What is Digital Thermostat? Simply speaking, it is a conditional switcher that could control the input power supply status of the wired loads. Considering our products mainly for industrial and commercial purpose, where requires a long term and constantly temperature range, therefore our digital temperature controllers without the setting option for time spans. How digital thermostat...

Digital Thermostat Introduction for beginners

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What is Digital Thermostat?

Simply speaking, it is a conditional switcher that could control the input power supply status of the wired loads.

Considering our products mainly for industrial and commercial purpose, where requires a long term and constantly temperature range, therefore our digital temperature controllers without the setting option for time spans.

How digital thermostat works?

It's about the temperature and time, Simply speaking, 3 steps

  1. Collects the data from the NTC temperature sensor;
  2. Computing: The inside micro-computer compares it with the pre-set parameters, to get a result;
  3. Action: Change the power supply status of the corresponding relay if conditions are reached.

1.1 Target Temperature Range

We have to emphasize that a constant temperature actually is a temperature range, but not a temperature point; you'll find that setting up a temperature controller is an easy task once you understand this.

Target temperature Range is the most important parameter to a digital temperature controller no matter it is a programmable thermostat or non-editable.

Assign it mainly through below two methods:

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Just like you turn on navigation when driving a car, set a starting and an ending; Once the instant room temperature lower than the [Lower limit Value],
  • The relay to the heater power on;
  • The relay to the refrigerator power off.
on the contrary, once the instant room temperature higher than the [Upper limit Value],
  • The relay to the refrigerator power on;
  • The relay to the heater power off.
That is why it was called “High Low Limit Temperature Controller”.
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[Temperature set-point] like the position of the boy's hand, [hysteresis] like the length of the yoyo rope; these two parameters determine the "target temperature range".

Most thermostats use bidirectional [hysteresis], but some thermostats may only use unidirectional [hysteresis], please check the product manual.

  • One advantage of this design is that it is easy to implement hierarchical management, that is, the administrator can set a limit setting range for the SP to avoid misoperation by ordinary users. Such as the STC-9100 and 9200 controllers.
  • Another reason is it is easy to operate to users, especially mounted on dispaly fridgers; that is why most of our big panel thermostat for commercial purpose are base on the Set-point method.

Since they are easily misunderstood, once you come across the words "Lower and Upper" or "high and low limit", take care to see if it's for the SP or target temperature range or the alarm temperature range?

1.2 Alarming Temperature

Most of the digital thermostats within the alert function, mainly through visible (the screen shows error code), audible (buzzer screams), some of them exist an output relay to wiring the remote alertor.

Once the instant room temperature exceeds the indicated silent range, the controller could alarm to remind people to check the problems as soon as possible, in this way to reduce the loss.

Like the “target temperature range”, the “safe/silent temperature range” also usually be realized in two methods:

  • Assign a high limit and a lower limit temperature value separately;
  • Set an “Over-Temp Value“, plus or minus it with other parameters ( e.g. set-point) will get the safe range border.

Time controlling is an important parameter in the digital temperature controller, but it is not like the household thermostat, which often offers multiple time spans that could set different aim temperature; the time count and control function in our controller mainly for control the loads:

2.1 Working Time/Duration

Determine the time of a load lasting working.

2.2 Interval Time

Determine the time-space between two loops.

2.3 Delay Time

usually exist below types:

  • Compressor Delay Time: To protect the loads from start-stop switching frequently, the relay for cooling without electricity before this time over;
  • Alarm Delay Time: for example, when summer coming, Your idle freezer is starting to cool again. You know, at the beginning it will cost a long time to low down the room temperature, you do not want to be alerted by the controller without interupt;
  • Fan Delay Time: The compressor just starts, the temperature of the evaporator is not cold enough, some people do not want the fan to blow the hot air into the room; some people want to fan starts earlier than the compressor startup, others like the fan and compressor start and stop simultaneously, all these could be set in the fan delay time.

The above content explained the basic principle of the digital thermostat, When it comes to the production process, more aspects will be involved; e.g.

  • the shell material, thickness;
  • the front panel size and the mounting dimension;
  • the waterproof performance;
  • the LED digits refresh rate, Red LED tube or blue or yellow;
  • The max current of the relay could bears;
  • The voltage and temperature unit for different countries/locations;
  • The man-machine interactive ways;
  • the temperature sampling period and so on.

we can not list all related parameters here, please check it from each product page, and just contact us if you still have a question.

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