Service manual

9
FLOW SWITCH (shipped loose)
A water flow switch is shipped loose and is to be
installed in the outlet piping on all heating boilers
and hot water supply boilers. The flow switch is
wired in series with the 24VAC safety control
circuit. A diagnostic light will be indicated on the
control display on a low flow condition.
7.2 FREEZE PROTECTION
• Appliance installations are not
recommended outdoors or in areas
where danger of freezing exists unless
precautions are taken. Maintaining a
mixture of 50% water and 50%
propylene glycol is the preferred method
of freeze protection in hydronic systems.
This mixture will protect the appliance to
approximately -35ºF (-37ºC). To
maintain the same temperature rise
across the appliance increase the GPM
flow by 15% and the head loss by 20%.
The following example demonstrates the
procedure to follow for calculating the revised
head for the heat exchanger when using a
water/glycol mixture.
• Given for example that Camus is
showing a heat exchanger flow and
head loss of 100 gpm @ 10 feet
• Increasing the flow by 15% now results in
a head loss of 13 feet at 115 gpm (from
B&G system syzer). At this increased flow
Camus now recommends to increase the
head loss by 20%.
• The requirement for the heat exchanger
with water / glycol mixture will now be
115 gpm @ 15.6 feet. (ie. 1.2 x 13ft. =
15.6 ft.)
• A similar procedure must be followed to
calculate the additional head loss in pipe
and fittings in order to arrive at the
proper pump selection.
For Outdoor installations a snow screen should
be installed to prevent snow and ice
accumulation around the appliance. Regular
inspections should be made to ensure that air
intake and vent are free of snow and ice. Always
consider the use of a shelter such as a garden
shed in lieu of direct exposure of the appliance
to the elements. The additional protection
afforded by the shelter will help to minimize
nuisance problems with electrical connections
and will allow easier servicing of the appliance
under severe weather conditions.
7.3 CHILLED WATER SYSTEMS
When an appliance is connected to an air
conditioning system where the same water is
used for heating and cooling, the chiller must be
piped in parallel with the appliance. Appropriate
flow control valves; manual or motorized must
be provided to prevent the chilled water from
entering the appliance. (See Figure 6)
Figure 4: Typical Chilled Water System
When an appliance is connected to heating coils
located in air handling units (where they may be
exposed to refrigerated air circulation), the
appliance piping system shall be equipped with
a flow control valve or other automatic means to
prevent gravity circulation of chilled water
through the appliance. Chilled water in the
appliance will create condensate on the
appliance tubes, which will collect in the
combustion chamber causing corrosion.
7.4 HEATING SYSTEM PIPING
In larger systems, it is advisable to connect the
appliance to the piping employing the primary-
secondary pumping system. This system is used
to provide system advantages that would not be
available with a single pumping system.
Primary-secondary pumping is illustrated in
Figure 9.
The following are some advantages of the
primary-secondary pumping system:
• Greatly reduce the stand by losses
through the appliance
• Minimize heat exchanger wear.
• Reduce power consumption