Base Loading, Relay Control - HydroTherm HeatNet KN -6 User Information

CONTROL METHODS

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 15 Base loading with KN boilers
Enable the base load feature by setting:
ADVANCED SETUP:SYSTEM:OPTION to BASE LOAD. This
setting the OPTION Relay to be used as control for a Base
Load Boiler.
ADVANCED SETUP:SYSTEM:OPTION to BASE LOAD.
1.
This setting the OPTION Relay to be used as control
for a Base Load Boiler.
The ADVANCED SETUP:BASE LOAD BOILERS:
2.
BASE LOAD BOILERS: to 1. Currently allows (1) base
load boiler.
The START & STOP qualifier condition to the method
3.
discussed below.
The DELAY TIME to the amount of time required after
4.
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: ADVANCED SETUP:FIRING MODE:
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 .
http://www.smithboiler.com/
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:
(4) 2 million BTU HeatNet boilers = 8 million BTUs and
(1) 6 million BTU Base Load boiler.
When all (4) HeatNet boilers are running @ 95%, the Base
Load boiler is called on (demand is approx. 8 million
BTUs). As the Base load boiler comes on it introduces 6
million BTUs and the HeatNet boilers modulate down to
25% for a total output of 2 million BTUs and running at
high efficiency. The HeatNet boilers can now modulate to
the load from 1.6 million BTUs (20% mod) to another 8
million BTUs.
HeatNet Control V3 2.x
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