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The position you select on the temperature adjustment knob
will depend on the temperature of the incoming water (50°F
is average in the U.S.). In warm weather regions where the
incoming cold water is generally warmer, or during the hot
weather months in some other areas a midway setting on
the  temperature  adjustment  knob  would  produce  a
temperature  rise  of  about  70°F,  giving  an  output  of
approximately 120°F.   At this setting,  if it is still necessary,
one could mix a small amount of cold water in a shower and
have a comfortable shower at about 3 gallons/minute. During
the  colder  months,  or  in  cold  climate  areas,  it  might  be
necessary  to  set  the  control  to  the  maximum  position,  all
the way clockwise to the right.

If you supply the 425 HN, with preheated water (i.e.) in a
solar installation the unit could overheat.

 It will then shut off

on safety when the outlet temperature reaches 194°F. For
this type of application, purchase a solar model 125B LPS
or 125B NGS.
If  the  inlet  water  temperature  to  the  water  heater  is  very
warm  the  heater  can  produce  temperatures  that  may  be
found to be too hot. A temperature balance shower valve
can automatically mix in cold water to reduce such hot water
temperature, in the event of any temperature instability with
the  use  of  a  temperature  balance  shower  valve,  refer  to
shower  valve  manufactures  instructions  for  internal
adjustment  setting.  Adjustments  should  be  made  to  the
hottest  setting  in  the  shower  valve.  Additionally  the
temperature control of the heater can be adjusted to produce
a more comfortable hot water temperature.

Fig. 8 - Temperature Adjustment Knob

LIGHTING AND OPERATING INSTRUCTIONS

1.

STOP! Read the safety information above on this label.

2.

The gas valve must be shut off by putting the ON/OFF
switch to position “

”. Wait five (5) minutes to clear

out any gas. If you smell gas, STOP! Follow “B” in the
safety information above. If you do not smell gas, go to
the next step.

3.

This water heater is equipped with a safety pilot burner
and an automatic ignition control system.

4.

Set the ON/OFF switch (flip down cover plate on front
panel strip) to the “

” position. In this position, the

water heater is ready to use.

5.

If the red LED indicator light is flashing, this is a warning
that the water pressure is not enough to ignite the main
burner.

6.

Turn  the  hot  water  faucet  on  to  the  minimum  flow  rate
required  to  activate  the  heater.  The  automatic  ignition
system  first  ignites  the  safety  pilot  burner  which  then
ignites the main burner in about 4 seconds.

7.

The green LED indicator is on when the main burner is

on.

8.

The  pilot  flame  will  extinguish  10-30  seconds  after  the
burners come on. The burners will remain on until the hot
water tap is turned off.

NOTE

: On a first time initial installation, existence of air in

the gas supply line and in the water line may cause some
ignition delay. In that case, repeatedly open and close the
hot water tap in order to restart the ignition process until all
the air has been purged.

TO TURN OFF GAS TO APPLIANCE

Turn off the manual lever on the gas supply line to the heater
and set the ON/OFF switch to the OFF ( 

 ) position.

See Fig 9.

SETTING THE WATER TEMPERATURE

The 425 HN LP and 425 HN NG water heaters have a gas
control that modulates burner input in response to flow. Its
purpose  is  to  ensure  that  the  hot  water  temperature  will
remain steady, although the water flow demand might vary
(down to 1/2 gal/minute). To adjust the temperature on your
425 HN, turn on a hot water faucet to its maximum flow. At
the water heater, turn the large knob located beneath the
main gas control on the front of the heater all the way to the
right (clockwise). See Fig 8. This will produce a temperature
rise  of  approximately  90°F  at  flow  rates  between  0.5  and
2.0 gallons per minute. Given that average incoming water
temperatures  are  50°F,  this  heater  will  produce
approximately 140°F water at these flow rates. Turning the
dial all the way to the left (counterclockwise) will produce a
temperature rise of approximately 45°F for flow rates between
1.1  and  3.7  gallons  per  minute.  It  is  safest  to  select  a
comfortable temperature and not have to mix in cold water.

Temperature  Adjustment  Knob

To start and to shut down
the  appliance  press  the
button  “

”.

