INSTRUCTIONS For Locating, Downloading and Running THE WOOD HEAT CONVERSION CALCULATOR. --------------------------------------------------------------------- 1. Print out or download Answer # 3 of this conference. It contains a list of Stove efficiency figures and fuel BTU contents. It is an easy to use reference list for entering the proper figures as you run the Wood Heat Conversion program. 2. Return to the Source command prompt by typing: Quit at the Action-> prompt. 3. Prepare to download the program listing as a BASIC file into your computers memory. 4. To retrieve the program listing from the Sharefiles area: At the command prompt enter: TYPSHR At the next prompt enter: BBZ465 And then enter the filename: WOODHEAT The program listing will then be displayed as you are downloading it. 5. Although this program is written in BASIC and will run on virtually any kind of micro computer, you may have to make a few modifications. In LINE 320 the command: HOME is used to clear the screen. Depending on your brand of computer, you may have to replace that command with: CLS 6. You are now ready to run the program using the lists of efficiency and BTU figures as a reference. Answer 2 (of 4) NEW SHELTER, on WED, OCT 24 1984 at 17:21 (4562 characters) Running the Program Here are a few tips on how to get the most from the program: 1) The program begins by asking several questions about the heating fuel you presently use. If you use more than one heating fuel, choose the one you would like to replace with firewood. For example, let's say you now use oil for your primary heating fuel and electricity for back-up heat. You want to install a woodstove to replace electricity as your back up. OK, for you, the first questions in the program apply to electricity. 2) The program will ask how many fuel units you used for heat last year. A "fuel unit" is a gallon, therm, cord, etc.--whatever unit of measure applies to the heating fuel you use. To continue with the example we used above, the unit for electricity is a kilowatt hour. If you used 3000 kilowatt hours for heat last year, type "3000." Note: Sometimes it's hard to know how much fuel you used for heat and how much you used for other purposes. Electricity is a case in point. Besides heat, you presumably also used electricity for light, appliances, your computer, etc. To decide how many kilowatt hours probably went for heat, check your electric bills from months when you neither heated the home nor used electric air conditioning. The average electrical consumption from these months is the amount of electricity you normally use for lights, appliances, and so forth. Subtract this amount from the total electrical usage during each month when you used electric heat. The result will be a good estimate of the amount of electricity you used for heat. For example, if you used an average of 1,000 kilowatt hours during months when you neither heated nor air conditioned, and if you used 5,000 kilowatt hours during January, then it's safe to say you used about 4,000 kilowatt hours for heat. 3) When answering the questions, type numbers only. Don't type "4000 kilowatt hours," for example--just type "4000." Or when telling how much money you spent for 3000 kilowatt hours, don't type" $320," just type 320. 4) The chart in Answer #3 of this conference tells how many BTUs (British Thermal Units) are present in a fuel unit. For example, one kilowatt hour contains 3,413 BTUs. 5) To learn the efficiency rating of your heating system, consult the chart also in Answer #3 of this conference. Use the same chart to learn the efficiency rating of the woodburning device you want to install. 6) The program lets you specify how much heat you want to get from your woodburning device. It asks, "Percentage of your present heater's heat output to be delivered by the woodburning device?" If you want the woodburner to replace your electric heaters completely, type "100" (for 100 percent). If you want the woodburner to contribute half of the heat that you now get from electricity, type "50." The program will accept any percentage from 1 to 100. 7) The program gives two sets of results. First, it tells you how many cords of wood you'll have to burn, how much money this will cost, and how much you will save each year by burning this amount of wood. Next, the program tells you how long the woodburning device will take to pay for itself. (Note: If the computer gives you a minus number for annual savings, this means wood will cost you more than your present fuel. Thus, a result of -100 means that wood will cost $100 more each year than your present heating fuel.) 8) The program is highly flexible. After giving you the results of its calculations, it lets you test alternatives. For example, if you're unsure whether you gave an accurate estimate of the amount of electricity you used for heat, the program lets you revise your estimate. The program also lets you revise the type of woodburner you want to buy, the amount of heat you want to get from wood, and the type of wood you will burn. In each case, the program instantly recalculates its results and presents them to you. 9) The program will work on most computers exactly as shown here. In some rare cases, however, you may need to modify the program slightly to suit your computer. For example, we have included several commands on most lines of the program. Thus, line 130 consists of three commands, separated by colons. If your computer will only accept one command per line, you should break line 130 into three lines: 130 BC = 19000000 131 W$ = "HARDWOOD" 132 GOTO 160 nOfDATAPAC: parity error Answer 3 (of 4) NEW SHELTER, on WED, OCT 24 1984 at 17:30 (1784 characters) System Efficiencies ----------------------------------------- Fuel Oil or Kerosene New high-efficiency furnace .85 Recently tuned furnace with stack damper .7 Recently tuned furnace with no stack damper .6 Ordinary, untuned furnace .5 Natural Gas, LPG, or Propane New high-efficiency furnace .9 Above-average furnace with pilotless ignition .8 Recently tuned furnace .7 Ordinary, untuned furnace .6 Coal New high-efficiency furnace .7 Recently tuned furnace with stack damper .6 Recently tuned furnace with no stack damper .55 Ordinary, untuned furnace .5 Electricity Resistance heat .95 Heat pump used in warm climate 2.0 Heat pump used in cold climate 1.5 Wood Wood furnace or topflight woodstove .75 Ordinary woodstove .5 Fireplace or inferior woodstove .25 BTU Contents ---------------------- Fuel Unit BTUs Oil Gallon 138,700 Kerosene Gallon 135,000 Natural Gas Therm 100,000 Cubic Foot 1,025 Hundred Cubic Feet 102,500 Propane or LPG Therm 100,000 Cubic Foot 2,500 Hundred Cubic Feet 250,000 Gallon 91,000 Pound 21,500 Coal Ton 27,000,000 Hardwood Cord 19,000,000 Softwood Cord 15,000,000 Electricity Kilowatt Hour 3,413 Answer 4 (of 4) NEW SHELTER, on WED, OCT 24 1984 at 17:37 (10986 characters) New Shelter's WOOD HEAT CONVERSION CALCULATOR Program Documentation -------------------------------------------------------------- LINE 20 The first command dimensions the string variables K$ and W$. The next commands clear the screen (GOSUB 320), print the name of the program, and print a blank line. LINE 30 prints the sentence "THE FOLLOWING QUESTIONS APPLY TO THE FUEL YOU WANT TO REPLACE WITH WOOD." Then the second command prints a blank line. LINE 40 gets two inputs: FU (the number of fuel units used for heat last year) and BU (the number of BTUs in one fuel unit). LINE 50 gets one input: FC (the amount of money spent on the heating fuel). Then the line clears the screen. LINE 60 The first three commands get an input: SE (the system efficiency of the present heating system). The fourth command calculates BT (the total number of BTUs supplied by the heating system). The final two commands go to subroutines. LINE 70 After clearing the screen, this line prints the question "PERCENTAGE OF YOUR PRESENT HEATER'S HEAT OUTPUT TO BE DELIVERED BY THE WOODBURNING DEVICE=" LINE 80 The first command gets an input: PH (the percentage of the present heater's heat output to be supplied by wood heat). The second command divides PH by 100 so that BT (the total number of BTUs) and FC (the amount of money spent on the present heating fuel) can be multiplied by PH in lines 330 and 280. The third command tells the computer to repeat line 80 if PH is less than or equal to 0 or if it is greater than 1. LINE 90 goes to the subroutine at line 330. LINE 100 After clearing the screen, this line asks "WHAT KIND OF WOOD WILL YOU BURN IN THE NEW WOODBURNING DEVICE?" LINE 110 prints the three types of wood the user can choose from in answering the question printed by line 100. LINE 120 The first command gets an input: W (the type of wood to be burned). The second command sends the computer to the appropriate line, based on the type of wood chosen. LINES 130-150 The first command in each line assigns a value to BC (the number of BTUs in one cord of the type of wood chosen); the second command assigns a value to W$ (the name of the type of wood chosen). The final command in both line 130 and 140 tells the computer to proceed to line 160 (line 150 does not need this command, since the computer will automatically go to line 160 after executing line 150). LINE 160 After going to the subroutines at lines 390 and 320, line 160 gets an input: CC (the cost of one cord of the type of wood to be used in the woodburner). LINE 170 calculates CO (the number of cords that will be needed to supply the desired amount of heat) and WC (the cost of this many cords). Then the line goes to the subroutine at line 340. LINES 180-190 present the first batch of results: CO (the number of cords needed), WC (the cost of this many cords), and AS (the annual savings achieved by burning wood). LINE 200 After going to the subroutines at lines 300 and 390, this line sends the computer to either line 210 or 220. If the annual savings reported by line 190 are less than or equal to zero (i.e., if burning wood will not result in financial savings), the computer is sent to line 220. Otherwise, it goes to line 210. LINE 210 tells how many years the woodburning device will take to pay for itself (PB). In presenting PB, it uses the formula INT (PB * 10) / 10 so that only one decimal position will be printed. To print all decimal positions, replace the formula with PB. Thus, the second command in line 210 would become PRINT "IN "; PB; "YEARS" Line 210 then goes to two subroutines, and it finishes by sending the computer to line 230. LINE 220 If the woodburning device will never pay for itself (because the annual savings from burning wood are less than or equal to zero), this line delivers the bad news. LINES 230-240 print the continuation options. LINE 250 prints a blank line, then it gets an input: OP (the continuation option chosen). The third command sends the computer to the appropriate line, based on the option chosen. LINE 260 If, at line 250, the user selects options 2 or 4, the computer goes to line 260, which prints a blank line and then gets an input: X (the new value for the amount of heat desired or for the amount of money paid for heat). The fourth command clears the screen, then the fifth command sends the computer to either line 270 or 280, depending on the option chosen in line 250. LINE 270 calculates new values of BT (the total number of BTUs used) and FC (the amount of money spent) so that they correspond to the new PH (the