## Heat Recovery calculator

### Sensible Heat Recovery

air flow (cfm)
t1 (oF)
t2 (oF)
recovery efficiency

t2 - outside air temperature after the heat exchanger
t1 - outside air temperature before the heat exchanger

### Total Heat Recovery

air flow (cfm)
h2 (Btu/lb.ºF)
h1 (Btu/lb.ºF)
recovery unit efficiency

h1 - enthalpy outside air after the heat recovery unit (Btu/lb.ºF)
h2 - enthalpy outside air before the heat recovery unit (Btu/lb.ºF)

### Sensible Heat-Recovery Systems formula

H = 1.08 q (t2 - t1) η

where

η = heat-recover efficiency

q = quantity of airflow (cfm)

H = heat transferred (Btu/h)

1.08 = a constant for sensible heat equations

t2 = air temperature of outside air after the heat recovery unit (oF)

t1 = air temperature of the exhaust air before the heat recovery unit (oF)

### Total Enthalpy Heat Recovery System formula

H = 4.5 q (h2 - h1) η

where

h2 = air enthalpy of outside air after the heat recovery unit (Btu/lbºF)

h1 = air enthalpy of the exhaust air before the heat recovery unit (Btu/lbºF)

4.5 = a constant for total heat equations

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