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Annual Heating Cost
Art M.
Member Posts: 20
If I know what my heat loss BTU's are, can I roughly calculate my total consumption of fuel, be it gas, oil or electricity?
If so, what is the formula.
Thanks
If so, what is the formula.
Thanks
0
Comments

You'll also need...
The number of degree days to figure this out. Try NOAA or The National Weather Service to find this for your area.
I know there is a formula, but can't bring it to memory....It's Friday. Good luck. Chris0 
DD Formula
Heat Loss (BTUH) x Degree Days x 24 (Hours)
______________________________________ xCd factor**
DeltaT* x Efficiency of Plant x Fuel Units
Where:
* DeltaT referred to is the design DeltaT used to calculate the heat loss,
** The Cd factor is a variable which accounts for solar and internal gains and is based on degreedays in your area. Typically for the 55006500 degreeday areas this is about 0.60 to 0.63
Degree days can be the normal 30year average for budgeting or over a given year for specific targeting.
Here is an example:
House with 75,000 BTU heat loss, 6,000 degreedays, 70 degree design DeltaT and 85% (0.85) plant efficiency using gas at 100,000 BTU's per therm:
75,000 x 6,000 x 24
_________________ = 1,815.13 therms (gross)
70 x 0.85 x 100,000
x Cd of 0.60 = 1,089 therms net for the year.
If you are using oil, use 138,000 BTU's per gallon.
If you are using electricity, use 3,413 BTU's per kWH.
Efficiencies vary of course.
Naturally you multiply the fuel units used by the cost which also varies.
Hope this helps.
Brad0 
fuel cost
It depends. It depends on where you live, how your home was built, how many kids you have [they "never" leave the door open] If your wife works, if she is home in the day time if she turns the tstat up. Or if your kids crank it up when they get home from school.
It depends on how you make your hot water, how comfortable you keep your home. How much solar gain. How the system was installed. Insulation ? many factors.0 
If a condensing/modulating boiler is in this comparison, you'll have a problem making comparisons with any other form of boiler. AFUE will NOT be a reasonably accurate efficiency predictor for a condensing/modulating boiler provided that it's properly installed/controlled in a wellsuited system.
If your needed supply temperature maxes around 140F AND you have proportionality either via mass (think highly conductive radiant floors/walls/ceilings) or control (TRVs/FHVs/Pneumatic) use 140%150% efficiency based on a ManualJ calculationseriously...
0
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