55
TABLE 11B: 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
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 12: ZONE REQUEST, PARAMETER
ZC_
=
ZR
7
.
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
11A.
8. ZC and ZR Terminal Function
The boiler control allows configuration of the ZC
output functionality to help the MPO-IQ 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:
a. 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 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 11A.
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 11B.
b. When
ZC_
is set equal to Zone Request (
ZR
)
When there is no IWH the “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
x. OPERATING (continued)
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 11A: DOMESTIC HOT WATER DEMAND,
(PARAMETER
ZC_
=
DH
)
control two independent heating zones. Refer to
Table 12. 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.
Summary of Contents for MPO - IQ
Page 6: ...6 Figure 1 MPO IQ84 Thru MPO IQ231 Water Boiler ...
Page 22: ...22 Figure 11 Boiler Removal from Skid III UNIT PAK BOILER ASSEMBLY TRIM CONTROLS continued ...
Page 42: ...42 Figure 28A Schematic Wiring Diagram VII ELECTRICAL continued ...
Page 43: ...43 Figure 28B Schematic Wiring Diagram Burner Options VII ELECTRICAL continued ...
Page 44: ...44 Figure 28C Ladder Diagram VII ELECTRICAL continued ...
Page 70: ...70 Bare Boiler Assembly XIV Repair Parts continued ...
Page 72: ...72 Jacket Assembly XIV Repair Parts continued ...
Page 74: ...74 MPO IQ84 Thru MPO IQ231 Water Boilers Trim and Controls XIV Repair Parts continued ...
Page 78: ...78 Beckett AFG Burner XIV Repair Parts continued ...
Page 80: ...80 Beckett NX Burner XIV Repair Parts continued ...
Page 92: ...92 U S Boiler Company Inc P O Box 3020 Lancaster PA 17604 1 888 432 8887 www usboiler net ...
