Line tap valves
These are sometimes referred to as piercing valves. They consist of a small clamp which is in two sections fitted to the pipework.
Totally sealed systems will involve the use of this type of valve in order to gain access to the system. A special charging/gauge adaptor is screwed on to the piercing valve assembly (see Figure 8).
The valve assemblies are available for a wide range of pipe sizes and the adaptor is a standard fitting to the assemblies.
Related posts:
System Choice Matrix
Energy Conservation Measures:Heat Recovery
IDENTIFYING DIODE LEADS
Electric Furnaces:Thermal Overload Protector , Electrical Wiring and Air Conditioning
Gas Furnaces:Troubleshooting Charts
Fireplaces, Stoves, and Chimneys:Chimney Downdraft
Ventilation Principles:Roof Ventilators
Oil Furnaces:Installation Checklist
Controls:Architecture and Advantages of Direct Digital Controls