help me with Storage questions and wood consumption.

[musclecar joe]

ok I have a few questions.......

1st question:

How do I figure out how many btu's I am burning in a 24 hour period? some info to help calculation...I do not have storage and I burn 11 full cords (4x4x8) of hard wood per year to heat my 3000 square ft home using baseboard rads and 1300 square ft garage using a modine heat exchanger.

2nd question:

If I add 1000 gallons of storage how much wood will I conserve or add to my annual burning. Will I save cord wood?

My calculations have determined that I burn 150,000 btu's per day as an average using 11 cord therefore with storage assuming a 30degree top to bottom swing in usable temp swing I will have an additional 275,000 btu's I can use, therefore I should cut my wood consumption in half. Are my calculations and thought process right or wrong? can someone guide me?

Thanks for your help in advance

Muscle car Joe
Econburn 150

 

[jimbom]

Burn in a 24 hour period? What I did was weigh the wood used in a few 24 hour periods on cloudy non windy days. Then I went to the net for degree days in my area. Here is the site for Pittsburgh:

http://www.wunderground.com/history/airport/KAGC/2012/2/20/DailyHistory.html

You see that yesterday, Pittsburgh had 35 heating degree days.

I divided the pounds of wood burned by degree days for my area and came up with how many pounds of wood I use per degree day. In my case it is about 2 pounds/DD.

The amount of heat I get out of my pound of wood depends on the moisture content, stove efficiency, and far and above most importantly, how smart an operator I manage to be.

As I get better at running the stove and estimating when to start and end a fire, the wood use is coming down. I also have to guess how much sun we will get, as a sunny day means we don't use wood if the outside temperature is above about 40 °F. This depends also.

So I know if there should be about 300 degree days in the next two weeks, I will stock 600 pounds of wood on the porch ready to go. If we have a few sunny days, all the better.

 

[hobbyheater]

[quote author="musclecar joe" date="1329866522"]

If I add 1000 gallons of storage how much wood will I conserve or add to my annual burning.

I added storage to a none gasification boiler and seen a drop in wood consumption that mirrored the 40% number below .

This article on storage I found in the "Eko Line Manual". Hot Water Storage

For the best results, the use of a heat storage tank is recommended. A properly sized storage tank
can cut wood consumption by as much as 40%. Hot water storage allows the boiler to run at optimum
capacity regardless of the demand for heat from the building being heated. The stored heat can be
recovered later, both stretching the time between boiler re-fuelings, and as an additional source of
heat on very cold days. Generally, the bigger the storage tank the better, as the boiler is most efficient
when running at full capacity. The rule of thumb on tank sizing is that 13 gallons of water can store
about 1KW of boiler heat. Using the EKO 25 as an example: 13 gal/1KW x 31KW = 421 gallons, 421
gallons x 91% efficiency = 383 gallon minimum size water tank. A hot water storage tank connected to
an EKO boiler can also be used to store hot water from a solar water heater.

 

[stee6043]

ok I have a few questions.......

1st question:

How do I figure out how many btu's I am burning in a 24 hour period? some info to help calculation...I do not have storage and I burn 11 full cords (4x4x8) of hard wood per year to heat my 3000 square ft home using baseboard rads and 1300 square ft garage using a modine heat exchanger.

2nd question:

If I add 1000 gallons of storage how much wood will I conserve or add to my annual burning. Will I save cord wood?

My calculations have determined that I burn 150,000 btu's per day as an average using 11 cord therefore with storage assuming a 30degree top to bottom swing in usable temp swing I will have an additional 275,000 btu's I can use, therefore I should cut my wood consumption in half. Are my calculations and thought process right or wrong? can someone guide me?

Thanks for your help in advance

Muscle car Joe
Econburn 150

Well first, storage will never give you "more btu's" than you had before storage. It may allow you to store heat that would have otherwise been wasted.

150,000 btu per day would be a very, very low heat load for a 3,000 square foot house and a garage. That is 6,250 btu/hr. I heat what would be considered an average insulated home, 3,200 sq. ft. and my average heat load is 20,000 btu/hr. My peak is somewhere near 50,000 btu/hr. You could heat your house with a few 100W lightbulbs if your load was really 150,000 btu per day!

11 cord per year is a whole heap of wood. Does your boiler idle a lot? Is it inside?

 

[musclecar joe]

ok I have a few questions.......

1st question:

How do I figure out how many btu's I am burning in a 24 hour period? some info to help calculation...I do not have storage and I burn 11 full cords (4x4x8) of hard wood per year to heat my 3000 square ft home using baseboard rads and 1300 square ft garage using a modine heat exchanger.

2nd question:

If I add 1000 gallons of storage how much wood will I conserve or add to my annual burning. Will I save cord wood?

My calculations have determined that I burn 150,000 btu's per day as an average using 11 cord therefore with storage assuming a 30degree top to bottom swing in usable temp swing I will have an additional 275,000 btu's I can use, therefore I should cut my wood consumption in half. Are my calculations and thought process right or wrong? can someone guide me?

