A.O. Smith NW 37-670 warranty Maintenance

4.Close the vent as water starts to flow from the opening. Place the make-up water valve in the desired position. The boiler is now ready for START UP and TEMPERATURE REGULATION if being placed in operation for the first time.

Tank flushing and circulating pump lubrication should be performed in accordance with the above schedule. Tank sediment removal and element lime scale removal must be performed when needed as determined by period inspections. Following are the instructions for performing recommended maintenance.

START UP

The following checks should be made by the installer when the boiler is placed into operation for the first time:

1.Check all factory and field made water and electrical connections for tightness.

•Repair water leaks and tighten electrical connections as necessary.

2.Turn on the electrical disconnect switch and pilot switch(es) mounted on the boiler cabinet.

3.Observe the operation of the boiler during the first heating cycle.

•Temperature control and contactor operation should be checked by allowing the boiler to come up to temperature and shutoff automatically.

TEMPERATURE REGULATION

Always turn off the electricity at the electrical disconnect switch when making a temperature control adjustment.

It is suggested the temperature adjustment be turned to the lowest setting which satisfies the hot water requirements of the system.

•Additional instructional literature is provided with the boiler for adjusting this control.

Always close and lock the cabinet door after making a temperature adjustment. Turn on electricity.

DRAINING

The boiler must be drained if it is to be shut down and exposed to freezing temperatures. Maintenance and service procedures may also require draining the boiler.

1.Turn off the electrical disconnect switch.

2.Close the make-up water valve and system valves as necessary.

3.Open a nearby outlet to vent the parts of the system being drained.

4.Open the boiler drain valve.

5.If the boiler is being drained for an extended shutdown, it is suggested the drain valve be left open during this period.

• Follow FILLING instructions to restore boiler to service.

MAINTENANCE

Boiler maintenance includes periodic tank flushing and cleaning, and removal of lime scale from the heating elements. Circulating pumps should be oiled.

MAINTENANCE SCHEDULE

Component	Operation	Interval	Required
Tank	Flushing	Monthly
	Sediment	As Needed
	Removal
	Lime Scale	As Needed	UN•LIME®
Elements	Removal		Delimer and
			element
			gaskets.
Circulating	Oiling	Per pump makers
Pump(s)		instructions

FLUSHING

1.Turn off the electrical disconnect switch.

2.Open the boiler drain valve. Allow water to flow to an open drain until it runs clean. Do not come in contact with the water being drained as it may be very hot.

3.Close the drain valve when finished flushing.

4.Turn on the 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. In time, if not removed, the level of sediment might reach the heating elements.

For convenience, sediment removal and element lime scale removal should be performed at the same time as follows:

WATER AND LIME SCALE REMOVAL

Water and lime scale accumulations on the heating elements is a normal condition, common to all immersion type elements. Factors which affect the amount of this formation are:

1.Amount of make-up water used. As the volume of make-up water heated increases, more scale results.

2.Water temperature. As the temperature of the water is increased, more scale is deposited on the elements.

3.Characteristics of water supply. Regardless of water treatment, the elements should be examined regularly.

Water scale accumulations may cause noises to occur during operation.

It is recommended that a lower heating element be removed periodically for examination. If it is scaled, all of the elements should be removed and cleaned. If the tank bottom has an accumulation of sediment, it should be cleaned.

Lime scale should be removed from the elements by dissolving the accumulation in UN•LIME® delimer. UN•LIME is a non-muriatic delimer, available through your dealer or distributor. Do not use muratic or hydrochloric acid base deliming solutions to remove lime scale from the elements. Do not pour delimer into tank.

All models:

1.Turn off electrical disconnect switch.

2.Drain the boiler following DRAINING instructions.

3.Remove the cabinet panel which covers the heating elements.

•Remove insulation as necessary to reach the element area.

4.Remove the bolts from each element and remove the elements from the opening.

•Disconnect element wiring as necessary.

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