Vitodens Operation

Mike T., Swampeast MO

<B>Notes:</B>

1) My outside temp sensor is solar powered and must get some sunlight (would GREATLY prefer battery but not available). The big jumps you see in daytime temperature are solar influenced!

2) Still don't have the condensate working properly--ignore.

3) Unless you have a very large monitor, probably best to view this by printing on a color printer.

4) "Supply Target" is MY computation based on a flat-line reset curve. The published Vitodens reset curves are NOT flat as they drop off at warmer temps and pick up a bit when really cold.

5) There have been no changes to the Vitodens reset curve (or any other parameter for that matter) during the entire period represented.

6) All graphs show a total period of 12 hours, with 1 hour between vertical divisions.

<B>Regarding "Vito Pulse (early).pdf":</B>

This was 10 days after the boiler went into operation. Note the change in frequency of firings at about 5:00 a.m. No real change in outside temperature, but <I>something</I> definitely happened! Cycles per hour dropped from about eight to about five.

In earlier days, there were even more frequent cycles--so many that I was beginning to get a bit worried...

Those earlier cycles consumed about 1/3 cubic foot of gas each--VERY short burn time at full burner output (at least I'm fairly certain it's full output). Burn times are still very short, but they now consume between 1/2 and 3/4 cubic foot of gas--usually just a touch over 1/2.

<B>Regarding "Vito Pulse (later).pdf":</B>

23 days later now with very similar outside temperature. Note that the five cycles per hour is holding very steady. While that is a 12-hour period, outside temp and operation was consistent for 24-hours and gas meter showed 1 ccf used, but I'm not interpolating smaller amounts.

The boiler has been in this type of firing mode for at least 50% of the time since it was put into operation on November 2.

<B>Regarding Vito Burst (early).pdf</B>

As outside temperature drops from the 50s to the 40s, operation changes and there are long, continual fires generally followed by a few pulses--again about five per hour.

<B>Regarding Vito Burst (later).pdf</B>

(Note that flue temp had a protracted period of no reads--I don't know why and it's again working perfectly--these wireless sensors certainly aren't perfect...)

This was last night through this morning. Almost perfectly steady temp (it's been raining continually). A touch warmer than the previous graph showing the bursts. Note that the bursts now seem a bit shorter but also somewhat flatter at the top. Delta-t <I>as I measure here</I> seems perfectly consistent during these bursts. This is the only type of maintenance operation where return temperature changes rapidly and significantly. Note that firing almost always seems to end just as the measured supply temperature hits my "supply target". There has not been much of this type of operation and it's generally only occurred over night. It has now continued for nearly two days straight. In the "early" version notice how return temperature almost meets supply temperature on the way "down" from the burst. In the later version you notice that they aren't as close. In the earliest graphs, the supply/return temps would meet and even crossed once or twice. Again, I believe this shows how the boiler is modifying its operation over time and adjusting its operation to best suit the system with best fuel economy.

<B>Regarding "Vito Mod (steady).pdf"</B>

During this period there were no changes in TRV setting. Note that a "burst" is captured at the far left, but curiously there are no "pulses" following.

I find it <I>very</I> interesting that a few hours into such a burn that the "Boiler Temperature" reported in the default display on the boiler is almost always within 1° of MY computed "Supply Target". The "Target Temperature" as reported in the operational status menu is almost always within 1° of my <I>measured</I> supply temperature!

If I use MY computed "Supply Target" as the maximum system temp and compare to measured return temp, the delta-t is almost exactly what I predicted using those spreadsheets I made (still for sale for $10 by the way).

<B>Regarding "Vito Mod (TRVs changed).pdf"</B>

IMPORTANT: AM/PM is in REVERSE in this chart and the dates are off as well. I was doing a bunch of zooming and moving to capture just this period--obviously there's a bug in my program that I have to find... (Times/dates are notoriously difficult to work with in programming.)

Here are 12 solid hours of modulation. The dips you see were when TRV setting(s) were increased on rads that had been set back considerably. Note the nosedive in return and supply temperatures, followed by a perfect resumption of the overall shape.

The first change was made and stayed at the higher setting throughout this period. The second was my first little experiment that I reported last Saturday morning. The TRVs were put back to deep setback within 15 minutes or so. I believe you can see the point where I turned them back down as the little "hump" in the supply temperature!

The rise you see in outside temp is solar influenced--again those are actually a.m. times, NOT p.m.!