Thanks for your help in advance

Muscle car Joe
Econburn 150

Well first, storage will never give you "more btu's" than you had before storage. It may allow you to store heat that would have otherwise been wasted.

150,000 btu per day would be a very, very low heat load for a 3,000 square foot house and a garage. That is 6,250 btu/hr. I heat what would be considered an average insulated home, 3,200 sq. ft. and my average heat load is 20,000 btu/hr. My peak is somewhere near 50,000 btu/hr. You could heat your house with a few 100W lightbulbs if your load was really 150,000 btu per day!

11 cord per year is a whole heap of wood. Does your boiler idle a lot? Is it inside?

Yes I do idle a lot. I load the boiler 3 times a day and I have to re light every morning. I have to say it probably kicks on to burn about every 20 minutes and not because its calling for heat but to keep the fire going (factory setting). my house is fairly well insulated. 11 cord a year has been the norm for the last 4 years. if i burn oil i normally burn 1000 gallons a year. What i would like to cut down wood consumption to about 5 cords. so I thought maybe storage would help with 2 of my objectives, A) eliminate my oil furnace coming on at 5am and B) reducing wood consumption.

 

[flyingcow]

I don't think you'll save much wood. It will some, but 40%? seems like a sales pitch to sell you storage. I use storage more for convenience than anything. I was able to buy a boiler designed to have storage, which gives me higher rating on the boiler.

 

[goosegunner]

Something doesn't add up.

Lets use 5000 btus per lb of wood that is 30lbs a day for 150,000 btus.

November 1st to April 1st is roughly 180 days.

180 days X 30lbs day =5400lbs

Now lets say that Oak is 3800 lbs per cord that is 1.42 cords.


gg

 

[willworkforwood]

Yes I do idle a lot. I load the boiler 3 times a day and I have to re light every morning. I have to say it probably kicks on to burn about every 20 minutes and not because its calling for heat but to keep the fire going (factory setting). my house is fairly well insulated. 11 cord a year has been the norm for the last 4 years. if i burn oil i normally burn 1000 gallons a year. What i would like to cut down wood consumption to about 5 cords. so I thought maybe storage would help with 2 of my objectives, A) eliminate my oil furnace coming on at 5am and B) reducing wood consumption.

I'm having trouble figuring out the numbers that you posted Joe, and the description of the way your boiler runs. 11 cords of hardwood should work out to around 1650 gallons of oil, and you said you had used only 1000 in your prior life. So you need to figure out where all the heat is going, and the first guess on that would be up the stack. Do you know your flue temp range during a typical burn (via flue therm readings)? Next, do you have a BD installed, and do you know what your chimney draft is? How about the 2 door gaskets - are they completely airtight - nice deep symetrical groves around the entire perimeters? Any possibility that the damper door is hanging up, and not closing airtight? How about the heat tubes - have they been cleaned recently? If the heat isn't going up the stack, maybe it's boiling off extra water in the wood. If your wood supply hasn't been split and stacked for 2 years, have you checked it frequently with a MM? If it's dry (20% or less) then how about wood species - pine would be less than 150 gals/cord, and that might explain some of what's going on. Finally, your description of lots of lengthy idling doesn't match up with heavy wood usage. Lots of idling is normally a sign of a boiler that is way oversized for the load, and regularly doesn't have anything to do, but it certainly seems like your heat load is enough to keep a 150 busy (this year excepted). So something is definitely going on with your system, and if you post more information (especially flue temps), something may jump out.

 

[hobbyheater]

eliminate my oil furnace coming on at 5am

The oil boiler is it plumbed in series with the wood boiler ?

 

[musclecar joe]

Yes I do idle a lot. I load the boiler 3 times a day and I have to re light every morning. I have to say it probably kicks on to burn about every 20 minutes and not because its calling for heat but to keep the fire going (factory setting). my house is fairly well insulated. 11 cord a year has been the norm for the last 4 years. if i burn oil i normally burn 1000 gallons a year. What i would like to cut down wood consumption to about 5 cords. so I thought maybe storage would help with 2 of my objectives, A) eliminate my oil furnace coming on at 5am and B) reducing wood consumption.

I'm having trouble figuring out the numbers that you posted Joe, and the description of the way your boiler runs. 11 cords of hardwood should work out to around 1650 gallons of oil, and you said you had used only 1000 in your prior life. So you need to figure out where all the heat is going, and the first guess on that would be up the stack. Do you know your flue temp range during a typical burn (via flue therm readings)? Next, do you have a BD installed, and do you know what your chimney draft is? How about the 2 door gaskets - are they completely airtight - nice deep symetrical groves around the entire perimeters? Any possibility that the damper door is hanging up, and not closing airtight? How about the heat tubes - have they been cleaned recently? If the heat isn't going up the stack, maybe it's boiling off extra water in the wood. If your wood supply hasn't been split and stacked for 2 years, have you checked it frequently with a MM? If it's dry (20% or less) then how about wood species - pine would be less than 150 gals/cord, and that might explain some of what's going on. Finally, your description of lots of lengthy idling doesn't match up with heavy wood usage. Lots of idling is normally a sign of a boiler that is way oversized for the load, and regularly doesn't have anything to do, but it certainly seems like your heat load is enough to keep a 150 busy (this year excepted). So something is definitely going on with your system, and if you post more information (especially flue temps), something may jump out.

