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Is it possible to tell how much a Vitodens is firing?
D107
Member Posts: 1,931
boiler piping. What's the brand? (I'd guess heating the basement with uninsulated overhead supply piping would be less efficient than a few rads on the floor.)
Very neat setup.....
Thanks,
David
Very neat setup.....
Thanks,
David
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Comments
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Is it possible to tell how much a Vitodens is firing?
OK so I'm at my outdoor Design Temperature (-10 F);
Is it possible to determine from somewhere in the diagnostics or setup panel what the modulation rate of a Vitodens is at.
It is clearly off of minimum firing rate - but it'd be interesting to know if it is at 50%, 75%, etc...
Perry0 -
Clock your meter!
Perry just go outside, see how much your fastest gas needle moves in 2 minutes and multiply by 30. Even simpler where you are than here. Thats your hourly consumption.0 -
What's your definition of simple..
I was hoping I could just look at it in my jammies in the morning...
Let see, currently -11 F, and dark, and meter access requires stomping through snow... (the utility reads the meters with a radio transmitter).
Tomorrow susposed to be colder.
Now I'm not sure if that is simplier than what you have or not.
Perry0 -
Put in your own meter...
Like I did :-)
It gives a pulse closure for every cubic foot of gas going through it, has a 1 cubic foot needle for easy clocking, and I don't have to be dressed to read it:-)
I'm sure the Iman Yousef knows how to tell what the current firing rate is on the Vitodens, but he's probably not going to share it...
ME0 -
Temps vary...
Mine's outside beside the house...
If you wanted to do a spot measurement of your house's performance @ -10F then yes you would have to do that. I'd love a cheap USB camera and a light on a switch out there. Easy to clock with a PC that way.0 -
Clocking the meter is the only way I've found.0 -
Hijacked
With the Ultra, 2 pushes of a button, gives you fan speed, from fan speed, you can determine gas Input
Chock one up for the underdog
At 11 deg, was running at 1700 rpm and 21,824k btu0 -
maybe?
Correct me if I am wrong, but as I remember the Vitodens controls the fan speed and the differential pressure created by the fan controls the gas input. If you measured this dP and gathered a little data from clocking your meter and plotting it against the dP you might be able to read it at the boiler. I believe this is the reason for the weighted door at the air inlet. I do not know the range of these pressures.
It would be nice if the display had a little bar that read 25-100%.
Even easier: A rotometer and two thermometers will give you boiler output instantly.0 -
That's my understanding of the air/fuel mix process as well. Don't believe that I'd ever tap into the differential pressure however...
Am fairly certain that a 0-10V signal is used somewhere (at least such can be used to control the boiler with the appropriate communications equipment).0 -
The fan motor...
It might be possible to measure the fan motor speed externally from pulses or otheriwse if you can't read it through the controls - it seems like it is 100% certain that it's in there. As for the 0-10v DC input interface, I'd be shocked and surprised if it had any output functions.
Wouldn't it be nice to have small digital gas flow device that is piped in right before the boiler? All the advantage of ME's solution in a much smaller package and complete with a USB cable.0 -
0
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oil .. it's just better...
and easier to measure...
meter-1
http://65.175.105.116/users/transfer/bbrainz/p1010062-1.jpg
ss0 -
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I'm sure this will sound goofy, but I'm not sure that the Vitodens itself has more than a "good guess" at how much it's firing.
With that "non-mechanical proportional pneumatic link between fuel and combustion air" a given fan speed won't correspond to a given volume of air and fuel except in a laboratory. First it adapts for the venting system used in each installation. Then it adapts for variances---both in the flue and fuel pressure.
The Vitodens control seems to care about one thing--change over time. Given the fact that there's only one internal sensor (immersion type right after the HX) I can only say that it's proportional heaven with everything relative to a goal. Maintain space temperature without sensing space temperature...0 -
an idea?
I think you are probably right, Mike.
Could that not be calibrated out by clocking the meter once things have adapted and comparing the input to the fan speed at several outdoor temperatures?
I'm guessing at all of this, because I do not know the exact algorithm used to calculate fuel input.
This is getting a little nuts. I wonder how much those Fox meters are.0 -
what is that?
I use oil -- what is that, a relay, a meter? Can you please start a new thread and explain?0 -
There are several different metering technologies
that could be used if you are going to cut into the line to install them.
I'm not sure I'd got the Fox meter route.
What I can do is get a differential pressure meter and measure my system head. I have available ports installed where I could do that (behind valves). Then I could look at the pump curve to get a really good estimate of flow. I already have system in and out temperature (to and from LLH).
I was hoping that some of those codes in the setup menue - on things you are not susposed to change (or can't change) actually related to some kind of boiler load signal. Actually - they might. I am sure that Viessmann has some stuff that can plug into the boiler and read these things... (at the factory lab) and I'm sure that it is stuff they read on the "unused/unsettable" setup locations that are what they are accessing.
Perry0 -
Clocking the meter...
