• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Controller ideas for advanced radiant heat controller. PID, PLC, etc

Status
Not open for further replies.

fastline

Member
I am trying to get a general idea of what I am looking for. I am building a radiant slab heat system, heated by a wood burner. I will want to automate some of this system such as relay function to open/close an air intake door, basic programming of on/off of certain functions based on thermocouple inputs, and set delays and "if" statements such as to stop one pump at a set temp but run another until a certain other temp is met.


I know they make basic thermostat controls for this but I would like a variety of inputs and would prefer something software based so I could put this on the network. That might be wishing though because this system is on a budget.

The only real sensor inputs I need is K thermocouples and hall sensor type flow meters.
I will need 5V outputs for the hall sensors as well as a variety of programmable relay outputs.

What am I looking for?
 

MaxHeadRoom78

Well-Known Member
Check out Smart Relay, there are a few to choose from, most are the same, just relabled.
Otherwise a Picmicro would do the job.
Max.
 

fastline

Member
Thanks, I will check the link. I looked into the smart relays as Max mentioned and though they seem to cover most bases in terms of programming, PC interface, modular, etc, they seem to be pretty light on the analog I/Os? I really would only have K type TCs and the hall sensors which just return pulsing that is calculated to be a certain flowrate. I would need to provide 5VDC to the flow sensors too.

Most of the sensors I need will be purely passive as I just need to display and monitor their values, not really drive logic functions from them. For instance, I probably will need my air temp to drive the system as a thermostat but I will also monitor the slab temp and soil temp below the slab simply for engineering data.

I figure I could need 10 or more analog inputs and most of the smart relays seem to focus on digital I/O?
 

alec_t

Well-Known Member
Most Helpful Member

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
For sensor interfacing, you might want to look into this http://www.digikey.com/en/product-highlight/l/linear-tech/ltc2983-digital-temp-measurement-ic IC.

Thermocouples are "expensive" and they really are not very accurate. Repeatable, yes. Accurate, No. "K" is usually "Preferred" unless there's a reason not too. "J and "K" the junctions are welded. We used a special spot welder and a carbon block for those. For R &S, we used a Hydrogen Oxygen Torch. We used "T" for primarily Cryogenics and room temperature. W had to use "C" for one process as well.

Maxxim's 1-wire temperature sensors might be a better choice for room measurements.

Thermisters work within a limited range and also might be OK.
 

alec_t

Well-Known Member
Most Helpful Member
For this application, LM35 temp sensors could be a simpler/cheaper solution than thermocouples.
 

spec

Well-Known Member
Most Helpful Member
I am trying to get a general idea of what I am looking for. I am building a radiant slab heat system, heated by a wood burner. I will want to automate some of this system such as relay function to open/close an air intake door, basic programming of on/off of certain functions based on thermocouple inputs, and set delays and "if" statements such as to stop one pump at a set temp but run another until a certain other temp is met.


I know they make basic thermostat controls for this but I would like a variety of inputs and would prefer something software based so I could put this on the network. That might be wishing though because this system is on a budget.

The only real sensor inputs I need is K thermocouples and hall sensor type flow meters.
I will need 5V outputs for the hall sensors as well as a variety of programmable relay outputs.

What am I looking for?
Hy fastline,

Where are you from; care to put it next to 'Location' in your user page so that it shows in the window on the left of your posts.

To answer your question, yes you could make a great system with a low cost and unlimited performance and flexibility, but it would depend on the tools that you have and your skills.

This application is made for an Arduino Mega microcontoller, a couple of shields (input output modules) and a power supply. For a more powerful processor with more functions, a Raspberry Pi single-board computer would be a good choice.

In both instances, ready made modules would simplify the task, but you would need to write a simple program to get the system to function as you want.

An Arduino Megga clone is available for around £4 UK and clone shields are available for around £3. A Raspberry Pi clone is available for around £12 and clone shields for £9.

The supporting software, but not the application software, is free on the net.

spec
 
Last edited:
Status
Not open for further replies.

EE World Online Articles

Loading
Top