U.S. Boiler Company MPO - IQ, Service Instructions Manual

Page: 54 / 92

54
x. OPERATING (continued)
Call for
Heat
ZC
and
ZR
Terminal
Function
(
ZC_
)
Boiler
Temp.
Boiler Status,
(B1 Output)
TT = on -- < 140 Start with no delay
TT = on -- >140 Start after 2 minute delay
ZR
= on
ZC_
=
ZR
<140 Start with no delay
ZR = on
ZC_
=
ZR
>140 Start after 2 minute delay
ZR = on
ZC_
=
DH
<140 Start with no delay
ZR = on
ZC_
=
DH
>140 Start with no delay
TABLE 10: CIRCULATOR PRE-PURGE TIME ExAMPLE,
PARAMETER PP_= 2 MINUTES
F. CHANGING THE ADJUSTABLE PARAMETERS
To adjust parameters such as the High Limit Setpoint and
High Limit Differential:
1. Using the Boiler Control display, access the adjustment
mode by pressing and holding the Up
ñ
, Down
ò
,
and “
I
” keys simultaneously for three (3) seconds.
This procedure is intended to discourage unauthorized
changes or accidental changes to limit settings.
2. Press the " I " key to display available Adjustment
Mode options. Select an option.
Adjustment Mode Options
HL_
140-240°F Adjust High Limit Setting
HdF
10-30°F Adjust High Limit Differential
ZC_ dh
,
ZR
or
ELL
ZC and ZR Terminal Function
Or_
0-10 minutes Pump Overrun Time
PP_
0-20 minutes Pump Pre-purge Time
St_
140 - 180°F Start Temperature
Pt_ On
or
Off
Priority Time
f-C F
or
C
Select degrees F or C Mode
bac
Back to Operating Mode
3. Press the Up
ñ
and Down
ò
keys to adjust the
displayed setpoint to the desired value.
4. To return to the normal operating mode from the
Adjustment Mode, when the "
bAc
” option is displayed,
press either the Up
ñ
or Down
ò
key. If no keys are
pressed, after five (5) minutes the Boiler Control will
automatically return to the Operating Mode.
G. MORE INFORMATION ABOUT ADJUSTABLE
PARAMETERS
1. High Limit (
HL_
)
The Boiler Control is factory programmed with a
High Limit Setpoint of 180 ° F. The boiler turns "off"
when the boiler water temperature (
bt
) is above this
value. The High Limit setpoint is adjustable between
140 ° and 240 ° F. The Operating Setpoint (
SP
) will
equal the High Limit Setpoint unless an Outdoor Reset
Option Card is installed. The Outdoor Reset Option
Card reduces the Operating Setpoint to regulate heat
delivery, increase home comfort and save energy.
Refer to Appendix A for additional information.
2. Differential (
HDF
)
The Boiler Control is factory programmed with a
Differential of 15 ° F. The Differential is the number of
degrees the boiler temperature must decrease below the
Operating Setpoint before the boiler can restart. The
differential is adjustable between 10 ° and 30 ° F.
3. Circulator Overrun Time (
OR_
)
Circulator Overrun Time (also called “circulator off
delay” or “circulator post purge”) continues circulator
operation after a call for heat has ended, sending
excess heat from the boiler into the priority zone.
Ensure system piping and zone panel settings allow
water flow to the priority zone after the call for heat
ends. The Circulator Overrun Time has a factor
setting of 0 minutes and is field adjustable between 0
and 10 minutes.
5. Circulator Pre-Purge Time (
PP_
)
When the boiler is warm [boiler water temperature
higher than 140°F (adjustable using Start Temperature
parameter)] and there is a thermostat call for heat, the
system circulator is started and boiler firing is delayed
pre-purge minutes. If the temperature drops below
140°F or there is a DHW Call for Heat the boiler is
started without delay. Additionally, the boiler is started
without delay if the thermostat call for heat is initiated
when the boiler water temperature is less than 140°F.
This feature helps save energy by satisfying home
heating needs with residual boiler heat rather than
cycling the boiler. The Circulator Pre-purge time has
a factory setting of 2 minutes and is field adjustable
between 2 and 20 minutes. When reset card is installed
pre-purge time may be adjusted down to zero (0)
minutes. Refer to Table 10.
6. Start Temperature (
St_
)
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.