Controls and Function

HIGH ALTITUDE INSTALLATIONS

IN CANADA

Acceptance of these models for use at altitudes above 2000 feet (600 m) is based on field test of the individual installation by the provincial/state authority having jurisdiction.

IN THE U.S.A.

WARNING

INSTALLATIONS ABOVE 2000 FEET REQUIRE REPLACEMENT OF THE BURNER ORIFICES IN ACCORDANCE WITH THE CURRENT EDITION OF THE NATIONAL FUEL GAS CODE (ANSI Z223.1). FAILURE TO REPLACE THE ORIFICES WILL RESULT IN IMPROPER AND INEFFICIENT OPERATION OF THE APPLIANCE RESULTING IN THE PRODUCTION OF INCREASED LEVELS OF CARBON MONOXIDE GAS IN EXCESS OF SAFE LIMITS WHICH COULD RESULT IN SERIOUS PERSONAL INJURY OR DEATH.

For specific orifice requirements, please refer to the appropriate section of the National Fuel Gas Code ANSI Z223.1.

You should contact your gas supplier for any specific changes which may be required in your area.

Ratings specified by manufacturers for most boilers apply for elevations up to 2000 feet (600 m). For elevations above 2000 feet (600 m) ratings must be reduced by a rate of 4% for each 1000 feet (300 m) above sea level.

Example: If a boiler is rated at 610,000 Btu/hr. at sea level, to operate the boiler at 5000 feet (1500 m) it must be derated by 20% (4% x 5) to a new rating of 488,000 Btu/hr.

A. O. Smith does build some models specifically for high altitude service. Please check the rating plate before making changes.

The input reduction is primarily achieved by reducing the size of the main burner orifices. To do this, the main burner orifices require replacement with orifices sized for the particular installation elevation. When ordering, be sure to state the model number and the altitude of the location where the boiler is being installed.

Upon field deration of the boiler, adjustment to the gas pressure regulator is required. See CHECKING AND ADJUSTING THE INPUT in this manual for inlet and manifold pressure requirements. Also, due to the input rating reduction required at high altitudes, the output rating of the appliance is also reduced and should be compensated for in the sizing of the equipment for applications.

AUTO RESET HIGH LIMIT

The high limit is a safety device wired in series with the ignition system. Set the high limit control to approximately 100F above the maximum designed system temperature. If the boiler outlet water temperature should exceed the high limit setting, the main gas valve will close but the circulator will continue to operate. Maximum adjustable setting is 1150C (239°F) cut-out with a 30C (50F) to 250C (450F) adjustable differential, see Figure 2.

3.Opens the pilot valve.

4.Discontinues ignition spark when the pilot flame is established. The S-8600 control used on propane gas models provides safety lockout if the pilot fails to ignite within the pilot flame establishing period. The S-8600 control used on natural gas models continues trial for ignition until pilot flame is established.

5.After proof of pilot flame, opens then main valve.

6.On a power loss, shuts the heater down. When power is restored it will begin a new ignition cycle.

7.On a loss of flame, shuts off main gas and starts trial for pilot ignition.

PLEASE SEE TROUBLESHOOTING SECTION FOR MORE INFORMATION.

FIGURE 2.

INTERMITTENT IGNITION CONTROL MODULE

The Honeywell S-8600 control module contains the electronic components of the system and also serves as a control wiring system for the controls mounted on the heater. The control module performs the following functions:

1.Checks for safe-start by sensing for a false flame condition on start-up.

2.Generates a potential of 15,000 volts for spark ignition of the pilot burner.

S-8600 INTERMITTENT IGNITION

CONTROL MODULE (IID)

FIGURE 3.