Temperature Monitoring

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Superduner

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I'm trying to set up a system to monitor the temperatures around my central heating system, which is powered by a woodburner.

I want to be able to monitor (the temperature of) about 5 points around the system, and as a bonus to be able to see when any of the three water pumps are on or off. An extra bonus would be to be able to override one of the three thermostats and kick the circulation pumps on manually.

All of the tanks and pumps are in the cellar, so I'd like to have a display panel up in the living room to save having to go outside and into a coldish cellar to check readings.

At present I'm using Bluetooth temperature sensors to see what's going on, but the range is limited and the batteries go flat fairly quickly.

I'm guessing that thermistors are the way to go? The furthest distance from sensor to display would be 10 metres. I can't believe that this is an unusual requirement.

Why do I want to do it? Primarily to improve the efficiency, and secondly to have a gadget to fiddle with during the winter.
 

Spectric

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I'm guessing that thermistors are the way to go?
I would look at thermocouples, type K are very common and I would say you need a microcontroller to interface between your data inputs and to provide outputs for display and pumps. Look at Click Boards - MikroElektronika for a range of boards that will make interfacing thermocouples to a micro easier and also driver boards for outputs.
 

gcusick

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Alternatively, the digital 1-wire temp sensors (18B20) are easy to use with Raspberry Pi, which could also easily host a webpage displaying the temperatures.
 

Sideways

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Sensorpush bluetooth sensors are excellent. Long range, very clean reliable mobile app and batteries last 2-3 years. For indoor and outdoor temp and humidity logging and graphing they are very good.
I don't see them as a device for direct contact with hot water tanks and the like.
Just flagging these up because they don't suffer the problems you have been experiencing with other bluetooth sensors.
I gave one to my wife for keeping an eye on temps in the garden, when to wrap up the plants for winter etc. She's a fan :)
 

shed9

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You need a multi channel data logger as that will record over time all the temperatures and the activation of the pumps within that timeframe.

Pico is a good brand, something like a TC08 would track up to 8 thermocouples. You could use an additional smaller and simpler separate Pico logger to detect the pumps using a current sense circuit to track the switching of the mains (merging the two two data sets) or alternatively use thermocouples on the pumps as well; given you are pumping hot water you will see a recognisable curve to that probes detection of the pump moving hot water simply by the probe being on the pump housing. The TC-08's often pop up on Ebay if you want to save a bit. They aren't cheap but then you are also paying for the software which is the clever part of the setup and Pico are well know for this.
 
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Sandyn

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I created a two channel data logger using a a velleman VM110 or the earlier 8055 and K type thermocouples . I wrote the functions to control the board from the Velleman K8055 DLL, then created a small program to run everything.
I just checked the price of the board and shocked to see it has almost doubled in cost over the last couple of years!!.
I created the system about 15 years ago as a quick/cheap solution for a datalogger, so I never really refined the program, but it works quite well. It's not very accurate because the temperature conversion is based on the 5V level of the board, which is supplied from the 5V USB. This will vary from PC to PC and depend on the USB cable length, but that's a limitation of the Velleman board. The scaling is a bit out on the graph, but I just used it for an indication. The data are saved in a CSV file.
The system was developed using OPUS Pro and the functions written in Java Script. Opus has died as a product about 5 years ago. It was a very niche product, but a very versatile product.
The Velleman also has two PWM outputs, 8 open collector outputs and 5 digital inputs, in addition to the two analogue inputs I use for the k type thermocouples. The design could be expanded to have many more thermocouples by multiplexing and could also control other systems via interface circuitry.

I think there are more up too date products, such as the Pi, Arduino and BeagleBone Black, which could do a better job, especially with the range of modules you can get for them.

datalogger.JPG


data.JPG
 

pe2dave

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"Smart home" devices? Philips do a sensor which includes temperature, other makes are available.
Controlled from PC or even Raspberry Pi?
 

Superduner

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Thanks for all the input everyone. I'll have a look into it all and make a decision on which way to go.
The Sensorpush I'd already looked at, but I need something that will go above 60 degrees
 

southendwoodworker

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Depending on how techy you are, I have done similar things using an ESP8266 or ESP32 and a a ds18b20 temp sensor.

The esp32 or esp8266 are wifi and bluetooth enabled arduino compatible microcontrollers. Dirt cheap. esp8266 (older cheaper version of the esp32) you can get for a a couple quid, the esp32 (more powerful version) is about £5 from banggood/aliexpress/ebay and even amazon.

The temp sensor is simple, uses a few wires, and has a range of -55 degrees to 125 degrees. here is an example. In the past Ive grabbed from banggood/ebay/aliexpress and paid £2-ish per sensor.


Why esp32 or esp8266?

They have wifi, easy to program, cheap, arduino compatible (thus loads of documentation and support) and tiny, has 4-8MB of onboard storage, and can be powered by a battery and last for ages. You can program it to power down everything, then power up every so often, take a temp reading, then send the data to a server, or save to its onboard storage. This means it can be battery powered and last months. I don't use batteries, I just power mine through a normal cellphone charger and leave them plugged in all the time.

You can have all 5 temp sensors running off a single esp32/esp8266 and long cables on the sensors. OR because they are so cheap, you can have an esp32/esp8266 per temp sensor.

So that is a rough idea of the sensor side of things, but how do you get access to the data from all 5 sensors?

The easiest way is to have the esp use a webcall to a webserver upon each temp reading. This web call would basically send sensor location, time, and temp. The webserver, through a relatively simple setup, then saves that data to a database, or a file or whatever. Genuinely, it is simpler than it sounds. Could even put it in to a google spreadsheet. The webserver can be on a computer in your house, or hosted for free in the cloud.

