CM 3200 MECHANICAL & ELECTRICAL SYSTEMS EXAM 1 QUESTIONS AND ANSWERS | EXAM
PREP 2026/2027
To calculate the latent heat gain due to ventilation for a room design to be 75* F and the
outdoor temperature is 87* F, which of the following equations would you use? - ANS
✔✔Q=(4840) x (CFM) x (W final -W initial)
Which type of heat transfer occurs when thermal energy flows through a solid material? - ANS
✔✔Conduction
This occurs when latent heat is increased in a space. - ANS ✔✔Humidifying
Latent heat is energy that results in a measurable change in temperature - ANS ✔✔False
In thermodynamics, thermal energy flows from cold to hot. - ANS ✔✔False
Wet bulb temperature readings indicate what? - ANS ✔✔Moisture in the air
What does specific volume mean? - ANS ✔✔Volume of one pound of dry air
Ventilation loads an be calculated using CFM per person or room changes per hour (RCH) - ANS
✔✔True
The crack method is more accurate than the air change method for calculating loads. - ANS
✔✔True
In thermodynamics, thermal energy flows from hot to cold - ANS ✔✔True
, A heating system load totals 300,000 Btuh. How much heating water flow is required to satisfy
the load if the system is design for a 25°F temperature change? How much water flow is
required for a 35°F change? - ANS ✔✔Q = 500xGPM xTD
GPM =Q/(500xTD) =300,000/(500x25)= 24 GPM
GPM =Q/(500xTD) =300,000/(500x35)= 17.14 GPM
An office measures 50' x 90' with 16' high walls. 1.25 air exchanges/hour are desired. Find the
heat loss (in Btuh) when indoor temperature is 70°F and outdoor temperature is 36°F. - ANS
✔✔CFM = Volume of Room(ACH)/60 = 72000(1.25)/60 = 1,500CFM
Qsensible = (CFM)(1.1)(TD) = (1,500)(1.1)(34) = 56,100Btuh
A 3.5 ton, air cooled, DX window unit has a SEER of 15. If the unit operate for 1,700 hours
during the summer, how many kWh of electricity will be used? - ANS ✔✔1 ton of AC = 12,000
btuh
(3.5)(1,2000) = 42,000 buth
Total btu's for summer = (42,000)(1,700) = 71,400,000 btu
kWh = total btu for season/(electricity use in kWh)(1,000 kWh)
kWh = (71,400,000) / (15)(1,000 kWh) = 4760 kWh
Which of the following is the primary cause of corrosion in ferrous piping systems - ANS
✔✔Oxygen
A ___________________ is a mechanical draft created by air pushed through the boiler firebox
by a blower or fan at the front of a boiler. - ANS ✔✔Forced
PREP 2026/2027
To calculate the latent heat gain due to ventilation for a room design to be 75* F and the
outdoor temperature is 87* F, which of the following equations would you use? - ANS
✔✔Q=(4840) x (CFM) x (W final -W initial)
Which type of heat transfer occurs when thermal energy flows through a solid material? - ANS
✔✔Conduction
This occurs when latent heat is increased in a space. - ANS ✔✔Humidifying
Latent heat is energy that results in a measurable change in temperature - ANS ✔✔False
In thermodynamics, thermal energy flows from cold to hot. - ANS ✔✔False
Wet bulb temperature readings indicate what? - ANS ✔✔Moisture in the air
What does specific volume mean? - ANS ✔✔Volume of one pound of dry air
Ventilation loads an be calculated using CFM per person or room changes per hour (RCH) - ANS
✔✔True
The crack method is more accurate than the air change method for calculating loads. - ANS
✔✔True
In thermodynamics, thermal energy flows from hot to cold - ANS ✔✔True
, A heating system load totals 300,000 Btuh. How much heating water flow is required to satisfy
the load if the system is design for a 25°F temperature change? How much water flow is
required for a 35°F change? - ANS ✔✔Q = 500xGPM xTD
GPM =Q/(500xTD) =300,000/(500x25)= 24 GPM
GPM =Q/(500xTD) =300,000/(500x35)= 17.14 GPM
An office measures 50' x 90' with 16' high walls. 1.25 air exchanges/hour are desired. Find the
heat loss (in Btuh) when indoor temperature is 70°F and outdoor temperature is 36°F. - ANS
✔✔CFM = Volume of Room(ACH)/60 = 72000(1.25)/60 = 1,500CFM
Qsensible = (CFM)(1.1)(TD) = (1,500)(1.1)(34) = 56,100Btuh
A 3.5 ton, air cooled, DX window unit has a SEER of 15. If the unit operate for 1,700 hours
during the summer, how many kWh of electricity will be used? - ANS ✔✔1 ton of AC = 12,000
btuh
(3.5)(1,2000) = 42,000 buth
Total btu's for summer = (42,000)(1,700) = 71,400,000 btu
kWh = total btu for season/(electricity use in kWh)(1,000 kWh)
kWh = (71,400,000) / (15)(1,000 kWh) = 4760 kWh
Which of the following is the primary cause of corrosion in ferrous piping systems - ANS
✔✔Oxygen
A ___________________ is a mechanical draft created by air pushed through the boiler firebox
by a blower or fan at the front of a boiler. - ANS ✔✔Forced
