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Hi-E2
to the collector pressure tap, as shown in Figure
40, leaving the positive side open to ambient (This
requires a pressure tap with a 1/4" NPT thread). When
the heater is operating, the pressure at this location
should be about 2.8 ± 0.5" WC less than ambient for
a model 350. If a greater reading is observed (i.e.
more negative), fl ow is restricted within the heater,
most likely at the burner or the heat exchanger. If the
reading is substantially less (i.e. less negative), the
combustion blower is not operating properly or fl ow is
blocked after the blower, possibly in the vent. Correct
any such problems and verify normal operation by
returning to the venturi system checkout procedures.
Pressure readings will be less if the heater is
located at an elevation signifi cantly above sea level.
Figure 39. Venturi inlet pressure measurement.
Figure 40. Collector pressure measurement.
4F-4. Fuel Gas Type and Gas Orifi ce Size
The Hi-E
venturi combustion system re quires
2
only a gas orifi ce change to change from natural to
propane gas or vice-versa. Required venturi system
and gas pressures are the same for either gas. Required
gas orifi ces are listed in the replacement parts list.
Jandy confi gures its heaters for natural gas with 0.60
specifi c gravity and 1035 Btu/Ft
with 1.52 specifi c gravity and 2500 Btu/Ft3. Consult
your Jandy representative if the available gas is
substantially different.
4F-5. High Elevation Operation
The venturi combustion fl ow system com plete ly
compensates for installation at el e va tions other than
sea level. Gas orifi ce chang es are not necessary.
Unlike con ven tion al systems with open type burners
and positive pressure regulators, the gas orifi ce
differential pressure is created by the air fl ow, and it
is automatically reduced when air density decreased.
A Hi-E2 heater com mis sioned at sea level will operate
at nearly the same air/gas mixture when operated at
higher elevation. Its fi ring rate will decrease about 3%
per 1000 feet due to the barometric pressure change.
In servicing a Hi-E2 heater at high elevation be
aware that the input will be naturally reduced by this
amount and that the dif fer en tial pressures, as discussed
in prior sections, will also be reduced. Pressure
readings at various elevations will be approximately as
follows:
Elevation
Gas Orifi ce
Ft (m)
Differential
Sea Level
4.0" (102 mm) WC
2000 (610)
3.7 (94)
4000 (1220)
3.4 (86)
6000 (1830
3.2 (81)
8000 (2440)
2.9 (74)
10000 (3050)
2.7 (69)
The gas pressure offset is determined by the
regulator spring adjustment, not air density. It is not
affected by elevation change.
4G. Combustion Condensate
The condensate disposal system of the Hi-E
heater is quite simple, but must be properly installed
and maintained. See the installation instructions for
information on correct tubing installation. Condensate
drainage should be observed routinely and if
nec es sary, the fl ow-ways should be cleaned.
In normal operation, condensate drains from
the condensate collector behind the combustion fan.
A 5/8" I.D. drain tube conducts this water into the
condensate trap/neutralizer, where a "water seal"
prevents room air from being pulled into the system. A
smaller amount of condensate may drain from the vent
Page 29
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or for propane gas
Unfi red Venturi
Differential
4.7" (119 mm) WC
4.3 (109)
4.0 (102)
3.7 (94)
3.5 (89)
3.2 (81)
pool
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