HydroTherm HeatNet KN -6 User Information page 40

OPTIONAL FEATURES
UPPER DHW DIFF) and boilers are firing. After
a DHW call for heat ends:
A. The pump will remain on during a post
purge pump cycle until the post purge timer
expires.
2. Next, enter the DOMESTIC HOT WATER
menu on the Master boiler. When prompted for
DHW BOILER?, enter NO. The Master treats
this method as a DHW system much like a space
heating system.
Member boilers may set the DHW BOILER? to
LOCAL and go offline to perform secondary
DHW heating, but the Master setting must be set
to NO.
Setting the DHW BOILER?, to MIXED using
this method will cause erratic operation and the
DHW pump to not be enabled.
3. Change the DHW SETPOINT to the desired
target temperature of the water in the tank. Once
the control determines there is a call for DHW,
the DHW SETPOINT is loaded and the Master
boiler will target the setpoint.
4. Now, change the DHW LOWER DIFF to the
desired temperature (DHW SETPOINT –
LOWER DHW DIFF) 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 DHW DIFF).
How long the temperature of the tank stays below
the temperature (DHW SETPOINT – LOWER
DHW DIFF)) is used to determine when boilers
are started along with the ADD BOILER DELAY
TIME.
5. Next, change the DHW UPPER DIFF to the
desired temperature (DHW SETPOINT + UPPER
DHW DIFF) 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
DHW DIFF). Setting the SHED BOILER
DELAY TIME = 0 will shut off all boilers
immediately once the (DHW SETPOINT +
UPPER DHW DIFF) is exceeded.
6. Press the DOWN arrow key again to position the
cursor beside the menu item DHW 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.
7. Press the DOWN arrow again and the menu item
POST PURGE should appear. This is the time
that the DHW pump relay remains energized after
the DHW SETPOINT has been satisfied.
A. The pump will remain on during a post
purge pump cycle until the post purge timer
expires.
B. Pump on the Master boiler functions as a
global pump.
8. Scroll down to USE SENSOR? Press the
SELECT key and select YES, then press the
SELECT key again. This will allow the boiler to
control the tank or DHW loop temperature using
the DHW sensor. The upper and lower
differential temperatures will also be loaded.
9. Press the DOWN arrow again and the menu item:
SHARING?, will be displayed.
If this item is set to OFF, only boilers that are not
firing will be checked for runtimes and fired. Set
the SHARING? to OFF.
10. Press the DOWN arrow again and the menu item
LOCAL PUMP OFF: will be displayed.
Set this value to NO. This will leave the local
pump on during a DHW heating cycle
(backwards compatibility). Setting this value to
YES will always keep the local pump off.
The Master's DHW relay will remain on as long
as there are boiler's firing and the DHW
temperature is below the (DHW SETPOINT +
UPPER DHW DIFF). Once all boilers are off and
the DHW temp is equal to or above the (DHW
SETPOINT + UPPER DHW DIFF), the DHW
pump will begin its post-purge time. If during this
post-purge time the DHW temp falls below the
(DHW SETPOINT + UPPER DHW DIFF), the
DHW pump will remain on.
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.
11. Press the DOWN arrow again and the menu item
PURGE TO THE: will be displayed.
Set this value 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. Set PURGE TO
THE: TANK.
If the PURGE TO THE: 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 is to be used only for mixed
space and DHW heating.
HeatNet Control V3 2.x
Page 40