Bosch GWH 1000 - Manual (Page 17)

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Maintenance and service
17
5 Maintenance and service
5.1 Maintenance intervals
The GWH 1000 P requires periodic maintenance. The
below time maintenance intervals should keep the unit
operating for many years.
Every year
B Inspect inlet water filter screen ( 5.2)
B Inspect pilot assembly and flame ( 5.3)
B Inspect burner assembly ( 5.4)
Every 2 years
B Lubricate and clean water valve ( 5.2)
Every 3 to 5 years
B Rebuild water valve ( 5.2)
B Clean pilot assembly and clean or replace orifice
( 5.3)
5.2 Water valve
The water valve is the main control that tells the heater
to fire. If the periodic maintenance is neglected, more
costly damage may occur over time.
Inspecting inlet water filter screen
Shut off the installer supplied cold water isolation valve
to the heater. If one is not installed, install before
proceeding. Open the nearest hot water tap to drain the
plumbing lines. Position a bucket under the heater's
water valve assembly to catch any water that may drain
from the heater. Remove the filter retaining pin located
at base of water valve (see Fig. 25). Remove the
threaded bushing to access the cylindrical filter inside.
Remove filter, clean with water and inspect for damage.
If the filter is at all damaged, it should be replaced.
Lubricating the water valve
A more detailed instruction is available on our website
at www.boschhotwater.com. Shut off the installer
supplied cold water isolation valve to the heater. If one
is not installed, install before proceeding. Open the
nearest hot water tap to drain the plumbing lines.
Position a bucket under the heater's water valve
assembly to catch any water that may drain from the
heater. Disconnect the inlet water pipe going to the
back of the water valve. Disconnect the water pipe
leading out of water valve to the heat exchanger. Do this
by removing the retaining clip on water valve assembly
and pulling the pipe free from the water valve. Loosen
the two set screws at the bottom of the water valve
where it connects to the gas valve. If the set screws are
seized, STOP and call Bosch tech support before
proceeding. Forcing and snapping seized set screws
may cause irrevocable damage to the water valve and
gas valve assemblies. Remove the water valve by
pulling it to the right. Separate the two halves of the
water valve by removing the five screws on the left side
of the water valve. Apply lithium or faucet & valve grease
to the pushrod and o-ring. (See Fig. 25, num. 23).
Inspect the venturi and clean if necessary. (see Fig 28,
num. 23).
Rebuilding the water valve
Several parts within the water valve should be replaced
every 3 to 5 years depending on water quality and
usage. The parts list and instructions can be found on
our website at www.boschhotwater.com. Failure to
rebuild the water valve can result in decreased
performance or damage to the heater.
5.3 Pilot
Inspecting pilot
The pilot should burn with a clean sharp blue flame. The
flame should fully engulf the tip of the thermocouple. If
it does not, clean the pilot assembly per procedure
below.
Cleaning pilot assembly
Shut off gas supply to the heater using installer supplied
manual gas shutoff. Locate pilot gas tubing mounted in
the center of the burner assembly. At the base of the
pilot gas tubing there is a retaining clip. Release pilot
gas tubing from this clip. Push upwards on other end of
pilot gas tubing to release it from burner mount.
Remove brass hex headed pilot orifice from gas valve
(located near base of pilot gas tubing). Soak orifice and
pilot gas tubing in carburetor cleaner for 30 minutes.
Dry off and reinsert orifice in gas valve. If heater is an LP
unit, replace orifice. Reinstall the pilot gas tubing
following removal instructions in reverse. Open gas
supply and return heater to service.
Warning: Failure to perform
recommended maintenance may result
in complete failure of the unit over time.
The warranty does not cover failures
due to improper or insufficient
maintenance.
Caution: Do not ream or poke orifice as
it will enlarge orifice opening.