Chapter 5 - Piping, Fittings, and Valves

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

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.

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

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.

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

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

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

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

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.

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

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

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

Copper tubing must be properly supported to prevent sagging or buckling. On horizontal runs of hard temper tubing, the maximum support spacing for 1/2- and 3/4-inch tube is __________ feet.

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

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

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.

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.

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

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

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 __________.