I did another heatup and fooled around with settings again. At some point it became stable at 400I, 0d, 20 degree throttle range. Earlier it was oscillating at the same settings. Weird.
Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime
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Beagle Dad
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If you find the valve hunts too much try reducing the effect of the proportional gain which I think translates to increasing the throttling range. This should cause the control to be mostly from the Integral which will result in the valve lagging behind the error between the setpoint - measured value.
watch the controller output to see if it seems to hunt around a certain output range, i have noticed that when the supply and mix temps have a large delta and the valve output is under 15% it will hunt. The best operating valve range for me seems to be from 25% and up.
Other than the control issues, which is big. I think I might have done a bad move in relocating the spirovent where I did-now it seems the zones won't clear the air as well as before-plus the tank top will see the same hot water as closer to the boiler, except when recirculating. Perhaps another spirovent? Also thinking of changing swing check to spring.
I'm thinking of not commenting on this thread anymore since it really highlights my dumbassedness.
I'm thinking of not commenting on this thread anymore since it really highlights my dumbassedness.
I'm gonna comment anyway.
Came home, boiler on, at some point in its cycle. Rock steady at 160. I don't get it. I'll see if I can monitor a cycle from the start again.
A comment from previous messing about with derivative: while it seemed to help keep the temp closer, the recirc % varied wildly, exercising the valve a lot. Right now, the recirc % varies a percent or two. It's great-I wish I could bottle it.
Came home, boiler on, at some point in its cycle. Rock steady at 160. I don't get it. I'll see if I can monitor a cycle from the start again.
A comment from previous messing about with derivative: while it seemed to help keep the temp closer, the recirc % varied wildly, exercising the valve a lot. Right now, the recirc % varies a percent or two. It's great-I wish I could bottle it.
Yes, I noticed that increasing the throttling range from 10 to 20 degrees in my previous run helped. I still can't fully explain how it started working though, though I shouldn't complain too much. I'm sure things will mess up on the next observed run.
And the previous run for me it seemed to thrive and a wide supply/mix delta-buffer tank bottom still cold, boiler around 178 or so. When mine was oscillating, it would go from high to low percentages and the temps would be plus or minus at least 5 degrees.
Just noticed that the speed control on one of the Ecocirc Vario pumps doesn't work. Seems to be stuck on high. Great.
Did quick and dirty fix involving a 1/16" hex wrench and some clear plastic tape to keep the water out and allow seeing the power on indicator light.
I moved the sensor 6 feet down the return pipe from the mix valve and after the zone circ return connections. The effect of the cold water that has been lying in the distribution pipes is big time - bringing the return temp down to past throttling range and closing off the tank completely while the boiler returns back to temperature.
The valve still controls well, even after those big hits. It takes somewhat of a while to bring it back, and it always seems to be a degree or two above setpoint, never below.
My pellet boiler and baseboard output are pretty well matched, so that's why recovery from a double zone hit can take a while, I suppose.
I moved the sensor 6 feet down the return pipe from the mix valve and after the zone circ return connections. The effect of the cold water that has been lying in the distribution pipes is big time - bringing the return temp down to past throttling range and closing off the tank completely while the boiler returns back to temperature.
The valve still controls well, even after those big hits. It takes somewhat of a while to bring it back, and it always seems to be a degree or two above setpoint, never below.
My pellet boiler and baseboard output are pretty well matched, so that's why recovery from a double zone hit can take a while, I suppose.
This does seem to be key. It was oscillating again and increasing the throttling range from 20 to 40 smoothed it right out.
Another note on the Honeywell controller. If there's enough ambient light you can disconnect the lead to the display leds and still read it. The leds are pretty bright, as I've said before.
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