OPTIONAL FEATURES
HeatNet Control REV 1.38-1
Page 28
Domestic Hot Water Methods
The HeatNet control supports Domestic Hot Water control
using (4) methods. When using the Domestic Hot Water
methods, the wire jumper, JPS1 on each control board
providing Domestic Hot Water, must be cut to limit the
boiler’s maximum output temperature of 200F. Refer to the
wiring Figures for control input and output locations.
Figure 24
Jumper JPS1
Jumper JPS1
JPS1
The following Domestic Hot Water setup information will
include a walkthrough using the menus.
DHW METHOD 1: DHW Tank Sensor
Input
DHW METHOD 1a: DHW Heating ONLY using a
Single Boiler or a DHW MASTER and Member
boiler(s) employing H-Net
This method utilizes a 10k thermistor connected to the DHW
Sensor input of a DHW MASTER, or a stand alone boiler,
and a DHW tank WITHOUT a HEADER sensor. It requires a
DHW setpoint and other parameters to be set. This method is
used when the water temperature in the tank needs to be no
greater than the setpoint, with little overshoot of temperature.
One of its limitations is that it may short cycle. It functions
much in the same way a tank thermostat works.
This method works with (2) settings. A target tank water
setpoint (DHW SETPOINT) and a start/add boiler
temperature setting (DHW DIFF). Boilers are started as long
as the tank’s water temperature is below the (DHW
SETPOINT – DHW DIFF). The first boiler is started
immediately. The next boiler(s) is started after the ADD
BOILER DELAY time expires. Boilers are not added when
the temperature is above the (DHW SETPOINT – DHW
DIFF) and below the DHW SETPOINT. Once the DHW
SETPOINT is reached all boilers shut off. This limits the tank
temperature to the se post purge time of the DHW
pump.
Setting up this method is done via the menus in:
SETUP:DOMESTIC HOT WATER
.
1.
Connect a
10k thermistor from the DHW tank’s
sensor well to J10B terminals 1 & 2 on the DHW
MASTER, or stand alone boiler. Wire any pump
or valve from the DHW Pump relay (normally
open) contact to control flow of the heating water
into the tank’s coil.
2.
Next, enter the
DOMESTIC HOT WATER
menu.
When prompted for
DHW BOILER?
, enter
NO
.
We will enter
YES
when we are finished entering
all parameters
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 this new setpoint.
4.
Now, change the
DHW DIFF
to the desired
differential. 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
DHW
SETPOINT – DHW DIFF
.
5.
How long the temperature of the tank stays below
the (DHW SETPOINT – DHW DIFF)
is used to
determine when boilers are started along with the
ADD BOILER DELAY
.
6.
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 temperature using its sensor.
7.
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.
8.
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. Once
the tank has reached setpoint all boilers will shut
off. Using the POST PURGE time to dump the
boiler’s heat into the tank may heat the tank
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