LAARS HWG-M2-250 - Installation, Operation and Maintenance Instructions - Manual (Page 12)

Page 12
LAARS Heating Systems
Figure 11. Manual gas shutoff.
Figure 12. Gas orifice union.
7. Shut off pump and disconnect from hose. Carefully
drain solution from hoses and connect city water to
lower hose to flush combustion coil. Flush for
approximately 5 minutes with city water.
8. Remove hoses, close drain cock, close drain on
cold / return, and replace lower front panel .
9. Remove cover from thermostatic valve and
remove tape. Replace thermostat, spring, brass
ring and valve cover, and tighten bolts.
10. Open shut off valves and purge air from petcock
at top of thermostatic valve cover.
11. Re-open gas supply and turn on main disconnect
switch to return heater to service.
5.3 Thermostat Replacement
1. Isolate the water heater and relieve pressure.
2. Remove the screws (4) and access cover from
the jacket top.
3. Remove the hex head machine screws (3) from
the top of the thermostatic valve, remove the
valve top and internal parts.
4. Install new parts (P/N 2400-130).
5. Install new O-ring valve top and replace valve
top on valve and install and tighten screws
6. Restore pressure to water heater, bleed air from
the petcock on the valve and restart water heater.
7. Replace access cover.
5.4 Vent and Condensate Drain
Inspection (performed annually)
1. Inspect the vent terminals for blockage or
restrictions.
2. Check the condition of the internal vent fittings
and hose and replace as necessary.
3. Check the condensate drain lines for blockage
and optional condensate pump for proper
operation.
5.5 Cleaning Combustion Chamber Coil
and/or Burner
Note: In normal operation this procedure is
seldom required. Should it prove necessary, the
following procedure is used to access the coil for
cleaning (see Figure 14).
1.
Turn off the gas and electrical power to unit and
remove covers to the unit.
2. Remove water heater plastic exhaust assembly
by undoing the four nuts that hold the plastic
flange to the lower head. Disconnect one or more
of the rubber vent couplings above the tee, and
pull the elbow and tee out from under unit.
3. Shut off water to the system and disconnect and
remove the water inlet connection.
Figure 13. Switch location.