Guideline for the design of KSP to go® radiant panels

Introduction

This instruction serves as a guideline to heating engineers, who want deal more intensively with the design and technology of radiant panels. It aims to help you avoiding mistakes in the planning and finding the optimal connection possibilities.

Nomenclature:

Our KSP to go® ceiling radiant panels are made of: 4, 6 or 8 pcs base elements of lamellas of 150 mm width, with 4, 6 or 8 steel header pipes 28 x 1.5 mm, recessed in 0.8 mm aluminium sheet, material grade ALMgMn H26, and frictionally via metal heat conduction strips with the radiation surface connected. This ensures an optimum heat transfer and a homogeneous heating behaviour of the entire pipe surface on the panel. The panels are provided with four suspension points. Basic element lengths 2 m and 3 m, side wing 50 mm, total height 70 mm.

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 (L_Band), and the position of fixed points (rigid suspensions, direct screwing, etc.)
Calculate the expansion Δl = L_Band * (t_{max,operation} - t_min,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

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.

wrong execution

correct execution

1. suspension before expansion, 2. suspension at maximum expansion, 3. radiant panel, Δl maximum expansion

Connecting of radiant panel strips

1. Individual connection
4 individual heating circuits

2. Parallel connection
4 parallel heating circuits

3. Serial connection
1 heating circuit - serial connection

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

	Kvs [m³/h]
Distributor kit KSP to go®600 (Box 4)	7,40
Distributor kit KSP to go®900 (Box 5)	8,13
Distributor kit KSP to go®1200 (Box 6)	6,12
2 pcs KSP to go®-stainless steel corrugated hose	5,94

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 (t_i = 18 ° C)
Condensing boiler: (t_w1 =70 °C, t_w2 = 55 °C)
Our online calculator calculates: 2strips, each 4 meters long, KSP to go®600

Result output:

Box Nr.	Content	Piece	Q_i,pc [W]	Q_i,BAND [W]	Q_i,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 ∙ L_i,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:

Δp_TOT = 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.