Thermalec Products
– 24THR Instruction Manual (rev 2)
Page 2 of 5
Flow Rate
15kW
18kW
21kW
24kW
Hard water maximum
- use bypass above this rate
- minimise scale formation
4000 gal/hr
303 l/min
4000 gal/hr
303 l/min
4000 gal/hr
303 l/min
4000 gal/hr
300 l/min
Soft water maximum
- use bypass above this rate
- improves element life
2000 gal/hr
152 l/min
2000 gal/hr
152 l/min
2000 gal/hr
152 l/min
2000 gal/hr
152 l/min
Minimum
300 gal/hr
25 l/min
360 gal/hr
30 l/min
420 gal/hr
35 l/min
480 gal/hr
40 l/min
To calculate the exact flow rate allow the pump to run without the heater on for a few minutes and then take a
reading of the thermometer. Then switch the heater on and allow about five minutes for the temperature to
stabilise before taking a second reading. The difference between the two readings gives the exact temperature
rise for that flow rate. Use the following formulae to establish the rate:
Heater kW rating x 190
Flow (Gallons/hour) = ---------------------------------------
Temperature rise in degrees C.
Heater kW rating x 14.4
Flow (Litres/min.) = --------------------------------------
Temperature rise in degrees C.
Plumbing.
To enable the supply cable to be inserted through the back panel, allow space behind the heater
equal to at least the depth of the heater casing. The minimum clearance above the heater should be 400mm.
Flow direction through the heater is left to right, allowing the temperature controller to sense the temperature
coming from the pool. The direction may be changed by reversing the probes of the control thermostat and the
safety thermostat, as follows:
a) Switch heater circuit breakers to OFF;
b) Switch main power supply and pump interlock supply to OFF;
c) Remove main cover;
d) Reverse two probes. Controller probe is situated at the left-hand end of the element plate; the safety
thermostat probe at the right (marked with a short length of white sheathing);
e) Move the thermometer probe to the empty pocket on the left-hand side;
f) Reinstate the top cover before reconnecting connecting electrical supplies.
Pipe connections are stub flanges to suit 2" nominal bore pipe (uPVC or ABS). If using ABS the solvent
jointing compound must be suitable for both materials. Reducers may be fitted to suit smaller pipes. It is not
necessary to fit unions either side of the heater as the stub flanges are easily disconnected from the heater, by
removing the nuts securing the aluminium backing flanges to the heater. In very tight installations, the studs
themselves may be unscrewed.
Levelling Screws are provided for use in the four holes in the base of the heater to level it, but more importantly
they will stop the heater rocking on its base. If the heater is shelf mounted, the holes may be used to screw the
heater down, either by bolting down with the packing screws from underneath, or by using wood screws from
the top. If the heater is connected with rigid pipework and is floor mounting, the levelling screws, together with
the pipes and cable will make the heater stable.
Electrical Installation.
All work must be carried out by a “competent person” as defined in section 2.
To provide earth leakage protection, a Residual Current Device (RCD) must be fitted to installations involving
swimming pools or spas. The RCD must be rated to carry the current drawn by the heater (see table below)
and the current drawn by other items of equipment on the same supply
