LAARS Mighty Therm LO-NOx PH (Sizes 250/400) - Install and Operating Manual - Manual (Page 25)

Mighty Therm LO-NOx Hydronic Boiler Page 25
5.1.1 Checking the Main Line
Gas Pressure
1. Attach a manometer (or a dry gas pressure gauge)
to boiler jacket (see Figure 37).
2. Open both columns on the manometer.
3. Use shutoff valve outside the boiler jacket to shut
off all gas supply to the boiler.
4. Remove the 1/8 inch NPT test plug in the inlet
side of the gas valve and replace it with the 1/8
inch NPT fitting from the manometer kit.
5. Attach one end of the manometer hose to the
fitting on the gas valve and the other end to the
manometer.
6. Open gas supply shutoff valve outside the boiler
and follow the lighting instructions in Figures 28
and 29 to turn on the boiler.
7. With the main burners firing, the manometer
reading should be between 6 and 10.5 inches
(15.2 and 26.7 cm) W.C.
NOTE: Use only the correct carbide tipped reamers
which are available from Laars.
4. Ream the insides of the tubes (see Figure 36).
5. Pull the reamer out frequently to remove lime
powder and prevent the drill from binding in the
tube.
6. Install new gaskets. Do not reuse the old ones.
7. Tighten the header bolts progressively, starting
with the two center bolts. Maximum torque is 20
inch pounds (27 Nm). Do not over-torque.
8. Pressure test the heat exchanger for leaks with
city water supply before re-installing.
9. When placing the heat exchanger back in the
boiler, carefully hold the refractory insulation
blocks apart and lower the heat exchanger into
place. Be sure the sheet metal covers, which
protect the insulation blocks, are replaced
carefully.
10. If a header bolt is stripped, drive it out of the
header plate and replace it (see Section 6, Parts
List).
11. Reinstall the heat exchanger.
SECTION 5.
Troubleshooting and Service
5.1 Gas Pressure Tests
Use the following procedures to check the main
gas supply and manifold gas pressures. A manometer
kit is available from Laars and instructions for its use
are included in the kit. A dry gas pressure gauge may
also be used for either test.
Figure 36. Heat Exchanger Tube Cleaning.
Notes:
1.
When pressure relief valve is used, it must be removed and the hole plugged, as shown.
2. Remove the plug before reinstalling the heat exchanger.
City
Water
Supply
400-500 RPM
Drill Motor
Suggested
Manometer
Position
Main
Shutoff Valve
(Field
Supplied)
Figure 37. Gas Manifold Pressure Test.
OUT OF
PRODUCTION