Vitodens Forced Into Digital Operation

Mike T., Swampeast MO

Here's a couple graphs. Remaining sensors are supposed to come in today. Graphs from the unit itself so can't do overlays. Will have everything plotted onto the same graph when I set up my own program.

Inside temp at normal evening levels--about 1/3 of the house at 67° and the rest around 60°.

<B>Regarding the flue temp from 11-8-04:</B>

Still not really cold as you see and the day before was very sunny and peaked around 70°.

Note the spikes on the left side of the flue temp chart. That's when the boiler will come on for a few seconds at high fire and then stop. Was in the basement at that time those ultra-short firings happened fairly frequently for around a half an hour.

Then there was that nice long fire for about an hour and a half. Went to bed after that cycle ended. Then you see another but shorter "fit" of those short firings followed by a nearly four-hour continuous burn. Slept late this morning and was only there for the end of that final burn when the supply temp had risen to 122° with a setpoint of 111°. Again, a few of those short burns on the way down but by that time outside temp had risen. (Note that that outside sensor is solar powered and gets a couple hours of morning sun so it didn't rise that high and that fast. Actual temp about 53°.)

<B>Regarding flue temp from 11-5-04:</B>

Outside temp was essentially identical--exact same shape and just a few 10ths of a degree difference at most times.

Note that you can still see those ultra-short bursts. If you print out, put one over the top of the other and compare you'll notice that the burn times are longer three days later--particularly that long, final burn when loss is the greatest.

Am not certain of the purpose of those micro burns, but I believe it has something to do with learning... Even though VERY short, they hit the high limit I've set for the supply--150°.

mac

What are we trying to...

learn here? I'll be putting in my first Vitodens shortly and hoping you could clarify this info.
Thanks!

Mike T., Swampeast MO

Sorry, forgot something.

Model 6-24 with minimum output of around 22 mbh.

Heat loss during this period less than 22 mbh.

Single circuit with TRVs and no low-loss header. No DHW production.

Temp probe in that handy-dandy test area to the inner portion of the concentric flue adapter.

Graphs show the actual flue gas temperature measured just a few inches away from the HX. Those long, gradual rises are single firing events.

Am presuming that the burner is at minimum modulation during those long firing times. Blower has ramped WAY down and gas meter tells me the unit is drawing about 24 cubic feet per hour.

joel_19

Hey!

That is like so cool what are you using to track and compute the data??? I've got a couple of young nerds here that where up at 2 A.M. playing Halo2 last night ,they would be all over that stuff.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mike T., Swampeast MO

It's actually a wireless weather system (La Crosse Technology WS-2010) with a bunch of extra sensors and a computer interface that uses a serial port.

The remote probe sensors have a high enough limit for lower temp hydronic systems and the Vitodens flue (where temp is lower than the water coming out) but I certainly wouldn't stick the probe in the draft hood of the old cast iron boiler as it would melt!

jerry scharf_2

sharing data

Mike,

We should look at some way to pour your data and mine into a common format. I've given a bit of thought to this, but want your thoughts as well before I out anything on paper.

jerry

Mike T., Swampeast MO

Software gives a raw data dump so I can translate to nearly any format. Manual says the data dump format is easily accepted by Excel, but haven't experimented yet.

Mike T., Swampeast MO

Update & Amazement

New sensors arrived and installed. Set unit to read every two minutes (shortest possible period).

As mentioned previously, I swore that in this weather the old boiler was loosing at least 80% of its input up the flue.

As far as I can see, tell and measure, fuel consumption has dropped in the order of 90% with the Vitodens in similar conditions!

Am doing my damndest not to cloud my objectivity.

Forthcoming numbers should be a reasonable "proof".

Dale Pickard

Mike,

I love you but I'm afraid for you....; -)
While you are logging data and pondering it's meaning.....please keep your life.
I knew you'd love the Vitodens.

Dale

Mike T., Swampeast MO

I hardly have a life to begin with. There's got to be something to give it meaning and heat seems to be it for me.

Mike T., Swampeast MO

Didn't Even Go Down in the Basement Today, Dale

Sanity is still reasonable...

Rained last night and all day with steady temp in the low 50s. Return temp varied by no more than 0.5 degrees; supply temp by 4 degrees. Flue temp by 6.

These are "strap-on" sensors so measurement is always a bit "weighted" by the black iron.

The short fires are interesting. I know the house is loosing some heat...

Dale Pickard

Common affliction

I put a great deal of instrumentation on my heating system. When it gets really cold out, I've been known to disappear into the crawl space with a IR thermometer and a six pack of beer.

Some folks, like my wife, thinks it's strange. She married me so her judgement is clearly not to be trusted. : -)

You need to get some automatic data logging equipment tho....check out National Instruments.....www.ni.com

Dale

Mike T., Swampeast MO

They do do log data automatically. That's why I wasn't in the basement! Well...had a LOT of other work to get done and actually managed to do it all and more.

Ron Schroeder_2

Hi Dale,

I know what you mean. My wife thinks I am having an affair with some woman that I am hiding in the basement ;-)

I have 16 thermocouples on my heating system and 3 more on my solar electric system and for weather monitoring. I am also recording about 15 electrical measurements at the same time. Isn't Labview great.

Ron

Mike T., Swampeast MO

Some REALLY COOL Data Coming This Evening

In a bit more than 24 hours of data I have captured what appear to be three distinct "modes" of operation:

1) A "pulsing" output with extremely low supply and return temps when heat loss in the house is VERY low. Exceptionally low variance in the supply temperature but spikey output due to the really short, full output burns.

2) Digital operation when heat loss is less than the lowest possible modulation rate. Actual supply temperature varies greatly in this mode on this system. You can literally see the "target" level in the graphs, but it's forced to heat significantly higher and let fall significantly below to achieve a good, long burn. Return temp mirrors this output, but with significantly less variance. (That "buffer effect" in the mains.)

3) Proportional, modulating output--finally! Did have to "force" it a bit by bringing a number of setback spaces up to normal room temperature. This one is ongoing. Supply and return temps are virtually "nailed" at the averages of "digital mode".

Response to the call to raise temperature by about 12° has been PHENOMENAL. With the old boiler (a bit over twice the output of the Vitodens), the oversized standing iron and the B&G 100, I said that temp response was nearly as fast as forced air. IT STILL IS with ONLY the built-in circulator that's currently WAY down in rotation speed because the weather is still not cold! Well, do you call a 10° rise in 40 minutes fast??? About 2½ hours for the air temp to stabilize good?

May have to post a screen dump from the actual program provided with the data-logger. Am working on my own program to graph just the way I want, but might not get it done by this evening.