EPV SERIES CONDENSING WATER BOILER
34-501 07/13
14
This section is for two-stage firing only:
After adjusting the high fire manifold gas pressure, it is now important to check the operation of the first stage
(low fire). There is a toggle switch on the control cabinet labeled “Auto/Low Fire”. Switch from the auto
position to low fire and the main valve will de-energize shutting off the high fire gas supply and the air damper
will close reducing the airflow to a minimum. Once the boiler is at low fire the manifold gas pressure can be
adjusted as described in the previous paragraph but using the pilot gas regulator instead of the main gas
regulator. Proceed to paragraph 10 to test and document combustion results for low fire and high fire.
18. Check flue gases with an electronic flue analyzer to make final settings of gas pressure regulator.
19. The readings need to be taken from a hole in the vent several inches downstream of the fan outlet
connection.
20. Insert 0-6" W.C. manometer into the test opening in the vent. Pressure in stack should not exceed 2" W.C.
21. When water in tank is above 120°F, insert analyzer or O
2
testing in test opening; take O
2
reading in
percentage.
22. Increase manifold gas pressure at the main gas pressure regulator taking O
2
reading at each adjustment of
gas regulator until optimum O
2
% (5-7%) is reached. If O
2
% decreases, reduce the gas pressure to last
reading where the greatest reading is achieved.
23. CO should not exceed 200 ppm. A reading greater than 200 ppm indicates lack of air. Reduce manifold gas
pressure slightly and take readings until CO is within proper range. Optimum reading is no CO.
24. If manifold pressure was changed during startup, take a final CO and O
2
reading.
25. Record CO
2
and
NO
x
if applicable. See paragraph 27 if NO
x
measurement is required.
26. Insert vent temperature gauge in test opening and read gross vent temperature; maximum gross stack is to
be 275°F. If an excessively high gross vent temperature is recorded; consult the factory.
27. When the Power VT Boiler is equipped for Low NO
x
operation, it may be necessary to measure the NO
x
levels in the flue products for compliance verification. The NO
x
concentrations are measured in ppm (parts per
million). When documenting the measurements on the startup report, be sure to note whether or not the
readings are corrected to a baseline O
2
level. If during the course of startup the NO
x
levels do not meet your
locally mandated requirements, it may be necessary to change the FGR (flue gas re-circulation) orifice. This
orifice is contained in the FGR union shown on page 11, Figure 501-6. This union may contain two or more
orifices. This allows the removal of one or more of the orifices in order to increase the flow of FGR and
thereby reduce NO
x
in the flue products. If the FGR orifice is changed for any reason, the startup procedure in
paragraph 18-26 should be repeated.
28. Check each operating and limit control to be sure they function properly by lowering and raising the
temperature setting on each of the controls, causing burner to cycle on and off.
NOTE
: During the initial firing of the burner, smoke that is not related to the burner will be emitted from the
heater. This is normal during "burn in" and could possibly continue for several hours.