Weighing wood loads for gasification boiler

[mark cline]

I have a 4000lb platform scale that I would like to weigh my wood going into the boiler to calculate the BTU’s needed to raise the boiler storage water temperature up to 190F. Anybody doing this ? I believe I saw a formula somewhere that can calculate the weight of wood to the amount of btu’s needed to raise the boiler storage temperature to a set value. I realize that my numbers would have to be adjusted to my boiler efficiency, wood species and quality, moisture content etc.
This may sound crazy to some but after having one knee replacement surgery and another one in 2 months , I’m getting bored out of my gourd. I hate to sit and watch tv so help a fellow wood burner out to keep my sanity in check . Dish network and internet in the boiler house ? Thanks Airlina , giving it some thought. 👍

 

[hobbyheater]

I have a 4000lb platform scale that I would like to weigh my wood going into the boiler to calculate the BTU’s needed to raise the boiler storage water temperature up to 190F. Anybody doing this ? I believe I saw a formula somewhere that can calculate the weight of wood to the amount of btu’s needed to raise the boiler storage temperature to a set value. I realize that my numbers would have to be adjusted to my boiler efficiency, wood species and quality, moisture content etc.
This may sound crazy to some but after having one knee replacement surgery and another one in 2 months , I’m getting bored out of my gourd. I hate to sit and watch tv so help a fellow wood burner out to keep my sanity in check . Dish network and internet in the boiler house ? Thanks Airlina , giving it some thought. 👍

I've done it to determine boiler efficiency!

 

[Tonty]

I weigh all my wood going into my boiler. It doesn’t matter the species, you get the same amount of BTU’s per pound, the lighter wood just takes more volume, at least the way I understand it. I have 600 gallons of storage, and it takes one pound of wood to raise it one degree.

Edit: That one pound per degree would be when there isn’t any heat being used.

 

[mark cline]

Here are some numbers that I have come up with , feel free to comment.
1) 8.33 btu to raise 1 gal water 1 degree F
2) 8600 btu/ lb of wood x 20% MC
= 3600 btu / lb of wood
3) 1700 gallons in my system
4)60 degree temperature rise
5)1700x 8.33= 14161 btu/ gal up 1 degree
6) 14161x60 degree rise =849660 to raise 1700 gal up 60 degrees
7)849660 / 3600 btu / lb wood at 20% MC=
236.016 lbs.
This sounds about what I have been loading per day . How do I calculate the efficiency of my boiler ? Thanks Mark

 

[Bad LP]

Sounds like watching grass grow.

 

[mark cline]

Sounds like watching grass grow.

Or playing golf

 

[Tonty]

I’m not sure if the 3600 btu is correct. This page puts it at 6500-7500 btu for 20%.

(broken link removed to https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1628.pdf)

But I’m not saying for sure…the 3600 doesn’t work out with how my boiler performs. According to that, I’m getting over 100% efficiency. 🤔I’m not a mathematician though, so my figures could be off. I do know from experience how much I put in my boiler and what it does.

 

[eauzonedan]

Sounds like watching grass grow.

My Garn 1500 uses 2.4# to raise the 1500 gallons one degree. I use 3 sensors inside the tank at 1/4 points - and double weight the center reading as that reflects twice the volume of water. Due to stratification of the heat in the tank - you can get numbers 30 degrees apart and you’re after the average temp of your storage! Stratification is your friend in discharge but your enemy on recharge. It can be controlled with the circ or filter pumps to your advantage.

Great way to hit your recharge temp point and not overshoot it. Dan

 

[sloeffle]

I’m not sure if the 3600 btu is correct. This page puts it at 6500-7500 btu for 20%.

I thought the same thing.

8500 * .20% for moisture = loss of 1700 btu
8500 - 1700 btu due to water = 6,800 useable btu's

 

[eauzonedan]

I can give you my math but if you just record the storage temp and wood weights a few times you’ll get the number for your current system and wood. Think mine hit around 75% efficient if you compared it to theoretical..,

 

[mark cline]

I had questioned the 3600 btu my self and found a different source that put the number up 8450 .
I just started and then loaded my Econoburn 300 with 200lbs of mostly white ash with a 17% MC. But the full boiler weight of 200 lbs is very close in line with my burning up to this point to achieve the 190 storage temperature.

 

[JRHAWK9]

FWIW, I use 6,500 BTU's/lb......

Screen capture from the PDF I attached below.

 

[mark cline]

This was one of my sources to come up with the 6480 btu number. I ll see how this run comes out and I’ll adjust from there. 🇺🇸

 

[mark cline]

This burn that I finished this evening brought my storage up to 190, like I calculated. Using 6000 btu per lb , calculations came out perfect but my stack temperatures hit 700 then settled back to about 550 for the majority of time. I can cut back on my primary air a little and see what happens. Thanks all for the feedback

 

[eauzonedan]

You can really drive yourself nuts if you try to apply a corrector for wood moisture content , outdoor combustion air temp as well any draw down during the burn…… my wife and I used to bet beers on how close I could hit the number. ….. yea I know….. cabin fever in mid winter…