Installation / Operation Instruction Manual

Page 96
Isolation Valve - Single Boiler Operation
1. Disabled – if the isolation valve functionality is disabled, via the display, the isolation valve output will not actuate,
and the boiler will ignore the status of the limit switch inputs.
2. Enabled – if the isolation valve functionality is enabled (default setting), the following will occur:
i. Upon a heat demand, the valve will open. Once the boiler receives feedback from the open limit switch that the
valve is fully open, the boiler (and system pump, if congured to run with the boiler pump) pump will run.
If the isolation valve open limit switch feedback is not achieved within the “Open Time Delay” setting (adjustable
via the display), the boiler will fault with an “Isolation Valve Failed to Open” fault indication across the navigation
banner of the display. This condition requires a manual reset.
ii. If the temperature set point has been reached, but the heat demand remains (i.e. boiler pump remains running),
the isolation valve will remain open.
iii. If the heat demand has been satised and the call for heat has been removed, the isolation valve will remain
open for the duration of the boiler pump post circulation time. Once the boiler pump turns o󰀨, the isolation
valve will close.
If the isolation valve close limit switch feedback is not achieved within the “Close Time Delay” setting
(adjustable via the display), the boiler will fault with an “Isolation Valve Failed to Close” fault indication across
the navigation banner of the display. This condition requires a manual reset.
Isolation Valve - Cascade Boiler Operation
In cascade operations, all isolation valves settings are made at the lead boiler.
1. Disabled – if the isolation valve functionality is disabled on the lead boiler, the isolation valve output will not actuate
on the cascaded boilers, and the boiler will ignore the status of the limit switch inputs on the cascaded boilers.
2. Enabled – if the isolation valve functionality is enabled, it is imperative that at least 1 isolation valve remain open
at all times to prevent the system pump from dead heading. If the isolation valve functionality is enabled (default
setting) of the lead boiler, the following will occur:
i. Prior to reacting to a heat demand, the lead boiler will look at the value of the parameter “Min. # of Open
Valves” set at the lead boiler. If this value is 1, the isolation valve of the boiler in sequence to re rst will
automatically open. If this value is 2, the lead boiler will tell the rst two boilers in sequence to re rst to open
their isolation valves automatically. This pattern would continue as the “Min. # of Open Valves” reaches the
maximum value of 8. The opening of the isolation valves prior to a heat demand prevents the system pump
from dead heading and is chosen to match system ow requirements.
If the isolation valve open limit switch feedback is not achieved within the “Open Time Delay” setting (adjustable
via the display), the boiler will fault with an “Isolation Valve Failed to Open” fault indication across the navigation
banner of the display. This condition requires a manual reset. The lead boiler will then transition to the next
boiler in the cascade sequence, as it would with any fault condition, and verify that the isolation valve is open.
ii. Upon a heat demand, the isolation valve on the rst (non-faulted) boiler in the ring sequence will already be
open (or multiple isolation valves will be open if the value of “Min # of Open Valves” is greater than 1), and the
boiler will run, following typical cascade – base load functionality.
iii. As the demand increases and another boiler is called upon by the lead boiler to re, the isolation valve of that
unit must open prior to initiating the ring sequence (or might already be opened, based on the value of “Min. #
of Open Valves”), otherwise follow the functionality as explained above.
iv. As the demand decreases and a boiler is turned o󰀨, the isolation valve of that boiler will close, unless it is
required to remain open based on the value of “Min. # of Open Valves”.
If the isolation valve close limit switch feedback is not achieved within the “Close Time Delay” setting
(adjustable via the display), the boiler will fault with an “Isolation Valve Failed to Close” fault indication across
the navigation banner of the display. This condition requires a manual reset.
v. As the heat demand is satised, and the last boiler running turns o󰀨, the isolation valve to that boiler remains