What is the purpose of a primary-secondary loop?

The Primary-Secondary piping arrangement includes two sets of pumps, system pumps and boiler pumps. The system pumps distribute water to the terminal units and the boiler pumps circulate water through a loop that serves the heating equipment only.

What is the maximum spacing recommended for the closely spaced tees on a primary-secondary system?

It is VERY important that the closely spaced tees be no further apart than 4 times the diameter of whatever size pipe constitutes the primary/secondary loop, and it is equally important that the length of the straight pipes extending from the closely spaced tees be at least 6 times that same pipe diameter.

What is primary pipe?

The primary piping elements include steel pipes, connecting elements (flanges, pipe bends, pipe elbows, tees), stop and shut-off-and-regulating valves (slide gates and valves), drain devices, expansion joints, supporting structures and parts, hangers and fastening elements, thermal insulation.

What is primary flow and return?

The coil, or “heat exchanger” forms part of the central heating circuit, and its water heating abilities are purely a by-product of its main function, which is to heat the radiators. This heating is called the “primary” circuit, the pipes running to and from the boiler are called the primary flow and return.

What does a hydro separator do?

The Hydraulic Separator is multi-purpose equipment that replaces several components in the system, simplifying piping and reducing installation time. BENEFITS, FEATURES AND FUNCTIONS: Hydraulically separates primary and secondary circuits. Separates and vents air from the system.

Do boilers need a primary loop?

Primary Loop Piping is commonly used in boiler heating systems that run needing multiple temperatures or contstant temperature at the hydronic boiler is required.

How do closely spaced tees work?

If you are going to build a true primary/secondary system, each load circuit and each heat source needs to connect to the primary loop using a pair of closely spaced tees. These tees isolate the pressure dynamics of each circulator from the other circulators in the system. This is called hydraulic separation.

What is a secondary loop?

A secondary loop refrigeration system incorporates two different refrigerants to provide cooling. In all systems, the primary loop is a traditional direct expansion design that uses a phase change refrigerant such as R-404A and a compressor to circulate the refrigerant.

What is primary pump and secondary pump in chiller?

The primary loop uses a constant speed pump to circulate the working fluid (water). The secondary loop uses a variable speed pump to manipulate the flow of the fluid such that the cooling coil demand is satisfied. The above mentioned pumps are considered as a primary/secondary pumping pair.

What is a primary-secondary piping arrangement?

Traditionally, Primary-Secondary piping arrangements have meant full flow in the boiler loop and variable flow in the system loop. Manufacturers tend to prefer Primary-Secondary because it ensures proper flow through the boiler.

Which piping is common to both the secondary and primary loops?

The piping common to both the secondary and primary loops are the two tees and the common piping shown above. Rule “1” tells us to keep that common pressure drop very low.

What is parallel primary and secondary loop?

primary loopclosely spaced tees …a drop in water temperature from one secondary circuit to the next when operating simultaneously A parallelprimary/secondary piping configuration provides the same water temperature to each secondary circuit: This benefit is achieved at the expense of more complicated and costly piping.

How is the secondary circuit “hydraulically separated”?

The secondary circuit is “hydraulically separated” from the primary circuit by the closely spaced tees. This concept can be extended to multiple secondary circuits served by a common primary loop: