Heat-Timer® Corporation

Multi-MOD (Modulating)

Multiple Boiler Modulating Controls for Heating and Cooling Systems

Available with optional Internet, BACnet, or Modbus communication


The Multi-MOD is an outdoor reset or set point control. It is the perfect control whenever multiple fully modulating stages are required for heating or cooling applications. The Multi-MOD controls the on/off and the modulation of each stage to maintain precise set point control using PID type control logic.

Controls Voltage, 4-20 mA, or 135 Ω modulating motors. The Multi-MOD is designed to accurately control the output from 0 to 100% of modulation for large variety of motors ( 0-5V, 0-10V, 1-5V, 2-10V, 4-20mA, and 0-135 Ω ) One Multi-Mod can even control two different types of motors.

Only One Sensor. The Multi-Mod requires only one sensor located in the common output header of all stages.

Digital Display of all System Settings. The Multi-MOD’s 80 character alphanumeric digital display names each system parameter in plain English and shows its precise value. The easy to follow menu system allows user to quickly make changes to any system setting without having to learn any specialized codes or keyboard commands. Password protection is available to prevent unauthorized users from making adjustments to control settings.

Automatic Rotation among Stages. Rotating the first stage to be activated on a call for output promotes even wear on each stage. The Multi-MOD has three modes of rotation : Manual, First ON/First OFF, or automatically every selected time period from every hour to every 7 days.

Outdoor Reset Capability. The Multi-MOD can be connected to existing or new Heat-Timer outdoor reset controls (HWR for hot water heat, or MPC for steam heat). The Multi-Mod also has built in hot water reset with adjustable reset ratios,offset and outdoor cutoff.

Connects to Energy Management Systems. All Multi-MODs can be disabled by an Energy Management System(EMS) or other controller when there is no output requirement. Multi-MODs that control temperature systems can also accept a 4-20 mA input signal from an EMS to adjust the set point according to outdoor temperature or other factors.

Monitors Stage Status. The Multi-MOD is designed to accept Lockout inputs from each stage. If any stage is in Lockout, the Multi-Mod will automatically skip it when adding more capacity. If a stage goes into Lockout during normal operation, the next stage will be activated immediately to maintain the desired output capacity.

System Output is Active when Any Stage is Active. This output can be used to activate a system pump, combustion air damper, or perform any other function that is required when any stage is active. A System Prove input checks the status of components activated by the System output before stages can be activated.

Internet Communication Upgrade Available. The Multi-MOD can be upgraded to communicate over the Internet to monitor and control all the Multi-MOD functions from a web browser. The Internet upgrade package also allows the Multi-MOD to accept sensors, to monitor their status, and to provide alarms if the sensor values are not in the correct range. In addition, Heat-Timer can provide a cellular Internet connection to the control (See Internet communication ).

BACnet IP or MSTP Communication Upgrade Available. The Multi-MOD can be upgraded to communicate over a BACnet IP or MSTP network system to monitor and control all Multi-MOD functions.

Modbus Communication Upgrade Available. The Multi-MOD can be upgraded to communicate over a Modbus RTU network system to monitor and control all Multi-MOD functions.

DHW with or without priority on Internet packages. When a Multi-MOD that is operating a Hydronic system is upgraded to Heat-Timer’s Internet ICMS system, it will have DHW functionality as a feature with multiple settings to customize its operation.

Additional features include: A purge timer, a low fire adjustment, a firing point setting for the next stage based on the firing rate of the current stage, a lag stage timer, a last stage hold adjustment, and many others.

