Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: victor6deep on October 15, 2013, 07:10:17 AM
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What's the theory behind this?
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HUH
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HUH
Slimjim, you know what im talkin bout dude?
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No I really don't understand your question, Pump speed or water flow has very little to do with wood consumption. Wood consumption would have far more to do with heat load and heat loss, pump speed / flow has lots more to do with Delta T and not shocking the boiler with cold water being returned to the boiler.
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Here we go again lol
Pump speed does not change the btu requirements of your home is the most simple answer
Second, you or most would anyway, want there pump to pump fast enough to have a proper delta t
I'm playing around with a taco bumblebee pump right now, it slows down and speeds up based on demand with delta t sensors, Sooo, when there is no load on it, the water slows to a couple gpm, in theory I'm pushing less btu through the lines, but I'm not seeing any advantages to this in terms or wood usage...
But back to reality, pump speed should be appropriate for delta t, if you can run on med vs high and have proper delta t, you'll save on electric but not wood
By the way, the reason for the bumblebee pump is electric savings not wood..... I though it would be interesting to see if there were any fringe benefits but I don't see any other than the little sucker is using 9 watts of power most of the time, where your broeder is running 185 watts on medium. The bumble bee only runs 42 watts on high, broeder is about 260 if I remember correctly
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Here we go again lol
Pump speed does not change the btu requirements of your home is the most simple answer
Second, you or most would anyway, want there pump to pump fast enough to have a proper delta t
I'm playing around with a taco bumblebee pump right now, it slows down and speeds up based on demand with delta t sensors, Sooo, when there is no load on it, the water slows to a couple gpm, in theory I'm pushing less btu through the lines, but I'm not seeing any advantages to this in terms or wood usage...
But back to reality, pump speed should be appropriate for delta t, if you can run on med vs high and have proper delta t, you'll save on electric but not wood
By the way, the reason for the bumblebee pump is electric savings not wood..... I though it would be interesting to see if there were any fringe benefits but I don't see any other than the little sucker is using 9 watts of power most of the time, where your broeder is running 185 watts on medium. The bumble bee only runs 42 watts on high, broeder is about 260 if I remember correctly
I've been pondering getting a bumblebee but not sure if it would move enough water compared to the broeder.
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Didn't you say you were 60ft away with 1" pex through a plate exchanger and a coil!?
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Yes
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Sure.. It would work..
I've got more pex than you, 20 plate, and coil.
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Running 165-180 guys and gals and have the E9 pushing tidal waves of treated water. What another dumb thread initiated by Vic 6 Deep. Booyah
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Oh come on Victor you know we all love you anyways
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http://www.taco-hvac.com/uploads/FileLibrary/100-68.pdf (http://www.taco-hvac.com/uploads/FileLibrary/100-68.pdf)
http://m.youtube.com/watch?v=d6Pbrz8wwcI (http://m.youtube.com/watch?v=d6Pbrz8wwcI)
http://m.youtube.com/watch?v=caYoFXWzgRg (http://m.youtube.com/watch?v=caYoFXWzgRg)
http://m.youtube.com/watch?v=hYOYY40-HDg (http://m.youtube.com/watch?v=hYOYY40-HDg)
Yup, here we go again. There are no dumb posts, someone will always learn from questions. I couldn't post the direct videos on more details on how variable speed pumping does save fuel, not just electricity. It can't get any clearer and easier to understand, you just have to break the old way of thinking and self taught theory.
In one of the videos, it shows where you can sign up for free and use the taco flo pro university courses and videos. Lots to learn and understand. Or just watch the 2 other videos on variable speed pumping.
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There is some circumstances where it only needs to send the amount of heat it needs. In those cases yes it can be more efficient. But for the general public and 99% of outdoor boiler installs protecting the stove with a proper delta t is most crucial.
I have tested pumps here and went down to ducmenting wood use via weighing it and moisture checking, documenting temps, and never saw any wood savings between my bumble bee and lets say a grundfos 15-58
Thats not to say that in a complex boiler system where there is in floor heating, storage tanks, and stuff like that that proper zone pumps etc arent important to the design
However nearly all of my installs are very simple, most consist of a 20 plate heat exchanger and a 16x18 coil over a forced air furnace.
