Heat Controller, Inc. | DXM2 UNIT CONTROLS | Application, Operation, & Maintenance Manual |
DXM2 Controls
will change to the appropriate Heating Stage 3 airflow. With continuing Heating Stage 3 demand, EH2 will turn on after 10 minutes. EH1 and EH2 are turned off immediately when the Heating Stage 3 demand is removed, and the control reverts to Heating Stage 2 Mode. During Heating Stage 3 Mode, EH2 will be off (or will turn off if already on) if LT1 is greater than 45°F AND LT2 is greater than 110°F (LT2 greater than 110°F includes the condition that LT2 is shorted). This condition will have a
Emergency Heat - In Emergency Heat Mode, the selected fan output(s) will be activated at high speed or the appropriate airflow for Emergency Heat, and EH1 is turned on immediately. With continuing Emergency Heat demand, EH2 will turn on after 5 minutes. EH1 and EH2 are turned off immediately when the Emergency Heat demand is removed. The selected fan output(s) will turn off after the selected heating blower off delay and the control reverts to Standby Mode.
Cooling Stage 1 - In Cooling Stage 1 Mode, the selected fan output(s), Compressor, and RV relays are turned on immediately. If configured as Stage 2 (DIP1.2 = off), then the compressor and fan will not turn on until there is Stage 2 demand. The Compressor relay is turned off immediately when the Cooling Stage 1 demand is removed. The selected Fan output(s) will turn off after the selected cooling blower off delay, and the control then reverts to Standby Mode. The RV relay will remain on until there is a Heating demand. If there is a Master/Slave situation or a Dual Compressor situation, all Compressor relays and related functions will track with their associated DIP1.2.
Cooling Stage 2 - In Cooling Stage 2 Mode, the selected Fan output(s), Compressor, and RV relays remain on. The Compressor Speed relay is turned on, and
Night Low Limit (NLL) Staged Heating - In NLL Staged Heating Mode, the OVR input becomes active and is recognized as a call for Heating (OVR is an alternate means of calling for Heating Mode). In NLL Staged Heating Mode, the control will immediately go into Heating Stage 1 Mode with an additional 30 minutes of NLL demand, the control will go into Heating Stage 2 Mode. With an additional 30 minutes of NLL demand, the control will go into Heating Stage 3 Mode.
Blower Configurations – The DXM2 may be configured to operate several different blowers and blower configurations. The configurations include:
a)2 Speed PSC Blower – The default configuration of the DXM2 is to operate for a 2 Speed PSC blower, with the K1 relay operating as a blower enable relay, and the
K2 relay operating as a blower speed relay. With this configuration, the blower enable relay is momentarily
will be active and K2 will be inactive. For high speed blower operation (High Speed Constant Fan, Heating 2, Heating 3, Emergency Heat, Cooling 2), K1 and K2 will be active.
b)ECM Blower – If the DXM2 is configured for an ECM blower, OR an ECM blower is detected, the DXM2 will directly control an ECM blower using selected or default airflows for each operating mode. When operating an ECM blower, the K1 relay becomes a loop pump relay active anytime the compressor relay is active, and the K2 relay becomes a HWG pump relay.
c)Single Speed PSC Blower – If the DXM2 is configured for a single speed PSC blower, the K1 relay will operate as the blower relay, and the K2 relay becomes a HWG pump relay.
d)Dual Stage PSC Blower – If the DXM2 is configured for a dual stage PSC blower, the K1 relay will operate as a blower enable relay, and the K2 relay will operate as a blower speed relay. The dual stage PSC configuration operates very similar to the 2 Speed PSC, except the blower enable relay is not
e)No Blower – If the DXM2 is configured for no blower (TTS and TTP units), the K1 relay will become a loop pump relay and the K2 relay will become a HWG pump relay.
ECM Blower Operation – When the DXM2 is configured to operate an ECM Blower, or an ECM Blower is connected to the DXM2, the ECM blower will be directly controlled by the DXM2, with advanced operating features including:
a)Airflow Settings – The DXM2 allows the target airflow for each operating mode to be selected individually, within the allowable operating range.
b)Soft Start Ramping – During the first 2 minutes of blower operation during a heating or cooling demand, the ECM blower will ramp up to the selected target
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