Pressure Regulation; Temperature Regulation - Bosch WR 400-3.K Série Mode D'emploi

PRESSURE REGULATION

The pressure regulator supplied with the water heater is
adjusted to operate on the gas specified on the rating plate
and:
- in Canada, is factory preset to deliver gas at the high
altitude setting listed on the rating plate and as shown
below.
- in the U.S.A., is factory preset to deliver gas at the
standard altitude setting listed on the rating plate and
as show below.
The pressure setting of the gas pressure regulator should
be checked at installation to assure that the setting is cor-
rect for the gas being used and the altitude at which the
appliance is installed. See rating plate on the unit, Table 1,
below, for proper setting.
In Canada for a heater being installed at standard altitude
(0- 2.000 ft. above sea level) the manifold pressure should
be reset at installation to the value shown on the rating
plate, or Table 1, below, for standard altitude.
Figure 11
The gas pressures specified below refer to flow pressure
taken at the pressure tap in the gas inlet pipe just above the
pressure regulator,(see figure 11) while the heater is operating
at full input.
Gas pressures read at burner test point D (see fig.7 (a) will
usually read 1-1.5'' W.C. less than below.
Table 1
Appliane Regulator Pressure Setting
Pressure tap
Type of Gas
kPa
natural 1.41
propone 2.61
natural 1.14
propane 2.09
* Note: The high altitude ratings listed are Canadian Gas Association
high altitude ratings for the appliances and are only valid in
Canada. In the U.S. the National Fuel Gas Code, ANSI 1-
1988, recommends for high altitude installations, above
2000 feet that the input rate be reduced 4% for each 1.000
feet above sea level.
8
MANIFOLD TEST
PRESSURE TAP T
ADJUSTABLE
PRESSURE REGULATOR
Altitude
Inches, W.C.
standart
5.7
(0.2,000 ft.)
10.5
high*
4.6
(2,000-4,500 ft.)
8.4
Your appliance dealer and/or local gas supplier should be
consulted in regard to any high altitude installation. If field
adjustment is required it should be performed by a qualified
serviceman experienced in such work.

TEMPERATURE REGULATION

The BOSCH WR400-3.K.. is equipped with a modulating
gas valve which adjusts the flow of gas to the main burner
in proportion to the water flow rate. Within its heating
capacity the WR400-3.K.. attempts to maintain the set
temperature rise across the heater. This temperature rise
can be set in range of 25ºC –to-50ªC (45ªF-to-90ªF), by
means of the water flow selector. See figure 12. When the
water flow selector is turned to the right hand stop the water
heater is set for 50ºC (90ºF) temperature rise; when the
water flow selector is set to the left hand stop it is set for
25ºC (45ºF) temperature rise.
Temperature Adjustment Knob
Decrease
temperature and
increase flow
Figure 12 - Principles of Operation
With the water flow selector turned to its right hand stop
position (50ºC rise setting ) and with an inlet water
temperature of 10ºC (50Fº) the outlet water temperature
will be maintained at approximately 60ºC (140ºF) in the water
flow rate range of approximately 2 litres/min (0.5 U.S. gals./
min.) to 8 litres /min. (2. 1 U.S. gals./min.).
The minimum flow rate for operation, the "Threshold Flow
Rate" referred to in the lighting instructions is 2 Litres/min
(0.5 U.S. gals./min). If the water flow rate is below this level
the main burner will not fire. If flow rate exceeds 8 litres/min
(2. 1 U.S. gals./min.) the temperature rise across the heater
will decrease in proportion to the rate above this temperature.
HIGH TEMPERATURE LIMIT SWITCH
The BOSCH series instantaneous gas water heaters are
equipped with a high temperature limit switch with a set
point of approximately 90ºC (195º F). If the water temperature
at sensing points exceeds the set point the switch will open,
interrupting the safety circuit and stopping gas flow to the
pilot and main burner.
Outage as the result of high limit operation indicates that
the heater is not functioning properly. The heater should be
checked by a qualified serviceman and the reason for the
malfunction corrected.
Increases
temperature and
decreases flow