Like slim was saying the other day, how many folks do we see with a cobbled up boiler system but have a 60k dollar truck
Well, all I can say is, im not sure who you all work for. Most all of my customers are trying to decide how to get through the next month, how are they gonna put food on there table next month when there electric bill is 600 bucks. So when it comes to the install, all we can do is offer them the best and let them to buy what they can afford.
I know premium lines like logstor are hard to beat, but many of my customers stagger backwards when I tell them my cheapest line sets are 6 bucks per foot. Some even leave immediately cussing under there breath callin me who knows what
So its like comparing apples and oranges.. if someone can afford mass storage, 20k dollar installs etc, then they have the ability to chase every speck of efficiency available. I get jobs like that as well, but if I depended on those to run my business, id starve the first month. I live in the poorest region in our nation.
Once again, not saying your wrong, but for the way outdoor boilers are gernally ran proper sizing of the pump to help protect the stove from low return temps is our main concern. However most dont even concern themselves with that.
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Awesome reply Scott, very well said. Just the fact that you use a 15-58 pump on the supply is rare, I think I've only seen a couple. That being said, most are shoving 20-40 GPM on a call or worse they run them 24/7. And using a delta T circ will show more savings. They make the VDT SERIES from 006-0014. When making these kind of changes , it's NOT Always a swap and go, full understanding and tweeking. It's not difficult to make improvements, I wouldn't describe it as chasing ever ounce of efficiency. And there's no need to spend 20 large in any residential app. That's for the yuppies with too much money. Even a non leaking , non gasser can be improved a lot , just with standby losses and pex upgrade or improvements.
I completely understand about getting a system you can afford, since this is why some are even looking at wood in the first place. I think as long as the consumer knows the differences and they make the educated choice, it's OK. But we both know its more like, " I'm quoting the cheapest equipment available to make the sale" type of sales that goes on most of the time. It gives the good guys a bad rap, and the good guys need to police their industry. Best they can before the sale. I'm by far not the biggest, nor do I do the most. But I am one of the most recommended. I know I'm gonna loose jobs cuz I'm higher, but my customer knows enuff when I'm done to make his own decision. And his pocket book sometimes makes his. I know I'll probably see them soon to fix or upgrade, and the I told you so. But rather than mass quantity, I take pride having my work shown off, or saving a boiler that was going to be abandoned and not getting the horror story complaints. I couldn't sleep at night with that.
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Yea, the ones where they tell you to do it like youd do your own and hand me the bill are awesome and a ton of fun.
Ive been in areas where there was enough money flowing that folks could afford to take the good jobs and ditch the cheap ones. There are some products I cant and wont selll but all we can do is recommend they buy the best they can afford. Where you get in trouble is cutting prices for the guy who could afford to do it right but wont cause hes a cheap skate lol
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Pump speed or water flow has very little to do with wood consumption...
I've read enough of your posts to trust your advice, but I'm wondering if the pump speed was too low, and the water returning to the OWB was cooler than with a fast pump speed, would more wood be burned trying to heat up the cooler water?
Also, what exactly, (in terms an idiot like me can unnerstand!), is 'delta T'?
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yea what is this delta t ???
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Its about boiler protection... if return temps are allowed to drop below 140 it can cause condensation inside the fire box that allows it to mix with ash and cause a premature failure of firebox
No it wont use more wood
Delta t is simply the difference between the water in ur supply line vs the temp of water in your return line
To measure turn on anything in house that uses heat and.check the differences in temp at your supply and return on back of stove.
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yea what is this delta t ???
These are the spoon fed variety. With just DT I can determine how many btu's your consuming, GPM flowing, and how efficient your wood is.
If you watch any of those videos or search it, you will learn way more than us just saying its the difference in temp between 2 points. Whether it be supply n return, or from stove to inside house on the same line.
Btu =DT x GPM x 500
The bumblebee I think is accurate in flow measurement. I thought it might just be a set programmed number for each wattage, but I have seen several GPM displayed for the same wattage. Balancing valves show up.
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yea what is this delta t ???
"Delta" means change, "T" stands for temperature.
