Raychem Manual / Auto Control System (MACS)
Setup and Operation Manual
General Description
The Raychem Manual/Auto Control System uses an ambient sensing controller to provide an energy-efficient control system. The ambient sensing controller feeds power to the heater circuits only when the sensed ambient temperature is below the controller's Heater On set value and above its Low Temp Cutout set value. The temperature controller has been factory programmed and is ready for use. Refer to the following steps for proper initial setup and continuing operation of the Manual/Auto Control System (MACS).
System Setup
- To familiarize yourself with the general configuration of the MACS, refer to one of the following drawings:
- R50-050-A017 (120V incoming power)
- R50-050-A009 (208/120V incoming power)
- R50-050-A008 (240/120V incoming power)
- R50-050-A013 (480/277V incoming power)
- Refer to the project specific RIM System Control Panel drawing for proper wiring of the RIM heater sections and the RTD to the terminal blocks in the control panel.
- For proper positioning of the Ambient Sensing RTD, refer to drawing R50-052-A020.
Operation Modes
- Auto Mode Operation: When a given Control Zone's HOA switch is set to Auto Mode and the ambient temperature falls below the controller's Heater On set point, the Heater On light will illuminate and the heaters in that Control Zone will be energized. When the ambient temperature falls below the controller's Low Temp Cutout set point, the Low Temp Cutout light will illuminate and the given Control Zone's heaters will be de-energized. Once the sensed ambient temperature rises above the Low Temp Cutout set point the heaters will again be energized.
- Hand Mode Operation: When a given Control Zone's HOA switch is set to Hand Mode (manual operation), heaters in that Control Zone will be energized without regard to sensed temperature.
- Off Mode: When a given Control Zone's HOA switch is set to Off Mode, heaters in that Control Zone will be prevented from being energized without regard to sensed temperature.
Seasonal Operation
Fall Testing
Some time prior to the winter season, test each branch circuit for proper heater operation. First, confirm all branch circuit breakers are set to the off position and that the main power feed into the control panel is delivering the proper voltage. Next, set each Control Zone's 3-position HOA switch to Hand mode. Next, turn on each circuit breaker, one at a time, at 20 to 30 second intervals. Once all circuits are operational, leave them on for 10-15 minutes. If any circuit breaker trips, reset it for a second test. If the circuit breaker trips again, refer to the "RIM System Troubleshooting Guide". Once testing is complete, set the HOA switches to Off mode.
Winter Startup
At the onset of snow accumulation on the roof surface (typically November/December), turn on the branch circuit breakers and set each Control Zone's 3-position HOA switch to Auto mode. Or, if a significant amount of snow has accumulated, the HOA switch may be set to Hand mode until the snow has been melted off the RIM panels, then the HOA switches may be set to Auto mode.
Unusual Winter Conditions
Most winters start with gradual snow accumulation on the roof in November/December and continued snow accumulation through March/April. Sometimes, however, the snow either melts or slides off roof areas, and those areas remain without snow until the next snowstorm. At the option of the owner or responsible party, individual heater circuits in those areas may be de-energized (via turning off branch circuit breakers), or entire heater Sections may be turned off (via Control Zone HOA switch set to Off mode). The owner or responsible party must then remember to reset branch circuit breakers or HOA switches back to the proper operational position.
Spring Shutdown
In the spring when snow has melted off the roof surface, the owner or responsible party should de-energize (turn off branch circuit breakers) the RIM System for the summer. As mentioned above, some roof sections (primarily south facing) can be de-energized before the balance of the roof sections (north facing and shaded areas).
Ambient Temperature Sensing with Low Temp Cutout for Roof Ice Melt Systems
Heater On Set Value
When the ambient temperature falls below the Heater On set value (SEt 1), the Heater On Indication Light will illuminate, indicating that the heater circuits are energized (unless the ambient temperature falls below the Low Temp Cutout set value).
Adjusting Set Values
Two set values are available: SEt 1 = Heater On, SEt 2 = Low Temp Cutout. To toggle between which set value is displayed, press the up arrow. To change the displayed set value, hold down the square button and press the up or down arrow (the longer the arrow button is held down, the faster the value will change).
