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[zimmer988]

I am building a Gasification OWB and would like to set it up to display and datalog the realtime BTU output of the boiler.  I think it would be cool to see what kind of a demand that I have on the boiler as well as how many BTU's that it can output. I plan on using an old anhydrous tank for heat storage, so it would be cool to get some numbers on how well that performs as well.  I program PLC's and and design control systems for a living, so I'm kind of a tech junkie, but I do not know a lot about HVAC.  What would I need to calculate this?  I'm assuming that a flow meter of the water exiting or returning the boiler along with a delta T reading of the supply and returns would be able to get these calculations but I'm not sure.  I know that 1 BTU is the energy required to heat 1 pound of water 1 degree but that's about it.  I do have a web sever set up with my current home heating system which is using a add on wood furnace and a propane forced air furnace. 

If anyone wants to check it out, the site is:
http://38.121.112.79:8080/
Username: guest
Password: guest

I will be setting up my OWB the same way when I complete it so that I will be able to check water temps, flue temps, ect.  I will keep everyone posted.
Thanks.

[willieG]

real time btu  usage..you need to be a real number cruncher unless being very close is good enough. we know 1 btu raises 1 pound of water 1 degree but water changes weight  per gallon with temps as density changes (not much but some) numbers we would most likely  use would be water at 160 degrees weighs 8.1537 pounds per American gallon and at 180 degrees would weigh 8.0969 per American gallon so most often the weight used is 8 pounds per American gallon

so if you know the gpm flow and the temps on each side of your exchanger  you could in fact calculate the btu per min being used when the blower was running

gpm x 8 =pounds per min  at X temp of hot side of exchanger - temp on cold side of exchanger = difference  x weight = btu per minute

example ....lets say we are moving 6 gpm = 48 pound of water per min  and we lose 10 degrees from  hot side to cold side = 480 btu per min when blower is running
at least if my math is good

[zimmer988]

Thanks for the info.  The beauty of the PLC is that it can program the equations inside it to dynamically compensate for the weight of the water in the equation depending on the temperature of the water.  So for example, in order to calculate how many BTU's that it takes to bring my boiler up to temp, I need to multiply the total volume of the boiler lets say 250 gallons x 8 and the temperature change say 70 deg to 170 deg (100 deg).

250 gallons x 8= 2000 pounds of water
2000 Lbs of water x 100 degree difference = 200,000 BTU

Is this correct aside from the water density variation?

While I have your attention, how do I calculate BTU's in a forced air system such as my add on wood furnace?
Thanks

[oldchenowth]

HUH?

Just use my calculation  H=75 known as Tina's constant

The wife likes the house at 75, there for I throw wood in the OWB, heat the water and the house is 75.  That is all I need to know to keep the B factor low.

H=75= Happiness
B= Bitchy

Finally, math I can do.

[snakedriver]

Oldchenowth,

Thank you for providing some much-needed levity. I love it!

Jerry

[martyinmi]

HUH?

Just use my calculation  H=75 known as Tina's constant

The wife likes the house at 75, there for I throw wood in the OWB, heat the water and the house is 75.  That is all I need to know to keep the B factor low.

H=75= Happiness
B= Bitchy

Finally, math I can do.

How did I miss this! You are a hoot Rich! That there is some easy, accurate math!

[willieG]

man that was a lot easier than my calculation

[Scott7m]

man that was a lot easier than my calculation

and far more beneficial lol

j/k willie!  that was some good stuff!