJ button to enable or disable the alarm? When I do that I hear a beep, but there is no audio symbol on my display. So I suppose some units just have this bug and there is no way to visually tell if the alarm is on or not.

  15. I got one of these, and loved it so much I got 2 more for different rooms. But the second and third ones goes beep, beep, beep every time I press the buttons and it drives me nuts. Cannot figure out how to put them on silent mode, any ideas?

  16. I am wondering how I go about getting the humidity to read the actual humidity%. Mine has been reading 10 for 2 days and don’t change

  17. Thank you.. Tried to figure out how to switch between Celsius and Fahrenheit. Almost tossed this device out til I read your easy instructions. Again, thank you.

  18. Andrew ……. great listing
    I am in Brasil and ordered one of these off our eBay = Mercado Livre, came today. I love it. Had some shitty chinese directions clear as mud. Swearing at it trying to change from C to F, MODE didn’t do shit ! NO clue from those instructions as they are in english translated from Chinese by a blind man.
    Then had an idea, many times in the past lacking decent instructions I can find a manual online somewhere. BOOM… did a search and found you posting
    PROBLEM SOLVED in 2 seconds. How in the hell would I have figured out that there was a black button ON THE BACK of the damn thing to switch it to F ! NO WAY.
    So I pushed it and damned if it didn’t go to F !
    Reminds me of the story of the guy who fixed problems with a hammer. BUT he knew just the right place to tap, whereas nobody else could figure it out, so he demanded a huge service fee and got it.
    YOU supplied me with the right spot to HIT and solved the problem !

  19. I received this temperature clock/humidity HTC-1 from Ebac Industrial Products, Inc. as a manufacturer’s representative-as a salesperson and marketing agent, defined as: Hawaii. I’ve noticed the temperature F and humidity % in my home office is not correct for many years but the time and date work fine. Now that I have the time to write a reply to your company, I cannot believe Hawaii temperature and humidity reading are all most the same as Reno, Salt Lake City and Los Angeles.
    Oahu forecast: today Shower this afternoon, Wind E at 10-20 mph 88/76
    According to your temperature clock/humidity HTC-1, reads: 101.3 F and 64% humidity. This product does not work properly. What can I do to make this product read out the temperature F and humidity reading work in Hawaii forecast.

    • Hi Dennis,

      This is a personal blog and I am not affiliated with a manufacturer or seller of the product you are referring to.

      I am not taking a view whether your product is working correctly or not. What I will say is that ‘inside’ my apartment (flat) I have different readings in different rooms of my home, which I believe also take into account various indoor factors related to my situation.

      I have found the device effective in helping me to gauge the results of my actions in relation to temperature and humidity indoors.

      Best regards


  20. Hello all,

    I would like to thank everybody who writes a comment, especially those saying thank you and leaving kind feedback. I published this blog post over four years ago and I am glad my instructions have helped so many people.

    I am still using a device in my bedroom and another in my lounge. I have noticed the results of my actions, including in response to the sun shining on my lounge on a cold winter’s morning when I shut the lounge door.

    Please continue to leave comments asking questions and/or providing feedback.

    I wish everybody reading this a great 2022.

    Best regards


  21. Thanks for the video. Meanwhile, my device shows a totally incorrect Humidity value. For example, it is showing 65% today whereas all Google sites give a value of 48%. So I woud say it is a good-for-nothing device.

  22. HTC-1 clock and alarm work correctly, however, I want to set both the humidity and temperature readings. There does not seem to be any understandable instructions available.
    If someone has been able to figure out how to adjust temperature and humidity – please direct me.

  23. Hi and Thank you for this enhanced device user_guide,
    unfortunately device can’t be used overnight
    Memory doesn’t seem to record all Min/Max temperature & humidity values

  24. Thanks for posting the instructions. Like many other folks, the included instructions were printed in the smallest font possible in a language faintly similar to English. The only thing that is lacking is a way to calibrate it as it seems to be a few degrees off.

  25. Bought this device. Set it up ok to dates and time. Tried every which way to change C to F with no hope. Never looked at device hidden button. Read your post, thank you so much.
    The Chinese , English institutions are vague incomplete.

  26. I figured everything out myself except switching from Celsius to Fahrenheit. Never would have thought to look for that button. Thanks.

  27. Hello from Canada. Thanks for the guide! Much better than the printed instructions I recall (which were lost long ago). Fwiw, my unit has two buttons on the back and it’s the bottom button that toggles the temperature display units. The top button (labelled RESET) is the same as removing and replacing the battery and the unit needs to be re-configured.

  28. I lost the instruction ages ago and had just about given up trying to alter the time and date. But tonight I thought I would check if there was any info on the Internet: and hey presto! So very grateful

  29. My HTC-1 was working properly since 2018 but now it shows HH for Temperature and — for humidity. How can I get it to display the temperature again? The time and date function is working properly.

  30. Why does my unit never measure humidity? Does it have to be at a certain percentage for it to register? I always have two dashes before the % sign. Thanks.

  31. I’ve never seen that on either of my two units. They do indicate humidity 20% apart from each other, I may have said above.

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