The  switch  is  located
behind the flip down cover
plate  on  the  front  panel
strip.

G661_004

Decrease  temperature
and increase flow

Increases  temperature

and decreases flow

Fig. 9 - Principles of Operation

 - on

 - off

Green  light  on  =  main
burner  on.

Green  light  off  =  main
burner  off.

If the red light is flashing,
that means the water flow
is  not  enough  to  ignite
the burner.

Содержание GWH 425 HN

Страница 1: ...aintenance can cause injury or property damage Refer to this manual For assistance or additional information consult a qualified installer service agency or the gas supplier In the Commonwealth of Massachusetts this product must be installed by a licensed plumber or gas fitter Upon completion of the installation these instructions should be handed to the user of the appliance for future reference ...

Страница 2: ...er appliance WHAT TO DO IF YOU SMELL GAS Do not try to light any appliance Do not touch any electrical switch do not use any phone in your building Immediately call your gas supplier from a neighbor s phone Follow the gas supplier s instructions If you cannot reach your gas supplier call the fire department Installation and service must be performed by a qualified installer service agency or the g...

Страница 3: ... will not exceed the heating capacity of the heater On Off Switch to activate system Red LED indicator flashes with low water pressure Green LED indicator main burner operation BOSCH is constantly improving our products therefore specifications are subject to change without prior notice 425 HN LP and 425 HN NG Specifications Gas Input max 117 000 Btu hr min 28 000 Btu hr Water Connection Thread fi...

Страница 4: ...INIMUM INSTALLATION CLEARANCES FROM COMBUSTIBLE AND NON COMBUSTIBLE MATERIALS FOR ALCOVE OR CLOSET INSTALLATIONS FRONT VIEW SIDE VIEW MODEL 425HN MODEL 425 HN TOP A 12 FRONT B 4 BACK 0 SIDES 4 FLOOR C 12 VENT DIAMETER 5 ...

Страница 5: ...control which has been underwater PROPER LOCATION FOR INSTALLING YOUR HEATER Carefully select the location of your new heater For your safety and for proper heater operation you must provide an abundant supply of combustion air and a proper venting Fig 1 Water heater drain plug The heater may still operate even when improperly vented It will however be less efficient and could eventually damage th...

Страница 6: ...00 Btu hr if all air is taken from the outside by horizontal ducts 4000 Btu hr if all air is taken from the outside by direct openings or vertical ducts Or the confined space must be provided with one permanent opening or duct that is within 12 inches of the ceiling of the enclosure This opening must have a minimum free area of one square inch per 3000 Btu hr if all air is taken from the outside b...

Страница 7: ...s stamped with a number 79 for LPG and 120 for Natural Gas Fig 2 Mounting the Heater WALL STUDS 1 X 4 SPACE BOARD SUPPORT BOARD 13 Fig 3 Incandescent Particle Tray Illustration The incandescent particle tray shipped loose in the carton with the water heater must be attached at the bottom of the water heater front cover at the time of installation Use the screws provided See figure 3 SCREWS INCANDE...

Страница 8: ...ter heater to a masonry chimney the following connector guidelines must be followed for safe and proper operation An approved gas vent connector must be attached to the top of the water heater and rise vertically at least 12 before entering into an approved gas vent connector elbow Any gas vent section that is greater than 45 degrees from the vertical is considered horizontal If a horizontal vent ...

Страница 9: ...the gas lines or malfunction of the supply system the gas valve and regulator must be checked for safe operation Make sure that the regulator vent is protected against blockage When your connections are made check for gas leaks at all joints not just the ones you made Apply some soapy water to all gas fittings and gas valve Soap bubbles are a sign of a leak NOTE Do not apply soap solution to the p...

Страница 10: ...l length of piping and then adding 5 ft for every elbow or T to the actual length Use the charts below to determine the pipe diameter necessary to accommodate the BTU demand of the unit If there are more gas drawing appliances on the line size according to the maximum amount of BTU demand Follow boxed numbers for piping just one 425 HN example 3 4 B I Natural Gas pipe for 30 ft will handle 152 000...

