Thermalec Products
– 24THR Instruction Manual (rev 2)
Page 1 of 5
1) INTRODUCTION
The Thermalec THR heater is designed for use with swimming pools, spas and other similar installations. To
prevent damage to the heater it must not be operated unless it is fully flooded with a sufficient flow of pool
water. An interlock is fitted, ensuring that the heater cannot be operated unless the filter pump is running.
A temperature controller is fitted to allow control of the water temperature in the range 15 to 45
C. The
maximum water temperature is limited to 52
C by a safety thermostat.
The heater is designed to have a maximum operating pressure of 2 bar (30 psi). Exceeding this limit will
operate the pressure relief valves located on the heater vessel.
The IP rating of the heater is IP21 and it should be installed in a weatherproof enclosure with good drainage
The pool temperature will gradually rise if the heater has been sized according to our published sizing charts.
Our Economy 7 charts are sized such that in early May (of an average year) an outdoor pool with a solar cover
will reach the required temperature in about five nights. The actual time taken to reach temperature is
determined by the ambient air and water temperatures and by the overall heat losses from the pool.
2) INSTALLATION
Regulations & Codes of Practice
. The heater should be installed by a competent person in accordance with
the relevant standards for the country of use. In the UK these standards are BS 7671 (IEE Regulations, 16th
Edition) and the SPATA standards. Electrical installations for swimming pools in the UK are classified as
‘Notifiable’ under Part P of the Building Regulations 2005. This means that a qualified electrician, registered
with a self-certification scheme, must carry out the work. Alternatively, another person may carry out the work,
but it must be notified to the local authority who will arrange for inspection & testing to be carried out.
Plant Layout.
Chemical dosing systems should not be installed adjacent to the heater. If installed upstream of the heater it
must be before the filter. If installed downstream, a check valve must be fitted to prevent backflow of chemicals
when the filter pump is not operating. There should be a drop in level between the pipe leaving the heater and
entering the dosing system.
The pipe system should have valves to isolate the heater. A shut off valve should be included in the bypass to
stop the flow around the heater when not required. The flow rate through the heater should be chosen with
regard to the table below:
