CONTROL METHODS
HeatNet Control V3 3.x
Page 27
Base Loading, Relay Control
The control has the ability to control (1) base load boiler
using the K8 Relay contacts on J4 pins 2 & 6. In order to
connect to this plug, (2) wires with pins are required and
inserted in J4. Base Loading via relay requires these (2)
flying leads (loose wires available from the factory) to be
inserted into J4, pins 2 & 6. These (2) wires then make up
the Normally Open contacts. This feature also can be used
on MASTER or MEMBER boilers. The solid-state relay
K8,
with contact connections on
J4.2 & J4.6
has a rating of
0.1 to 1 Amp
.
If the base load boiler is of the modulating type, a 4-20mA
signal is also provided on J4 pins 1 and 5. Jumper shunt JS1
will then need to be set to 4-20mA position. Two additional
wires (available from the factory) will need to be added to
the J4 pins at 1 & 5. Pin 1 is the + output of the 4-20mA
transmitter, and pin 5 is the – output. This modulating
control signal is used to modulate the base load boiler along
with the HeatNet boilers in parallel. The ADAPTIVE MOD
does not function in lowering the modulation rate when the
base load boiler is added. The PID will adapt to the newly
fired base load boiler and lower its modulation rate when
the increase in water temperature is observed.
Figure 18
Base Loading with KN Boilers
Enable the base load feature by setting:
1.
SETTINGS: BOILER: OPTION
to
BASE LOAD
.
This setting uses the OPTION Relay K8 (J4 pins 2 & 6)
as control for a Base Load Boiler.
2.
The
SETTINGS: BASE LOADING: BOILERS:
to
1
.
Currently allows (1) base load boiler.
3.
The
START WHEN: & STOP
WHEN
: qualifier
condition to the method discussed below.
4.
The
DELAY TIME
to the amount of time required
after the start qualifier condition has been met to start
the boiler.
If a MINIMUM OFF time of the Base Load boiler is
needed, the Base Load boiler will share the MIN OFF TIME
of the boiler controlling it. If the base load boiler was
running and shuts off, the MIN OFF TIME will need to
expire before the boiler can start again. Once this time
expires, the DELAY TIME also needs to expire to start the
boiler. This will help in minimizing short cycle conditions
and can be set at
SETTINGS:
FIRING MODE: MIN
OFF TIME
.
Preferred:
A modulating base load boiler that can accept a 4-20mA
control signal such as the SMITH 28-Series (and is
preferred) or a non-modulating base load boiler that is sized
correctly to the H-Net boilers. The Smith 28-Series also has
a HeatNet option. A 135-ohm input for the base load boiler
will need a converter from 4-20mA to 135 ohm.
If the base load boiler is not of the modulating type,
stopping the Base Load boiler will require that the size of
the Base Load boiler in BTUs to be known relative to the
HeatNet boilers. Boiler selection is ideally; having more
total BTUs in the HeatNet boilers than total BTUs of the
Base Load boiler. This will prevent short cycling. Example: