Bosch 520-HN-N Specifications download pdf (Page 22)

6 720 608 032

Troubleshooting

• 3. Inlet water is preheated. This model does not have

a thermostat and will not modulate flame height in

order to prevent overheating. It is designed for a cold

water feed only. Replumb the heater with cold water

to the inlet.

• 4. Increase flow rate. Restrictions in the water path

can slow the flow of water through the heater,

resulting in very hot outlet temperatures. Restrictive

showerheads and faucet aerators should be cleaned

out or upgraded with less restrictive ones. In

addition, the inlet filter on the water heater should be

cleaned and inspected. See chapter 5.2.

• 5. If water is still too hot, consult service bulletins on

www.boschhotwater.com

to lower outlet

temperatures further.

• 6. If the water has a high mineral content, the heat

exchanger may be scaled internally. This restricts the

water path, causing the water to boil and produce

extremely hot temperatures. To descale the heat

exchanger, consult service bulletins on

www.boschhotwater.com.

6.8 Water is not hot enough

• 1. Verify gas type indicated in the rating sticker

located on the cover's right hand side, coincides with

the gas type you are using. NG is a natural gas unit

and LP is for liquid propane (see chapter 2.2).

• 2. Flow at one particular tap is too great or too many

fixtures are running at one time. Lower flow to stay

within heater's specifications.

• 3. Ensure the power adjustment knob is all the way

clockwise for highest temperatures. In addition, the

temperature adjustment knob maybe set too low.

Raise the setting and test the water temperature.

This dial turns counterclockwise for lower

temperatures and clockwise for higher temperatures.

• 4. Close installer supplied cold water shut off valve (if

none installed, install before proceeding). Open all

hot water taps supplied by the heater. Wait 5

minutes and check all taps. Any water running is a

sign of a plumbing crossover. Consult local plumber

or service person for help correcting a plumbing

crossover.

• 5. Inspect the water path outside the heater for

obstructions. Make sure all outlets (i.e. showerheads,

faucet aerators and whole house filters) are clear of

debris. Also, the water heater's inlet filter should be

inspected and cleaned. See chapter 5.2.

• 6. The water valve assembly, which allows gas flow

to the burners, requires periodic maintenance (every

2-5 years depending on water quality and use). Visit

www.boschhotwater.com to purchase water valve

rebuild kit to service the water valve.

• 7. Gas pressure is too low. Ensure gas pressure is in

accordance with specifications in the installation

manual. See chapter 3.9. A gas pressure reading is

needed to proceed further. Contact your original

installer or a local certified gas technician to obtain

this reading.

6.9 Burners ignite without water flow

• 1. The water valve may be dirty and sticking,

prohibiting it from fully closing the gas valve. This part

requires periodic maintenance (every 2-5 years

depending on water quality and use). Visit

www.boschhotwater.com to purchase water valve

rebuild kit to service the water valve.

6.10 Low hot water pressure

• 1. Confirm adequate flow rate through the unit. With

cold supply shut off to the unit, disconnect hot outlet

side to the unit. Place a gallon jug under hot water

outlet to catch water. Open cold water supply and

measure flow rate out of the unit. With temperature

adjustment knob set all the way clockwise, the flow

rate should be close to 2GPM (filling the jug in 30

seconds or less). If the flow rate is not adequate,

inspect and clean inlet filter screen. See chapter 5.2.

• 2. Confirm the incoming water pressure to the unit is

above the required 30psi.

• 3. Inspect the water path outside the heater for

obstructions. Make sure all outlets (i.e. showerheads,

faucet aerators and whole house filters) are clear of

debris.

• 4. Be sure to run only one major fixture at a time with

this water heater. Opening too many taps at one time

can disperse water flow resulting in diminished flow/

pressure at all outlets.

• 5. If the water has a high mineral content, the heat

exchanger may be scaled internally. This restricts the

water path, causing diminished water flow. To

descale the heat exchanger, consult service bulletins

at www.boschhotwater.com.

6.11 Noise when heater is running

• 1. Confirm adequate flow rate through the unit. With

cold supply shut off to the unit, disconnect hot outlet

side to the unit. Place a gallon jug under hot water

outlet to catch water. Open cold water supply and

measure flow rate out of the unit. With temperature

adjustment knob set all the way clockwise, the flow

rate should be close to 2GPM (filling the jug in 30

seconds or less). If the flow rate is not adequate,

inspect and clean inlet filter screen. See chapter 5.2.

• 2. Inspect the water path for obstructions. Make sure

all outlets (i.e. showerheads, faucet aerators and

whole house filters) are clear of debris. Restrictions

1 2 ... 17 18 19 20 21 22 23 24 25 26 27 28

Comments to this Manuals

No comments

Bosch 520-HN-N Specifications Page 22

Comments to this Manuals

Related products and manuals for Water heaters & boilers Bosch 520-HN-N