Dhw Maximum Runtime - RBI FUTERA XLF Series Control Manual
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Also See for FUTERA XLF Series:
- Installation and operation instructions manual (44 pages) ,
- Manual (40 pages) ,
- Manual (61 pages)
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CONTROL METHODS
Figure 26
Jumper JPS1
Most of these methods use a separate PID
control for the DHW. This means that the Master
boiler can be used to individually control its own DHW tank
and provide space heating functionality at the same time.
A MASTER TYPE is required when using DHW. Its setting
is located under the DISTRIBUTED CTRL menu. Any time
its setting is changed, a power cycle is required. The menu
choices are:
AUTO: will handle normal heating only applications. It
may also be used when Member boilers have tanks
connected and are controlled with the DHW BOILER: set
to LOCAL.
DHW: is for DHW applications without space heating.
COMBO: Will allow combination Space and DHW
heating control of boilers by the Master.
The OR OVR input now functions in many of the methods as
a DHW Heat Demand input (except DHW Heating Only
method), but still retains the original OR OVR functionality in
AUTO, if the DHW menus are not used (DHW BOILER?
NO). If the DISABLE TO CHANGE message appears,
remember to remove the any call for heat including the OR
OVR input.
When the MASTER TYPE is set to COMBO (Combination)
the MODULAR BOILER SET menu will contain (2)
separate menus for controlling the ADD BOILER DELAY,
SHED BOILER DELAY, MODULATE DELAY, and the
MOD MAX. This allows the independent control of boilers
for each of the (2) PIDs.
When using MASTER TYPE: COMBO, the Master may
control DHW and Space Heating needs. If the Master goes
down or loses communication with the Member, a Failsafe
mode is available to provide temporary heat.
The DHW Failsafe mode is active when a Member boiler's
SETUP: AUX FUNTIONS: FAILSAFE MODES: H-NET
COMM LOST: is set to ON. When this is set to on, normal
DHW heating using the OR OVR or DHW sensor is disabled,
even though there may be a DHW call on one of these inputs.
When the Master Boiler's communication is lost, and after 10
minutes of not being restored, the DHW inputs become
active. The boiler now enters a standalone mode. The Heat
Demand on that boiler becomes active and not only runs to
provide failsafe space heating, but DHW heat as well. The
STATUS screen will display an '*' and H-NET LOST. If a
thermostat is used, the boiler will run to Method 5A until the
thermostat input removes the DHW call. If a DHW
temperature sensor is used, the boiler will modulate to
maintain tank temperature. The DHW Call always has priority
over space heating. A dual 10k sensor is available that can be
wired from one tank to two boilers.
The Failsafe boiler needs to either have a thermostat input
from a DHW tank or a temperature sensor connected to a
tank. When these sensors are connected normally, they would
override any call to the boiler by the Master (when in
SETUP: DOMESTIC HOT WATER: DHW BOILER:
COMBO) and enter a DHW heating mode. With the Failsafe
active, this function is inhibited and the Failsafe boiler only
responds to these inputs with the loss of the Master's
communication.
For more details see DHW Method 2: Failsafe Combination
DHW and Space Heating with a MASTER Boiler and
MEMBER Boilers page 34.
DHW Maximum Runtime
When a Combination system has a call for DHW heat and
services it for a time that is longer then designed, the DHW
may need to be locked out or held off for a predetermined
amount of time (retry).
Two settings are provided to control this situation: the
Maximum Runtime, and the Holdoff Time. The Maximum
Runtime is set to allow the DHW call to occur for the design
time of the system. If for some reason this time is exceeded,
the Holdoff Time setting goes into effect. The Holdoff time
can be set to a Lockout (the OR OVR input needs to toggle or
a power cycle to clear the Lockout), or a fixed amount of
boiler off time. If the fixed amount of Holdoff time is
selected, the DHW functionality will be cycled between the
boilers running for the Maximum Runtime, and stopped for
the duration of the Holdoff Time.
HeatNet Control V3
Page 29
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