Help with Oxigen tuning

[joukeder]

Do you know if there is somewhere a functional description of the woody box?

[tn]

Hi Torben,
I feel very assured that you are looking over my shoulder. It is so good that you verify and challenge my train of thought. Thanks!

When manually controlling burning and putting the high auger at 30 Oxygen goes down to .1 and certainly a lot of smoke exits the chimney stack. Burning is dark red and light is very low on the lux meter.
Back to auger high at 21 and Oxygen is around 7.2 and NO smoke.

I have a computer controlled telescope. It has only so-so mechanical gear. The designers compensated that by having the electronics compensate for the peculiarities of that gear train. They say its cheaper then making better mechanics and it works very well!

Extrapolating that to the burner you would expect that the designers know that the auger feed is not all THAT accurate anyway and compensate that by steering the auger to compensate for the feed anomalies. If that is so, we are perhaps looking at a feedback problem? at the Oxygen gain of 100 it was perhaps overcompensating and oscilating.
Has anyone experimented with the PID parameters?
Or do you still think its mechanical?
I cleaned the burner unit including the ventilator with pressured air a few days ago. There was not too much debris in it anyway. The ventilator is working very freely. It has a very long wind down time.
Whats bothering mee is why would it burn about OK at 21 AUger high where it should be about 33?

Regards
Jouke

The 30 is in min. and you should just keep that, it's only used in boilers where you can burn other things than pellets, by feeding it manually into the boiler. In that case it shouts off the pellets feed, and only control the air feed.
You should not be conserned about the 21 instead of 33 . the 33 is calculated from the effekt 24 KW, but what is important is to have the right burning without smoke, and if the 21 gives you enough effekt for your house, then everything is fine. Otherwise you have to raise the blower setting for high thats currently is 15.
You are right that perhabs it's just to lower the gain for the oxygen controll, but what is strange is that the oxygen level keeps going down below the target and back again. It should go slowly down to target and then stay around the target, because even with 100 in gain it's quite small adjustments to the pellets high / low per time unit, but it seem that those small adjustments changes the oxygen level a lot. Do you think that you have very low draft in you chimney , perhabs other things (boilers) connected to the same chimney?.

[tn]

Do you know if there is somewhere a functional description of the woody box?

Don't you have a manual for it.

I found this , perhabs that could be usefull
http://www.opop.cz/soubory/BioComfort-ENG.pdf

[tn]

Has anyone experimented with the PID parameters?
Regards
Jouke

The PID has to do with the regulation of effekt, and has as so nothing to do with the oxygen control.
But you probably can have a more smooth effekt curve and a more stable temperature by changing the default settings.
Here are some explanation


P_EFFEKT = GAIN_P * (Target_temp – Actual_temp)

eksempel:

GAIN_P = 10 %/C, target temp = 60 C and actual temp = 58 C

P_EFFEKT = 10 %/C * (60 C – 58 C) = 20 %



I_EFFEKT = GAIN_I * Σ(target_TEMP – actual_TEMP)dt

eksempel:

GAIN_I = 1,0 %/C/MIN, for 20 min the diff between target and actual temp has been 2 C:

I_EFFEKT = 1,0 %/C/MIN * 20 MIN * 2 C = 40 %


D_EFFEKT = -GAIN_D * ( target_TEMP(t) – actual_TEMP(t-1) )

eksempel:

GAIN_D = 10 %/C, temp = 59 C, temp 1 minut ago = 58 C:

D_EFFEKT = - 10 %/C * (59 C – 58 C) = -10 %

The total effekt would be the sum of the 3 parts. P+I+D

In practic is the most importen change that I is lowered from the 100 to about 10 in order to avoid overshoot of temp.

P should be in the range 20-35 and D in the range 0-20

So now you have something to play with.

[joukeder]

You are right that perhaps it's just to lower the gain for the oxygen control, but what is strange is that the oxygen level keeps going down below the target and back again. It should go slowly down to target and then stay around the target, because even with 100 in gain it's quite small adjustments to the pellets high / low per time unit, but it seem that those small adjustments changes the oxygen level a lot. Do you think that you have very low draft in you chimney , perhaps other things (boilers) connected to the same chimney?.

I have a draft reducer installed in the new Stainless steel chimney and there is nothing else connected to this chimney.
I am going to check all the seals on the unit to see if they are tight. But the unit is new so I do not expect any problems. Would you know any area's where others had problems with seals?
Jouke

[tn]

I have a draft reducer installed in the new Stainless steel chimney and there is nothing else connected to this chimney.
I am going to check all the seals on the unit to see if they are tight. But the unit is new so I do not expect any problems. Would you know any area's where others had problems with seals?
Jouke

No I don't think the seals can effekt the draft much, so the chimny seems to be allright.

[joukeder]

Hi Torben,
There is a sticky on the general board about the ventilator settings for Bio comfort. I can't read it. Would you like to tell be what the essence of it is?
Jouke

[tn]

Hi Torben,
There is a sticky on the general board about the ventilator settings for Bio comfort. I can't read it. Would you like to tell be what the essence of it is?
Jouke

The essence is, that the blower low should be set together with the pellets low to give you a good fire without smoke and be set as low as it can. in practice the blower canøt go any lower than about 5 in order to give a stable air.
The blower high and the pellets high should be set so the fit together and give you no smoke, and so high as your effekt need is in the cold periods.
The effekt figure entered in KW is only a figure in order to show the right effekt on the display, ie percent effekt multiplied with the entered effekt in KW.
This figure is at factory set to 24 KW because that what your burner is designed for.
and the blower low=5 is the lowest possible blower setting, and the blower high=15 is the blower setting, that with normal draft and pellets high about 30 gives you 24 KW.

So by lower the blower high and the pellets high, you can have you effekt going from f.instance 3-10 KW instead of 3-24 KW. And so use the 100 step regulation in 3-10 KW area instead.
The to tables provided is for to types of blower and are some default values.

[joukeder]

Hi Torben,

I have been monitoring the Oxygen control and came to the conclusion that the inter-update timing is too long. I measure it as 1 min 05 sec.

If I steer the Auger high value manually in-between these updates I am able to control oxygen much better the the CPU.

Is it possible the set the inter-update timing?
I don't know if the system is just waiting or really integrating the delta Oxygen during that time, but it is clearly too long.

I think that with the ability to set this (integration) time combined with the gain should give a good Oxygen control, evening out the irregularities of my auger system.
Regards
Jouke

[tn]

Hi Torben,

I have been monitoring the Oxygen control and came to the conclusion that the inter-update timing is too long. I measure it as 1 min 05 sec.

If I steer the Auger high value manually in-between these updates I am able to control oxygen much better the the CPU.

Is it possible the set the inter-update timing?
I don't know if the system is just waiting or really integrating the delta Oxygen during that time, but it is clearly too long.

I think that with the ability to set this (integration) time combined with the gain should give a good Oxygen control, evening out the irregularities of my auger system.
Regards
Jouke

Hi Jouke
The update timing is not adjustable.
Actually it should be quite slow, because normally the oxygen level should be constant.
Of cause the oxygen reading goes a bit up and down all the time, but the control should not react on this, because that is unadjustable (caused by the burning process)
The thing that changes it more steady, is the whether condition (draft) and the changes in feed of pellets.
Both should be quite slow.
As i remember your curves the swing was also quite slow , about 10-20 minuttes, so that should be adjustable.
Have you tryed to clean the sensor, I think about if that could be a long time about to sense a change.