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Thow in an IoT feature for customers too, like a temperature and humidity sensing + display and alarm.

Lots of hobbies require specific temperature and humidity limits, yet at the same time that separate space or building may go unattended for weeks due to busy work and home lives, such that if the environmental controls fail there could be ruined supplies or mildew before the customer knows.

So easy with software to keep it separate from the gauge data. Plus, it has tangible value seen directly by the customer. They will also call the contractor immediately, before things get ruined.

Just use these: https://climate.emerson.com/en-us/pr...wner/iot-sensi

Axiom Cloud

[a business called axiom cloud was on the hvac school podcast and does this with grocery refrigeration at least. They also have an AI monitor it and look for triggers like high head, low superheat or whatever to flag different stuff. I believe it was also smart enough to note when the problem happened like only when aisle 2 was on did superheat drop, etc.

That's all cool!

Originally Posted by psmilligan1

I also want to install pressure transducers at my 410A condenser and interface them to an Arduino. I can handle the Arduino/software side but I am not sure what transducers to use. I’ve been researching 0-500 psi transducers with 3-wire interface (pwr, gnd, and 0-5v signal output). Also, I would prefer to attach them to the service ports so I don’t have to open up the system and braze them in. Can anybody recommend a good quality reasonably priced one? BTW I would also use a hard coded s/w table for the pressure temperature lookup.

https://cdn.sanhuaeurope.co.uk/new_c...technical-info


Those sensors don't show up on their American website, but it should give you an idea of the varieties available. There's lots for sale on eBay, like from this store, https://www.ebay.com/usr/conversionh...p2047675.l2559 but those seem to be for automotive and air use, none of them say anything about refrigerant use, and I'm not sure I'd trust a no-name one on the high side of the system.

Probably best bet is to get two transducers from Carrier for something like a 30RB or 38AP, they will be 410a, high and low pressure, and they're already 1/4" flare with a core depressor so no adapter needed, just put them on a tee. Then you can figure out the conversion of the output voltage to input data, and where to get those Packard connectors.

Originally Posted by psmilligan1

I also want to install pressure transducers at my 410A condenser and interface them to an Arduino. I can handle the Arduino/software side but I am not sure what transducers to use. I’ve been researching 0-500 psi transducers with 3-wire interface (pwr, gnd, and 0-5v signal output). Also, I would prefer to attach them to the service ports so I don’t have to open up the system and braze them in. Can anybody recommend a good quality reasonably priced one? BTW I would also use a hard coded s/w table for the pressure temperature lookup.

There are also some to be found on Amazon by searching "500 psi pressure sensor" but I cannot vouch for the accuracy or quality. You might consider the Yellow Jacket 19110 connectors if you want to use the service ports. They are 1/8-in NPT to 1/4-in flare with pin for the schrader.

Attachment 825895

https://digi-cool.com/product/low-an...ransducers-set

IoT Gauges

I also want to install pressure transducers at my 410A condenser and interface them to an Arduino. I can handle the Arduino/software side but I am not sure what transducers to use. I’ve been researching 0-500 psi transducers with 3-wire interface (pwr, gnd, and 0-5v signal output). Also, I would prefer to attach them to the service ports so I don’t have to open up the system and braze them in. Can anybody recommend a good quality reasonably priced one? BTW I would also use a hard coded s/w table for the pressure temperature lookup.

Originally Posted by Greend88

Depending on what you are using another option is to create an array with a known data set from a PT chart and use that to convert pressure to sat temps.

That is exactly how I would do it.

There is going to be two different formulas for r410a. One for Dew Point and one for Bubble Point. SH = Line Temp - Sat Temp (Dew). and SC = Sat Temp (Bubble) - Line Temp. This PDF has some formulas if you can figure them out for both bubble and dew point. https://www.cantas.com/urunpdf/20.09...mo_prop_si.pdf Depending on what you are using another option is to create an array with a known data set from a PT chart and use that to convert pressure to sat temps.

I have wanted to add superheat and subcool readings for my units at the house. I already monitor compressor amps, fan status, and shut down on over amping. I was going to add transducers to monitor pressures, but when I look at the pressure/temp for the r-410 chart, the readings are not linear.

So, two things what is the mathematical equation to get SH/SC and where is the best place to put the suction and discharge temp sensors? At the CU or where the lines go into the evap coil?

Attachment 825305

Thanks for the detailed review!!!

I made a similar monitoring system to the original described above.

My system uses [2] ESP8266 Wemos D1 mini modules programmed using the Arduino IDE. One is located near the electrical panel and it monitors condensing unit current and outside temperature near the condensing unit. [It also monitors whole-house electrical consumption which I also like to keep records on.]

The other is located near the air handler and it monitors return duct temperature, return duct relative humidity, and supply duct temperature. These functions could have also been performed by the first module, but I didn't want to run wires from the sensors near the air handler all the way back to the electrical panel since there was no easy or clean way to do this, and these wifi modules are very inexpensive.

Both modules are connected to a wifi network so they can communicate with each other as well as the outside world.

The first module performs the following functions

- computes cooling degree days based on 30-min outside temp readings near the condensing unit

- records number of run cycles each day

- records duration of each run cycle

- records each run cycle outside temperature

- records each run cycle condensing unit current draw

- records each run cycle duct temperatures and humidity level [queries the second module via wifi for this data near the end of each running cycle]

Each day at 11:59 PM the first module sends me an email with all the above data which I can then add to a spreadsheet.

Both modules include a web server which can be accessed at any time over the wifi network using any web browser to get current and stored data for the current day in real time.

This data allows me to monitor duct delta-T vs RH for system performance, and condensing unit current vs outside temperature as well as cycle duration, frequency, and total daily running time vs degree days as basic indicators of proper refrigerant charge level and system performance.

Condensing unit refrigerant pressures and line temps could also be monitored to calculate SC and SH, but I figured the above was adequate to keep tabs on the performance and health of the system.

Let me know if anyone has questions or would like additional information, or if you have any ideas on how to improve the system.

Example of real time web server data report.

Attachment 823224

Sensi Predict....
https://sensi.emerson.com/en-us/products/sensi-predict

https://imanifold.com/pulse/

I havent used it, but they have rolled out a system, that is $700, and $9/mth the numbers are loaded in your dashboard for monitoring and alerts are sent to your phone/email.

Of course, it's hard to start something new during a pandemic!

Originally Posted by ahanktcd

I made my own always-on A/C monitoring system which reports the PT's to the cloud where I can go view graphs from all time.

Here is the setup from bottom up
DS18S20 temp sensor & refrigeration tape
0-5V, 0-500 psi pressure transducer, Digikey
Custom PCB
ESP8266
NodeMCU LUA code
Thingspeak.com

All A/C's should send their information to the cloud. A system like this either factory installed or service company installed would be great. We could sell monitoring for a $2/mo fee and predict when the system will need servicing. The Internet service would (on the tech's end) detect certain problems before they are major in a way that only an always-on system could: tiny leaks, TX valve sticking, partial clogs, minor compressor wear. Then reach out to the home owner and offer service as a reduced cost for them to avoid major service.

A very practical idea indeed! Have you been able to implement it on a production scale?

Did this ever go anywhere?

I am quite interested. Please send me more info.

Sure, I'm interested.

Originally Posted by weber

In the 90's we had this product that would tie into your phone line, in the mid 2000's we developed one that connects to wifi. Today I have a cell based monitoring system. Pressures, temps, amps, SH & SC, flood protection, water usage, and a predictive breakdown algorithm. Along with much more.

If you're interested in learning more about the product or how to incorporate it into your business model let me know.

Pitch away. Seems like a very cool way to go. Message me.