OK, I clocked it:
0 F outdoor temp.
4 Minutes 5 seconds for 2.5 Cu Ft
1025 Btu/ Cu Ft
= 37,653 Btu/Hr input
@ 94% efficiency ==> 35,393 output
House at 68 F.
Vitodens 6-24 firing at less than 50% at 0 F outdoor.
I guess I needed a Vitodens 3-12... (or 4-16) if I am ever going to stop the spring, fall, and over 20 F cycling.
This is much less than my heat loss speadsheet - and the heat loss calculator (I thought it was about 50,000 at zero and 55,000 at -10 - I'll have to find it).
Anyway, that is one data point. I guess I'll have to take a few more...
Perry0 -
perry
3 points would be nice, maybe 4.
say 0F, 10F, 15F and 20F? anything above min modulation.
I wonder if 5 minutes is truely adequate for an hour of burn cycle? several hours for that matter?
what is your indoor design temp? 72F in mich.0 -
See why I keep saying that heat loss calculations have all the necessary "fudge factor"?
Want to have fun?
Clock the meter again. Open a window in any reasonably sized room but not the room with your remote control. Best if you can isolate that from the rest of the house via a closed door. Wait 5 minutes or so--less if it's windy. Re-clock the meter.
If anything like what happens when I do similar, you'll see why I keep saying that the Vitodens has an uncanny ability to match its output to the load on a nearly real-time basis.0 -
Vitodens firing rate
you can also use a manometer or check voltage on the boiler to see how many BTU's you are firing at. Call Viessmann tech support and find out how0 -
Vitodens firing rate
you can also use a manometer or check voltage on the boiler to see how many BTU's you are firing at. Call Viessmann tech support and find out how0 -
sent you an email on it..
hi tim,
check your email. sent you a note that explains everything that it measures - including the whole 3rd page of zones & cycles/hr info which is missing from this older flyer. but that should get you started. any questions call or email.
b-brain
thanx.
ss0 -
Gas usage comparison
Mike, how much has your gas consumption decreased since you installed the Vitodens? I seem to remember that you used to have an old W-M atmospheric boiler previously.0 -
About 43% the first season as a whole. Boiler was only change. Old boiler used full outdoor reset (same heating curve), true constant circulation (circulator was only stopped by the warm-weather shutdown control) and TRVs on standing iron rads.
Second season I optimized the Vitodens heating curve for economy. About 50% savings.0 -
Thats pretty impressive. How long do you think it will take you to pay back the cost of the Vitodens install in fuel savings?0 -
If I don't include labor (I was the installing contractor as it's in my own home) and the fact that it was installed the season before gas price nearly doubled, the boiler itself is paid for this year (the third season).
Since I already had the TRVs and it's a gravity conversion system with zero (for calculation purposes) head loss in the piping, the Vitodens itself was essentially "plug and play". Only required "accessory" was a wye strainer, but I also included a simple air separator just in case.0 -
I Like the fresh air hole at the end of the boiler area... time to cough up a few bucks for an 8" cap Mark! Boost your profit margin on the next one; they'll never know they bought you a piece of sheet metal
is that the flow meter you said was 99% accurate? How about a hose in a bucket, and back into the system? Guilty until proven innocent when it comes to GPM, CFM (I'll trust my $2000 TSI hot tip Velocicalc) and all the other goodies (Delta T should/is a brainless act).
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
If Tekmar can do it, why can't Viessmann? I'm pretty sure they could if they so desired.
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
vitodens issues
Mike I'm wondering about your conclusions from the window test you describe. I believe that the increased gas consumption you observe is simply a result of a higher energy transfer based on the increased delta t between the room air and the radiators, not the proportional logic of the boiler. I made similar observations while heating my slab with a polaris tank hot water at a fixed temperature under constant circulation. What I noticed was a very apparent relationship between outside temperatures and the run times for the heater. By experience I would make seasonal adjustments to this circulation temperature (80 to 90 f) Generally I would under-heat slightly and use a wood stove to make things nice and warm if necessary. Remarkably room temperatures were fairly consistent without any indoor or outdoor feedback controls, (except for my occasional intuitive tweaking of the supply temp.) My conclusion from these observations; relatively small changes in indoor air temperature have meaningful effect on heat transfers from radiation sources, In effect a natural feedback mechanism is at work here based on the principle of thermodynamic equilibrium.
I recently installed a vitodens which is great except for it's lack of differential temperature control. I really hate the 30 second or less firing times that are the rule when it's not that cold out. I guess my 20,000 btu house is just too low energy for this boiler, still I want the 70,000 when I need it for dhw.
I believe the LLH may have been a mistake in my system, perhaps a 3 way mix valve, or just a direct connection would have worked better. There seems to be a real push for the LLH with sales folks in my area. I don't believe the flow rates in my system justified it's use. There is also a strong possibility for a drop in condensing efficiency if these headers are not carefully balanced, as cold return water can become "diluted " by the warm supply stream. Additionally what happens to the mysterious variable speed pump logic and the fancy 50hrz. grundfos circulator. (which I'm sure added to the cost of this unit in the first place) when the LLH is used?0 -
vitodens issues
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Scott: I really don't know what will happen if Perry does this experiment. I know what happens in my system but it's completely different. Two-pipe standing iron TRVd rads compared to one-pipe (monoflow) cast iron baseboard. I'm curious about just how much "natural" feedback is affected by the general design of the system...
