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Question
Which of these is an advantage of a thermostatically controlled tankless electric water heater?
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Answer
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Related questions
Q:
What is the simple payback of a renewable energy heating system? a.
the installation cost divided by the annual operating cost savings b.
the number of years required for the investment to repay the higher initial cost using the savings it generates, relative to that of a conventional system c.
the number of years required for the annual operating cost savings to equal the installation cost d.
the installation cost divided by the difference between the installation cost of the system and a conventional system
Q:
How is after-tax lost opportunity cost calculated? a.
total interest income earned multiplied by percentage of income retained by the owner b.
total interest income earned multiplied by income tax percentage c.
installation cost divided by annual operating cost savings d.
total cost of owning and operating a system on an annual basis
Q:
What do straight lines on a simple payback curve imply? a.
The inflation of fuel cost was included. b.
The inflation of fuel cost was not included. c.
The fuel cost was not considered in the calculation. d.
The installation cost was not considered in the calculation.
Q:
What is the function of a variable-speed setpoint circulator? a.
It protects a wood-fired or pellet-fired boiler from low inlet water temperature. b.
It protects a wood-fired or pellet-fired boiler against over-pressure conditions. c.
It senses when flue-gas condensation is occurring. d.
It allows automatic fuel dispensing into the boiler.
Q:
Why is creosote dangerous? a.
It is difficult to clean up. b.
It is a product of incomplete combustion. c.
It decreases thermal efficiency. d.
It is toxic when touched.
Q:
What value represents the actual amount of air supplied to the combustion process divided by the stoichiometric air requirement? a.
beta ratio b.
delta ratio c.
gamma ratio d.
lambda ratio
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Outdoor wood-fired hydronic heaters have relatively high PM2.5 particulate emissions, which represent a human health concern. a.
True b.
False Indicate the answer choice that best completes the statement or answers the question.
Q:
What type of antifreeze solution is most widely used in geothermal heat pump applications? a.
an alcohol-based solution b.
a salt-based solution c.
an inhibited propylene glycol solution d.
a noble-gas-based solution
Q:
Besides HDPE, which material is commonly used in earth loop heat exchanger piping? a.
PEX b.
APEX c.
stainless steel d.
copper
Q:
Which factor is strongly influenced by head loss in design of an earth loop system? a.
minimum fluid temperature b.
serial or parallel piping layout c.
type of piping that may be used d.
required circulator power
Q:
What is the ground water temperature in most drilled wells? a.
about equal to the average annual outside air temperature b.
about equal to the average low summer air temperature c.
about equal to the average high winter air temperature d.
about 65 degrees F in most areas of North America
Q:
What is the heating capacity of a heat pump? a.
the ratio of heating load to total heating and cooling load b.
the percentage of total load it can meet c.
the rate at which it delivers heat to the load d.
ratio of beneficial heat output to input electrical energy
Q:
For a heat pump system with diurnal heat storage, when is the most favorable time for the heat pump to operate during winter? a.
daytime b.
overnight c.
early morning d.
late evening
Q:
In general, the larger the temperature difference between the source media and the load media, the higher the heat pumps COP. a.
True b.
False
Q:
What is the recommended flow velocity for establishing a siphon? a.
1 foot per second b.
2 feet per second c.
3 feet per second d.
5 feet per second
Q:
Which is a benefit of a closed-loop drainback system? a.
Its components last longer because they must be made of non-corroding materials. b.
It can be connected directly to a space heating distribution system. c.
It can be operated at a slight negative pressure. d.
It does not need to accommodate the thermal expansion of system water.
Q:
Maximum head loss is generally independent of flow rate. a.
True b.
False
Q:
Which code requirements may vary between locations? a.
use of double-wall heat exchangers and collector array grounding b.
percent of total heat load that may be supplied by solar energy c.
requirement for grounding and pressure-relief valves d.
none, because of the requirement of uniform code requirements
Q:
What would result from increasing the pressure rating of the relief valve? a.
A smaller expansion tank would be required. b.
A larger expansion tank would be required. c.
The size of the expansion tank would not be affected. d.
Boiling in the collector array would be prevented.
Q:
What two reasons make domestic water heating a practical application for solar thermal systems? a.
intermittent load; heating starts at low temperatures b.
year-round load; heating starts at low temperatures c.
intermittent load; heating starts at high temperatures d.
year-round load; heating starts at high temperatures
Q:
Heat dumps and over-temperature protection are not required on drainback-type solar thermal systems. a.
True b.
False
Q:
Collector absorber plate temperature can exceed 350 degrees if stagnation occurs on a bright summer afternoon. a.
True b.
False
Q:
Which configuration allows heat to be transferred to the load as quickly as possible after the heat source turns on? a.
2-pipe buffer tank configuration b.
4-pipe buffer tank configuration c.
6-pipe buffer tank configuration d.
vertical flow jet configuration
Q:
What are two factors that influence the rate of heat loss from a vertical cylindrical tank? a.
average temperature of water in the tank and outer diameter of tank insulation b.
piping arrangement and inlet water temperature c.
average water temperature in the tank and size of heat exchanger d.
piping arrangement and surface area of heat exchanger
Q:
Repurposed propane tanks can be used in both open and closed hydronic systems. a.
True b.
False
Q:
What is used to calculate net collector area for an evacuated tube solar collector? a.
outer dimensions of the collector housing b.
dimensions of exposed glazing c.
dimensions of the absorber plate and headers d.
dimensions of the mounting surface minus the dimensions of the absorber plate
Q:
What optical property represents the percent of thermal radiation released by a surface compared to that released by a black body at the same temperature? a.
transmissivity b.
absorptivity c.
emissivity d.
reflectivity
Q:
With which type of solar collector does the instantaneous thermal efficiency vary the most as the inlet parameter changes? a.
glazed flat-plate collector b.
unglazed pool collector c.
evacuated tube collector d.
glazed and insulated pool collector
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Flat-plate collectors without glazing or insulation are commonly used for domestic water heating. a.
True b.
False
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Building orientation could not be determined before the advent of detailed satellite imaging. a.
True b.
False