Thermal Load calculator to determine HVAC sizing   [ manual J  calculations ]
This  calculator will determine the right size Heat & AC system for providing you the best comfort & efficiency 

Click here for Instructions
STEP 1 - Customer Information optional for your use
Name Phone
Address City
State Zip
Job

STEP 2:- Design Temperatures
  Inside Outside
Winter Deg F Deg F
Summer Deg F Deg F

STEP 3 - Construction Details
Gross Wall
SqFt
Ceiling
SqFt
Floor
SqFt
Infiltration Vol Cu Ft  Fireplaces 
Duct Gain/Loss
People (Assume two persons per bedroom)
Appliances
STEP 4 - Additional Items
BTUH Loss Heating Factor Description Cooling Factor BTUH Gain
1.
2.
         
STEP 5 HEATING: DOORS & WINDOWS (per 10 deg F)
For sliding glass doors - use factors for the same type window
Window & Door Types Frames Area BTUH
Loss
1) Single Pane Clear
2) Single Pane With Storm
3) Double Pane Clear
4) Double Pane With Storm
5) Triple Pane Clear
6) Jalousie Single
7) Jalousie Single w/storm
8) Skylights Single
9) Skylights Double
10) Door Wood Only
11) Door Wood w/Storm
12) Door Urethane Core (R-5)
13) Door Urethane Core (R-5)w/Storm
TOTALS
STEP 6 COOLING: DOORS & WINDOWS (per 10 deg F)
Table assumes windows have inside shading by draperies or
Venetian blinds and sliding glass doors are treated as windows
Direction Panes Temp
Diff		 Area BTUH
Gain
1) N
2) NE & NW
3) E & W
4) SE & SW
5) S
6) Skylights
7) Wood Door
8) Metal Door
TOTALS


STEP 7:

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