The short firing of the Vitodens bothers me as well. Even though my calculated loss is much higher (100,000 btu) I can keep loss MUCH lower. Literally thousands of cycles of less than 10 seconds for the entire operational cycle. BUT, such cycles actually heat the house! I've talked and written about this with all levels of Viessmann North America. ALL say that it's what the boiler is supposed to do.
As to the use of the low-loss header, all I can say is that it's generally "recommended" just like EVERY mod-con manufacturer recommendeds primary-secondary.
BUT, it's that "mysterious" variable speed pump logic that MAKES THE LOW-LOSS HEADER WORK! "Boiler circuit mode" is simple and straight-forward when you look at the function of the LLH as driven by a Vitodens. It's "system circuit mode" when driving a TRVd system that continues to mystify me.0 -
Every?
Date: January 02, 2007 02:53 PM
Author: Patrick Linhardt, "Linhardt's Field Guide to Steam Heating"
Subject: Prestige P/S not needed
Hi Andrew,
I was in Blackwoods NJ in October for a class on the Prestige boiler. They are recommending that P/S not be used unless desired. Size the system circulator(s) for the pressure drop thru the boiler (chart in back of install manual) and the zone(s).
Best regards, Pat
***************
I've confirmed this with T-T as well.0 -
Mike, thanks for the reply. The" boiler circuit mode" and "system circuit mode" that you describe, are these coding addresses? I don't recall seeing any like this in the the literature. Personaly I can't except 10 second burns. How efficient can this be? the boiler doesn't even get a chance to adjust down to min. modulation. The slight smell of raw gas at ignition tells me I'm not getting complete combustion in that first second or so, multiply that by thousands of cycles and I believe you have a meaningful and preventable waste of fule. Plus these excessive ignition cycles must be putting more wear and tear on the burner than necessary. As far as the gospel of primary secondary. Yes it obviously helps prevent these low mass boilers from over heating by insuring adequate flow thru the heat exchanger. However if we are designing to harness as much of the latent energy in the flue gas condensation as possible ( as I am interested in doing) direct piping is best. Check out this pdf from Viessmanns german website. It has a real clear description of net and gross caloric fuel values, potential energy in flue gas condensation, and the variables that effect it. also included a recent job photo0 -
pump logic etc.
Mike, thanks for the reply. The" boiler circuit mode" and "system circuit mode" that you describe, are these coding addresses? I don't recall seeing any like this in the the literature. Personaly I can't except 10 second burns. How efficient can this be? the boiler doesn't even get a chance to adjust down to min. modulation. The slight smell of raw gas at ignition tells me I'm not getting complete combustion in that first second or so, multiply that by thousands of cycles and I believe you have a meaningful and preventable waste of fuel. Plus these excessive ignition cycles must be putting more wear and tear on the burner than necessary. As far as the gospel of primary secondary. Yes it obviously helps prevent these low mass boilers from over heating by insuring adequate flow thru the heat exchanger. However if we are designing to harness as much of the latent energy in the flue gas condensation as possible ( as I am interested in doing) direct piping seems best. Check out this pdf from Viessmanns german website. It has a real clear description of net and gross caloric fuel values, potential energy in flue gas condensation, and the variables that effect it. also included a recent job photo0 -
p/s
The only Vitodens model that cannot be piped directly *in most situations* is the 8-32. I cannot think of a situation where an 8-32 would work with the internal pump.
It's not that the low loss header is bad. It's just that it is unnecessary. Your boiler would cycle just as much without the LLH. The problem is the 6-24 is too big for most houses, a major oversight on the part of every boiler manufacturer to date. A buffer tank is the only option to lengthen the cycle times at minimum firing rate. I think a 3-12 would be a very nice size.
However, I have to think that the collective knowledge of the boiler manufacturers would have seen this? Is there a reason these low firing rates are not available? Is it an engineering reason or an economic reason?0 -
Install the temperature sensor for the low-loss header and the 6-24 and 8-32 automatically switches the circulator to "boiler circuit mode".
If you smell even a whif of gas with the combustion chamber cover installed, shut it down and take immediate corrective action.
Fire with the combustion chamber cover removed and who knows what will happen. You might even get condensation on the outside of the stainless jacket surrounding the combustion chamber.
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gas smell
Mike, I mean outside the house from the vent, and it's very subtle. Hell maybe I'm just remembering my old rough starting pollaris. What I'm really getting at here is that I imagine it takes a half a second or so for stable complete combustion to begin after initial ignition. If so many of our burns only last 10 to 15 seconds then this ignition period starts to represent a measurable amount of the overall run time. Yes this is splitting hairs, I just have a hard time excepting that this is just the way these boilers run . Especially from Veissmann with their reputation for highly engineered energy conserving products.0
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