Страница 11: ...runs as short as possible When facing the heater the cold water inlet will be on the right and the hot water outlet on the left Although water piping throughout the building may be other than copper copper or galvanized piping should be used when connecting to the heaters male NPT flex connectors follow local codes if more stringent Plastics or other PEX type plumbing line materials are not suitab...

Страница 12: ...icator light is flashing this is a warning that the water pressure is not enough to ignite the main burner 6 Turn the hot water faucet on to the minimum flow rate required to activate the heater The automatic ignition system first ignites the safety pilot burner which then ignites the main burner in about 4 seconds 7 The green LED indicator is on when the main burner is on 8 The pilot flame will e...

Страница 13: ...ers have yellow flames while others have good flames it is likely that dust lint or spider webs have partially clogged the burner venturis To clean the burners contact a gas service person Mineral Scale Build up The 425 HN heater when operated at lower temperature settings does not accumulate mineral build up If however the heater is used at the higher temperature settings and the water has a high...

Страница 14: ...and component parts must be totally free of dirt In hard water areas mineral deposits can eventually 3 5 years in hard water areas corrode the water valve parts to a point where they will need replacing Any sign of moisture or corrosion at the joint of the water valve and the gas valve is a sign that the water valve components need to be serviced immediately 7 Poor circuit connections at the ECO o...

Страница 15: ...is mixing with the hot water between the 425 HN and the outlet Compare water temperature at outlet of the 425 HN hold the 425 HN outlet pipe with your hand and at the tap If these two are very different check for mixing valve or plumbing crossover see NO SPARK AT THE PILOT paragraph 4 5 Parts in water valve are dirty or damaged which will prevent the gas valve from being fully opened Water valve m...

Страница 16: ... reduce such hot water temperature in the event of any temperature instability with the use of a temperature balance shower valve refer to shower valve manufactures instructions for internal adjustment setting Adjustments should be made to the hottest setting in the shower valve Additionally the temperature control of the heater can be adjusted to produce a more comfortable hot water temperature S...

Страница 17: ...ner manifold gas pressure test nipple 4 Main gas burner 5 Pilot gas tubing 6 LED failure indicator 7 on off switch 8 LED operation indicator 9 Water valve 10 Temperature adjustment selector 11 Gas inlet gas pressure test nipple 12 Hose 3 1 4 10 11 2 9 8 6 7 5 12 6 720 606 804 10 1AL ...

Страница 18: ...18 6 720 607 026 Fig 15 INTERIOR COMPONENTS DIAGRAM AND PARTS LIST ...

Страница 19: ...7 Pilot electrovalve 8 708 501 249 18 Burner electrovalve 8 708 501 250 19 O ring 8 700 205 023 20 Hydro generator 8 707 406 043 21 Cold water pipe 8 700 705 947 22 Outlet flex hose 8 700 703 139 23 Washer 8 700 103 658 24 Water valve 8 707 002 649 25 Water valve cover 8 705 500 101 26 Diaphragm 8 700 503 053 27 Water inlet filter 8 700 507 001 28 Water valve selector screw 8 708 500 289 29 Volume...

Страница 20: ...20 6 720 607 026 Fig 16 Flow chart of 425 HN ...

Страница 21: ... may not apply to you This warranty gives specific legal rights You may also have other rights which vary from state to state Fifteen Year Limited Warranty General BOSCH PRO water heaters are warranted by the Manufacturer BOSCH through Controlled Energy Corp Controlled Energy Corp CEC will furnish a replacement heat exchanger and will furnish a replacement of any other part which fails in normal u...

Страница 22: ...22 6 720 607 026 ...

Страница 23: ...23 6 720 607 026 ...

Страница 24: ...k Waitsfield Vermont 05673 Phone 866 330 2730 Fax 802 496 6924 www protankless com techsupport protankless com 3 1 e g a p e e s E L B A T E C N A N E T N I A M R A E Y Y R E V E S R A E Y 2 Y R E V E S R A E Y 5 3 Y R E V E E V L A V R E T A W E T A C I R B U L E V L A V R E T A W D L I U B E R N E E R C S R E T L I F R E T A W T C E P S N I Y L B M E S S A T O L I P T C E P S N I Y L B M E S S A...

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