thanks for the response. A) yes i do use 1000 gallons in the 3000sqft home but i heat the 1200sqft garage with wood alone. so that is the difference between wood and oil use. B) yes I have a BD C) Stack temp : i do not know and will check and post. D) Heat tubes are cleaned regularly. E) wood is dry, between 18% and 21% F and all hard wood like oak cherry etc.) G)gaskets are perfect and air tight.

hopefully this gives more info to help me reduce this wood consumption.

joe

 

[musclecar joe]

eliminate my oil furnace coming on at 5am

The oil boiler is it plumbed in series with the wood boiler ?

yes it is.

 

[willworkforwood]

.... yes i do use 1000 gallons in the 3000sqft home but i heat the 1200sqft garage with wood alone. so that is the difference between wood and oil use. .....

Now that you've explained that you heat the garage with wood (but not previously with oil), it seems much more likely that there is actually no "wasted" heat loss (up the stack, etc). So now it's more a question of what the load from the garage is - did you do a heat loss calc on it? Since you know it took around 1000 gallons of oil to heat the house, the thing you would like to know is how much wood it takes to heat just the house alone (in a normal year). If that number was around 6.5 cord, you would know that the WB is running well. But that would mean shutting down the garage heat for an entire Winter, and you probably don't want to do that. Have you tried running some on/off experiments with the heat to the garage for a day or so (with similar Weather conditions)? It may be that your seemingly high wood usage is actually reasonable, if you in fact have a large garage (or underground line) heat loss.

 

[rkusek]

Joe do you have any bad underground pex that could be causing the high wood usage? Are you on a hill exposed to a lot of wind? What kind of insulation in the home and garage? 11 cord sounds like an awful lot of wood. If no UG Pex, it sounds like it could be the idling on the Econoburn. If it is then the storage may help recapture that wasted heat.

 

[musclecar joe]

.... yes i do use 1000 gallons in the 3000sqft home but i heat the 1200sqft garage with wood alone. so that is the difference between wood and oil use. .....

Now that you've explained that you heat the garage with wood (but not previously with oil), it seems much more likely that there is actually no "wasted" heat loss (up the stack, etc). So now it's more a question of what the load from the garage is - did you do a heat loss calc on it? Since you know it took around 1000 gallons of oil to heat the house, the thing you would like to know is how much wood it takes to heat just the house alone (in a normal year). If that number was around 6.5 cord, you would know that the WB is running well. But that would mean shutting down the garage heat for an entire Winter, and you probably don't want to do that. Have you tried running some on/off experiments with the heat to the garage for a day or so (with similar Weather conditions)? It may be that your seemingly high wood usage is actually reasonable, if you in fact have a large garage (or underground line) heat loss.

I keep the garage thermostat at 50* so rarely does the heat come on in there unless i am in there. I will run some experiments as you suggest but i expect no change in wood usage.

thanks! i will try it out

Musclecar joe

 

[musclecar joe]

Joe do you have any bad underground pex that could be causing the high wood usage? Are you on a hill exposed to a lot of wind? What kind of insulation in the home and garage? 11 cord sounds like an awful lot of wood. If no UG Pex, it sounds like it could be the idling on the Econoburn. If it is then the storage may help recapture that wasted heat.

yes i am on hill and wind is there but not really that bad. my underground pex is insulated with 5 inches of foam insulation so that is not an issue. house insulation is blow in certanteed brand fiber r-20 in walls. attic is deficiient with only r-19. I would like to address that lack of attic insulation but wife is being difficult about me cleaning out the attic of her holiday stuff. Garage is r-19 in walls and 24 inches of blow in in the attic.

thanks much,

muscle car joe

 

[rkusek]

UG pex not the issue unless water has somehow infiltrated which I can't see how. If that were the problem it would be easy to detect by measuring the temp at each end with no load. You could probably even use your hand to test the difference. R19 in ceiling some of it possibly.

 

[flyingcow]

2nd question:

If I add 1000 gallons of storage how much wood will I conserve or add to my annual burning. Will I save cord wood?

Original question---idon't see a large savings of wood with storage.


FWIW- I have an 1800 sq/ft, 2 story house, avg insulation, on top of a windy hill in northern Maine. Plus 3 teeagers. Now this isn't as warm as western Pa, but i go thru about 8 cords of wood. When i first started burning, i replaced 1000 gals of oil with 6.5 cord of wood. But after that first year, my wife(the keeper of the T-stat) keeps the house much warmer than before. So now we're burning very close to 8 cord.

Why i wrote this is that 11 cord on a 3000 sq/ft house, plus the garage really isn't that far off. A little more than i would think, but i don't know how cold western pa winters are and how high the T-stats in the house are set. Yes, you're attic needs more insulation, maybe your windows are aged and a little drafty. Are there outlets on the outside walls? Are those drafty? Many ceiling fixtures on the top floor? Those will let alot of heat out if not insulated good. just my 2 cents