CONTROL METHODS
HeatNet Control V3 3.x
Page 39
3.
Now, change the
LOWER BAND
to the desired
temperature (DHW SETPOINT – LOWER BAND)
below which boilers are to be added. This setting
corresponds to the minimum water temperature
required in the tank. DHW heating will be initiated
when the DHW tank’s water temperature is below the
temperature (DHW SETPOINT – LOWER BAND).
How long the temperature of the tank stays below the
temperature (DHW SETPOINT – LOWER BAND)
is
used to determine when boilers are started along with
the ADD BOILER DELAY TIME.
4.
Next, change the
UPPER BAND
to the desired
temperature (DHW SE UPPER BAND)
above which boilers are to be shed. This setting is the
maximum tank temperature. Setting the SHED
BOILER DELAY TIME correctly will limit the
maximum tank temperature to the (DHW SETPOINT
+ UPPER BAND). Setting the SHED BOILER
DELAY TIME = 0 will shut off all boilers
immediately once the (DHW SE UPPER
BAND) is exceeded.
5.
Now, determine if the DHW Priority is required by
the menu item
PUMP PRIORITY?
. Setting this
value to YES will turn OFF the system pump when
the DHW mode is active. Setting this value to NO
leaves the system pump on.
6.
Select the amount of time for the
POST PURGE
of
the DHW pump. This is the time that the MASTER’S
DHW pump relay remains energized after the DHW
SETPOINT has been satisfied.
A.
The Local pump will remain on during a post
purge pump cycle until the post purge timer
expires.
B.
The System pump on the MASTER boiler
functions as a global pump and remains on as
long as the heat demand is enabled.
C.
The DHW pump will remain on until the last
boiler on the network has stopped firing and the
post-purge time has expired.
7.
Now, in order to be a MASTER boiler, it must have a
Header sensor. In method 1, DHW Only, we will
employ the DHW sensor (J10-A, 9 & 10) in this
system instead of a Header sensor.
USE SENSOR
in
this example will be set to
YES.
This will allow the
boiler to control the DHW tank or system loop
temperature as a MASTER boiler using the DHW
sensor. The upper and lower differential temperatures
will also be loaded.
8.
The
SHARING
function is not applicable in “DHW
Only” set-up.
9.
Set the
LOCAL PUMP OFF
value to
NO.
This
will
leave the local pump on during a DHW heating cycle
(backwards compatibility).
Setting this value to
YES,
will shut the local pump
off during a DHW heating cycle, but will keep the
local pump on for the LOCAL DELAY: 10s time
before shutting off. This LOCAL DELAY: time
can be adjusted in the next menu item by pressing
the down arrow again.
The MASTER’s DHW relay will remain on as long
as there are boiler’s firing and the DHW
temperature is below the (DHW SE
UPPER BAND). Once all boilers are off and the
DHW temp is equal to or above the (DHW
SE UPPER BAND), the DHW pump
will begin its post-purge time. If during this post-
purge time the DHW temp falls below the (DHW
SE UPPER BAND), the DHW pump
will remain on.
10.
Menu item
: PURGE TO:
will be displayed.
Set the
PURGE TO:
setting to
TANK.
This will
purge the heat from the boiler into the tank or
system loop. This will be done using the DHW
pump after the DHW heating cycle is complete.
If the
PURGE TO:
is set to
SPACE
, once the
DHW cycle has completed, the MASTER will shut
the DHW pump off within a few seconds. The
SPACE
setting should only be used
for COMBINATION and DHW
LOCAL heating.
Now in the,
SETTINGS: DISTRIBUTED CONTROL:
MASTER TYPE
select
DHW Only
.
JPS1 MUST be cut on all DHW boilers.