Chapter 33

Expansion tanks must always be bled from the top until all of the air is removed from it.

False

Hydronic heat circulators are centrifugal pumps.

True

It is important to note that the air separator does not remove air from the system.

True

The more sections a boiler has, the higher its capacity will be.

True

The expansion tank provides a means of removing air from the system as well as provides _____.

a space for water expansion and contraction with water temperature changes

An expansion joint is a device used to _____.

allow for expansion and contraction of the loop piping with water temperature changes

The high-limit control, like the _____, is a device that opens and closes it contacts in response to boiler water temperature.

aquastat

On systems that use two-port zone valves, excessive pressure in the supply header may result when multiple zone valves _____.

close

The vanes of the impellers used in circulating pumps in hot water heating systems are usually enclosed, and are referred to as _____ impellers.

closed

The low-water _____ valve is responsible for de-energizing the hydronic system in the event the level of water in the system drops below the desired point.

cutoff

The more common type of expansion tank is the _____ expansion tank.

diaphragm-type

Most residences with modern hydronic heating systems use _____ baseboard heat transfer for terminal heating units

finned-tube

The pressure relief valve _____.

is set to relieve the pressure in the boiler below its maximum design pressure

A high-limit control on a hot water boiler is needed to _____.

protect the boiler against excessive water temperatures

In hot water hydronic systems, water is heated and circulated through pipes to a heat transfer component called a(n) _____ unit.

terminal

A pressure relief valve is set at 30 psig. The valve is constantly opening and flooding the floor. What is causing the relief valve to constantly open?

the system is overfiring

Zone control valves are controlled by the _____.

thermostat

A series loop hydronic system is not desirable for use in a large residence because _____.

- all of the heated water will flow to all rooms - some rooms will overheat before other rooms are warm

The reason for using zone valves on a hyronic heating system is to _____.

- allow different areas of the structure to maintain different temperatures - prevent unused parts of the house from getting warm, and wasting energy

Air in a hydronic system can cause _____.

- reduced water circulation - corrosion

A column of water 1 ft. high exerts a pressure of _____.

0.433 psig

In a series loop, the water going through the last terminal unit will be the same temperature as the water through the first terminal unit.

False

The only place a bleed valve is needed is on top of the boiler.

False

A tankless domestic water system provides hot water from a coil in the boiler.

True

Automatic air vents rely on an internal disc that swells when water is sensed.

True

Pumps generally have a cast-iron body with the impeller and other moving parts made of _____ or other nonferrous metals.

bronze

An automatic air vent controls the airflow out of the system by means of a(n) _____, which rises and falls with the amount of air in the system.

float

The series loop system is the hydronic system that is found most often, primarily because of the _____.

low installation costs