34000 Autry Street, Livonia, MI 48150 • 800.968.5530 • Fax 734.419.0209 • www.hamiltonengineering.com • LIT91127 REV 3/09
MAINTENANCE
F. INSTALLATION AT HIGH ALTITUDES
The appliance’s primary controller (FMT 914) operates all functions of needed control and safety. It
contains sophisticated logic that allows it to operate at very precise temperatures while minimizing burner on/off
cycling. When multiple units are operated as a Cascade to handle a common load, the control contains the
ability to control all of the units as efciently as one. Cascade operation is a factory-installed and programmed
option, requiring a eld wiring connection between appliances for operation. A number of parameters must be
programmed at the factory to provide proper operation and temperature control, including Controlling sensor;
Setpoint, Offset, Hysterisis and bandwidth. Secondary sensor; Setpoint & Offset.
• desired operating water temperature (this is set by the end user)
• amount the temperature is allowed to go above Setpoint before nally shutting off
• amount the temperature is allowed to drop under Setpoint plus offset before the appliance
turns on
• the range over which ame modulation occurs (this only takes place below Setpoint)
This appliance is equipped with an automatic combustion characteristic adjustment system, provided the
installed elevation above sea level is entered into the operating control (FMT 914) when the height is greater
than 2,000 feet and less than or equal to 9,000 feet. To enter the operating elevation:
• Press the reset button continuously for 3 seconds, the appliance shows the adjusted altitude
of the appliance (0 = sea level). Each time the service button is pressed, the value increases by
100 feet (20 through 90 = 2,000 through 9,000 feet). After reaching the maximum value, the
counter returns to the minimum value (example: when the value is 90 and the service button is
pressed, the new value will be 20). When the right altitude has been set (example: 53 = 5,300
feet of elevation above sea level), press the reset button for one second and the value will be
programmed. The factory default is 20 (which equals 2,000 feet), and there is no need to adjust
below that. See Figure 8-3 for the button locations.
• The adjusted altitude entered is internally converted to an offset on top of the maximum fan
speed.
• By adjusting the combustion characteristics as described above, there is no de-rate
required at altitudes up to 9,000 feet. For elevations in excess of 9,000 feet or gas BTU
content levels below 950 BTU/cubic foot, consult the factory at 734.419.0200 or 800.968.5530
for adjustments and de-rating information.
G. COIL ANTI-SCALING PREVENTION FEATURE
The EVO controller (FMT 914) contains sophisticated software that enables it to monitor the rate of temperature
rise through the heat exchanger. By doing this, it greatly reduces the possibility of heat exchanger failure due
to scaling or fouling. A set of parameters are programmed in at the factory, to provide a design temperature rise
(∆T) setting on each size unit that is xed. The Anti-Scale is based on an increase over the design ∆T through
the heat exchanger. This Anti-Scale is determined using the inlet and outlet sensors, even if a tank thermistor
is being used. If the Anti-Scale setting is reached, the unit will display A8, shut down and not re-re until it has
cooled. After the rst three times this condition is reached in the FMT 914 reset life cycle (reset life cycle is the
time between factory service history downloads), the FMT 914 control will go into hard Lockout, display E6, and
have to be manually reset. After it has been reset, it will re again, but at a maximum of 50% of rated input in
an attempt to prevent further damage but still provide some hot water. Once the heat exchanger has been acid
cleaned contact the factory for instructions on resetting the unit for full rated BTU input.
Typical causes for repeated E6 indications at start up are air trapped in the heat exchanger (be sure air vent cap
is loose) or contaminates lodging in the piping or heat exchanger during installation, both of these causes can
generally be cleared by isolating the hot water system and ushing water at full city pressure through the drain
valve or relief valve on the heater outlet.
Please note: Scale monitoring feature only available on HWD (water heater) models.
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