Hydronics: Exam 2 Flashcards
The water in a hydronic heating system should have a PH between
- 1-4
- 2-5
- 7-10
- 10-12
7 - 10
When a circulating pump stops operating, ____ control valves prevent water from _______
flow, migrating
Which of the following systems is designed so all of the circulating water passes through each component in the system?
- series loop hydronic system
- one-pipe hydronic
- two-pipe hydronic
series loop hydronic
Conventional boilers typically operate at water temperatures above
140F
In which of the following systems does the terminal unit farthest from the boiler have the longest length of supply piping, but the shortest length of return piping?
- direct return system
- one-pipe system
- series loop
- reverse return hydronic system
reverse return hydronic system
If a hydronic system is providing uneven heating, a technician should check;
- air blockage
- pump operation
- zone valve operation
- all of the above
all of the above
Which of the following statements about oil-fired boilers is false?
- a pilot light ignites the atomized fuel spray
- the fuel oil is pumped into the burner nozzle
- the combustion chamber is lined with refractory material
- a pilot light ignites the atomized fuel spray
A tridicator is used on an oil fired boiler to indicate water _______ and _______
pressure and temperature
Which of the following statements about low-water cutoffs is false?
- They may be float-operated
- They may operate a makeup water valve to add more water to a system
- They may operate a flow switch to cutoff water circulation
3.
Water returning to a boiler should be at least ___ lower in temperature than water leaving the boiler.
20F
T or F
glycol intended for automobile cooling systems may be used in some newer hydronic systems
false
T or F
Water at a lower pressure can hold more dissolved oxygen than water at a higher pressure
false
T or F
If a zone has its own circulating pump, the one valve may close a switch that starts the pump to circulate heated water through the zone
true
T or F
Radiant heating systems use copper water tubing
false
T or F
In a one-pipe steam heating system, the thermostatic radiator valve should be installed on the supply side of the radiator
false
T or F
Excessive air bubbles in a hydronic heating system may be verified by using the systems petcocks
true
T or F
Air vents may be installed on top of air separators to vent the air separated by those devices
true
T or F
A four pipe hydronic system shares piping so that both the heating and cooling systems cannot function simultaneously
true
T or F
Some combination heating and cooling systems are designed to operate simultaneously, allowing some spaces to be warmed and others to be cooled at the same time
true
The type of air that consists of small air bubbles that travel along with circulating water is called ________ air
entrained air
Valves installed in a hydronic system to ensure that water flows in the proper direction through the system are called _____ control valves
flow control valves
An ________ measures the temperature of the boiler water
aqua stat
If an expansion tank is hot from top to bottom, the tank is ______ logged
water logged
A boiler that heats water only when heat is called for is an
instantaneous boiler
A boiler in which the area under the combustion chamber is dry is a
dry-base boiler
Boiler that is over 90% efficient is a
condensing boiler
Boiler that operates at water temperatures above 140F is a
conventional boiler
Boiler that uses finned copper tubes as heat exchangers is a
copper boiler
A valve installed in the makeup water line to control pressure
Pressure-reducing valve
Valve that adjusts water flow to each terminal unit so that heat is evenly distributed
balancing valve
Valve installed in the makeup water line to prevent water from flowing into the water main
back flow preventer
Valve that prevents water from migrating when the circulating pump quits operating
flow-control valve
Valve that blends hot water from one inlet with cooler water from another inlet
mixing valve
Why do room temperatures remain steady for longer periods of time with hydronic systems than with forced-air systems?
hydronic systems continue to radiate residual heat from water lines
Name a way to reduce corrosion in hydronic system?
neutralize acidic water with alkaline
What are corrosion inhibitors?
protective coating on surface of metal
When should hydronic systems be purged?
if it contains large amounts of draft air
