View the terms and conditions for the guarantees that apply to our Greenstar gas-fired boilers.

Worcester Greenstar gas-fired boilers

The heatcell on the Worcester range of Greenstar gas-fired boilers are guaranteed in both part or parts and labour for a period of time as detailed in the standard guarantee periods table and or extended guarantee product offer. Providing terms and conditions are complied with.

Products installed from 1st January 2007 are covered within these terms and conditions, which are as follows:

Appliances covered

The cast aluminium WB3, WB5 or WB7 primary heatcell within the following appliances is covered:

  • Greenstar 12, 15, 18, 24, 27 & 30Ri boilers
  • Greenstar 9,12, 15, 18, 21, 24, 27 & 30i System boilers
  • Greenstar 25, 30i boilers
  • Greenstar 24 & 28i Junior combination boilers
  • Greenstar 25 & 30Si Compact Combination boilers
  • Greenstar 28, 32 & 36CDi Compact combination boilers
  • Greenstar 29, 34, 38 & 42CDi Classic combination boilers
  • Greenstar 30 & 40CDi Classic Regular boilers
  • Greenstar Highflow 440 & 550 CDi boilers
  • Greenstar 30 & 40CDi FS Regular boilers
  • Greenstar 30 & 35CDi Classic System boilers

Installation criteria

Boiler sizing

The boiler must be sized in accordance with BS5449 and the whole house boiler sizing method, so to meet the hot water and heating demands of the property. This is based upon the following:

  1. Total heat loss from rooms.
  2. Distribution losses (add 10% if required).
  3. Hot water allowance.

Distribution losses may be disregarded if all of the pipe work is located entirely within the heated space of the dwelling when losses are incurred outside the heated space such as when the boiler is located in a garage then add up to 10% for the calculated space heating.

System design

If the system is an open vent type the feed and expansion pipework must be correctly located relative to the circulating pump so that a positive system pressure is created. A close coupled feed and expansion pipework arrangement must be used wherever possible, connecting into a horizontal run of pipe immediately before the circulating pump.

If the system is of a sealed primary type then it must be connected as per the installation instructions with all joints capable of sustaining a pressure of up to 3 bar.

System cleansing

The system must be flushed and cleansed in accordance with BS7593. Water that is naturally soft must not be used without a suitable corrosion inhibitor. Water that is artificially softened via a Base Exchange Softening System must not be used. It is essential that the pH level does not exceed 8.

In all instances a corrosion inhibitor must be introduced into the clean primary water system and the effectiveness or strength of the inhibitor checked every 2 years.

Circuit design

The circuit must be designed so to achieve a temperature differential between the heating flow and return of approximately 20ºC for condensing.

Service and maintenance

The appliance and the system need to be serviced on a regular basis, generally this is at least once per year. The service process must be as described within the installation and maintenance instructions of the appliance. A record must be kept of the service findings and left with the householder.

10 year guarantee

This primary heat exchanger is guaranteed against faulty materials or workmanship for a period of 120 calendar months from the date of installation subject to the following conditions and exceptions.

  • That during the period of this guarantee the heat exchanger which has proved to be faulty or defective in manufacture will be exchanged or repaired free of material charges (and free of labour charges if within the main product warranty period) if repaired directly by Bosch Thermotechnology Ltd.
  • Invoices for attendance and repair of the heat exchanger by third parties will not be accepted for payment by Bosch Thermotechnology Ltd.
  • That the householder may be asked to prove the date of installation, that the appliance was correctly commissioned and that the annual service has been completed to manufactures requirements to the satisfaction of Bosch Thermotechnology Ltd, when requested.
  • The guarantee card must also be returned within 30 days of installation.
  • Bosch Thermotechnology Ltd. will not accept responsibility for damage caused by faulty installation, neglect, misuse or accidental damage the non-observance of the instructions contained in the Installation and Users Instructions leaflets.
  • That the appliance has been used only for normal domestic purposes for which it was designed.
  • That this guarantee applies only to equipment purchased and used in the United Kingdom, Ireland, Isle of Man and the Channel Islands.