How to Preform the Worcester Greenstar Fan Pressure Test

This page is dedicated to performing the Worcester Greenstar Fan Pressure Test. This test is to determine if the heat exchanger requires cleaning or attention.

The information published on this page only applies to the following range of boilers:

Natural Gas:

• Greenstar 9i System ErP. GC Number: 41-406-21
• Greenstar 12i System ErP. GC Number: 41-406-23
• Greenstar 15i System ErP. GC Number: 41-406-25
• Greenstar 18i System ErP. GC Number: 41-406-27
• Greenstar 21i System ErP. GC Number: 41-406-29
• Greenstar 24i System ErP. GC Number: 41-406-31

LPG:

• Greenstar 9i System ErP. GC Number: 41-406-22
• Greenstar 12i System ErP. GC Number: 41-406-24
• Greenstar 15i System ErP. GC Number: 41-406-26
• Greenstar 18i System ErP. GC Number: 41-406-28
• Greenstar 21i System ErP. GC Number: 41-406-30
• Greenstar 24i System ErP. GC Number: 41-406-32

How to Reset the Service Reminder Function

Setting the appliance to minimum or maximum mode when the service reminder function is active, a service reminder reset notification is displayed h13/H13.

How to reset the service reminder value in boiler settings menu:

• Press the back arrow/spanner button and tick button for approximately 5 seconds to enter appliance menu.
• Use the DHW up and DHW down buttons to scroll through the boiler settings.
• Press the tick button to select “info menu”.
• Use the DHW up and DHW down buttons to scroll through the menu.
• Press the tick button to select “2.5F” – service reminder time.
• Range from 0-72 months (0 = off). Press the tick button to confirm.
• Press the back arrow / spanner button to leave info menu.

Starting the Worcester Greenstar fan pressure test

Set the appliance to maximum rate.

Set the appliance to maximum output by pressing the chimney sweep button for at least 5 seconds.
The chimney sweep symbol will be displayed at the top of the screen and the word “Max” will flash at the bottom of the screen. The appliance will ramp up to maximum output in 30 to 35 seconds. Ensure that the appliance has stabilised at maximum output.

When running at maximum output, and the water temperature is 65°C or less, the appliance will operate both the central heating and DHW circuits with the diverter valve in the mid position. It will be necessary to run sufficient water through the DHW circuit to ensure that the appliance will not cycle on low heating demands. This is to allow sufficient time for the setting procedure. When the water temperature reaches 75°C the diverter valve will switch to CH only.

Connect the tubing from a digital manometer to the fan pressure test point.

The fan pressure will read negative value.

Natural Gas Appliances:

• 9i system boiler: Clean Heat Exchanger < -5.0mb =< Heat Exchanger OK
• 12i system boiler: Clean Heat Exchanger < -8.6mb =< Heat Exchanger OK
• 15i system boiler: Clean Heat Exchanger < -4.8mb =< Heat Exchanger OK
• 18i system boiler: Clean Heat Exchanger < -7.0mb =< Heat Exchanger OK
• 21i system boiler: Clean Heat Exchanger < -3.4mb =< Heat Exchanger OK
• 24i system boiler: Clean Heat Exchanger < -4.2mb =< Heat Exchanger OK

LPG Appliances:

• 9i system boiler: Clean Heat Exchanger < -5.3mb =< Heat Exchanger OK
• 12i system boiler: Clean Heat Exchanger < -9.8mb =< Heat Exchanger OK
• 15i system boiler: Clean Heat Exchanger < -5.4mb =< Heat Exchanger OK
• 18i system boiler: Clean Heat Exchanger < -7.9mb =< Heat Exchanger OK
• 21i system boiler: Clean Heat Exchanger < -3.8mb =< Heat Exchanger OK
• 24i system boiler: Clean Heat Exchanger < -4.7mb =< Heat Exchanger OK

After completing your fan pressure test:

• If during the fan test your manometer reading indicates the heat exchanger needs cleaning, then carry out the following checks:
  – Check that the siphon is not blocked.
  – Check the exhaust paths for restrictions.
  – Clean the heat exchanger with a suitable cleaning tool, refer to section 7.6 – Cleaning the heat exchanger.
• Re-check the fan pressure readings.
  If the appliance, after completing the above checks, fails the fan pressure test then contact Worcester, Bosch Group for advice.
• After the measurements are taken switch the appliance off.
• Disconnect the manometer and replace the test point cover.
• Replace the combustion air intake pipe.

If you’re based in Lincolnshire and you’d like to book an iWarm gas engineer for your Worcester Greenstar boiler service, use the contact form or call us on 07825 121000.

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