iWorx® LCI3
502-050A, Effective: April 22, 2013
17
© 2013 Taco Electronic Solutions, Inc.
BLMC, BZU2, & ZXU1 TECHNICAL TIPS AND HINTS
The BLMC can be used in a Stand Alone or Networked Mode of operation. If the BLMC will be used with BZUx control-
lers then an Local Control Interface user interface is required.
What does the BLMC Do?
The BLMC controller can control up to 4 single stage boilers or 4 modulating boilers, and domestic hot water. Up to 24
controllers of type BZU2 and ZXU1 can be associated to a BLMC to provide network demands to the BLMC controller.
Since the BLMC may be configured for many different scenarios it is strongly recommended that the
iWorx® BLMC
Application Guide
be reviewed prior to installation and commissioning. The next section points out many things the
installer/commissioning technician should be aware of when configuring and setting up a hydronic system.
When to use the BLMC?
The BLMC can be used for boiler staging and cascading for up to 8 boilers. (See the
iWorx® BLMC Application Guide
for details.)
Important Wiring information
• For complete wiring information please refer to the
iWorx® BLMC Application Guide
or
Installation Guide
.
• Make Sure Terminal 40 ‘GND’ is properly connected to earth ground on the BLMC and BZUx controllers.
• Make Sure Terminal 38 ‘COM’ is properly connected to earth ground on the BZUx controller.
• Make Sure Terminal 39 ‘GND’ is properly connected to earth ground on the BZUx controller.
• Ensure that only Echelon approved cable is used on the LON Bus. The cable we recommend is Level 4, 22 AWG
stranded twisted pair.
• When connecting temperature inputs (Analog sensors) to the controller, shielded cable is recommended. Recom-
mended wire includes 14-22 AWG shielded twisted pair for all analog inputs with 18 AWG recommended. Shields
must be connected to an earth ground near the controller.
Important Config Settings for BLMC and BZUx
• If BZUx is used to handle high temperatures (slate or concrete floors), only set the BLMC Heat demand to “ON” in
the All Settings screen of the BZUx. The BZUx will communicate a primary loop demand and cause the boilers to
fire.
• If BZUx is used to handle low temperatures (baseboard, exotic wood floors), only set the Boiler Zone demand to
“ON” in the All Settings screen of the BZUx. The BZUx will communicate a Setpoint Demand to the boiler.
• For interaction with the BLMR only, if using a BZU with firmware version v1.00 you must set the Kp and Ki for each
zone to the suggested values of, Kp=10 & Ki=5. If left at the defaults of 20 you may experience short cycling of the
BZUx zones and Boiler Zone Pump when at or near setpoint!
• NEVER Leave ANY Commissioning Switch set to the ‘ON’ position. If it is set to the ON position all of the control-
ler’s outputs will be ON and the boilers or zone pumps will cycle on and off based on its internal temperature limit/
protection.
• Snow melt can be done with a ZXU1 connected to a BLMC. The ZXU1 communicates the demand as a primary
demand to the BLMC. In the
All Settings
menu, the
Setpoint Mode
settings must be specified as
Snowmelt
or
Snowmelt Differential
and the System design temperature values have to be set up in the
Reset Settings Heat
structure. A Snowmelt sensor of digital dry contact type must be wired into the Heat Demand Input of the ZXU1
(Terminal 9 and 10, UI7 and Com).