For my setup, I use a more complex system, which creates a graphs.
 

pe2dave

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Depending on how techy you are, I have done similar things using an ESP8266 or ESP32 and a a ds18b20 temp sensor.

The esp32 or esp8266 are wifi and bluetooth enabled arduino compatible microcontrollers. Dirt cheap. esp8266 (older cheaper version of the esp32) you can get for a a couple quid, the esp32 (more powerful version) is about £5 from banggood/aliexpress/ebay and even amazon.

The temp sensor is simple, uses a few wires, and has a range of -55 degrees to 125 degrees. here is an example. In the past Ive grabbed from banggood/ebay/aliexpress and paid £2-ish per sensor.


Why esp32 or esp8266?

They have wifi, easy to program, cheap, arduino compatible (thus loads of documentation and support) and tiny, has 4-8MB of onboard storage, and can be powered by a battery and last for ages. You can program it to power down everything, then power up every so often, take a temp reading, then send the data to a server, or save to its onboard storage. This means it can be battery powered and last months. I don't use batteries, I just power mine through a normal cellphone charger and leave them plugged in all the time.

You can have all 5 temp sensors running off a single esp32/esp8266 and long cables on the sensors. OR because they are so cheap, you can have an esp32/esp8266 per temp sensor.

So that is a rough idea of the sensor side of things, but how do you get access to the data from all 5 sensors?

The easiest way is to have the esp use a webcall to a webserver upon each temp reading. This web call would basically send sensor location, time, and temp. The webserver, through a relatively simple setup, then saves that data to a database, or a file or whatever. Genuinely, it is simpler than it sounds. Could even put it in to a google spreadsheet. The webserver can be on a computer in your house, or hosted for free in the cloud.

For my setup, I use a more complex system, which creates a graphs.
No wifi according to spec? Introduction to ESP32 | Specifications, ESP32 DevKit Board, Layout,
 

southendwoodworker

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Yup it does, it is these lines:

  • Supports 802.11 b/g/n Wi-Fi connectivity with speeds up to 150 Mbps.
  • Support for both Classic Bluetooth v4.2 and BLE specifications.

There are loads of models of esp32 and esp8266. A confusing array in fact which can make purchasing one confusing. If people are interested I can be more specific, and point to some which will cater for 99% of peoples needs very cheaply.

The programming of the controller and the design and implementation of the backend system, are something I can knock up in a couple evenings. The soldering, putting it all in a case, and making it look pretty - im bad and slow at.

The esp32 and esp8266 are powerful enough to even host their own webserver. I can connect via web browser to each device, see tempretures, reboot them, change configuration, update firmware. This is more complex but definately achievable, and far more within reach than what it first appears.
 

nickds1

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And how do you get the code onto the ESP32 then?
It has an inbuilt USB connector that appears as a COM port within the Eclipse IDE - you can then upload the compiled binary/program the ESP32 directly from the IDE without needing a separate programming dongle.

There are other options as an IDE - PlatformIO, Arduino, even Visual Studio Code and probably several others....

Whilst you can get them cheaper (by a small amount) from AliExpress/Banggood etc., for something this cheap, Amazon is often simpler & quicker. e.g.


For simple projects, like IoT motes, you can use stupidly cheap ESP-01 modules which are based on the ESP8266 (the precursor the ESP32 but easily good enough for most monitoring stuff), e.g. Crazepony-UK 4pcs ESP8266 Esp-01 Serial Wireless Wifi Transceiver Module Compatible with Arduino : Amazon.co.uk: Computers & Accessories but you'll also need a small programming adaptor - AZDelivery 5 x USB Adapter for ESP8266 ESP-01 Serial Wireless WIFI including eBook : Amazon.co.uk: Computers & Accessories

If you have any of those Sonoff smart WiFi switches, they are actually built round ESP8266 modules, as are many similar devices.
 
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clogs

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I just reach over and touch the radiator.....
if it's cooler than the norm I know I need some more logs in the boiler.....easy....
the tough bit is getting of ur arris and going outside but winter is only 6 weeks long on average here so not that bad.....hahaha...
 

nickds1

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I just reach over and touch the radiator.....
if it's cooler than the norm I know I need some more logs in the boiler.....easy....
the tough bit is getting of ur arris and going outside but winter is only 6 weeks long on average here so not that bad.....hahaha...
I used similar modules to monitor my beehives... difficult to just go and look at them when I was living 5,500 km away...
 

southendwoodworker

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I'll pull out some models later tonight. That one from amazon - that looks about right.


Here are some nice tutorials that explain how to wire it up and what code to use, this is how i learnt:

and

A neat one that uses a temp and humidity sensor, pretty graph and a web interface:

Other temp sensors can be used rather than the dht11 or dht22, or in a different form that better suits the need. some need to be attached to a circuit board, others come in on leads and are water and tempreture proof.

As @nickds1 said, there are a few different IDE softwares that you can write the code in and upload to the esp's.

I use the standard bland Arduino IDE, but there are a few others. Ive only learnt this one and ive stuck to it because im lazy to try others.

To flash the esp's you can do it a few ways:
- hooking up the esp directly with a standard usb cable to your computer, and hitting the "upload" button in the software
- doing it wirelessly way 1: write your code, add in a special couple librarys, flash via usb. This will get it on the network, so you can place anywhere in your house, not physically connected to the computer anymore . To then flash again, you just connect to it over the network in the arduino ide and just hit "upload" and itll send it over the network, flash it, and reboot it.
- doing wirelessly way 2: write your code, add a webserver with a special upload firmware page, flash by usb. this will get it on the network, so can be placed anywhere in your house, not physically connected to the computer anymore. then in the ide you compile then upload the new firmware directly to the esp from that webpage.
 
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