If you measure 195* water going into your water to air heat exchanger and 175* water coming out, your "Delta T", or "change temperature" would be 20*.
On this site "Delta T" is a term used for thermodynamic change in a given area of a hydronic system.
The term is also used in reference cooling systems too.
Whenever you read it here, just think "temperature change between two or more defined points in a hydronic system".
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yea what is this delta t ???
With just DT I can determine how many btu's your consuming, GPM flowing, and how efficient your wood is.
My DT across my water to air heat exchanger is 19*. My DT from the inlet of my sidearm to the outlet is 6*.
1) How many BTU's am I consuming?
2) How many GPM's am I flowing?
3) How efficient is my wood? (??????)
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:post:
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To figure wood usage would delta T be figured at the boiler? Instead of a heat exchanger?
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To figure wood usage would delta T be figured at the boiler? Instead of a heat exchanger?
If someone tells you there delta t, it is impossible to figure there wood usage or whatever based off of that number. Like marty said, he gave him all his delta t's and explained it in detail. But there are so many more variables
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I'm figuring my wood consumption by how much wood actually goes into the boiler. The rest of it seems a bit complicated for me. I was just wondering where you took that measurement from.
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Ok now you guys are being facetious, but I did type "with only DT" so I guess its my fault for not being more specific enough, or exacting for those who like to pic posts apart.
Knowing the BTU = GPM x DT x 500 formula you would need only two of the three variables to figure the unknown. With additional formulas common in hydronic books you can get very accurate estimates.
GPM = BTUh / DT x 500
DT = BTU/ GPM x 500
Now let's say you have a pretty good idea from monitoring over a set time of your btu output. You can use that to ESTIMATE how many pounds of wood you should be using IF you know the efficiency of the stove. Or compare the calculated lbs to the actual lbs you used, to tell you how much btu your getting from the wood minus the stove efficiency. OR if you have been measuring the moisture content of a known specie of wood or pounds of wood over moisture content , you can calculate some very close numbers. There are pages and pages of enginerds/wood boiler owners that do this to a T. Literally. Its real world versus the lab. And it sounds silly but some take it pretty serious. Kinda like that link to live monitoring of that boiler. Homemade lambda controls and boilers that come with them, just like fuel injection system on a car. The EPA is gonna push so far that all boilers or stove will require cats, oxygen sensors and idling will be illegal as it is in Europe, just like it is for diesel trucks in some states.
Going thru some of this can give you piece of mind or you might learn something, or you might be able to show someone that your properly run OWB is more efficient and cleaner than the neighbors new propane furnace that never had a heat calc or combustion test done when installed. Least of all you just might laugh so hard that someone would do all this. But why is burning wood so mezzmorizing or addicting.
Sorry if I got somebody worked up, but here's your spoon feeding for the day......hahahahah
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Facetious- "treating serious issues with deliberately inappropriate humor".
Not being facetious in any way, shape, or form, my fellow Michigander. Nothing but love coming from the center of our states Lower half. ;)
There are many more variables involved in calculating heat loss/btu's spent in a hydronic system that employs outdoor wood boiler as it's heat source-
radiant losses from the OWB, dew point and ambient temperatures both inside and out, earth temperatures, thermal transfer to the earth from insulated pex, plenum intake temperatures, plenum insulation, etc. to name a few of the obvious.
The point I'm trying to illustrate is that it would be very difficult to come up with a simple mathematical formula for determining either GPM or btu's solely based on a change in temperature in a given area of a hydronic system that employs an OWB. We would need more controls in place beforehand to aid in eliminating or reducing some very pertinent variables (knowing what the variables are that are precipitating said changes) . It's not as simple as calculating horsepower from an internal combustion engine: HP=(rpm x torque) divided by 5252).
Rest assured, you did not get me worked up, my friend.
Sometimes in this life we have tendencies to make tempests out of teapots. Other times, just the opposite.
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Glad you are an easy going, and understanding guy then. Sure there are lots of variables, but an experienced serviceman can get some very accurate estimates with some simple math. Enough to point you in the right direction or eliminate possibilities. Exact numbers do require more defined criteria or monitoring.