Hydronic Heating Systems

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.

A pipe size should be selected that keeps the average flow velocity between ____________ft,/sec.

2 and 4

A given volume of water can absorb over ____ times more heat as the same volume of air for the same temperature change.

3400

Water Tubing must be properly supported to prevent sagging or buckling. On horizontal runs of hard temper copper tubing, the maximum support spacing for 1/2" and 2/4" tubing is _________ feet.

5'

What range of efficiency is a high efficiency boiler?

84%-88%

What one device might a hot water boiler need that a steam boiler might not?

Circulator

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

Determining the flow rates in systems with several parallel branches does not require "number crunching."

False

Each component in a piping assembly of circuit has an associated hydraulic resistance that defines its ability to dissipate thermal energy from the fluid at any given flow rate.

False

Flow Velocity is a measurement of the volume of fluid that passes a given location in a pipe in a given time.

False

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

False

Ideally, the water in a hydronic heating system is replaced in the system every year.

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 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

Not every heating system consists of devices that convert one form of energy into another.

False

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

False

The equivalent hydraulic resistance of an entire assembly is always greater than the smallest individual hydraulic resistance.

False

The heating capacity of the heat pump drops rapidly with increasing source water temperature.

False

The pressure difference between the inside and outside of the tube has a very strong effect on Oxygen diffusion.

False

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

K, L, and M

The operation of which one of the following components of a boiler system should be checked on a residential boiler at least once a year and a commercial boiler once a month

Relief Valve

____________ represents the relationship between flow rate and head loss for a given piping circuit using a specific fluid at a given temperature.

System head loss curve

With regard to a condensing boiler, what can be justified by the extra energy savings?

The extra cost of a condensing boiler system

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

A properly designed and installed hydronic system can operate with virtually no detectable sound levels in the occupied areas of a home.

True

All boilers may condense at some point in their heating cycle.

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

Conventional gas- and oil-fired boilers are currently used in the vast majority of residential and light commercial hydronic systems in North America.

True

Due to the thermal expansion, the greater the length of the pipe, and the greater the temperature change, the greater the change in length.

True

Every piping system should be thought of as having an operating cost as well as an installation cost.

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

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

True

In a purely technical sense, the word fluid can mean either a liquid, such as water, or a gas, such as air.

True

Plumbing codes no longer allow solders containing lead to be used for domestic water service.

True

Properly designed hydronic systems control both the air temperature and surface temperatures of rooms to maintain optimal comfort.

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 equivalent length of a component is the amount of tubing, of the same pipe size, that would produce the same head loss (or pressure drop), as the actual component, at the same flow rate.

True

The molecular structure of nonmetallic tubes such as those made of PEX or rubber compounds is such that oxygen molecules can diffuse through their tube walls and be absorbed by the fluid within.

True

The static pressure at a given depth below the surface of a liquid remains exactly the same regardless of the diameter of the pipe.

True

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

True

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

True

Use of pressure drop charts based on 60 deg. F water will consistently overestimate the pressure drop in hydronic heating piping circuits because the water will usually be at higher temperatures.

True

Using pressure gauges to detect changes in the head of a liquid is like using thermometers to detect changes in the thermal energy content of that liquid.

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

piping schematics are the road maps of hydronic system design, Unfortunately, there is not universal standard for piping symbols to which all those in the hydronics industry subscribes.

True

The term"flow velocity" is commonly understood to mean the _____________ flow velocity of the fluid as it moves through a pipe.

average

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

Fittings for copper tubing are available in either wrought coper or ______________.

cast brass

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

closed loop

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

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

copper

The 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

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

After the hydraulic resistance of all devices in a piping assembly are determined, they can be combined into a(n) _______ resistance similar to how electrical resistances are combined in circuit analysis.

equivalent

Copper tubing is also subject to a condition called __________, which can literally scrub metal off the in side wall of a tube or fittings.

erosion corrosion

A flow restriction or stoppage in the ____ can lead to rapid formation of ice crystals on the cold heat exchanger surfaces separating the water and refrigerant.

evaporator

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

exactly match

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

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

handlers

Fluids in a hydronic system contain both thermal and mechanical energy. The mechanical energy, or _________, present in a fluid depends on several factors including its pressure, density, elevation, and velocity at some point in the system.

head

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

The piping paths that share common points of connection are said to be piped ________.

in parallel

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

Buildings with hydronic heating systems have shown ____ heating energy use compared to equivalent structures with forced-air heating systems.

lower

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

mounting rail

if the inlet pressure on the backflow preventer drops below the pressure in the hydronic system, springs return both check valves and movable cartridge to their ____________ positions.

original

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

purging valve

The simplest piping assemblies are formed by connecting piping components end to end. In some cases the collection of tubing, fittings, valves, and other components closes on itself to form a ______.

series circuit

A more efficient method can be used where the piping circuit contains a(n) ____________ of pipe, and valves.

single size

A boiler operates at _____ efficiency only when it is being fired continuously under non varying 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 hydronic heating systems will inherently attempt to find a point of ____ and remain in operation at that point.

thermal equilibrium

In solar anti-freeze based combisystems, the outside heat dump provides a way for the system to shed excess heat. It is activated if the temperature of the thermal storage tank reaches a ____ upper limit.

user-set

Whenever a fluid flows, an energy dissipating effect called _______develops both within the fluid stream and along any surfaces the fluid contacts.

viscous friction

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

wet-base