1.2 KiB
1.2 KiB
id, aliases, tags
| id | aliases | tags |
|---|---|---|
HVAC Calculations
Units
British Thermal Unit
Unit of heat energy
There are several definitions of the Btu, HVAC uses the IT definition, abbreviated BtuIT
\begin{align*}
1 \text{Btu}_\text{IT} &= \left( 4.1868 \times 453.59237 \times{\frac{5}{9}} \right) \text{J} \\
&\approx 1055.056 \text{J}
\end{align*}
More common than Btu itself is thousand British thermal units per hour (MBH), a unit of power.
\begin{align*}
1 \text{MBH} &= 1000 \text{Btu/hr} \\
&\approx 3.412 \text{W}
\end{align*}
Ton of Refrigeration (TR or TOR)
Unit of power
[!info] Also Known As
- refrigeration ton (RT)
- ton (refrigeration)
\begin{align*}
1 \text{TR} &= 12000 \text{Btu}_\text{IT}/\text{h} \\
&\approx 3516.853 \text{W}
\end{align*}
Cubic Feet per Minute (CFM)
Unit of volumetric flow
Measures
Airflow
- CFM
External static pressure (ESP) measured in inches of water
Heating/Cooling Capacity
- Tons (refrigeration)
- MBH
Entering air temperature (EAT) Leaving air temperature (LAT) Mixed air temperature (MAT)
Latent heat Sensible heat
Sensible -> dry bulb Latent -> wet bulb
???
OSA EAT (F) EXH EAT (F)
IN S.L. OUT ALT.
Efficiency
- η (eta)