  • Only one sensor is required (regardless of the number of stages being controlled)
  • Digital display of: System temperature or pressure, system set point, control parameters
  • Display of each boiler modulation percent
  • Manual overrides for each stage
  • Automatic or manual lead stage rotation
  • Can be cascaded to provide as many stages as needed using up to two Extension Panels (each can control up to 8 stages)
  • Plug-in relays
  • RWB mod motor output and N.O. contacts for each stage
  • DHW Operation option with Internet controls
  • Internet Communication option
  • BACnet IP or MSTP Communication option
  • Modbus RTU Communication option
  • Johnson Metasys® compatible
  • Can be field configured for heating or cooling
  • Can be field configured for setback (from external clock, temperature sensor, aquastat, etc.)
  • Temperature Multi-Mods can be configured to input a 4-20mA signal from an EMS system
  • Locking NEMA-1 enclosure
  • Solid state sensors can be extended up to 500′ from the control
  • Accuracy of ±1ºF or 1% of full scale
  • Network input allows the Multi-Mod to connect to multiple sensors (MIG Sensors, Neuron Sensors, Wireless Sensors, Water Meter, Gas Meter, Oil Level, Smoke Alarm) using the Internet communication package to monitor and fine tune its operation
  • Multi-MOD is UL Listed
  • Multi-MOD is NYC DEP Approved (DEE #2-03)
  • Built-In Outdoor Reset
  • Adjustable outdoor temperature cutoff
  • Pressure lockout
  • Battery backup of program clock
  • Digital display
  • Self diagnostics
  • Solid state sensors can be extended up to 500′ from the control
Multi-MOD Platinum 0 – 135 Ω Standard 926650-135
Multi-MOD Platinum 0 – 135 Ω with BACnet Communication 926650-135-BAC
Multi-MOD Platinum 0 – 135 Ω for Internet Communication (Ask about our Cellular Internet service) 926650-135-RINet
Multi-MOD Platinum 0 – 135 Ω with Modbus Communication 926650-135-BUS
Multi-MOD Platinum Current/Voltage Standard 926650-C/V
Multi-MOD Platinum Current/Voltage with BACnet Communication 926650-C/V-BAC
Multi-MOD Platinum Current/Voltage for Internet Communication(Ask about our Cellular Internet service) 926650-C/V-RINet
Multi-MOD Platinum Current/Voltage with Modbus Communication 926650-C/V-BUS
Internet Communication Upgrade (Ask about our Cellular Internet service) 900340-20-RINet
BACnet Communication upgrade 900204-20-BAC
Modbus Communication upgrade 900204-20-BUS
Extension Module adds 8 additional stages to the Multi-MOD (order Output cards and relays separately) 926650-Ext
Output Card Current Voltage for (4-20mA, 0-10V, 0-5V, 2-10V, 1-5V) 900201-C/V
Output Card 135 Ω 900201-135
Relay Plug 24VDC for the additional stages 500054-00
Wireless Network Sensor System

I installed Java. But when I login to the ICMS, I get a Java error. How can I fix that?
You will need to uninstall all the JAVA, JAVA 3D, and JRE upgrades first. For that you will need administrative rights on the computer. Then, download the latest JAVA and JAVA 3D through the ICMS System Requirements webpage. Close all browser windows. Also, make sure that both your Antivirus, and Antimalware are either set to accept the JAVA installation or to be fully turned off. Now you can install the latest JAVA. After the installation is complete install the JAVA 3D. Note that MAC OS 10.7 and later does not support the JAVA 3D.

Connected the control to power correctly but no display or LED is on.
Most controls are equipped with a fuse on the back of the main board to help protect the control against power surges. Check the fuse on the back of the control using a continuity meter. If continuity does not exist, replace the fuse with the same fuse size and rating.

My hot water outdoor reset control is giving me too much heat. What should I do?
Check if the control has any of the following: •Reset Ratio and Offset – If excessive heat occurs only in certain weather conditions, adjust the Reset Ratio and Offset. If excessive heat occurs year round, reduce the Offset. •Boiler Mode Settings – The control will only operate boilers their mode is set to Auto or Standby. Check to if any boiler stage is set to Manual or On. •Multi-Stage Control Settings – The Last-Stage-Hold will allow only the Lead boiler to stay on for an additional number of degrees. If the setting is too high, and only the Lead boiler is on, the system can over heat. Reduce the Last-Stage-Hold setting. •Domestic Hot Water Call – On a DHW call, the System Set Point will rise to the DHW Set Point or 200°F. If the increase in temperature is during DHW call, see about using any of the DHW Priority options available on the control.

