Operating Instructions

Chapter 2 – Applications
Basic Operation
11
Siemens Industry, Inc.
Owner's Manual
125-5083
06/30/2015
Chapter 2 – Applications
Basic Operation
The LCM-OAVS Room Pressurization with Two Slow-acting Venturi Air Valves (One
Supply, One Exhaust) and Hot Water Reheat provides Direct Digital Control (DDC)
technology for pressure independent Variable Air Volume (VAV) and Constant Volume
(CV) laboratory room applications.
Application 2922 LCM-OAVS Venturi Slow Speed
The controller controls pressurization, ventilation, and room temperature in a laboratory
room served by one single-duct supply terminal with a reheat coil, one general exhaust
terminal, and up to six fume hoods (multiple fume hood flow signals must be averaged
using a Fume Hood Flow Module (FFM).
NOTE:
If desired, the LCM can be used without any fume hoods attached. In this case, MAX
HOOD VOL should be set to 0 cfm to disable the alarming that would occur if
MINHOODVOLTS is set to 1 Volt or more and the fume hood flow input drops below
.4 Vdc.
Pressurization is controlled by maintaining a selected difference between supply and
exhaust airflows.
Temperature control is determined by input from the Room Temperature Sensor
(RTS).
This application uses 0-10V output signals for control of slow Venturi Air Valves for
both supply and general exhaust.
The discharge temperature setpoint is reset in sequence with the VAV flow to control
the room temperature using a BTU Compensation algorithm. The discharge
temperature is then controlled using the reheat coil.
The LCM controls pressure, ventilation, and temperature. When these functions
conflict, the priorities are:
1. Pressurization
2. Ventilation (supply minimum may be overridden to maintain negative
pressurization)
3. Temperature