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Hydronic Shop Heater

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Nathan K
(@nathan-k)
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Joined: 3 years ago
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Hey all, 

As I introduced myself a few days ago, I am diving head first into electronics as I tend to dive into everything else. 

I build myself a shop starting back in 2011. It is pretty nice,if I do say so myself. 32x40 feet. Did about 95% of the work on it myself.

It has a hydronic, in floor heating system and I love the fact that the shop is nice to work in year round, but the heating bill in the winter months leaves a little to be desired. So let's learn a new skill, hopefully lower the heating bill and possibly make the shop temperature stay a little more stable...

Purchased my first microcontroller a little over a month ago. Watched quite a few of Bill's videos teaching myself how to program that arduino mega and ended up here. So why not document the build.

Welcome to my workshop. 


   
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Nathan K
(@nathan-k)
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Joined: 3 years ago
Posts: 9
Topic starter  

Here is a photo of the shop and the heating board.

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 The plan is to tackle this project as a monitoring system as the first step.  This will involve:

- 1 x Arduino Nano Every

- 1 x DHT11 sensor to monitor the ambient air temperature at least in the utility room

- 6 x 10 kohm thermistors to monitor the boiler output temperature and the 5 return loops

- 1 x rtc module

- 1 x micro SD card reader

- 1 x 24 VAC relay to monitor the time on from the analog thermostat

 


   
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Nathan K
(@nathan-k)
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Joined: 3 years ago
Posts: 9
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I will get some shots of my breadboard tomorrow and will add my code as well.

Phase 1: The plan is to have the arduino log the ambient air temperature and rtc clock value every 15 minutes to one file on the SD card.

When the thermostat turns the boiler on the arduino will log the heating cycle to a new file. In this file it will log the rtc value when the boiler  turns on , then to begin with, log the rtc value, ambient air temp, and the temp from the 6 thermistors every 15 seconds for duration of the run time. Then log the rtc value when the thermostat turns off. I would like to have a new file created for the run log each time the thermostat turns the boiler on. 


   
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Nathan K
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Joined: 3 years ago
Posts: 9
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Phase 2: would expand the ambient temperature monitoring to all rooms in the shop as well as an exterior temp sensor.

I would also like to add power monitoring to the boiler and pump. 

Phase 2a: would like move some control of the hydronic system from the analog thermostat to the mcu. Basing the heat cycle on return loop temperature sensing and regular cycling of the circulation pump (ie every 15 minutes) when the boiler is turned off.

I could also at this point try adjusting the water temperature output of the boiler to see how that impacts power consumption. 


   
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Nathan K
(@nathan-k)
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Joined: 3 years ago
Posts: 9
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Phase 3: I would like to attempt to integrate a home brew geothermal heat pump into the circuit. Not a whole lot concrete on this stage, that is except for the concrete heat sink that also acts as my shop floor. This is a lofty goal but should be achievable in the long term. 


   
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Nathan K
(@nathan-k)
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Joined: 3 years ago
Posts: 9
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Here are the pretty well wired up monitoring components. I have been having issues getting the thermistors to give me accurate readings. So I am working on running the 3 point tests to develop the steinhart-hart equations. 

This post was modified 3 years ago by Nathan K

   
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Nathan K
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Posts: 9
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Installed some of the monitoring system components today. Been waiting for items to arrive for several weeks.

Installed a 24 vac relay to monitor when the thermostat turns on.

Installed thermistors on each return loop and the loop supply line after the boiler and pump. Mounted the arduino nano and power supply to a bread board and mounted that. Added some sensor wire management raceway.

I think I am going to move the SD card module, the real time clock module and possibly the digital temperature and humidity (dht) module onto a remote board as they kind of wobble wobble on the bread board.

The code is about 3/4 written to do the following:

- read the dht module every minute and write the average temp and humidity of the utility room every 15 minutes.

- monitor when the thermostat turns on and then monitor the the boiler output temperature and return loop temperatures provide and averaged temperature every 15 seconds, write those temperatures and the time to a separate file that is created on the SD card each time boiler is switched on.

This will allow me at least see how often the boiler runs, for how long and how the heating cycle affects the temperature in the shop.

It should be interesting.

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