Deck 8: Water Heaters and Hot Water Distribution

Question 1

Direct-fired water heaters may be tank or tankless types.

Answer 1

True

Question 2

It is usually desirable to pipe the boiler water connections for an indirect-fired water heater so that circulation will take place by gravity.

Answer 2

True

Question 3

Scale can build up on the inside of a water heater and reduce the amount of heat transfer.

Answer 3

True

Question 4

Because instantaneous water heaters are smaller and have no tank, they cost less to install.

Question 5

According to the National Standard Plumbing Code, water at 110°F is considered hot water.

Question 6

All codes require a vacuum breaker to be installed on a water heater.

Question 7

A storage tank added to an instantaneous water heater has no effect on short-term hot water capacity.

Question 8

Scaling can lead to mineral buildup in the tank and cause metal fatigue.

Question 9

Indirect-fired water heaters use steam, hot water, or other heated fluid to heat the water.

Question 10

The location of a temperature-and-pressure relief valve is not important as long as it is installed somewhere on the tank.

Question 11

Circulating hot water in a loop helps to minimize the waste of water.

Question 12

On electric water heaters with dual elements, the bottom element must be satisfied first before the top element will operate.

Question 13

Indirect-fired water heaters may be tank or tankless types.

Question 14

Converting from a tank-type water heater to a tankless water heater usually requires an increase in the gas line sizing or electrical wiring.

Question 15

The dip tube helps to get the maximum amount of hot water from the water heater before dilution occurs with incoming cold water.

Question 16

Indirect-fired water heater installations should include valves and tees to facilitate cleaning the coils.

Question 17

Direct-fired water heaters use a primary fuel to heat water.

Question 18

All water heaters must be equipped with a nameplate showing firing rate, storage capacity, working pressure, manufacturer's trademark, model, and serial number.

Question 19

Most electric water heaters have an upper and lower element.

Question 20

A new temperature-and-pressure relief valve is required for every replacement water heater installed.

Question 21

If you smell the gas odorizer (an additive) when you come to a job, you should first

A) evacuate the building and call the utility company.
B) ignite a flame to identify the source of the gas.
C) close all windows in the building and search for leaks.
D) make sure the gas is turned on.

Question 22

Most standards now require that a(n) ____ be used if antifreeze or another nonpotable fluid is used to transfer heat in an indirect-fired water heater.

A) double-wall heat exchanger
B) anode rod
C) dip tube
D) tank insulation

Question 23

Instantaneous water heaters

A) provide hot water to the system fixtures without a storage tank.
B) are available in direct- and indirect-fired models.
C) may be powered by electricity or gas.
D) all of the above.

Question 24

Hydronic systems are popular because they can be the same size regardless of building size and location.

Question 25

A circulating loop may be required when the farthest fixture is ____ feet away from the water heater.

A) 75
B) 50
C) 100
D) 200

Question 26

A water heater that uses solar heat collectors would be classified as a(n) ____ heater.

A) indirect-fired
B) direct-fired
C) tankless
D) convection

Question 27

If a gas water heater is noisy and makes a rumbling sound, which is a probable cause?

A) The pilot is extinguished.
B) Sediment may have built up in the tank.
C) The gas supply may be off.
D) There may be excessive demand.

Question 28

Scale buildup in water heaters is more likely to be found when

A) the water source is a public system.
B) water treatment systems have been installed.
C) hot water circulation is too slow.
D) the water source is a well.

Question 29

All water heaters must be equipped with

A) an operating thermostat.
B) a flame failure safety system if it is a fuel-fired system.
C) temperature-and-pressure relief valves.
D) all of the above.

Question 30

Radiant heat requires that the heat be conducted through an object, such as the floor.

Question 31

Water heaters must be marked with a permanent label indicating manufacturer, capacity, energy input, and ____.

A) working pressure
B) rebate information
C) height, weight
D) service/repair phone number

Question 32

Radiant floor heating systems can only be installed in new construction.

Question 33

In most jurisdictions in the United States and Canada, water heaters exceeding 100 gallons, 200 MBH input, or 200 degrees Fahrenheit operating temperature must be constructed according to

A) UL Standards.
B) AGA Standards.
C) ANSI Boiler and Pressure Vessel Code.
D) United States Government Standards.

Question 34

Hydronic heating systems operate at very high pressures.

Question 35

Which of the following controls are required on water heaters?

A) operating thermostat
B) relief valve
C) energy cutoff device
D) all of the above

Question 36

First hour rating is the amount of hot water in gallons that the water heater can supply per hour when the tank is initially filled with cold water.

Question 37

In a direct-fired water heater, water is heated by a

A) hot fluid from another source.
B) flame or electric heating element.
C) temperature and pressure relief valve.
D) pressure vessel.

Question 38

Hydronic heating systems use steam to transfer heat to the building.

Question 39

Water heaters are often sized based on the number of bedrooms and the number of bathrooms in a building.

Question 40

Convection is a method of heat transfer that involves heat moving through fluid mediums.

Question 41

On electric water heaters with dual elements

A) the top will be energized first.
B) the bottom will be energized first.
C) both are energized at the same time.
D) water heaters only have one element.

Question 42

In restaurants, hot water for sanitizing can be as high as

A) 120°F.
B) 140°F.
C) 180°F.
D) 212°F.

Question 43

Which piping material would conduct heat the best?

A) PEX
B) ABS
C) copper
D) they all conduct heat the same

Question 44

Describe the difference between direct-fired and indirect-fired instantaneous heaters.

Question 45

According to Table 8-1, what size electric water heater is required for a 4-bedroom house with 2.5 baths?

Question 46

What is the purpose of a circulating system?

Question 47

When is it permissible to valve off the discharge of a relief valve?

A) never
B) once a new one has been ordered
C) when leaks can damage the flooring
D) when servicing the unit

Question 48

One advantage of instantaneous water heaters is

A) they provide an unlimited supply of hot water.
B) they are immune to problems with scaling.
C) they save space and investment in a storage tank.
D) they are much less expensive than traditional water heaters.

Question 49

What size (BTUH requirement) tankless water heater would be needed to supply 5.0 gpm at a temperature rise of 70 degrees? Assume 85% efficiency.

Question 50

What size electric tankless water heater would be needed to supply a lavatory with a .75 gpm faucet? Assume a 70-degree temperature rise and 95% efficiency.