NoFossil Control System does PI control

[Nofossil]

Finally got beta code running to allow the NFCS to do closed-loop control.

It uses the new production variable speed control hardware and a modified PID algorithm to modulate an output to close the loop and control an input.

In this case, I have a doll house with a light bulb and temperature sensor in it. The light bulb is hooked up the the variable speed drive. The PI software controls the light bulb intensity to achieve the desired temperature.

The graph below shows a test. The dollhouse is stable at 38C. The setpoint is increased to 40C for a while, then returned to 38 C. You can see how the VS output responds, and how the room temperature tracks the changes in setpoint.

I'm pretty happy - can't wait to hook it up to real hardware. I've already done tests with a Taco circulator, so I know the hardware part will work.

 

[Gooserider]

Neat... So in terms of real world applications, does this get the NCFS closer to being able to do a retrofit Lambda control on the boiler, or is it just stuff like outdoor reset?

Gooserider

 

[Nofossil]

Neat... So in terms of real world applications, does this get the NCFS closer to being able to do a retrofit Lambda control on the boiler, or is it just stuff like outdoor reset?

Gooserider

I don't know enough about the control issues with lambda feedback. I suspect that there's an ideal lambda value that varies over the course of the fire. If that's the case, then PI control by itself won't do it.

It should be good for somewhat more sophisticated outdooor reset (without the outdoor part, if needed) as well as controlling boiler outlet temp by varying flow rate and/or blower speed. It also should be ideal for solar panels - varying the flow rate to get the desired outlet temp as sun or inlet temps change.

If you use a bypass circulator for inlet temp protection (ala Econoburn) then you could get more precise control of inlet temp using PI control of the bypass circulator.

There are probably many more. This is a very common technique in the industrial control world, but uncommon at present in residential heating systems.

 

[Jim K in PA]

Looks neat NoFo. How is this different from a Delta T ECM pump?

As far as Lambda control - this may work partially, as will a PID (partially). The Stoich for wood burning is pretty constant through the bulk of the burn. During start and taper it gets fuzzy. I think proper Lambda control will start with a time-to-temp starting phase for the beginning of the burn, switch to Lambda feedback to vary the input air (fan or damper) during the primary burn phase, and then switch to a temp-to-threshold for the taper phase.

 

[Huskurdu]

Looks neat NoFo. How is this different from a Delta T ECM pump?

As far as Lambda control - this may work partially, as will a PID (partially). The Stoich for wood burning is pretty constant through the bulk of the burn. During start and taper is gets fuzzy. I think proper Lambda control will start with a time-to-temp starting phase for the beginning of the burn, switch to Lambda feedback to vary the input air (van or damper) during the primary burn phase, and then switch to a temp-to-threshold for the taper phase.

You guys keep this crap up and I'll have to put a shortcut for Wikipedia.com on my desktop and increase my Advil intake!



np

 

[Nofossil]

Looks neat NoFo. How is this different from a Delta T ECM pump?

As far as Lambda control - this may work partially, as will a PID (partially). The Stoich for wood burning is pretty constant through the bulk of the burn. During start and taper it gets fuzzy. I think proper Lambda control will start with a time-to-temp starting phase for the beginning of the burn, switch to Lambda feedback to vary the input air (fan or damper) during the primary burn phase, and then switch to a temp-to-threshold for the taper phase.

Functionally, this is the control part of a Delta T pump. The big difference is that with the NFCS, you can dynamically change the target based on what's happening elsewhere in the system. The circ itself is a standard PSC, so not as efficient as the ECM designs, but still uses a lot less power than normal operation.

You guys keep this crap up and I’ll have to put a shortcut for Wikipedia.com on my desktop and increase my Advil intake!

How do you think we create these posts in the first place?

 

[Jim K in PA]

Looks neat NoFo. How is this different from a Delta T ECM pump?

Functionally, this is the control part of a Delta T pump. The big difference is that with the NFCS, you can dynamically change the target based on what's happening elsewhere in the system. The circ itself is a standard PSC, so not as efficient as the ECM designs, but still uses a lot less power than normal operation.

Aha - the third input, so to speak. Very cool.

You guys keep this crap up and I’ll have to put a shortcut for Wikipedia.com on my desktop and increase my Advil intake!

How do you think we create these posts in the first place?

Haha! Their onto us NoFo! :lol: ;-)

 

[pybyr]

[quote author="Jim K in PA" date="1253838529"

Haha! Their onto us NoFo! :lol: ;-)[/quote]

the brain, like most other things, only grows stronger when exercised to the point of hurting at least a bit...

thanks to the boiler room and certain folks who share a lot of knowledge and experience to offer all of us mental dumbbells for brain-exercise

 

[Gooserider]

Remember, be generous - Give your children mental blocks for Christmas... :lol:

Gooserider

 

[Huskurdu]

My system certainly is not the best layed-out system out there, but I did it all myself and it works well and is getting better all the time. Thanks (again) to all the guys on this forum for the mental exercise!

thanks again,
np

[quote author="Jim K in PA" date="1253838529"

Haha! Their onto us NoFo! :lol: ;-)

the brain, like most other things, only grows stronger when exercised to the point of hurting at least a bit...

thanks to the boiler room and certain folks who share a lot of knowledge and experience to offer all of us mental dumbbells for brain-exercise[/quote]