HVAC Unit 33 Hydronic Heat Study Guide Questions and Answers
with Verified Solutions | Latest 2026 Update
Q: Why are pressure differential bypass valves necessary?
Answer:
If a system is using two port zone valves, there can be excessive pressure if multiple
zones are closed. This can result in noisy and banging pipes. The pressure differential
bypass valve is located between the supply and return headers. It opens as zone
valves close. The circulator can keep pumping the same amount of water and any
excess hot water is recirculated back to the boiler.
Q: What are flow control valves?
Answer:
They are actually check valves. They prevent water from back flowing to a terminal
unit when the circulating pump is not operating.
Q: What is the outdoor reset control?
Answer:
It measures the outside temperature and adjusts the water temperature to higher or
lower depending on the outside temperature.
,HVAC Unit 33 Hydronic Heat Study Guide Questions and Answers
with Verified Solutions | Latest 2026 Update
Q: What type of heating is used with finned-tube baseboard units?
Answer:
Air enters at the bottom of the heating units and passes over the hot fins of the finned
tube unit. Heat is given off to the cooler air and causes it to rise by convection.
Q: How many lb/hr equals 1 gal of water flow per minute?
Answer:
1 gallon of water weighs 8.33 pounds. 1 gal/min = 8.33 lb/min 8.33 lb/min x 60
min/hr = 499.8 lb/hr rounded up to 500 lb/hr
Q: T or F - in a series loop, the temperature of the first terminal unit can be higher
or lower than
Answer:
the last terminal unit with the use of a thermostat. False - the temperature of the first
terminal unit will always be higher than the last terminal unit. As the water moves
down the
piping, it gives up heat.
, HVAC Unit 33 Hydronic Heat Study Guide Questions and Answers
with Verified Solutions | Latest 2026 Update
Q: In a series loop, what is the formula for calculating water flow and the amount of
temperature
Answer:
drop across each terminal unit.
terminal 1 20000, terminal 2 30000, terminal 3 50000
Q: Water supply temp 180 degrees
Answer:
Water return temp 160 degrees GPM = Q(total) / (500 x Delta T)
GPM = (20000 Btu/h + 30000 Btu/h + 50000 Btu/h) / (500 x (180-160))
GPM =
GPM = 10 gpm
Q: Delta T = Q1 / (500 x gpm)
Answer:
Delta T = 20000 / (500 x 10)
Delta T = 4 degrees
with Verified Solutions | Latest 2026 Update
Q: Why are pressure differential bypass valves necessary?
Answer:
If a system is using two port zone valves, there can be excessive pressure if multiple
zones are closed. This can result in noisy and banging pipes. The pressure differential
bypass valve is located between the supply and return headers. It opens as zone
valves close. The circulator can keep pumping the same amount of water and any
excess hot water is recirculated back to the boiler.
Q: What are flow control valves?
Answer:
They are actually check valves. They prevent water from back flowing to a terminal
unit when the circulating pump is not operating.
Q: What is the outdoor reset control?
Answer:
It measures the outside temperature and adjusts the water temperature to higher or
lower depending on the outside temperature.
,HVAC Unit 33 Hydronic Heat Study Guide Questions and Answers
with Verified Solutions | Latest 2026 Update
Q: What type of heating is used with finned-tube baseboard units?
Answer:
Air enters at the bottom of the heating units and passes over the hot fins of the finned
tube unit. Heat is given off to the cooler air and causes it to rise by convection.
Q: How many lb/hr equals 1 gal of water flow per minute?
Answer:
1 gallon of water weighs 8.33 pounds. 1 gal/min = 8.33 lb/min 8.33 lb/min x 60
min/hr = 499.8 lb/hr rounded up to 500 lb/hr
Q: T or F - in a series loop, the temperature of the first terminal unit can be higher
or lower than
Answer:
the last terminal unit with the use of a thermostat. False - the temperature of the first
terminal unit will always be higher than the last terminal unit. As the water moves
down the
piping, it gives up heat.
, HVAC Unit 33 Hydronic Heat Study Guide Questions and Answers
with Verified Solutions | Latest 2026 Update
Q: In a series loop, what is the formula for calculating water flow and the amount of
temperature
Answer:
drop across each terminal unit.
terminal 1 20000, terminal 2 30000, terminal 3 50000
Q: Water supply temp 180 degrees
Answer:
Water return temp 160 degrees GPM = Q(total) / (500 x Delta T)
GPM = (20000 Btu/h + 30000 Btu/h + 50000 Btu/h) / (500 x (180-160))
GPM =
GPM = 10 gpm
Q: Delta T = Q1 / (500 x gpm)
Answer:
Delta T = 20000 / (500 x 10)
Delta T = 4 degrees
