methodology question concerning gas consumption

gerry gill

If I want to check to see if a boiler is operating more efficiently after adjustments, would the following formula work? is the math methodology okay? If I take the cubic foot of gas used during the given time frame and divide it by the total heating degree days for that time, the answer would be the cubic foot used per single heating degree day..I think..is that right..we have a steam boiler we do experiments with (steam partners house) and we are constantly trying to tweak it for better effiency..were planning on putting a gas meter just on the boiler itself for better readings, but need a workable formula due to varying weather conditions....your thoughts please..

Weezbo

Gerry Gill, take a look at NewZelands Load Calc program

for new construction...maybe it is another take on careful observation and applied math.

gerry gill

not sure what that is

is it a heat loss program?

Weezbo

check on Google under ALF Heat loss...........

this is something that opens the eyes to perhaps a few more considerations...

Gordy

Degree Days

I'm just a homeowner Gerry,But that is what I used Degree days. You can break it down as far as Btus a sq. ft. This will work if you have the gas consumption narrowed down to just the heating plant. The only variables will be wind,infiltration,solar gain.

Its so hard to weed out all the variables. How many times you enter exit dwelling,wind speed,wind direction,solar gain,lack of solar gain,light usage,cooking heat.

Gordy

gerry gill

pretty interesting stuff

thanks weezbo.

gerry gill

yup, there are alot of variables Gordy

thanks..thats why i want to meter just the boiler we experment on..least if nothing else we get the other gas loads out of the equation.

jerry scharf_2

another variable

There is the standard assumption that a cubic foot of gas has 1000 BTUs of energy (caloric value.) The trouble is that when measured, it doesn't necessarily come out that way.

For people who buy and sell gas, it is standard to have an automatic gas calorimeter that samples the caloric value. Then they pay for BTUs delivered not cubic feet.

Of course, they never tell you what the caloric value they deliver is. The folks at HTP siad they used to do free caloric value tests for people with problems, and the local gas companies were none too happy about that. They reported results anywhere between 700 and 1600 BTUs per cubic foot! It made me appreciate the difficulties of building a high efficiency gas boiler much more.

Maybe a bunch of people could pool the costs, get one of these automatic samplers and automatically post the results to a web site. Wouldn't that get the gas company excited!

Ive been thinking about this because I want to compute input gas energy to my new boiler and it doesn't do much good counting the cubic feet if I don't have a clue as to the BTU content.

jerry

Gordy

Jerry

Good point! Another variable, that One can't control. That makes a big difference.

Starting to wonder why I bother keeping track, I went through the last two years of gas consumption, NICOR keeps a running tab on your consumption for two years on their web site.

My average was 5.11 Btus per HDD per square foot.

1880.00 total, for heating over the last 24 months, thats a before tax and fees figure at .6159 per therm avg. Taxes and fees brings the therm cost up to .7854 for a 2358.91 total for the period. I figured it costs me .1680 with fees per HDD to heat the house. Highest gas bill in the period was 251.00 for that 24 month. I don't think thats to bad for a 83% boiler and 3950 sqft.(including basement) of conditioned space at 72*.

As close as I can get Gordy