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4. WATER PIPING & CONTROLS
A. GENERAL
1. Size water supply and return piping in accordance
with system requirements. Do not use smaller
diameter piping than the boiler connections.
2. If the PureFire boiler is used to replace an existing
boiler, make sure that the system piping is thoroughly
cleaned and free from debris before installation.
3. In systems where sediment may exist, install a strainer
in the boiler return piping to prevent large particles
and pipe scale from entering the boiler heat
exchanger. Use a large mesh screen in the strainer.
4. Install this boiler so that the gas ignition system
components are protected from water (dripping, spraying,
etc.) during operation and service (pump replacement,
condensate trap cleaning, sensor replacement, etc.).
5. The PureFire boiler is supplied with a default tank
temperature setpoint of 120°F (49°C). However, the
setpoint can be set as high as 158°F (70°C) which can
potentially cause scald injury. If the tank temperature
is set to above 120°F (49°C), PB Heat recommends
the use of a mixing valve to provide lower
temperature water to faucets and shower heads.
DANGER
!
Water temperatures over 125°F
(52°C) can cause severe burns
instantly, or death from scalds.
Children, disabled, and elderly
are at the highest risk of being
scalded.
See instruction manual before
setting temperature at water heater.
Feel water before bathing or showering.
Temperature limiting valves are available, see
manual.
B. OPERATING PARAMETERS
1. The PureFire boiler is designed to operate in an open
loop domestic water heating system under forced
circulation with a water storage tank. The system must
be completely filled with water at all times and water
must be circulating through the boiler while the unit is
firing for it to operate effectively.
2. The minimum system pressure is 14.5 PSI (69 kPa).
3. Table 4.1 lists the minimum flow rates for each
PureFire model.
Table 4.1: Minimum Flow Rate
PureFire
Model
PFW-200
PFW-399
Minimum Water Flow Rate
GPM (LPM)
5.5 (20.8)
13.2 (50.0)
WATER PIPING AND CONTROLS
4. Table 4.2 provides the water volume of the heat
exchanger including the supply and return pipes that
are attached at the factory.
Table 4.2: Heat Exchanger Water Capacity
PureFire
Model
PFW-200
PFW-399
NOTICE
Water temperature rise and maximum flow data is
based on heating potable water with a hardness of 5
to 25 grains per gallon and total dissolved solids not
exceeding 350 ppm.
5. The required temperature rise and the standard
circulating pump are sized based on the heating of
potable water with a hardness of 5 to 25 grains per
gallon and a total dissolved solids not exceeding 350
ppm. Consult the manufacturer when heating potable
water exceeding these specifications.
Heating of high hardness and/or high total dissolved
solids water may require a larger circulating pump,
and a revised temperature rise specification based on
the water chemistry of the water to be heated.
Water with a hardness of less than 5 grains per gallon
will usually have a pH which can be aggressive and
corrosive causing non-warrantable damage to the
pump, and associated piping. Corrosion due to water
chemistry generally shows up first in the hot water
system because heated water increases the rate of
corrosive chemical reactions.
C. SYSTEM COMPONENTS
1. Pressure/Temperature Gauge: A combination
pressure/temperature gauge is provided with each
boiler to be mounted in the piping from the boiler
supply to the system as shown in Figure 4.1. Most
local codes require this gauge.
2. Potable Water Expansion Tank: An expansion tank is
required to provide room for expansion of the heating
medium (water or glycol solution). Consult the expansion
tank manufacturer's instructions for specific information
regarding installation. The expansion tank is to be sized
for the required system volume and capacity.
3. Y-Type Strainer or Filter Ball
recommends the use of a strainer device in the system
to prevent dirt or sediment from clogging the heat
exchanger. A 20 mesh stainless steel screen is
adequate to protect the heat exchanger. The strainer
should be cleaned often in the first several months of
operation. The Filter Ball
International incorporates a strainer into a ball valve
which allows the technician to isolate the water circuit
while cleaning the strainer.
Total Water Capacity
Gallons (Liters)
1.19 (4.50)
2.60 (9.84)
®
Valve: PB Heat
®
Valve from Jomar
15
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