DRAINING
The water heater must be drained if it is to be shut down and exposed to freezing temperatures. Maintenance and service procedures may also require draining the heater.
1.Turn off the oil burner electrical disconnect switch.
•If required by the reason for draining the heater, turn off the oil line supply valve.
2.Close the cold water inlet valve to heater.
3.Open a nearby hot water faucet to vent the system.
4.Open the heater drain valve.
5.If the heater is being drained for an extended shutdown, it is suggested the drain valve be left open during this period.
•Follow FILLING instructions when restarting hot water service.
MAINTENANCE 
GENERAL
Water heater maintenance includes periodic tank flushing and cleaning, and removal of lime scale. The oil burner should be inspected and adjusted to maintain proper combustion. Where used, the water heating system circulating pump should be oiled (See table 9).
The depth of lime buildup should be measured periodically. Heaters will have about 2" (50.8 mm) of lime buildup when the level of lime has reached the bottom of the cleanout opening or about 1" of lime buildup if it has reached the drain valve opening. A schedule for deliming should be setup, based on the amount of time it would take for a 1" (25.4 mm) buildup of lime.
Example 1: Initial inspection shows 1/2" (12.7 mm) of lime accumulation. Therefore, the heater can be delimed once a year.
Example 2: Initial inspection shows 2" (50.8 mm) of lime accumulation. Therefore, the heater should be delimed every 3 months.
Following are the instructions for performing some of the recommended maintenance. Oil burner inspection and adjustment should be performed by a competent technician.
TABLE 9 SUGGESTED MAINTENANCE SCHEDULE
|
|
| Semi- |
|
Relief Valve | Lift Lever | Annually |
| |
|
| Flushing | Monthly |
|
|
| Sediment | Semi- |
|
|
| Removal | Annually |
|
|
| Anode | Semi |
|
Tank | Inspection | Annually |
| |
|
| Lime Scale | As | UN•LIME® |
|
| Removal | Required | Delimer |
Circulating |
| Four | SAE No. 20 | |
Pump | Oiling | Months | motor oil | |
|
| Inspection |
| Combustion test |
|
| and | Semi- | kit & test specifications |
Oil Burner | Adjustment | Annually | (Page 26) | |
|
| Nozzle | Semi- |
|
|
| Replacement | Annually | New Nozzle |
Flue Baffle |
|
|
| |
Pipe | Cleaning | Annually | Wire Brush | |
Venting |
| Semi- |
| |
System | Inspected | Annually |
| |
* Replacement gasket, A.O. Smith Part No. 99038
RELIEF VALVES
At least twice a year, the system relief valves should be checked to ensure that they are in operating condition. To check a relief valve, lift the lever at the end of the valve several times. The valve should seat properly and operate freely.
If water does not flow, remove the valve and inspect for obstructions or corrosion. Replace with a new valve of the recommended size as necessary. Inspection of the valve should be performed at least every three years. Do not attempt to repair the valve, as this could result in improper operating and a tank explosion. In areas with poor water conditions, it may be necessary to inspect the T&P valve more often than twice a year.
DANGER
BEFORE MANUALLY OPERATING A RELIEF VALVE, MAKE SURE THAT DRAIN LINE HAS BEEN ATTACHED TO THE VALVE TO DIRECT THE DISCHARGE TOAN OPEN DRAIN. FAILURE TO TAKE THIS PRECAUTION COULD MEAN CONTACT WITH EXTREMELY HOT WATER PASSING OUT OF THE VALVE DURING THIS CHECK OPERATION.
If the temperature and pressure relief valve on the heater discharges periodically or continuously, it may be due to thermal expansion of water in a closed water supply system, or it may be due to a faulty relief valve.
Thermal expansion is the normal response of water when it is heated. In a closed system, thermal expansion will cause the system pressure to build until the relief valve actuation pressure is equaled. Then, the relief valve will open, allowing water to escape, slightly lowering the pressure.
Your water supplier or local plumbing inspector will know how to best correct this situation. Two common corrections are listed in the Checklist and Service Information which appears later in this manual.
ABOVEALL, DO NOT PLUG THETEMPERATUREAND PRESSURE RELIEF VALVE. THIS IS NOT A SOLUTION AND CAN CREATE A HAZARDOUS SITUATION.
FLUSHING
1.Turn off the oil burner electrical disconnect switch.
2.Open the drain valve and allow water to flow until it runs clean.
3.Close the drain valve when finished flushing.
4.Turn on the oil burner electrical disconnect switch.
SEDIMENT REMOVAL
Water borne impurities consist of fine particles of soil and sand which settle out and form a layer of sediment on the bottom of the tank.
For convenience, sediment removal and lime scale removal should be
performed at the same time.
LIME SCALE REMOVAL
The amount of calcium carbonate (Lime) released from water is in direct proportion to water temperature and usage, see chart. The higher the water temperature or water usage , the more lime deposits are dropped out of the water. This is the lime scale which forms in pipes, heaters and on cooking utensils.
WATER USAGE IN GALLONS PER DAY POUNDS OF LIME DEPOSITED VS. TEMPERATURE AND WATER USAGE
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