Modine Manufacturing Atherion MPR Installation And Service Manual Supplement page 5

GAS HEAT START-UP PROCEDURE
is needed, reset the "Manual Relay" and "Manual Position"
to "Yes" to restart.
19. Furnace Digit 11=A or D Only (quad furnaces): For units
with four furnace sections, furnace 1 is modulating. This
furnace is controlled as described in 13 and 14 above.
Furnaces 2, 3 and 4 are single stage furnaces controlled
by "Relay Outputs" labeled "Furnace 2" through "Furnace
4". Select the desired furnace and set both the "Manual
Relay" and "Manual Position" to "Yes" to fire each furnace
section. To turn off a furnace, set "Manual Relay" to "No".
As with the other furnaces described above, the furnaces
will operate for 5 minutes at a time in this condition before
the control resets "Manual Relay" to "No" and turns off the
furnace. If a longer run time is needed, reset the "Manual
Relay" and "Manual Position" to "Yes" to restart.
20. After testing is completed, press "Esc" multiple times until
the control is back to the main SA (Supply Air) temp screen.
Use the arrow buttons to navigate to the "Unit Status M99"
screen. Press "Enter" and set "Reset Unit To Auto Mode:"
to "Yes." This will clear any changes made in the Carel
program for manual operation and will return the unit to
normal operation.
Check/Adjust Pressure Upstream of Unit
With the field installed manual gas shut-off valve in the "OFF"
position, recheck the gas supply pressure at the field installed
manual shut-off valve. The inlet pressure should be 6"-7" W.C.
on natural gas (11"-14" W.C. on propane (LP) gas), while all
burners are operating, but never more than 14" W.C when the
burners are off. If inlet pressure is too high, install an additional
pressure regulator upstream of the combination gas control.
Modulated Furnace/Manifold Section
Gas pressure must be checked and adjusted as necessary, at
both the combination gas valve (A) and at the manifold (B) to
ensure appropriate gas pressures.
A. Check/Adjust Pressure at Combination Gas Valve
The following steps are required to check/adjust the manifold
pressure on the combination gas valve:
1. Open the field installed manual gas shut-off valve and set
the combination gas control valve to the "ON" position. Note
for C- and D-Cabinet sized units and units equipped with
split manifolds, the Gas Heating Option consists of one or
more heating sections that are not modulated. For this step,
only one combination gas valve on the modulated furnace
or manifold section is to be set to the "ON" position.
2. Enable the unit controls. The LED display on the furnace
control board (Figure 5.1) will briefly display the heat
exchanger size being modulated. Refer to Table 5.1.Verify
that the model readout is correct for the unit being started.
3. Ensure that the supply fan blower is operating at the proper
airflow and adjust the Carel controller as described in "Carel
Controller Settings" to create a call for heat.
4. Check the ignition control and gas valve for electrical operation.
5. Check to make sure that the main gas valve opens while
the supply fan blower is operating.
6. Check the gas pressure at the INLET to the combination
gas control valve (refer to figures on pages 10 through 15)
Figure 5.1 - Primary Furnace Control Board
NOTE:
FOR ACTUAL WIRING TO THE FURNACE CONTROL BOARD, REFER TO THE
WIRING DIAGRAM LOCATED IN THE FURNACE CONTROL COMPARTMENT.
Table 5.1
Furnace Control Board Modulated Heat Rating Display
Furnace Model
7.
ATH15-501.0 (Supplement to ATH15-500.10)
Cabinet
B C
Digits 4-7
0150 150 -
0175 175 -
0200 200 -
0225 225 -
0250 250 -
0300 300 150
0310 310 -
0350 - 175
0400 400 200
0450 - 225
0500 - 250
0600 - 600
and adjust as needed to maintain 6"-7" W.C for Natural Gas
(11-14" W.C. for Propane) while the burners are operating
at high fire. This pressure is required for proper ignition and
to attain the rated input of the unit. If this pressure cannot
be obtained, the gas supply is undersized and needs to be
corrected or the gas supplier must be contacted.
Check gas pressure on the OUTLET of the combination
gas control valve (refer to figures on pages 10 through 15)
when the burners are functioning. This should be set to 4.0-
4.5" W.C. for Natural Gas (10.5-11" W.C. for Propane) for
the modulated furnace or manifold section (see gas valve
instruction sheet for location.)
BUTTONS
Cabinet
Furnace Model
D
Digits 4-7
0350 175
0400 200
0450 225
0500 250
0600 300
0620 310
0800 400
0850 thru 1000 250
1200, 1220 300
1400 thru 1600 400
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