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:

Radiant panels

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.

Strips

Two and more KSP to go^® radiant panels can be joined together with press fittings to form longer sections. Separate covers and matching insulations are available for the connection points. The required distributors are available as a set and are also connected to the radiant panels with press fittings.

Water temperature differences

Difference between flow and return temperature.

Working temperature differences

Difference between average water temperature and planned room temperature.

Heating circuit

Single or multiple heating strips can form a heating circuit. In each heating circuit, the return temperature is inevitably lower than the flow temperature.

Suspensions

KSP to go^® radiant panels have to be suspended on flexible systems (wire ropes or nodal chains). Each traverse has two suspension points. The suspensions can be lead directly vertical to the ceiling (H- Type), can be suspended from a suspension point (A- Type; Y- Type) or can be suspended from the ceiling at an angle (V- Type).

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

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.

wrong execution

right 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

A) Heat distribution

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

B) Minimum flow rate

The heat output of our RP was tested by the HLK in Stuttgart according to DIN EN 14037. An essential prerequisite for achieving the specified heating capacity is that the water flow in the pipes is turbulent. This, in turn, requires a Reynolds number (Re)> 4000 as the rated variable. The Reynolds number is a measure in the flow gauge and describes the ratio of inertia to toughness. For RP, it is the result of a function consisting of flow velocity, pipe diameter and the kinematic viscosity of the fluid. In fact, the greater the flow velocity and the tube diameter, the greater the Re. The larger the viscosity, the smaller the Re. If the strips are mounted horizontally (without inclination), a sufficient flow velocity is also important for the venting. Air bubbles are driven to the highest point of the system, ideally in a return line, with connected venting.

C) Reduce piping and valves to a minimum

Each valve and screw connection in the ceiling area is a potential source of future leakage. Today, control valves are very popular and cheap, but they are also the largest weak point in the system and a repair under the hall roof is always relatively expensive. The parts, relevant for the service life of our RP, are pipes and press fittings. These can easily reach a service life of 20 years and more. Due to our high production quality, we give 10 years warranty on our ceiling radiators.

D) Pressure losses

The pressure losses in the KSP to go^® range of goods can be divided as follows:

Pressure losses of radiant panels Δp1
Pressure losses of distributors Δp2
Pressure losses of stainless steel corrugated hoses Δp3

The pressure losses of the radiant panels Δp1 can be found in Diagram 1. There you will find the data for each KSP to go^® type depending on the flow rate. The values given are the pressure losses per meter and must always be multiplied by the total length of the heating tape.

The pressure losses of the KSP to go^® distributor Δp2 can be found in the diagram 2. For clarity are the total values per strip already summed, so you can directly transfer the value in Pa or mbar. Alternatively, you can calculate the value yourself using the kvs values in the following table.

	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

Diagram 1

KSP to go^® radiant panels pressure losses

Diagram 2

Pressure losses of KSP to go^® accessories

For the calculation example

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.

KSP to go^® radiant panels are an extremely comfortable and energy-efficient heating system. They offer cozy warmth, freedom of drafts, dust and annoying noises. Admittedly, the initial investment is slightly higher than other heating systems. However, this pays for itself quickly through energy efficiency, maintenance-free operation and an extremely long service life. Hardly any product has such low lifecycle costs.

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:				1.243	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.

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: This email address is being protected from spambots. You need JavaScript enabled to view it. and our technicians will help you.

Guideline for the design of KSP to go® radiant panels