A.O. Smith Copper Boiler DB-840

Ensure water softening equipment is operational

Has the water temperature increased by approximately 5°F?

Inspect the interior of the inlet/outlet manifold through the pressure relief valve tapping for lime build-up

Obtain UN•LIME from dealer or distributor

Read the instructions on the label of the UN•LIME container

Ensure all necessary equipment is in place

Shut off all electric to the unit

Disconnect pilot line connection at main burner

Attach a pressure gauge or a manometer to the gauge port and check for correct manifold pressure.

Is the manifold pressure within the acceptable range?

Enter the time in seconds to burn one cubic foot of gas (T).

Enter the gas heating value in Btu per cubic foot of gas (H).

Calculate the actual boiler input per hour (Btuh) using the formula (3600/T)xH.

Ensure no other gas consuming appliances are ON during this interval.

Turn off the electrical power, main manual gas shutoff and pilot valves.

Allow boiler parts to cool before disassembly.

Remove the internal flue collector and vent pipe running to the chimney.

Check parts and chimney for obstructions and clean as necessary.

Remove burners from boiler and other metal parts as required to clean as necessary.

Refer to parts list supplied with this manual for disassembly aid.

Ensure the boiler is turned off and cooled down

Verify all necessary tools and cleaning solutions are available

Add the recommended percentage of cleaning solution to the system

Fire and circulate the system for one hour

Flush the system with fresh water until clean

Check if the water runs clear after flushing