AQ-N-LCD - various questions

I got my new AQ-N-LCD working and I have a few questions. I thought I would post them together rather than “spam” the forum with separate posts.

  1. The four arrow buttons on the device don’t seem to do anything other than turn on the screen backlight. Is that by design? Can they be configured to do anything?
  2. Related to the previous question, can the AQ-N-LCD be used as a simple setpoint device? (i.e., allow the user to set the desired/target temperature)
  3. The temperature reading seems a few degrees above the actual temperature. I know it can be calibrated, but it’s strange that the reading seems to be correct for a short time after the device is powered up. It’s almost as if the sensor heated up itself (or got extra heat from adjacent parts). Could that be the case?
  4. The on-board thermistor reading (modbus reg 106) is 0. Is that sensor missing?
  5. Everything related to CO2 readings shows up as 0 in the register list. Does the AQ-N-LCD have a CO2 sensor? (I assume no, but just want to make sure)
  6. How is the AQ value calculated? It seems to vary a lot if I just breathe close to the device. It goes from 120 to 900 in just a few seconds and then slowly back, while the RH varies by roughly 1% and the temperature is almost constant.
  1. Buttons: You can use the buttons to let the occupant change the ‘room setpoint’ which is just a variable maintained on the device, a separate controller would be responsible for reading and doing the controlling actions. The setpoint can also be written to at the end of the day to reset it to a default if you like, again the separate controller would be in charge of that.

  2. Setpoint Device: Yes, that’s the purpose of the display and buttons. Hit the rightmost button to start the setpoint adjustment mode, then the center two buttons will notch the setpoint up & down. You can connect to the device with our T3000 software and see many settings so do be sure to check that out, it can be downloaded from the product pages.

  3. Calibration: There’s internal heat gain from the electronics, be sure to do all your calibration and testing with the sensor mounted on a wall away from drafts.

  4. Registers: Please check the registers using our T3000 application, navigate to T3000 → tools → registerviewer and there you can see a list of all the registers and their current values. Temperature should definitely be there.

5: C02: On some models there is a C02 sensor on board, you can open up the case and see a black or in early models a gold C02 sensor in there, quite large.

6: AQ Measurements: AQ is measured by a silicon nanotechnology based broad spectrum sensor element which responds to many common indoor air pollutants. It is manufactured by Sensirion, you can read more about it here.

Thank you for the information. Please see my comments/questions below.


I understand that the setpoint is just a variable and this exactly what I expected.
However, pressing the buttons like you described doesn’t seem to do anything. This is a short video that shows the behavior:

Is there any T3000 setting that I have to change to enable the buttons?

CO2 Sensor

I’m not sure whether the sensor is present or not. This is a picture of the board I have:

Can you tell whether the sensor is present? Obviously there are some unpopulated pads, such as U14 and U16.

T3000 shows 0 for the CO2 level (and so does the register view). Screenshot below.

AQ Measurement

Thank you so much for adding a link to the exact sensor. The datasheet has all the information I need (and much more). It all makes sense now.

Ah, this is the AQ. I was describing the RTS-Node. I agree the user setpoint feature should be implemented here on the AQ, we will do that and post an update here shortly when the firmware is ready.

Also as you note, there is no C02 sensor present and this is not represented well in the UI, we will make it more clear in the UI in the next T3000 update.

Thank you. I’m looking forward to the updated AQ firmware. I really appreciate your support and willingness to address all the issues in firmware/software updates. Nice way to stand behind your products!

Is there an easy way for me to add the CO2 sensor to the AQ? For example, if I bought the sensor separately and soldered it?

I imagine it could be done, we would have to work up a procedure for you and document it. If its just a single unit it might be best to just order up another unit with C02 on board.

I’m just a hobbyist/enthusiast who is playing around with these things at home for DIY HVAC automation. I live in Canada and unfortunately the shipping cost is about half the price of these units. Besides, the CO2 sensor is just nice to have, and it’s not going to be the end of the world if I don’t have it.

That being said, it doesn’t have to be a full/detailed procedure. If it’s just about soldering the sensor (and maybe a few passives), you can just tell me the sensor model and its place on the board. If it’s more complicated than that, it’s probably not worth the trouble for either of us.

Thanks again for all the information and support.

Hobbyists are encouraged, one day you’ll be running a big controls contracting outfit. That’s how I got started out in this field myself.

Here’s the C02 module we’re using in our devices, its from Sensirion and can be sourced locally. On the link here there’s a list of distributors. The unit price at Qty=1 is pretty bad though, $54 USD!

You can solder it in with a 0.1in spacing header, there might be a register or two you need to activate the C02 readings but we’ll work with you to sort that out.


please update T3000 to the latest version (May20 2021.09 ) , and connect AQ to PC by RS485 converter ,
follow my screen shot to set contents displayed , TAB 1 : Show/Hide options on the upper LCD TAB 2: Show/Hide scroll display TAB 3 : Allow /forbid to change setpoint by keypad , right button to switch setpoint ,up and down button to adjust setpoint value .

@maurice Thank you for sharing the CO2 module information. I will definitely check it out. At first glance the module is a bit large to fit inside the AQ-N case. And the module price definitely explains the overall price of the AirLab :slight_smile: And yes, I know, CO2 sensors in general are expensive and have limited lifetime. The one you’re using is actually one of the most affordable.

@Temco_Spring Awesome!!! Thank you so much for the updated T3000 and AQ-N firmware. It works like a charm. Exactly what I wanted to use the AQ-N for.

I noticed one minor bug though. In the “Scroll Display” section I hid everything except the Temperature Setpoint and Humidity Setpoint. They were configured correctly in the AQ-N and the setting persists if I power cycle the AQ-N. However, if I select a different device in T3000 and then go back to the AQ-N, the Temperature Setpoint is shown as hidden (even though it’s still active in the AQ-N). Most likely a bug on the code path that reads the register off the AQ-N and sets the initial radio button state in the T3000 GUI.

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