D. PIPING AND PUMP SIZING
Correctly sized piping and pumps are necessary for the efficient and safe transport of heated water from the GARN® WHS unit to the building heating system.
All piping, pumps, wiring and controls, etc must be sized and installed by a qualified and licensed professional. All items are to be installed in full compliance with all national, state and local codes. For installations not covered in this
manual contact your local GARN® dealer for design assistance.
PIPING DESIGN AND CALULCATION GUIDELINES
Size all above grade and underground piping per standard industry guidelines: Maximum head loss of 4’ to 6’ per 100’ of pipe for energy conservation. Maximum velocity of 8’ per second to minimize surface erosion potential in most pipes. Maximum velocity of 6’ per second to limit noise. Incorrect pipe sizing will adversely affect the heating system performance, efficiency and cost of operation. Undersized piping may cost less to install, but the pump size must be increased, adding significantly to the pump cost and the cost of operation. Head loss data for a specific pipe or tubing, and for various fittings is tabulated in manufacturer literature, plumbing manuals, state plumbing codes and local building codes. A representative sample of the head loss associated with various fittings for copper or steel is listed below. Recommended flow rates for various pipe materials are tabulated on the next two pages. EQUIVALENT FEET OF PIPE FOR SCREWED FITTINGS AND VALVES (for steel and copper) NOMINAL PIPE SIZE, INCHES 1/2 3/4 1 1 1/4 1 1/2 2
45 Degree Elbow, Regular 90 Degree Elbow, Long 90 Degree Elbow, Regular
0.8 2.2 3.6 0.7 0.3
0.9 2.3 4.4 0.9 0.4
1.3 2.7 5.2 1.0 0.5
1.7 3.2 6.6 1.5 0.7
2.1 3.4 7.4 1.8 0.8
2.7 3.6 8.5 2.3 1.0
Gate Valve, Open
Ball valve, Full Port, Open
Globe Valve, Open Tee-Branch Flow
22.0
24.0
29.0
37.0
42.0
54.0 12.0
4.2 1.7 5.0 8.0
5.3 2.4 6.6 8.8
6.6 3.2 7.7
8.7 4.6
9.9 5.6
Tee-Line Flow
7.7
Strainer
18.0 13.0
20.0 15.0
27.0 19.0
Swing Check Valve
11.0
12
Hydronic System Design Manual ©DECTRA CORPORATION - March 2013
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