modern hydronic HVAC EXAM

Modern controls can maintain room air temperature +/- ___ °F of the desired setpoint temperature.

1

It is vital that the solar collectors and all exposed piping in a drain-back system be pitched a minimum of ____ toward the storage tank to allow complete drainage.

1/4 in/ft

When designing a piping system, select a circulator that delivers up to ____ more head than required at the desired flow rate.

10%

Modern two-stage cordwood gasification boilers can achieve thermal efficiencies in the range of ___.

70-80%

The gallons of hot water supplied as the first-hour rating are based on a ___ ºF temperature rise between the incoming cold water and the leaving hot water.

90

A(n)_____ is commonly used to mount an air vent at high points in piping circuits.

Baseboard Tee

Fittings for copper tubing are available in either wrought copper or ____.

Cast Brass

To compensate for the effect of internal heat gains, and warm-weather degree days, ASHRAE devised a correction multiplier known as _____.

Cd Factor

The emergence of electrically powered____ made it possible to move water at higher flow rates through much elaborate piping systems.

Circulators

In situations where good heat transfer through the walls of the pipe is desirable, ____ is unsurpassed.

Copper

One common method of factoring local weather conditions into estimates of heating energy use is based on heating ____.

Degree Days

Feed water valves operate by balancing the force generated by water pressure against an internal flexible ____, with the counterforce generated by a partially compressed spring.

Diaphragm

The difference in energy use by various heating and cooling distribution systems can be quantified using the concept of__________.

Distribution Effciency

Distribution efficiency (Btu/h/watt) is equal to the â rate of thermal energy delivery by distribution system (Btu/h)â ____ the â electrical power required to operate distribution system (watt).â

Divided-by

An air separator is designed to separate air from water and eject it from the system. The process is ____ the water is heated.

Enhanced as

When water is used as the source fluid for open loop systems, the heat pump must be configured to prevent freezing of the____.

Evaporator

In an ideal application, the rate of heat production by the heat source would ____ the rate of heat by the heat emitters.

Exactly match

A feed water valve is used to increase the pressure of water from a domestic water distribution pipe before it enters a hydronic system.

False

A well-planned piping assembly will use the largest number of fittings possible.

False

Heat from a basement or slab-on-grade foundation is not determined by complex interactions between the building, the surrounding soil, insulation materials, and air temperature above grade.

False

Hydronic heating systems should never use a combination of flexible and rigid piping materials.

False

In full storage ETS systems, all energy used during the subsequent on-peak period is purchased and stored during the peak cycle.

False

In single-loop systems, the flow-check valve allows hot water in the boiler to slowly circulate through the distribution system when the circulator is off.

False

In situations where both piping and electrical wiring are in close proximity, try to keep the piping above the electrical wiring.

False

It is not advisable to maintain water flow through the condenser whenever the heat pump is operating.

False

Maintaining comfort is simply a matter of supplying heat to the body.

False

Many boilers currently used in North America were designed with the intent that flue gases would condense within the boiler.

False

Many residential and commercial buildings have concrete floor slabs rather than crawl spaces or full basements. Downward heat losses are relatively large from interior areas of the floor slab.

False

One can assume that individual room heating loads are proportional to room floor area.

False

Some press fittings used in residential and light commercial buildings are rated to operate at pressures up to 200 psi and temperatures ranging from 0 to 250 ºF.

False

Thermal radiation is probably the most understood mode of heat transfer.

False

All electric, gas, and oil-fired storage type water heaters sold in the United States have a _____.

First-hour rating

In single-loop systems, the ____ prevents hot water in the boiler from slowly circulating through the distribution system when the circulator is off.

Flow-Check Valve

The proper approach is to perform a heat load calculation ____.

For each room

When fluid motion is caused by either a circulator, blower, or fan, the resulting heat transfer is more specifically called______.

Forced convection

______ are designed specifically for component isolation.

Gate Valves

Heat emitters that use fans or blowers to force air through a heat exchanger are usually called fan coils or air ____.

Handlers

Water has many characteristics that make it ideal for a hydronic system. It is readily available, nontoxic, nonflammable, and has one of the highest ____ storage abilities of any material known to man.

Heat

A ____ is a device for converting low-temperature heat into higher temperature heat.

Heat Pump

Boilers with low thermal mass tend to have ____ cycle efficiencies due to lesser amounts of heat remaining in the boiler following burner shutdown.

Higher

Heat always moves from an area of____ temperature to an area of____ temperature.

Higher, Lower

One method of approximating the heat loss through basement walls is based on dividing wall into___ strips based on the height of finish grade.

Horizontal

When the heating degree day method was developed, fuel was_____ and buildings were_____ insulated.

Inexpensive, Poorly

In addition to conduction losses, heat is also carried out of buildings by uncontrolled air leakage. This is called ____ heat loss.

Infiltration

Most water-to-water heat pumps have minimum____ source water temperatures specified by their manufacturer.

Inlet

In addition to the thermal resistances of the solid materials, there are two thermal resistances, called the___ film resistance and____ film resistance.

Inside air, outside air

The contour lines with temperatures labeled in ºC are called_____.

Isotherms

Copper water tube is available in three wall thicknesses designated as types ____ in order of decreasing wall thickness.

K, L, and M

Another specialty valve widely used in hydronic systems provides the ability to isolate, flow balance, and even drain individual heat emitters. It is called a ____.

Lockshield Valve

____ tubing consists of high-density polyethylene that has undergone molecule modification that creates sufficient tie chains between the polyethene molecules to allow it to operate at higher temperatures.

PE-RT

Hydronic heating systems, once assembled, must be purged of air and filled with fluid. A(n) ____ is specifically designed for this purpose.

Purging Valve

The U-value of any material or assembly is simply the reciprocal of the ____ of that material or assembly.

R-Value

An objectâ s thermal ____ can be defined as its thickness in the direction of heat flow divided by its thermal conductivity.

Resistance

A boiler operates at _____ efficiency only when it is being fired continuously under nonvarying conditions.

Steady-State

Heat is our perception of atomic vibrations within a material. Our means of expressing the intensity of these vibrations is called ____.

Temperature

All building surfaces that separate heated space from unheated space. (walls, windows, ceilings, doors, foundation, etc.) are called the ____ of the building.

Thermal Envelope

All hydronic heating systems will inherently attempt to find a point of ____ and remain in operation at that point.

Thermal Equilibrium

The combination of metal and water weight gives cast-iron boilers the ability to absorb a significant amount of heat. Such boilers are said to have a high ____.

Thermal Mass

Since the walls, floors, and ceilings of buildings are rarely constructed of a single material, It is often necessary to determine the______ of an assembly made up of several materials in contact with each other.

Total R-Value

ASTM F876 standard for PEX tubing establishes three simultaneous temperature/pressure ratings based on operation with water.

True

All heating systems consist of devices that convert one form of energy into another.

True

An important aspect of domestic water-heating loads is the peak hourly demand.

True

Condensing boilers are designed with large heat exchanger surfaces capable of extracting more heat from the exhaust gases compared to the heat exchangers in conventional boilers.

True

Hydronic heating systems use water (or water-based solutions) to move thermal energy from where it is produced to where it is needed.

True

Ideally, the water in a hydronic heating system remains in the system year after year.

True

If a cast-iron boiler is significantly oversized and experiences long off-times between firing cycles, much of the heat stored in the boilerâ s thermal mass can be carried up the flue by air currents passing through the combustion chamber.

True

In the absence of any building or mechanical codes that require otherwise, type M is the standard for copper tubing used in hydronic heating systems.

True

It is relatively impossible to assess the location and magnitude of all the air leakage paths in a typical building.

True

Many heat pumps have internal temperature controllers that monitor the inlet water temperature.

True

Piping schematics are the road maps of hydronic system design. Unfortunately, there is no universal standard for piping symbols to which all those in the hydronics industry subscribes.

True

Providing comfort is the primary objective of any heating system designer or installer.

True

The R-value of a material is directly proportional to its thickness.

True

The U-value of any material or assembly is simply the reciprocal of the R-value of that material or assembly.

True

The cast-iron sectional boiler is currently one of the most common boilers used in residential and light commercial buildings in North America.

True

The design heating load of a building is an estimate of the rate at which a building loses heat during the near minimum outdoor temperature.

True

The number of heating degree days that accumulate in a 24-hr. period is the difference between 65 ºF and the average outdoor air temperature during that period.

True

The seasonal efficiency of the heat source is also factored when determining the unit price of delivered energy.

True

The simplest hydronic system can be described as a loop or piping circuit.

True

The term â hydronic heat pumpâ always refers to a heat pump that delivers heat to a flowing stream of water.

True

The main difference between thermal radiation and visible light is the___ of the radiation.

Wavelength

___________ are called open-loop sources since, at some location, the water they contain is exposed to the atmosphere.

Wells, ponds, or lakes.

One type of boiler design surrounds the combustion chamber with a water-filled heat exchanger. This arrangement is called a ____ boiler.

Wet-Base

A device used to allow or prevent flow through a zone circuit is called a(n)_____.

Zone Valve

The most widely used hydronic heat pump is configured to extract heat from_________.

a water source

Unlike PEX tubing, PEX-AL-PEX tubing cannot be repaired by heating the tub until the PEX reaches its____ state.

amorphous

Drain-back combi-systems do not require_____ to properly operate.

antifreeze

Early hydronic systems did not have circulators. Instead, they relied on the ____ of hot water to move water between the boiler and the heat emitters.

buoyancy

Most cast-iron sectional boilers are limited to use in ____ hydronic systems.

closed loop

To estimate the annual space heating cost provided by an electrically operated heat pump, its average COP must be factored in. What does COP stand for?

coefficient of performance

All solar thermal systems use a_____ to consisting of one or more_________.

collection array, solar collectors

When long straight runs of rigid tubing are required, it may be necessary to install an expansion loop or an expansion offset to absorb the movement. Another alternative is to install an expansion ____ capable of absorbing the movement.

compensator

Analysis of combustion processes reveals that significant amounts of heat can be recaptured from the exhaust stream if the water vapor it contains can be ____.

condensed within the boiler

Some common pipe fittings in hydronic systems include___________.

couplings, elbows, and tees

When a pellet boiler is the sole heat in a system it is typically sized to the buildingâ s_____.

design heating load

In situations where open-loop water sources are not available or suitable for use, a closed-loop______ can supply low-temperature heat to a water source heat pump.

earth heat exchanger

The smaller the coefficient of linear expansion, the_____ tubing expands for a given change in temperature.

less the

The term___ radiant temperature describes the area-weighted average temperature of all surfaces within a room.

mean

In situations where several runs of piping and/or electrical conduit must be run in close proximity, a ____ system is a good option.

mounting rail

The driving force of________ is a lower concentration of dissolved oxygen molecules within the water inside the tube, compared to the concentration outside the tube.

oxygen diffusion

When soldering copper tubing be sure the tube cut is square. Use a(n) _______ with a blade suitable for the copper tubing.

wheel cutter or chop saw