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Question
In a system controlled by a high-limit controller, what is sometimes used to blend cool water returning from the heat emitters with heated water from the heat source?
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Answer
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Related questions
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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
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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.
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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.
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It is a product of incomplete combustion. c.
It decreases thermal efficiency. d.
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True b.
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an alcohol-based solution b.
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minimum fluid temperature b.
serial or parallel piping layout c.
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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.
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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.
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For a heat pump system with diurnal heat storage, when is the most favorable time for the heat pump to operate during winter? a.
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In general, the larger the temperature difference between the source media and the load media, the higher the heat pumps COP. a.
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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.
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Maximum head loss is generally independent of flow rate. a.
True b.
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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
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What would result from increasing the pressure rating of the relief valve? a.
A smaller expansion tank would be required. b.
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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
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Collector absorber plate temperature can exceed 350 degrees if stagnation occurs on a bright summer afternoon. a.
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2-pipe buffer tank configuration b.
4-pipe buffer tank configuration c.
6-pipe buffer tank configuration d.
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piping arrangement and inlet water temperature c.
average water temperature in the tank and size of heat exchanger d.
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Repurposed propane tanks can be used in both open and closed hydronic systems. a.
True b.
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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
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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.
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glazed flat-plate collector b.
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