Draining And Flushing; Service - A.O. Smith Gdhe 50 Instruction Manual

When checking the Temperature-Pressure Relief Valve operation,
make sure that (1) no one is in front of or around the outlet of the
Temperature-Pressure Relief Valve discharge line, and (2) that the
water discharge will not cause any property damage, as the water
may be extremely hot. Use care when operating valve as the valve
may be hot.
To check the relief valve, lift the lever at the end of the valve several
times, see Figure 37. The valve should seat properly and operate
freely.
If after manually operating the valve, it fails to completely reset
and continues to release water, immediately close the cold water
inlet to the water heater and drain the water heater, see Draining
And Flushing on page 47. Replace the Temperature-Pressure
Relief Valve with a properly rated/sized new one, see Temperature-
Pressure Relief Valve on page 17 for instructions on replacement.
TEMPERATURE-PRESSURE
RELIEF VALVE
DISCHARGE PIPE
fIGure 37.
If the Temperature-Pressure Relief Valve on the water heater weeps
or discharges periodically, this may be due to thermal expansion.
note: Excessive water pressure is the most common cause of
Temperature-Pressure Relief Valve leakage. Excessive water
system pressure is most often caused by "thermal expansion"
in a "closed system." See Closed Water Systems and Thermal
Expansion on pages 15 and 16. The Temperature-Pressure Relief
Valve is not intended for the constant relief of thermal expansion.
Temperature-Pressure Relief Valve leakage due to pressure build
up in a closed system that does not have a thermal expansion
tank installed is not covered under the limited warranty. Thermal
expansion tanks must be installed on all closed water systems.
do not pluG the teMperature-pressure relIef
valve openInG. thIs can cause propertY daMaGe,
serIous InjurY or death.

draInInG and flushInG

It is recommended that the water heater storage tank be drained
and flushed every 6 months to reduce sediment buildup. The
water heater should be drained if being shut down during
freezing temperatures. See Figure 1, Features And Components
in this manual for the location of the water heater components
described below.
Explosion Hazard
Temperature-Pressure Relief Valve
must comply with ANSI Z21.22-
CSA 4.4 and ASME code.
Properly sized temperature-
pressure relief valve must be
installed in opening provided.
Can result in overheating and
excessive tank pressure.
Can cause serious injury or death.
to draIn the water heater storaGe tanK:
1. Turn off the electrical supply to the water heater.
2. Turn off the gas supply at the Main Gas Shutoff Valve if the water
heater is going to be shut down for an extended period.
3. Ensure the cold water inlet valve is open.
4. Open a nearby hot water faucet and let the water run until the
water is no longer hot.
5. Close the cold water inlet valve to the water heater.
6. Connect a hose to the water heater drain valve and terminate it
to an adequate drain.
7. Open the water heater drain valve and allow all the water to drain
from the storage tank.
8. Close the water heater drain valve when all water in the storage
tank has drained.
9. Close the hot water faucet opened in Step 4.
10. If the water heater is going to be shut down for an extended
period, the drain valve should be left open.
to flush the water heater storaGe tanK:
1. Turn off the electrical supply to the water heater.
2. Ensure the cold water inlet valve is open.
3. Open a nearby hot water faucet and let the water run until the
water is no longer hot. Then close the hot water faucet.
4. Connect a hose to the drain valve and terminate it to an adequate
drain.
5. Ensure the drain hose is secured before and during the entire
flushing procedure. Flushing is performed with system water
pressure applied to the water heater.
6. Open the water heater drain valve to flush the storage tank.
7. Flush the water heater storage tank to remove sediment and
allow the water to flow until it runs clean.
8. Close the water heater drain valve when flushing is completed.
9. Remove the drain hose.
10. Fill the water heater - see Filling The Water Heater in this manual.
11. Turn on the electrical supply to place the water heater back in
operation.
12. Allow the water heater to complete several heating cycles to
ensure it is operating properly.

servIce

If a condition persists or you are uncertain about the operation of
the water heater contact a qualified service agency.
Use this guide to check a "Leaking" water heater. Many suspected
"Leakers" are not leaking tanks. Often the source of the water can
be found and corrected.
If you are not thoroughly familiar with gas codes, your water heater,
and safety practices, contact your gas supplier or qualified installer
to check the water heater.
Read this manual first. Then before checking the water heater
make sure the gas supply has been turned "OFF", and never turn
the gas "ON" before the tank is completely full of water.
47
Burn harzard.
Hot water discharge.
Keep hands clear of drain
valve discharge.