AKO-15226 Electronic Controller User Manual

AKO-15226 Electronic Controller

Product Information Constant Wattage W/m Parallel Heating Cable

The AKO-5231 heating cable is designed for frost heave protection in cold room stores. These stores have a layer of thermal insulation to reduce the heat that passes through the floor into the room and cools the subsoil. However, compensation has to be made for the amount of heat passing through to prevent the subsoil from freezing, causing frost heave. The AKO-5231 heating cable is recommended by the International Institute of Refrigeration as one of several forms of protection against frost heave.The cable ensures a constant wattage per meter, no matter what its length. This means that it can be cut-to-length on site at the moment of its installation. The AKO-5231 heating cable is easy to install and offers safety at low installation and maintenance costs.

Characteristics

The AKO-5231 heating cable is of the parallel type with constant wattage per linear meter. The heating element comprises a chrome-nickel wire that coils spirally around the two insulated cable conductors, with which it makes alternate contact at specific points. The cable forms an internal system consisting of several parallel resistances that are fed by the two conductors.

Length of Cable to be Installed

The wattage required in order to avoid frost heave in cold stores is lower than 20 W/m2 when certain insulation thicknesses are installed. For every square meter of floor surface, 2 meters of AKO-5231 heating cable should be installed.

Accessories

In order to ensure that the heating cable is correctly installed and that the installation is running properly, the appropriate accessories must be used. The characteristics of these accessories are described in the corresponding publications. The probe PTC or Pt100 can be selected from different models, ranging from 2m to 30m in length.

Product Usage Instructions

The heating cables must be installed in straight lines forming a grille shape, with a maximum distance of 500mm between each one. For safety reasons, the cables should be installed in plastic protection tubing with a minimum interior diameter of 19mm (25mm recommended).

Constant wattage W/m parallel heating cable for “frost heave” protection in cold room stores

Description

Cold stores are built on a layer of thermal insulation in order to reduce part of the heat that passes by conduction through the floor into the room, thus cooling the subsoil. Despite the thermal insulation of the floor, compensation has to be made for the amount of heat passing through it in order to prevent the subsoil from freezing. Were the latter to freeze, it would expand upwards with sufficient strength to lift and crack the floor of the cold store, even going as far as to weaken the foundations of the building. This effect is known as “frost heave”. The International Institute of Refrigeration recommends several forms of protection against frost heave, one of which is the use of electric heating elements placed beneath the thermal insulation and lain on the floor in the shape of a grille.

Heating cable

The AKO-5231 heating cable has been especially designed for this protection system and offers advantages such as:

Easy installation
The cable ensures a constant wattage per metre, no matter what its length. This means that the cable can be cut-to-length on site at the moment of its installation.

Safety at a low installation and maintenance costs
These advantages make this the best and cheapest technical solution for avoiding the problem explained in the section entitled “Description”.

Characteristics

The AKO-5231 heating cable is of the parallel type with constant wattage per linear metre. It is characterised by its heating element, comprising a chrome- nickel wire that coils spirally around the two insulated cable conductors, with which it makes alternate contact at specific points. The cable forms an internal system consisting of several parallel resistances that are fed by the two conductors.

Operation

On applying voltage between the two cable conductors, the heating wire receives this same voltage between contact points A-B, B-C, CD, etc. This means that the output power per linear metre of cable remains constant and independent of the cable length: the longer the cable, the greater the total power, but the power per linear metre is always the same. This kind of cable can be cut-to-length and finished on site, no matter what the multiple length of the heating zone and to be connected to 230 V supply.

Length of cable to be installed

The wattage required in order to avoid frost heave in cold stores is lower than 20 W/m2 when these insulation thickness are installed:

(ºC) Minimum cool temperature (ºC)|

Insulation thickness (mm)

Thermal conductivity / λref. at 10 ºC = 0.034 W/(mK)

---|---
-10| 50
-20| 100
-30| 150
-40| 200

Heating cable length to install:
-2 m of AKO-5231 cable per m2 of floor surface

Accessories

In order to ensure that the heating cable is correctly installed and that the installation is running properly, the appropriate accessories must be used. The characteristics of these accessories are described in the corresponding publications

Length probe PTC or Pt100 to be selected from the following models

The probes must be installed in such a way that they can be recovered and, when required, extended by means of a shielded cable.

Application instructions

The heating cables must be installed in straight lines forming a grille shape, and with a maximum distance of 500 mm between each one. For security’s sake, the cables will be installed in plastic protection tubing with a minimum interior diameter of 19 mm (25 mm recommended). The installation will be carried out according to the given example on the condition that it is possible to reach the two opposite sides of the cold store floor.

If the two opposite sides of the floor cannot be reached, different solutions can be adopted; some of which are given below by way of an example:

1. A Install manhole boxes in the floor through which to join the straight stretches of tubing, thereby permitting easy installation and maintenance.
2. B Install junction boxes to the lower part of the side walls.
3. C Install junction boxes beneath the thermal insulation and at the same height as the tubes, at 500 mm from the side walls.
4. D Install heating cable with a double circuit (one in service and one as a standby), directly burying the cables without a protection tube.

• The two cables will be installed together. The cable in service will be controlled by the thermostats and the other standby cable will be left inactive. Both cables will be installed with all of their kits and must reach the inside of the junction boxes.
• The end kits must stay on the outside and on the same side as the input boxes.
• The standby circuit will not be activated unless it is required for use due to a fault in the installation.
• Once the cable with its corresponding kits has been connected to the input boxes, and immediately after having lain the levelling mortar, but before covering it with the insulating layer, the following must be gauged and checked:
  • The resistance of the insulation (with the help of a megohmmeter) between the conducting cables and the earth in order to ensure that the cable insulation has not been damaged during installation.
  • The value of the resistance obtained must be over 20 MW at 1000 Vdc.
  • Energise the cable to ensure that neither the leakage detection nor the circuit breaker switches blow.
  • Check that the intensity of the cable corresponds to the number of metres installed

Should any of the measurements not have past the test correctly, remove the cable and check it. This is why the measurements must be taken immediately because, once the concrete has dried, it is no longer possible to remove the heating cable.

Temperature control

It is advisable to install 1 thermostats for each 90 m2 of floor area. AKO-15226 thermostat with a temperature Set point of 5 ºC, placing the probe sensor at the most unfavourable point and at an equal distance between the two heating cables, in order to see and control the ground temperature and save energy. Example of the layout of an electric connection:

AKO ELECTROMECÁNICA , S.A.L. Avda. Roquetes, 30-38 08812 Sant Pere de Ribes. Barcelona Spain www.ako.com

We reserve the right to supply materials that might vary slightly to those described in our Technical Sheets. Updated information is available on our website.

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