Lochinvar 399 - Manual (Page 32)

Hydronic Heating Boilers and
Domestic Water Heaters
32
INSTALLATION Continued
4. Locate the reference hose on the second gas valve which
goes from the vent fitting on the gas valve to a barbed
fitting on the deck of the unit (see FIG. 31).
5. Remove the flexible cap from the barbed fitting on the
“tee” located in this line and hook one side of the
manometer, or (-) side of a magnehelic gauge, to this “tee”.
Retain this cap for future use.
6. Remove the 1/8" hex plug from the manifold pressure tap
on the gas valve (see FIG. 31). Retain plug for future
use.
7. Install a fitting in this tap that is suitable for connection of
a hose to a manometer, or (+) side of a magnehelic gauge
(see FIG. 31).
8. Turn the power switch to the “I” or “ON” position.
9. Push the reset button(s) for the ignition control(s), if
necessary.
10. Set the electronic temperature control to call for heat (see
Programming Temperature Control).
11. Once the unit is firing the manometer/magnehelic will
reflect the Manifold Gas Pressure. Compare this reading
to the respective value in TABLE-M for Natural Gas or
Propane Gas.
12. If adjustment is necessary, remove the regulator cover
screw on the gas valve. NOTE: If the gas valve under
adjustment is located on a manifold assembly
monitored by an igniter, the unit may shut down and
recycle when the regulator cover screw is removed.
This is normal.
13. Turn the regulator adjustment screw “clockwise” to raise
the regulator gas pressure. Turn the regulator adjustment
screw “counterclockwise” to lower the regulator gas
pressure.
14. Replace the regulator cover screw and make sure it is tight
for proper operation.
15. Read the value on the manometer/magnehelic and compare
it to the values in TABLE-M.
16. Repeat this adjustment procedure for each gas valve as
necessary to adjust to the proper manifold gas pressure.
17. Remove hoses, replace and tighten plugs and caps when
complete.
18. Replace top front upper jacket access panels and control
panel door in reverse order.
FIG. 31 Measuring Manifold Gas Pressure
19. If proper ignition and burner operation is not achieved after
checking gas supply pressure, see Cleaning and
Maintenance, page 57 for Combustion Air Fan Adjustment.
Follow the procedure to adjust the combustion air fans as
necessary.
ressure
CONNECTING TO WATER
SUPPLY
Inlet and Outlet Connections
For ease of service, install unions on the water inlet and water
outlet of the unit. The connection to the unit marked “Inlet” on
the header should be used for return from the system. The
connection on the header marked “Outlet” is to be connected
to the supply side of the system.
399,999 - 750,000
Nat. Gas 1.8" w.c.
LP Gas 4.6" w.c.
990,000 - 2,070,000
Nat. Gas 1.2" w.c.
LP Gas 4.6" w.c.
TABLE-M
Net Manifold Pressure