Manifold Selection Guide
Manifold Selection Guide
The right manifold is selected in five steps: material → header diameter → branches → connections → options. The diagrams and tables below let you decide without doing the calculations by hand. Find the header diameter with the calculation tool, then move on to the manifold configurator: the technical drawing and quote summary are prepared with the same dimensions.
- 1MaterialThe type of installation and the fluid determine the material
- 2Header diameterTotal flow rate → velocity 1.0–1.5 m/s
- 3BranchesSize, number, direction and center-to-center spacing
- 4ConnectionsWeld end, thread, union, flange, valve
- 5OptionsValves, sensor pockets, supports, insulation
1 · Choose the material
The material is determined by the fluid, the temperature and the corrosion conditions. The decision tree is the quickest way:
- DN50 – DN500
- 110 °C heating line
- Most economical, available in every size
- DN50 – DN500
- Domestic water up to 100 °C / 110 °C heating line
- Zinc protection inside and out, economical
- DN50 – DN500
- Up to 200 °C
- No painting or maintenance needed, 200 °C
- Ø40 mm – Ø400 mm
- 70 °C continuous operation
- No corrosion or scale, lightweight
- Ø40 mm – Ø400 mm
- 40 °C
- Impact-resistant, welded joints
2 · Size the header for the flow rate
The header diameter is chosen so that it carries the total flow rate through the manifold at low velocity. Three formulas are enough:
Q (m³/h) = P (kW) ÷ (1.163 × ΔT)ΔT = flow–return temperature difference (usually 20 K)Q = A × v × 3600 · v = 1.0–1.5 m/sA = π × (inner diameter ÷ 2)² · the higher the velocity, the higher the pressure lossAheader ≥ 1.5 × ΣAbranchesIf not met, go up one header sizeStart from size: you choose the header and the branch outlet; the tool gives the capacity, the cross-section ratio and the approximate length. If you leave the Header length field empty, the length is calculated from the center-to-center spacing and the number of branches; if you enter it manually, the tool checks whether the length is sufficient. Start from output: you enter the heat output (or the flow rate); the tool selects a suitable header diameter. The calculation is based on Q = P / (1.163 × ΔT), Q = A × v × 3600 and Aheader ≥ 1.5 × ΣAbranches; the result is a preliminary selection, and the exact size is confirmed by the system design calculation.
| Header | Flow rate (1.0–1.5 m/s) | Upper-limit heat capacity (ΔT 20 K) |
|---|---|---|
| DN50 | 7.1 – 10.6 m³/h | 247 kW |
| DN65 | 11.9 – 17.9 m³/h | 417 kW |
| DN80 | 18.1 – 27.1 m³/h | 631 kW |
| DN100 | 28.3 – 42.4 m³/h | 986 kW |
| DN125 | 44.2 – 66.3 m³/h | 1.54 MW |
| DN150 | 63.6 – 95.4 m³/h | 2.22 MW |
| DN200 | 113.1 – 169.6 m³/h | 3.95 MW |
| DN250 | 176.7 – 265.1 m³/h | 6.17 MW |
| DN300 | 254.5 – 381.7 m³/h | 8.88 MW |
| DN400 | 452.4 – 678.6 m³/h | 15.78 MW |
| DN500 | 706.9 – 1,060.3 m³/h | 24.66 MW |
3 · Number, size and spacing of branches
Branches are positioned on the header by center dimensions measured from the left (or right) end. Two rules matter: the cross-section ratio and the center-to-center spacing.
4 · Choose the connection type
Outlets of different sizes and types can be combined on the same header.
5 · Add options
Parts that can be added to the manifold for easier operation and maintenance:
- Ball / butterfly valvecircuit shut-off
- Pressure gauge pocketpressure measurement
- Thermometer pockettemperature measurement
- Drain valvedrainage
- Air ventair release
- Strainerfiltering
- Meter unionheat meter installation
- UPN channel feet / bracketsupport
- Insulationheat loss
- Labelingcircuit numbers
Examples by application
Frequently asked questions
How do I choose the manifold diameter?
By the total flow rate. First find the flow rate with Q = P / (1.163 × ΔT), then choose the diameter that keeps the velocity in the header between 1.0 and 1.5 m/s. Finally, check that the header cross-section is at least 1.5 times the total cross-section of the branches.
How do I calculate the header length?
Number of branches × center-to-center spacing + two end allowances. The end allowance is usually equal to the header diameter. If you leave the length empty in the configurator, it does this calculation automatically.
What should the center-to-center spacing be?
It is the distance between the centers of two adjacent branches. If a valve, union or meter is to be fitted on the outlet, the spacing is increased by the fitting width plus an installation allowance; in practice, 2.5–3 times the branch diameter is a good starting point.
Which material should I choose?
Black steel is the usual choice for closed-loop heating, galvanized steel for domestic water and fire lines, stainless steel for hygiene or high temperatures, PPRC for hot and cold domestic water, and HDPE for cold water and pump lines.
What does the price of a manifold depend on?
Header diameter and length, number and size of branches, connection type, pressure rating and options. That is why we provide a project-specific quote instead of a list price.
How do I send my dimensions?
You can generate an A4 technical drawing in the configurator and send it via WhatsApp, or send us a hand-drawn dimensioned sketch.
Last updated: September 20, 2026 · Prepared by: Novus Energy technical team. Capacity values are calculated assuming a water velocity of 1.0–1.5 m/s and ΔT = 20 K; the final selection is based on the system design calculation.