Why doesn’t my Heat-Timer Visual Gold Remote Communication system show the history of the space temperatures?
Question (continued): I can communicate with the system and set any of the panel parameters, but when I go to check how well the system is holding space temperatures, I get only blanks.
To keep a record of the space temperatures (as well as the outdoor temperature and system sensor), the Remote Intercept Platinum or Gold control must know the current time and date. Either the Date and Time were not set or the battery has died and the control power was down for at least a short period of time. Use the SPT (Set Present Time) command. This will prompt for the present date and for the time of day. Once the system has this information, it will keep a log of the histories. If the battery did die, it must be replaced as it keeps the clock active.

Why is my control not turning the boiler on even when there is a call for heat?
First, check the display for any messages as many of the heating controls have several external inputs that can be used to shutdown the boiler. If the message relates to the PROVE input, it may not be shorted or the Prove terminal Jumper is not installed. In this case, the control will not start the boiler. If the message relates to the Shutdown input, the Shutdown maybe shorted remotely. If the message relates to the T-stat input, the T-Stat input maybe opened remotely.

My outdoor sensor reading does not match the actual temperature.
The outdoor sensor measurement may vary based on its location and its sun exposure. In most cases it will never match a weather station that is located several miles away. most current Heat-Timer controls have a Trim feature which allows the sensor reading to be slightly modified just a few degrees to satisfy similar circumstances. If the difference was large, then check the sensor by disconnecting one of its wires from the control. The control should read OPEN. If not, contact technical support.

Why is my temperature sensor reading Open on the control display?
Remove the sensor wires from the control and check for continuity across the wires with and meter. If no continuity existed, check or replace the wires. if continuity did exist, then contact technical support.

Why is my temperature sensor reading Short on the control display?
Remove one of the sensor wires from the control. The control display should change and display OPEN. Then check the sensor wiring specifically around spliced areas. If wiring was good, then disconnect the sensor wires from the control and check the sensor wires with an Ohm meter. The readings should match the sensor temperature chart on the control manual. It not, then replace the sensor. If after removing one of the sensor wires the control read SHORT, then contact tech support.

Why does my Heat-Timer hot water reset control (HWR) flash OPN instead of the outdoor temperature?
Heat-Timer controls use the code OPN when they can not detect a sensor. For example, if someone were working in the building and cut the wires leading to the outdoor sensor, the HWR would begin to flash OPN to signal that the sensor was no longer attached. To find the source of the OPN reading, first make sure that the outdoor sensor wires are attached to the input terminals (the IT terminals in the case of an HWR). Then place a jumper wire across the input terminals (IT). The display should change to read SH-I (the code for a shorted sensor). If the display does change, the HWR is working properly. Check the wires to make sure they are not broken, and locate the sensor to see if it has been damaged.

At times I notice the pressure reading on my Heat-Timer Multi-MOD is slightly above the pressure set point. Does this mean there is something wrong with the Multi-MOD?
The set point on a Multi-MOD is not a high limit as it is on many other pressure controllers. The Multi-MOD is designed to control multiple full modulation burners to maintain a given system pressure (or temperature), not to be used as a system high limit. The Multi-MOD will not necessarily bring the boilers down to low fire as the pressure approaches the set point. Instead, the set point of the Multi-MOD is the average pressure the Multi-MOD will modulate the boilers to maintain. Therefore, it is perfectly normal for the pressure to rise slightly over the set point. Set the Multi-MOD set point to the pressure you would like the system to hold, not the maximum pressure the system should reach.

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