Gas Valve And Burner Set-Up - NTI Vmax VM153 Installation And Operation Manual

Vmax I&O Manual

9.0 GAS VALVE AND BURNER SET-UP

Set-up of the Vmax gas valve must be performed by a licensed Gas Technician. Failure
to perform the set-up correctly may result in incorrect operation, component failure,
property damage, serious injury or death.
Gas Line Pressure
The boiler gas valve is equipped with a line pressure test port; see Figure 9-1. Use the following procedure to
measure the gas line pressure to the boiler to ensure if falls within the range given in Table 9-1:
1. Turn the supply of gas to the boiler off.
2. Open the bleed screw of the line pressure test port approximately 1-1/2 turns. This port is directly connected
to the gas line feeding the boiler. See Figure 9-1.
3. Force ¼ in. ID tubing over the housing of the line pressure test port; install the other end of the tubing to an
appropriate line pressure test gauge or manometer. Ensure both ends of the tubing make a tight connection.
4. Open the supply of gas to the boiler and check for gas leaks.
5. Observe the line pressure under static conditions and compare it to Table 9-1. The pressure will be greatest
under static conditions.
6. With all other gas appliances in the application running, operate the burner to the maximum firing rate (see
Table 9-2) and compare the observed line pressure with Table 9-1. The pressure will be lowest during the
maximum flow of gas.
7. Adjust the gas line pressure to ensure the parameters in Table 9-1 are attained under all conditions (see
NOTICE below). If possible adjust the line pressure to the "Nominal/Desired" value listed in Table 9-1,
while the unit is operating at the maximum modulation rate, see Table 9-2.
8. Continue observing the gas line pressure until the completion of the combustion analyses, in case
adjustments need to be made.
9. Complete pressure testing, and then return the bleed screw of the Line Pressure Test Port to the closed
position.
The line pressure is a function of the gas supply and is affected solely by field provided
parameters such as line size and regulator settings. Under no circumstances can the boiler
gas valve influence or be used to adjust the gas line pressure.
Failure to close the bleed screw of the Line Pressure Test Port will cause a severe leakage
of gas, resulting in a fire or explosion causing property damage, serious injury or death.
Table 9-1 Line Pressure and Combustion Parameters
Gas
Nominal/Desired
Natural 7
Propane 11
Notes:
1
Combustion calibration must only be performed with the burner operating at maximum modulation rate.
2
Combustion values listed are for burner operation at maximum modulation rate; CO
modulation rate.
3
When tested at minimum modulation rate, the CO
Table 9-2 Minimum and Maximum Modulation Rates
Model Gas
NG
VM110
LP
NG
VM110P
LP
NG
VM153
LP
NG
VM153P
LP
* Canada: Altitudes between 2000-4500 ft, de-rate by 10%. Consult local authorities for de-rating for altitudes above 4500ft.
Line Pressure (inches w.c.)
Min.
4
8
must be 0.4-0.8% lower than CO
2
Appliance Min. Modulation Rate
Number (RPM)
8
12
1680
9
15
10
13
1740
11
14
│Gas Valve and Burner Set-up
CO
Max. Min.
10.5 8.9
13 10.2
and CO values will be lower at minimum
2
at maximum modulation rate.
2
Max. Modulation Rate
(RPM)
7800
7680
7800
7680
7980
7500
7980
7500
(%)
CO (ppm)
2
Max.
Max.
9.5 175
10.8 175
Input Rate (MBH)
Min Max *
13.8 110
15.4 154
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