For Example:
Night Setback
of the system loop water
temperature,
Night Shutdown
and
Weekend Shutdown
of the
entire boiler / heating system, and Indoor / Outdoor Air Reset
of the system loop water temperature. If any of these Building
Management System control functions are being utilized on
the hydronic heating system, some type of low return water
protection
MUST BE
provided.
If the boiler heating system will be used on a Water Source Heat
Pump System, Radiant Floor Heating System, Snow Melting
Heating System, etc., some type of low return water protection
must be provided.
Condensation can cause operational problems, bad combustion,
sooting, flue gas spillage and reduced service life of the vent
system and related components.
To prevent the system return water temperature below 140°F
(60°C) from entering the boiler inlet, an electrically actuated
3-way mixing valve is available, consult manufacturer for kit
availability (see FIG. 5-6 on page 31). By using this valve, the
SMART TOUCH control will bypass outlet water back into the
inlet of the boiler to maintain the inlet temperature above 140°F
(60°C).
A fast acting, self contained mixing valve, set to 140°F (60°C),
may also be used. The installation of this valve must be done
as shown in FIG. 5-6. This arrangement will maintain the
required flow through the boiler.
When a mixing valve is used, an optional system return sensor
should be installed into the system return piping. This will allow
the display of the actual system return temperature, and will
also allow control of the system return temperature when the
SMART TOUCH control is programmed for inlet temperature
control. As always, installation of the system supply sensor is
strongly recommended as well. This will reduce the potential
for short cycling of the boiler, and provide more responsive
temperature regulation, even when the SMART TOUCH
control is programmed for inlet temperature control.
CAUTION
A boiler allowed to operate at set point
temperatures below the specified minimum
settings may experience operational
problems with the operating controls and
safety switches, obstruction of the flue gas
passages on the heat exchanger, incomplete
combustion and possible flue gas spillage.
Operation at lower than specified water
temperatures may cause hazardous
conditions that result in non-warrantable
damage to the appliance.
Three way valves in system
The installation of a three way valve on this boiler is not
generally recommended
because most piping methods allow
the three way valve to vary flow to the boiler. This boiler is a
low mass, high efficiency appliance which
requires a constant
water flow rate for proper operation.
Low flow rates can result
in overheating of the boiler water which can cause short burner
cycles, system noise, relief valve discharge and in extreme
cases, a knocking flash to steam. These conditions can cause
operational problems and non-warrantable failures of the
boiler.
Radiant floor and snow melt heating
systems
This type of heating boiler application operates in a low
temperature range which requires a boiler bypass as described
under the
Low Temperature Bypass Requirements
section. A
non-metallic rubber or plastic tubing installed in a radiant (in
floor) system must have an oxygen barrier to prevent oxygen
from entering the system through the walls of the installed
tubing. Excessive oxygen absorption into the system will result
in an accelerated rate of corrosion causing a sludge buildup.
This excessive corrosion will also damage the boiler and system
components. Sludge formed as the result of excessive oxygen
in the system can restrict water flow resulting in a premature
boiler failure. Any boiler damage due to excessive oxygenation
is non-warrantable.
TABLE - 5A
MAXIMUM FLOW FOR HEATING BOILER
The maximum flow rate through the boiler with a copper
heat exchanger must not exceed the following:
Model
Maximum Flow
2500, 3000, 3500, 4000 and 5000
225 GPM
If higher flow rates are required through the boiler, an optional
Cupro-Nickel heat exchanger is available. Consult the factory
for specific application requirements.
Minimum boiler water temperatures
Inlet water temperatures below the specified minimum of
140°F (60°C) can excessively cool the products of combustion
resulting in condensation on the heat exchanger. Condensation
on the heat exchanger can cause operational problems, bad
combustion, sooting, flue gas spillage and reduced service life
of the related components. See the
Low Temperature Bypass
Requirements
section for boiler system applications below the
minimum specified temperature.
Low temperature bypass requirements
To prevent condensation problems, a boiler MUST NOT be
operated (other than for brief periods during initial system
startup) with an inlet water temperature of less than 140°F
(60°C). If normal system return temperatures are less than the
required 140°F (60°C) boiler inlet requirement, a method of
low return water temperature protection
MUST BE
provided
to protect the boiler.
33
5
Water connections
(continued)
Installation & Operation Manual
