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Edge [ii] Controller Operation Manual

SECTION 6 – ADVANCED SETUP

OMM-139_E • 8/25/2020 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 139 of 196

Valve Balancing

NOTE:

This screen is available only after BST Cascade functionality has been enabled (see the

Unit Mode parameter in Section 6.3.1: Cascade Configuration) and the Valve Balancing

feature has been enabled in Section 6.3.4.4: Valve Configuration. If the unit is configured as

a BST Manager, the parameters apply to this unit and all BST Client units. If the unit is

configured as a BST Client, the parameters configured on the BST Manager will take

precedence.

The Valve Balancing screen is used to setup and configure the Balanced Flow Isolation

Valve feature. The goal of this feature is to raise or lower all unit’s current T (water outlet

temp minus water inlet temp) to match the plant’s target T, thereby balancing the load across

multiple boilers in a BST cascade.

Prior to balancing, in normal operation all isolation valves are either fully closed or fully open

(0% or 100% open). Valve balancing is accomplished by reducing the isolation valve’s “fully

open” position, thereby restricting the flow from the unit’s hot water outlet, as needed, until the

unit’s T matches the plant’s target T. This is repeated on the other units in the BST cascade

until each unit’s T is approximately the same.

The isolation valve’s “fully open” position is controlled by the number of volts sent to the valve;

before balancing 0.00V = “fully open”. Adjusting the “fully open” position is accomplished by

raising the voltage to something above 0.00V. After balancing, the new voltage is used to open

the valve when the boiler is firing. The “fully closed” voltage does not change.

The procedure described above is performed from the unit designated as the BST Manager; at

completion the BST Manager transmits the new voltage to each unit in the cascade.

Once valve balancing has been completed, the final step is to physically go to each isolation

valve and manually configure it to send the “valve open” signal to the Controller when it gets to

the new “fully open” position. Once in operation, each time the isolation valve is activated, it will

go to the new open position and send a “valve open” signal to the Controller, allowing ignition to

proceed.

Before starting this procedure, determine the T the plant was designed for.

1. Go to: Main Menu → Advanced Setup → BST Cascade → Operating Controls → Valve

Balancing. If this option is disabled, go to: Main Menu → Advanced Setup → BST

Cascade → Operating Controls → Valve Configuration and set the Valve Balancing

parameter to Enabled.

Figure 6.3.4.8-1: Operating Controls: Valve Balancing

Watts AERCO Edge [ii] User Manual

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