EWC BMPlus Zone Board + URD Dampers + DAPC

SYSTEM OVERVIEW

Control hierarchy:

1. EWC BMPlus zone controller – decides which zones are calling and issues open/close commands
2. DAPC – intercepts damper commands to protect static pressure by floating dampers
3. URD dampers (MA‑ND5 motors) – power open / power close, floating-point

Key concept:

The zone board decides WHO opens/closes. The DAPC decides HOW MUCH they open when static pressure rises.

POWER

• One dedicated transformer powers both the BMPlus zone board and the DAPC
• Transformer R and C is ran to the zone board and jumpered to the DAPC
• DO NOT steal power from the air handler

WIRING – HIGH‑LEVEL FLOW

Mount BMPlus and DAPC near each other

THERMOSTATS → BMPLUS → DAPC → DAMPERS
                 ↑
           HVAC SYSTEM

STEP 1 – HVAC SYSTEM SETUP

Before zoning is enabled:

• Confirm HVAC commissioning is complete
• Verify:
  • Correct airflow per tonnage
  • Staging behavior (Y1/Y2 or inverter logic)
  • Blower ramps correctly

Zoning should never be used to “fix” a bad base system.

STEP 2 – BMPLUS SYSTEM CONFIGURATION

DIP SWITCH SETTINGS (TYPICAL HEAT PUMP APPLICATION)

After ANY dip switch change, press RESET on BMPlus.

STEP 3 – ZONE BOARD → AIR HANDLER WIRING VERIFICATION

Verify every conductor:

• R → R (common transformer hot)
• C → C (shared common)
• Y1 / Y2 → GE Connect cooling inputs
• W1 / W2 → Auxiliary / staging logic
• G → Indoor blower enable

⚠️ Important:

• Indoor unit airflow staging is controlled by Y calls, not W

STEP 4 – DAMPER WIRING ARCHITECTURE

URD / MA‑ND5 TERMINALS

ZONE BOARD → DAPC (INPUT SIDE)

For each zone:

• BMPlus M4 → DAPC PO (input)
• BMPlus M6 → DAPC PC (input)
• BMPlus M1 → DAPC COM (input)

These go to the BOTTOM terminal blocks on the DAPC.

DAPC → DAMPERS (OUTPUT SIDE)

For each zone output:

• DAPC PO → Damper PO
• DAPC PC → Damper PC
• DAPC COM → Damper COM

Multiple dampers on one zone are wired in parallel.

STEP 5 – DAPC POWER & PRESSURE SENSING

• Power DAPC from same transformer as BMPlus
• Install pitot tubes:
  • One in supply
  • One in return
• Connect tubing correctly (Supply → Supply, Return → Return)

Incorrect tubing = false static readings.

STEP 6 – PRE‑COMMISSIONING CHECK

Before powering up:

• All zones calling same mode
• All dampers visually open
• GE Connect running at max airflow
• No zone satisfied

If this fails, STOP and fix wiring.

STEP 7 – DAPC MENU SETTINGS (BASELINE)

Floating Rules

• Allow largest zones to float
• Do NOT float small zones
• Never float fresh air dampers

STEP 8 – DAPC COMMISSIONING

1. Force all zones calling
2. Navigate to Commission = YES
3. Observe dampers:
   • Open
   • Close
   • Float
4. DAPC discovers non‑zoned static pressure
5. New SP setpoint is stored automatically

If commissioning fails:

• DAPC defaults to 0.5″ wc
• Fix wiring and retry

STEP 9 – FINAL FUNCTIONAL VERIFICATION

Test each zone individually:

• Single zone call
• Observe:
  • Other zones closing
  • DAPC floating large zones
  • Static pressure stabilized

Confirm:

• No duct noise
• No damper chatter
• No rapid staging

FAILURE MODES TO WATCH FOR