Lochinvar Harmony - Manual (Page 18)

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Lst on
• On power up, or any time the Harmony loses power, the Lead Stage
will be the lowest stage in Auto Mode (that is, A first, then B, C, or
D).
• The Lead Stage will always be the first stage brought on and
modulated when there is a call for output. As more output is needed,
additional stages are added.
• When less output is needed, the Lead Stage will be the first stage
turned off. The bracket indicating lead stage will then switch to the
next available stage in Auto Mode. For instance, if the stages were
added in the sequence A, B, and C, then they will be turned off in
the sequence A, B, and finally C. The lead stage will now be D when
more output is needed.
PURGE DELAY Default - 1.0 min
• Most fully modulating units must go through a purge cycle before
they are brought on line and can begin generating heating.
• After activating a new Stage, the Harmony does not adjust its
modulation until the Purge Delay is over. This allows the unit to fully
come on line and to begin producing output. Once the Purge Delay
is over, the Harmony can begin adjusting its modulation to hold the
set point.
• The Purge Delay helps to prevent short cycling of a newly activated
Stage. Once a Stage is activated, it MUST run through the entire
Purge Delay period.
• The minimum Purge Delay setting MUST be the time required for the
unit’s purge cycle.
• The actual Purge Delay should be set to the amount of time between
when a Stage is activated, and when the Harmony sensor begins to
see a change in output. This can be several minutes longer than the
actual purge time of the unit.
LAG DELAY Default - 0 min
• Set the Lag Delay to 0 min when two or more Stages will generally
be needed to hold the load.
• The Lag Delay requires the previous stage to remain at 100%
modulation for the full period of the Lag Delay before another Stage
can be activated. For example, if the Lag Delay is set to 10 minutes,
the Lead Stage would need to remain at 100% modulation for a full
ten minutes (never backing down to even 99%) before a lag stage
could be activated.
• The Lag Delay is useful in installations where one unit should
usually have enough output to hold the load unless it fails or load
conditions become extreme.
• The Lag Delay overrides the value of the Modulation Point selected
for each stage. Regardless of that setting, the previous stage must
reach 100% and stay there before another Stage can be activated.
• The full Lag Delay must always elapse regardless of what happens
to system temperature. Therefore, set the Lag Delay to 0 min if you
want smooth set point control from multiple units.
- SYSTEM SETTINGS 1-
Auto Rotate
>Purge Delay
Lag Delay
--- PURGE DELAY ---
Value -> New Value
--- PURGE DELAY ---
Value -> New Value
PRESS TO SELECT
ADJUST
Press to
show
setting
PRESS TO SELECT
ADJUST
Turn to
adjust
value
PRESS TO SELECT
ADJUST
Press to
select
new
- SYSTEM SETTINGS 1-
Purge Delay
>Lag Delay
Standby Time
--- LAG DELAY ---
Value -> New Value
--- LAG DELAY ---
Value -> New Value
PRESS TO SELECT
ADJUST
Press to
show
setting
PRESS TO SELECT
ADJUST
Turn to
adjust
value
PRESS TO SELECT
ADJUST
Press to
select
new
SYSYSYSYSY
STEM SETTINGS 1STEM SETTINGS 1STEM SETTINGS 1STEM SETTINGS 1STEM SETTINGS 1