User Guide

42
103876-08 - 1/19
CL Installation & Service Manual
Call for Heat
Priority
Time
(Pt_)
Circulator Status
T- T
Input
ZR
Input
System
Circulator
Output
DHW
Circulator
ZC Output
on off
On
on off
on on
On
off on
off on
On
off on
on off
OFF
on off
on on
OFF
on on
off on
OFF
off on
Table 9: Domestic Hot Water Demand,
(Parameter ZC_= DH)
is detected by a voltage on to the "ZR"
terminal. When a Priority Time parameter
is set to “off” the System Circulator is not
forced off for a DHW call for heat. Refer
to Table 9.
g. Start Temperature (t_)
The amount of “Heat available” is calculated by
taking the difference between measured boiler
water temperature and the Start Temperature
setting. Useful “Heat Available” is dependent
on the type of heating emitter installed in the
home. Heat emitters require a certain minimum
temperature to operate effectively. Our default
settings reflect cast iron radiators. Fan Coils
may require a start temperature setting of 180°F
or 160°F before providing heat to the home.
The Start Temperature has a factory setting of
140°F and is field adjustable between 140°F
and 180°F.
h. Priority Time (Pt_)
When the Priority Time parameter is set to “on”
and Domestic Hot Water (DHW) call for heat
is “on” the DHW demand will take “Priority”
over home heating demand and the system
circulator will be forced “off”. Priority Time
ends and the system circulator is released to
service home heating demand when Domestic
Hot Water call for heat is over. When Priority
Time parameter is set to “Off” the DHW call for
heat does not force “off” the system circulator.
The Priority Time has a factory setting of “On”
and is field adjustable between “On” and “Off”
Refer to Table 9.
i. ZC and ZR Terminal Function (ZC_)
The boiler control allows configuration of the
ZC output functionality to help the CL integrate
into each installation more effectively. The
ZC output can be connected to a domestic
hot water circulator or a second heating zone
circulator or be used to enable pumps in a
warm start application. These applications
are selected as follows:
i. When ZC_ is set equal to Domestic Hot
Water Demand (dh)
When there is an Indirect Water Heater
(IWH) the boiler control provides a “ZR”
input terminal for the IWH Aquastat
and “ZC” output terminal for the DHW
Circulator. When there is a DHW call for
heat, the System Circulator is “forced off”,
the DHW Circulator terminal is energized
and the circulator pre-purge time delay
control logic is bypassed to allow the
boiler to fire without delay. When DHW
demand ends the System Circulator
“force off” is removed, the circulator can
respond normally, and the DHW Circulator
is de-energized. The DHW call for heat
ii. When ZC_ is set equal to Zone Request
(ZR)
When there is no IWH the Cold Start Boiler
Control “ZC” output may be configured
to control a second heating zone. This is
particularly helpful when the home uses
only two heating zones. The boiler control
replaces the need for a two circulator zone
panel. When DHW Terminal Function
(dh_) is set to ZR the boiler control’s two
circulator outputs are used to control two
independent heating zones. Refer to Table
10. A "TT" input causes a call for heat and
energizes the System Circulator output to
service heating zone 1. A second zone’s
thermostat may be wired to the "ZR" input
to energize heating zone 2 circulator wired
to the "ZC" output. Both outputs function
independently, "TT" input controls only the
System Circulator output and the "ZR" input
controls only the "ZC" output. Both inputs
cause a boiler call for heat.
The Warm Start Boiler Control with ZC_ set
equal to Zone Request (ZR) energizes the
"ZC" terminal while the boiler is warm as
described earlier in this section (refer to
Paragraph A,2,f). The "ZR" input is a call
for heat that starts the boiler.
iii. External Low Limit, Parameter ZC = ELL
The Cold Start Boiler Control is capable of
functioning as a warm start control when
external limit control is installed that closes
a contact when boiler water temperature
falls below a setpoint. When an external
6 Operating (continued)