Guideline for the design of KSP to go® radiant panels
Introduction
Nomenclature:
Basics
Expansion
Aluminium and steel stretch differently when heated. The coefficient of linear thermal expansion of steel is 12.0 · 10-6 [m / mK] and of aluminium 22.2 · 10-6 [m / mK], which is nearly twice as high. Our designers have solved this problem as follows: As described above, the steel pipes and the heating surfaces are not welded together, so they can expand separately. When connecting several panels, the aluminium elements are not fixed together. The bottom covers are only attached to the pipes. In this way, only the pipe extension has to be considered.
- Determine the length of the suspensions, the total length of the RP strip (LBand), and the position of fixed points (rigid suspensions, direct screwing, etc.)
- Calculate the expansion Δl = LBand * (tmax,operation - tmin,montage) * 12,0 · 10-6
- Since the expansion is decisive only at the end of the strip, take into account the length of the last suspension. This one must be slightly longer to be flexible in the case of an expansion.
- If necessary, check and correct the planned suspension: This one must take into account Δl at maximum possible extent
Note
Pay close attention to the expansion, especially when low slopes or high temperatures are planned.
How to best compensate for expansion
- Use flexible suspension systems (wire ropes, nodal chains)
- Use longer suspensions, if possible
- If you plan to use the A-type or Y-type suspension for strips longer than 20 m, you should consider using at least one V-type suspension.
- If you are planning the suspension points on the ceiling, count in the changed distances of the RP suspension axes at operating temperature.
Connecting of radiant panel strips
Due to the radiant heat principle, RP can supply exactly the required heat. The only thing that matters is planning. Different workstations in a hall are influenced differently by the surrounding conditions. It is obvious that in a hall of e.g. 40 x 100 m with poorly insulated windows or walls, the well-being of an employee, in the middle of the hall, would only be slightly or not at all influenced. However, if this employee had his workplace on a cold exterior wall, the situation would be quite different. The requirements for hall heating are therefore very different. The heat emission should be planned according to the requirements. On cold outside walls, more heat is needed than in the centre of the hall. With RP, we can easily compensate for this. Either the RP is planned to be wider on the outer walls than in the middle, or the panels are so connected that the RP along the outer walls have higher water temperatures. [1]
[1] Kabele, K., Hojer, O., Kotrbatý, M., Sommer, K., Petráš, D. Energy efficient heating and ventilation of large halls. Rehva guidebook no. 15. REHVA. Bruxelles 2011. ISBN 978-2-930521-06-0
If you plan radiant panels for the first time:
- Check the minimum flow rate if you connect all the heating strips in a room into a series (only one heating circuit). Check the pressure losses (in most systems, heating circuits can be arranged so, that the pressure losses are less than 50 kPa - 500 mbar, including pipes and valves)!
- If the pressure losses are larger, divide the strips into several heating circuits (but connect some strips parallel).
- Check the pressure losses in the pipes and make a hydraulic adjustment.
Let yourself be inspired.
Best regards from Herrieden, Germany
Yours radia.expert team
Calculation example
You plan a room with the following dimensions: L x W x H = 6 x 4 x 3.5 m Heat losses: 1,700 W (ti = 18 ° C)
Condensing boiler: (tw1 =70 °C, tw2 = 55 °C)
Our online calculator calculates: 2strips, each 4 meters long, KSP to go®600
Result output:
Box Nr. | Content | Piece | Qi,pc [W] | Qi,BAND [W] | Qi,TOT [W] |
---|---|---|---|---|---|
Box 1.2 | KSP to go®600 / 2 m | 4 | 554 | 1108 | 2216 |
Box 4 | KSP to go® Distributor kit 600 | 2 | 135 | 135 | 270 |
Box 7 | KSP to go® Connection kit 600 | 2 | 0 | 0 | 0 |
Total | 1.244 | 2.486 |
- Calculate the mass flow in a strip (parallel connection):
Determine the pressure losses of all your components on the basis of your results. - According to diagram 1, the pressure loss of the KSP to go®600 panels is:
approx. 1 Pa/m (0,01 mbar/m).
Δp1 = R ∙ Li,Band = 1 Pa/m ∙ 4 m = 4 Pa (0,04 mbar) - According to diagram 2, the pressure loss of the KSP to go®600 distributor is: ΔP2 = approx. 30 Pa (0,30 mbar).
- According to diagram 2, the pressure loss of the KSP to go® corrugated hoses is:
Δp3 = ca. 45 Pa (0,45 mbar). - Add all pressure losses:
ΔpTOT = Δp1 + Δp2 + Δp3 = 4 + 30 + 45 = 79 Pa
As you can see, the pressure losses in this case are minimal. In general, these will be very low in most of the KSP to go® projects. This is why the control capability of the KSP to go® range is generally very high.
Note: If you calculate high pressure losses > 20 kPa (> 200 mbar) this is a signal that the KSP to go® range for this project is not suitable. In this case, you can change the product series and switch to Radia-Expert KSP. Send your project to: info@ksp2go.com and our technicians will help you.