1. Math in HVAC Presented by Mike Veeder HVAC instructor Columbia Greene Questar

2. Whole House Heat Loss question #1  Determine design temp difference  Find total square foot of windows and doors  Find gross walls  Subtract windows and doors from gross walls to find net walls  Determine exposed ceiling area  Find floor area

3.  Multiply each by U factor  Add all btu’s/degree Fahrenheit  Multiply by temp difference  Multiply by 15% for duct losses  Arrive at heating btu loss for house

4. Calculate annual heat loss Question #2  BTU annual = BTUH x HDD x 24hr/day x.75

5. BTU annual = 875 x 6860 x 24 x.75 BTU annual = 875 x 6860 x 24 x.75 Annual heat loss is 108,045,000 btus Annual heat loss is 108,045,000 btus

6. Propane Determine how many gallons of propane burned per year Determine how many gallons of propane burned per year Gal/yr = annual btu / 92,000btu / gal Gal/yr = annual btu / 92,000btu / gal Gal/yr = 108,045,000/92,000 Gal/yr = 108,045,000/92,000 Gal/yr = 1174 gal Gal/yr = 1174 gal Cost/yr = 1174 gal x $2.60/gal Cost/yr = 1174 gal x $2.60/gal Cost/yr = $3052.40 x stack loss of furnace Cost/yr = $3052.40 x stack loss of furnace Cost/yr = $3662.88 Cost/yr = $3662.88

7. Electricity Determine the amount of electricity used on a annual basis Determine the amount of electricity used on a annual basis Watt/yr = btu annual / 3.41 btu/watt Watt/yr = btu annual / 3.41 btu/watt Watt/yr = 108,045,000/3.41 Watt/yr = 108,045,000/3.41 Watt/yr = 31,684,750 / 1000 Watt/yr = 31,684,750 / 1000 KW/yr =31,684 x.14/kw KW/yr =31,684 x.14/kw Yearly cost of electric is $4435.87 Yearly cost of electric is $4435.87

8. Calculate BTU output of a Heat Pump Question 5 BTU=1.08 x cfm x delta “T” BTU=1.08 x cfm x delta “T” CFM= FPM x.66 x sq. ft of duct area CFM= FPM x.66 x sq. ft of duct area

9. Determine cfm of a Geothermal Heat pump Question #4 CFM = fpm x.66 x sq. ft CFM = fpm x.66 x sq. ft CFM = 606 fpm x.66 x 2 CFM = 606 fpm x.66 x 2 CFM = 800 cfm CFM = 800 cfm Btu = 1.08 x cfm x delta “t” Btu = 1.08 x cfm x delta “t” Btu = 1.08x 800 x (92 – 65) Btu = 1.08x 800 x (92 – 65) Btu = 23,328 btu Btu = 23,328 btu

10. Geothermal loop performance Question #6 Loop filled with 20% Methanol Btu = 485 x gpm x Delta “t” Btu = 485 x 6 x (40 – 32) Btu = 23,280 btu

11. BPI Building Airflow Standard (BAS) Living Space Area = 1500 sq. ft. Basement area = 700 sq. ft. Ceiling height = 8 ft. # of Occupants = 4 # of stories above grade = 2 Location = Albany, NY

12. Calculate ventilation required for building Airflow(b) =.35 x volume/60 Volume = 8 x (1500 + 700) = 17,600 cu. ft. Airflow(b) =.35 x 17,600 / 60 Airflow(b) = 102 cfm

13. Calculate ventilation required for people Airflow(p) = 15 x # of occupants Airflow(p) = 15 x 4 = 60 cfm

14. Using the higher airflow requirement Convert cfm to cfm50 Minimum cfm50 = airflow x N N = LBL conversion factor Minimium cfm50 = 102 cfm x 15.4 = 1570 cfm50

15. When we read the cfm50 from the blower door, 1570 is what is recommended for infiltration for this house

16. Determine course of action for home  Cfm50 x.7 = minimum ventilation  1570 cfm50 x.7 = 1099 cfm50

17.  If the blower door reads: –Above 1570 cfm then the house is too loose and you would recommend air sealing

18.  If the blower door reads: –Between 1570 cfm50 and 1099 cfm50, then the house is within the normal range for infiltration and ventilation

19.  If the blower door reads: –Below 1099 cfm50 then you need to mechanically ventilate the house using a hrv or equivalent device. The house is too tight at this point.

20. My class after a math lesson

21. Thanks for your attention !!  Any questions??????????