Low Temp Cutout Set Value
If the ambient temperature falls below the Low Temp Cutout set value (SEt 2), the Low Temp Cutout Indication Light will turn off, indicating that the heater circuits have been de-energized (the Heater On Indication Light remains on). The heater circuits will be re-energized when the ambient temperature rises above the Low Temp Cutout set value. Note: Low Temp Cutout can be avoided by setting its value below the lowest expected ambient temperature (for example: -150).
Controller Display Description: The controller display shows Ambient Temperature (PV=Process Value) and Set Values (SV=Set Value). Indicators include Heater On and Low Temp Cutout lights.
Example Display Values: Heater On (SEt 1) = 34, Low Temp Cutout (SEt 2) = 10.
Program Values - Ambient Temperature Sensing with Low Temp Cutout for Roof Ice Melt Applications
This section details program values for the controller used in this system. Default set values are Heater On (SEt 1) = 34 and Low Temp Cutout (SEt 2) = 10.
Diagram Description: A table lists various parameters (e.g., DTR, LTTL, SP H, RCH, RCE, RLC, RLC2) with their default values and programmed values. It also indicates that not all parameters are available for all controller models. A key indicates manufacturer's default values and programmed values.
Error Display:
| Error | Control Output Status | Meaning |
|---|---|---|
| Sensor break / over range condition | OFF | |
| Sensor reverse / under range condition | OFF |
RTD Range: -150 to 150 (Fahrenheit).
Interval Timer
ON Delay Function
This timer/function may be used in the MACS panel to limit in-rush current. Function E (ON Delay) delays operation of a group of heaters for the timer's specified interval (to reduce overall inrush current). Two events can initiate this interval: 1. Control system's HOA switch is reset from Off or Auto mode to Hand mode. 2. Control system's HOA switch is set to Auto mode and ambient conditions cause the temperature controller to call for heater power. The interval can be field adjusted for local ambient conditions. Refer to the project control panel wiring diagram and notes to determine the type of function the timer is used for, and the pre-set factory settings.
System Troubleshooting Guide, MACS
General Wiring Layout Using MACS Control System
Diagram Description: The diagram shows a typical wiring layout for the MACS control system, including components like the circuit breaker, ground fault breaker, contactor, ambient temperature sensor, junction box, power wiring, heating cable, splice tee, and end seals.
The RIM System must be installed and tested in accordance with manufacturer's installation and testing instructions.
| Symptom | Possible Cause | Remedy |
|---|---|---|
| RIM System will not heat when ambient temperature is below Heater On set point. | a. Circuit breaker and /or ground fault projection device turned off or tripped. b. Interconnect wiring has open circuit. c. Contactor coil not powering. d. Contactor defective or failed. e. Temperature controller Heater On set-point too low. |
a. Turn on / reset. b. Check continuity of wiring and connections via voltage reading at junction box. Check all splices in condolet boxes. c. Check for and reconnect any loose wires. Refer to control panel wiring diagram S-W-008 for proper wiring. d. Coil is defective and contactor must be replaced. e. Raise set-point (factory set at 34° F). Refer to Temperature Controller programming sheet. |
| Ambient temperature displayed on controller is higher than actual ambient temperature. | a. Ambient temperature controller sensor bulb is sensing a higher than ambient temperature (exposed to the solar gain or is near a heat source such as an exhaust fan). b. Sensor extension wire gauge is too small. |
a. Reposition sensor to a true ambient temperature location away from heat source. Refer to drawing R50-052-A024. b. Proper 300 Vac copper extension wire gauge size versus length: 16 gauge up to 60 ft max, 14 gauge up to 120 ft max, 12 gauge up to 240 ft max, 10 gauge up to 480 ft max. |
| Part of a circuit with a line or tee splice is not heating. | a. Improperly installed heating cable splice kit. | a. Replace heating cable splice kit, carefully following installation instructions. |
| Selec TC544A Controller displays S.br message | a. One or both ambient temperature sensor lead wires not properly connected. b. Damaged or defective ambient temperature sensor. |
a. Check all wire connections between control panel terminal blocks and ambient temperature sensor factory lead wires. Refer to control panel wiring diagram for proper terminal block connections. b. Refer to RTD Troubleshooting page to evaluate ambient temperature sensor functionality. |
| Selec TC544A Controller displays S.rE message | a. Ambient temperature sensor lead wires reversed. | a. Confirm that jumper wire on temperature controller is connected between pins 7 and 8. |
| Circuit breaker or ground fault protection device continues tripping. | a. Short circuit in heating cable or wiring has occurred. | a. Disconnect the power wires from circuit breaker and perform insulation resistance test of the power wiring at the circuit breaker. Refer to Insulation Resistance Test document H59331 in the Raychem RIM System Installation and Operation Manual (pp 15-16). If the test passes, proceed to Step “b”. If the test fails at the power wiring, perform test on heating cable at local junction box by disconnecting power wires from heating cable (for multiple heater cable runs on same circuit, test each run separately). If the test passes for each heating cable run, test power wiring. If insulation test fails for power wiring, fix or replace wiring until wiring passes test. If the test fails for a run of heating cable, check for moisture in junction box, damage to the heating cable, or improper power connection, splice or end seal installation. Repair or replace heating cable and components using approved materials. Retest. |
| b. Ground fault protection device rating is too low (e.g., 5mA). c. Defective ground fault protection device. |
b. Replace with 30mA EPD (Equipment Protection Device) ground fault protection device. c. Replace ground fault protection device as required. |
RTD Sensor Troubleshooting
- Use an accurate measuring device (quality glass or digital thermometer) to measure the ambient or surface temperature at the exact location of the RTD.
- Disconnect the RTD at the terminal blocks in the control panel and measure the resistance across the two wires.
- Consult the RTD Sensor Resistance vs Temperature chart to see if the measured resistance value matches the value the chart indicates it should be at the measured temperature.
- If the two resistance values match or are very close, reconnect the RTD to the terminal blocks and check the controller readout. Otherwise go to step 3.2.
- If the readout value matches or is very close to the measured temperature value then the system is working correctly.
- If the readout value is significantly different from the measured temperature value, check connections and components inside the control panel (refer to the control panel wiring diagram).
- If no obvious control panel wiring or component problem (such as a loose connection) shows up during the inspection, consult Chemelex.
- If the two resistance values are significantly different, then a wiring or connection problem exists somewhere between the control panel and the RTD, or in the RTD itself.
- Locate the point where the RTD’s factory leads are connected to the extension wire leads and disconnect them.
- Measure the resistance across the RTD’s two wires.
- Consult the RTD Sensor Resistance vs Temperature chart to see if the measured resistance value matches the value the chart indicates it should be at the measured temperature.
- If the two resistance values match or are very close, then there is a wiring or connection problem somewhere between the control panel and the RTD. Consult Table 1, below, for proper wire gauge versus extension wire length. Also check that all wire connections are clean and secure.
- If the two resistance values are significantly different, then the RTD must be replaced.
RTD Extension Wire Requirements
| Wire Gauge | Maximum Length |
|---|---|
| 16 gauge | up to 60 ft max |
| 14 gauge | up to 120 ft max |
| 12 gauge | up to 240 ft max |
| 10 gauge | up to 480 ft max |
Chart Description: The RTD Sensor Resistance vs Temperature chart graphically represents the relationship between ambient temperature and RTD resistance. The x-axis shows Ambient Temperature (°F) from 0 to 120, and the y-axis shows Resistance (ohms) from 90 to 120. The chart shows that as ambient temperature increases, the resistance of the RTD decreases.
Contact Information
North America:
Tel: +1 800 545 6258
Email: info@chemelex.com
©2025 Chemelex. All Chemelex marks and logos are owned or licensed by Chemelex Europe GmbH or its affiliates. All other trademarks are the property of their respective owners. Chemelex reserves the right to change specifications without notice.
Document Number: RAYCHEM-IM-H59376-RIMMACS-EN-2504
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