The THMU3 is a dedicated low cost automatic monitoring and control Trace Heating unit for use in Sprinkler Systems as required by BS EN 12845/LPC/FPA(RC38 ) regulations. The unit is housed in a weatherproof plastic enclosure to IP55 rating with a latching hinged viewing window with the user access to all the controls. The unit come complete with a Temperature sensor assembly .
If the Sensor Temperature falls below the Heating Set Point ( Pre Set for 5 o/ C ) the unit will automatically provide Heating power to the primary circuit . Should a fault occur in the Primary circuit the unit will automatically switch to the Secondary circuit output. The unit’s design monitors the actual power integrity of both the Primary and Secondary heating outputs at 2 hourly intervals. The Heating tape outputs are protected via a 16 Amp Type “ B “ MCB.
The Unit has two heating Set Points 5 or 8 o/ C selected via an internal DIL switch.
The Sensor temperature is indicated by an LED Bar display. A remote ( N/O ) input is also provided for a external Thermostat/Switch to be fitted to override the sensor circuit setting.
The Temperature sensor circuit is monitored for both open & short circuit conditions with LED indication. Should a fault occur in the sensor circuit the unit will automatically provide Heating power thus providing Failsafe operation
The THMU3 monitors Trace heating in the range from 30 W to 3.0 KW for Constant wattage Heating tape or 30 W to 2.0 KW for Self regulating Heating tape. On initial setup the unit will auto calibrate the heating load of both the Primary and secondary circuits.
LED indicators provide for visual indication’s for “ Heating On “ & “ Fault “ for both primary and secondary circuits. A “ TEST “ switch is fitted to enable manual testing of both primary & secondary outputs. On any fault condition the appropriate Fault LED will illuminate together with the internal buzzer. Fault contacts (CHO & N/O ) will also operate ( failsafe operation ) in any fault condition. The System ON LED will Flash under normal operating conditions. The unit can also be used as a “ Single Heating “ monitored unit selected by a DIL switch ( The secondary output monitoring/ Switching being isolated ).
All indications and controls together with user operating instructions are provided on the inner facia. The unit is designed for ease of installation. After removable of the front lid ( via 4 front screws ) the complete internal assembly can be removed via just two screws, thus giving complete back box access.