percentage of the present heater's heat output to be supplied by wood heat). The line begins by returning BT and FC to their original values. It does this by dividing BT and FC by the old PH. (Line 90 sent the computer to the subroutine at line 330, where BT and FC were multiplied by PH. Thus, to reverse the effects of line 330, line 270 divides BT and FC by PH). The third command in line 270 then creates a new value for PH (PH = X / 100). Next, the fourth command in the line goes to the subroutine at line 330 where BT and FC are multiplied by the new PH. Thus, line 270 has cancelled the effect of the old PH and it has modified BT and FC so that they correspond to the new PH. Finally, the fifth command in line 270 sends the computer to line 170. LINE 280 calculates a new value for FC (the amount of money spent) before sending the computer to line 170. It does this by multiplying FC by PH (the percentage of the present heater's heat output to be supplied by wood heat). For example, at line 260 you may have told the computer that you spent $500 for heat last year. But previously you had set the value of PH at .5 (i.e., you had said that you want the woodburner to give 50% as much heat as you got last year from your present heating fuel). Thus, line 280 multiplies 500 by .5 to get 250, the new value of FC. LINE 290 If, at line 250, the user selects option 1, the computer goes to line 290. After clearing the screen, line 290 resets BC (the number of BTUs received from a cord) to its original value. It does this by dividing BC by WE (the system efficiency of the woodburner), thereby reversing the effect of the subroutine at line 380 (the computer has previously gone to the subroutine at line 380, thanks to a command in line 160). Line 290 then goes to the subroutine at line 370 to get new values of WE and CW (the cost of the new woodburner). Next, line 370 goes to the subroutine at line 380 to establish a new value of BC that corresponds to the new value of WE. For example, if the new value of WE is .75, then 75 percent of the BTUs in a cord of wood will be released as usable heat. Thus, if you will be burning hardwoods (which have 19 million BTUs per cord), you will receive 14.25 million BTUs from each cord. Finally, line 290 sends the computer to line 170. LINE 300 is a subroutine that prints a blank line followed by "PRESS THE RETURN OR ENTER KEY." The line then gets an input: K$ (a keystoke; the computer will not proceed to the next stage of the program until the user presses the Return or Enter key). LINE 320 is a subroutine that clears the screen. If your computer uses a screen-clearing command other than HOME, substitute it for HOME. If your computer uses CLS, for example, then line 320 should be 320 CLS: RETURN LINE 330 is a subroutine that adjusts the value of BT (the total number of BTUs used for heat) and FC (the amount of money spent) so that they correspond to the value of PH (the percentage of the present heater's heat output that you want the woodburning device to deliver). For example, if you received 1,000 BTUs from your present heater at a cost of $100, and you want the woodburner to deliver 40 percent of the heat your got from your present heater, line 330 will reduce BT to 400 and FC to 40. That is, you want the woodburner to deliver 400 BTUs, and the cost of getting this many BTUs from your present heater is $40. LINES 340-360 are a subroutine that calculate annual savings and payback. ----------------------- LINE 340 calculates AS (the annual savings you will achieve by burning wood). If the annual savings are zero, the second command sends the computer to line 360 (the reason for this command is to avoid a division by zero error in line 350). LINE 350 calculates PB (the number of years the woodburner will take to pay for itself). LINE 360 If AS is zero (line 340), line 360 sets PB (payback) equal to zero. ----------------------- LINE 370 is a subroutine that gets two inputs: WE (the system efficiency of the woodburning device you want to install) and CW (the cost of buying and installing this woodburner). LINE 380 is a subroutine that adjusts BC (the number of BTUs received from a cord of wood) to correspond to WE (the system efficiency of the woodburning device). For example, if a cord of wood contains 19 million BTUs, and a woodburner has an efficiency of .5, then the woodburner will deliver half of those BTUs: 9.5 million. LINE 390 is a subroutine that prints "A WOODBURNING DEVICE WITH A SYSTEM EFFICIENCY OF " followed by WE (the woodburner's system efficiency). LINE 400 is a subroutine used by both line 210 and 220. For example, when used in conjunction with line 220, line 400 might leave this message on the screen: IF YOUR PRESENT FUEL COSTS $500 A YEAR AND YOU SWITCH TO HARDWOOD COSTING $110 PER CORD. LINE 410 If, at line 250, the user selects option 5, the computer goes to this line which clears the screen, prints "(END)," and then ends the run. LIST OF VARIABLES --------------------------------------------------------- AS annual savings from burning wood BC BTUs in, or received from, a cord of wood BT total number of BTUs used for heat BU BTUs in one fuel unit CM cost of a cord of wood CO number of cords needed FU number of fuel units used for heat K$ a keystroke NV new value for variable that is to be changed MW cost of new woodburner OP option chosen PE percent of home's total heat to be supplied by wood PK payback period for new woodburner SE system efficiency of present heating system TM fuel cost (total amount of money spent for heating fuel) WE system efficiency of woodburner you will install WM cost of the amount of wood you will need to buy WO type of wood to be burned W$ name of type of wood to be burned