HeatNet Smith Series, Руководство пользователя

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SETUP & OPERATION HeatNet Control REV 1.38-1
Page 17
Base Loading, Relay Control
The control has the ability to control (1) base load boiler
using the K8 Relay contacts on J4 terminals 1 & 2. In order
to connect to this plug, (2) wires are required and connected
to J4. Base Loading via relay requires these (2) flying leads.
These (2) wires then make up the Normally Open contacts.
The solid state relay K8, with contact connections on J4.1 &
J4.2 has a rating of
: 0.1 to 1 Amp .
If the base load boiler is of the modulating type, a 0-10VDC
signal is also provided on J4 pins 4- and 7+. Two additional
wires will need to be added to the J4 pins at 4- & 7+. Pin 7
is the + output of the 0-10VDC transmitter, and pin 4 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 13
Base loading with Smith Boilers
>BOILER TYPE
LOAD FIRMWARE
OPTION: BASE LOAD
>BASE LOAD BOILERS:1
START>MOD 95
STOP FIRST
DELAY TIME 10mins
BASE LOADING menu
(master boiler only)
SYSTEM menu
( ) master boiler only
Master
HeatNet Enabled 28A
Base load
Non - HeatNet
Enable the base load feature by setting
1.
ADVANCED SETUP:SYSTEM:OPTION
to
BASE
LOAD
. This sets the OPTION Relay to be used as
control for a Base Load Boiler.
2. The ADVANCED SETUP:BASE LOAD BOILERS:
BASE LOAD BOILERS: to 1. Currently only allows
(1) base load boiler.
3. The START & STOP 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:
ADVANCED SETUP:FIRING MODE:
MODE:MIN OFF TIME .
Preferred Example Base Load:
A modulating base load boiler that can accept a 0-10VDC
control signal such as the
Smith 28 series is preferred. A
135 ohm input for the base load boiler will need a converter
from 0-10VDC to 135 ohm if using KNs as the primary
HeatNet boiler. The Smith HeatNet control has the 135 ohm
feature built in.
Using the Smith HeatNet control on one Smith series boiler
can allow a second Smith series boiler or other boiler type to
be controlled using the base load feature.
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 is 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 @ 99%, 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.
Not Preferred Example Base Load:
Example of having a larger Base Load boiler that is not
of the modulating type: If there is a 6 Million BTU Base
Load boiler running with (3) 2 million BTU HeatNet
boilers, a short cycling situation will arise when the (3) 2
million BTU boilers are running @ 99% and the Base Load
boiler is called on. At this point there is a need for
approximately 6 million BTUs. The (3) smaller boilers will
then modulate down to low fire. At this point, the (3)
smaller boilers need to shut off or the Base load boiler needs
to shut off. There is no overlap. A selection for stopping the
boiler now needs to be determined. Setting the Stop