30
VII: OPERATING (continued)
forced off for a DHW call for heat. Refer to
Table 7A.
When an Outdoor Air Reset Option Card is
installed and there is a DHW call for heat
there is an adjustable DHW Temperature
Setpoint and Priority Timer included. Refer
to Table 7B.
Call for Heat
Circulator Status
T-T
Input
ZR
Input
Priority
Time
(
Pt_
)
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 7A: Domestic Hot Water Demand,
(Parameter
ZC_
=
DH
)
Table 7B: Domestic Hot Water Demand,
(Parameter
ZC_
=
DH
)
Outdoor Air Reset Option Card Installed
Call for
Heat
Outdoor Air Reset
Option Card
P/N 102294-01
Circulator
Status
T-T
Input
ZR
Input
DHW
Input
Priority
time
Priority
Time
Expired?
C1
Output
ZC
Output
off
--
off
> 0
no
off
off
on
--
off
> 0
no
on
off
on
--
on
> 0
no
off
on
on
--
on
> 0
yes
on
on
on
--
on
= 0
no
on
on
off
--
on
= 0
no
off
on
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
8. 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
limit contact closes (boiler water is cold)
the boiler is started and the “ZC” and “C1”
output terminals are de-energized. When
the “ZR” terminal is de-energized (boiler
water temperature is above setpoint) the call
for heat is ended and the “C1” terminal is
released to operation and the “ZC” terminal
is energized. An External Low Limit
Request is detected by sensing a voltage on
the “ZR” terminal. The Warm Start Boiler
Control does not have the External Low
Limit Option. Refer to Table 9.
Call for Heat
Circulator Status
T-T
Input
ZR
Input
C1
Output
ZC
Output
off
off
off
off
on
off
on
off
on
on
on
on
off
on
off
on
Table 8: Zone Request, Parameter
zc_
=
zr
Table 9: External Low Limit, Parameter
zc_
=
ell
Call for Heat
Circulator Status
T-T
Input
ZR
Input
C1
Output
ZC
Output
off
off
off
on
on
off
on
on
on
on
off
off
off
on
off
off