With cooler weather on the horizon in VT, I need to get back to work on planning and finishing my control system (to date, I've run by manual "wire nut logic"). [and I tend to have 'too many projects not enough time' which is why this is just now back to competing for front burner]
My system consists of an Econoburn 150, a 1200 gallon storage tank (unpressurized)(with a plate heat exchanger to tie in to the pressurized boiler system), and a water-air heat exchanger in ductwork for a single heat zone to the house.
Plumbing of the system is by primary/ secondary, with pumps, so it'll be easy to manage which way the hot water is coming or going as between the different heat sources/ loads [yeah, I know that valves can be more elegantly simple/ efficient, but I found it easier to get my head around the pumped system and have confidence that the physical plumbing layout would be right the first time].
I'm going to be using an Azel solar differential control to manage charging of the storage from the boiler, and an Azel DST 777 setpoint controller with variable pulse width modulation to provide return water temperature to the boiler. Already have those parts on hand.
I'm leaning towards using some Auber instruments PID temperature controllers for the other temperature sensing/ switching
http://www.auberins.com/
[by the way, I invite input on whether thermocouples will be OK for the temp. ranges involved, or whether I should go with 3-wire RTD sensors]
And then I plan to use relays if/ as necessary to get the right pumps flowing under the right conditions.
But, since I am better at lateral/ creative thinking than linear thinking, I am having a hard time with the initial stages of charting out a logic/ control tree.
I am familiar with the basic idea of "and" and "or" switching, which is what I plan to use the PID controls and relays for; I've done that (relays as and/ or...) on other projects, but not with something with this range of inputs and operating states.
So, where I'm struggling is in the aspect of what 'layer' of the switching/ input parameters/ operating modes to start mapping both the functional and electrical schematics.
I actively seek experience and wisdom to help me move forward on this.
Thanks
Trevor
My system consists of an Econoburn 150, a 1200 gallon storage tank (unpressurized)(with a plate heat exchanger to tie in to the pressurized boiler system), and a water-air heat exchanger in ductwork for a single heat zone to the house.
Plumbing of the system is by primary/ secondary, with pumps, so it'll be easy to manage which way the hot water is coming or going as between the different heat sources/ loads [yeah, I know that valves can be more elegantly simple/ efficient, but I found it easier to get my head around the pumped system and have confidence that the physical plumbing layout would be right the first time].
I'm going to be using an Azel solar differential control to manage charging of the storage from the boiler, and an Azel DST 777 setpoint controller with variable pulse width modulation to provide return water temperature to the boiler. Already have those parts on hand.
I'm leaning towards using some Auber instruments PID temperature controllers for the other temperature sensing/ switching
http://www.auberins.com/
[by the way, I invite input on whether thermocouples will be OK for the temp. ranges involved, or whether I should go with 3-wire RTD sensors]
And then I plan to use relays if/ as necessary to get the right pumps flowing under the right conditions.
But, since I am better at lateral/ creative thinking than linear thinking, I am having a hard time with the initial stages of charting out a logic/ control tree.
I am familiar with the basic idea of "and" and "or" switching, which is what I plan to use the PID controls and relays for; I've done that (relays as and/ or...) on other projects, but not with something with this range of inputs and operating states.
So, where I'm struggling is in the aspect of what 'layer' of the switching/ input parameters/ operating modes to start mapping both the functional and electrical schematics.
I actively seek experience and wisdom to help me move forward on this.
Thanks
Trevor