Worcester Greenstar system filters and water treatment: what the guarantee asks for

What does Worcester ask for on system water?

A clean system, dosed with inhibitor, filled with water that meets its limits. Worcester's professional primary heat exchanger guarantee terms are specific about it. The system must be flushed and cleansed in accordance with BS7593. A corrosion inhibitor must be introduced into the clean primary water system, and the effectiveness or strength of that inhibitor checked every two years. Water that is naturally soft must not be used without a suitable corrosion inhibitor, and water artificially softened through a base exchange softening system must not be used at all. Worcester adds that it is essential the pH level does not exceed 8.

Those water conditions sit on the same page as the installation criteria, so they are read together. The boiler must be sized in accordance with BS5449 and the whole house boiler sizing method. The circuit must be designed to achieve a temperature difference between heating flow and return of approximately 20 degrees C for condensing. On that basis the cast aluminium heatcell is guaranteed for 120 calendar months from the date of installation, and the guarantee card must be returned within 30 days.

Why does a system filter change the guarantee length?

Because Worcester ties the extended guarantee to one. The System Care Packs page states that each pack contains a system filter which unlocks an extended guarantee across the gas boiler portfolio, and that fitting any of the packs allows you to offer up to a twelve year guarantee. The conditions underneath the headline are where the detail sits. Worcester's homeowner terms say extended guarantees are available on specific appliances when installed by a Worcester Bosch Accredited Installer with a Greenstar System Filter, and are not available when the appliance is fitted with a System Filter Micro. The Greenstar 1000 and 2000 are handled differently, with the extended guarantee available subject to fitting any system filter, Worcester Bosch or third party.

The installer side has its own wording. The extension is free of charge for WAI and WAP VAULT members, while VAULT members who are Worcester Bosch Installers pay an additional 40 pounds to Bosch Thermotechnology through their VAULT account after the boiler has been installed and registered. Worcester also flags that system and regular boilers need additional accessories beyond what the care pack carries, so check the pack contents against the configuration before you price the job.

Which Greenstar System Filter goes in?

Two current sizes are published, and the difference is capacity rather than function. The Greenstar System Mini Filter, part number 7 733 600 266, is listed at 155 by 182mm with a 350ml canister when the valves are closed. The 22mm Greenstar System Filter, part number 7 733 600 236, is listed at 209 by 180mm with a 534ml canister. Both carry magnetic and non-magnetic filtration, isolation valve indicators, a one way valve for adding system chemicals, a detachable body for servicing and powerflushing, and a drainage point at the bottom. Worcester states they can be installed under or over the boiler, or remotely. The care packs ship with the Mini alongside a 265ml bottle each of WB1 inhibitor and WB3 cleaner.

What about hard water on the hot water side?

Different document, different limit. Worcester's domestic hot water secondary heat exchanger guarantee covers lime or calcium scale formation in the hot water section of the heat exchanger, and it states the temporary water hardness of the mains water must not exceed 200ppm. Above that figure the mains water must be protected by a suitable scale prevention device. It also states that any water softening device installed must not be used to fill the primary water within the heating system, which is the primary condition arriving from the other direction. Read that document against the appliance in front of you, because the list it names is the older Greenstar combis and the Heatslave II range rather than the current 2000, 4000 and 8000.

What should you record on the visit?

• The flush and cleanse: what product went in, and that the work followed BS7593.
• The inhibitor: product, dose and date, because the strength check falls due two years later.
• The filter: make, model and where it sits on the system, since the extended guarantee turns on it.
• Mains hardness where you have tested it, plus any scale prevention device fitted.
• The registration date. The heat exchanger terms want the guarantee card back within 30 days of installation.
• The service itself. Worcester says the householder may be asked to prove the appliance was correctly commissioned and the annual service completed.

Worcester's own wording on servicing is that the appliance and the system need attention on a regular basis, generally at least once per year, following the process in the installation and maintenance instructions, with a record of the findings kept and left with the householder. Two years later, when the inhibitor strength check falls due, that record is the only thing that says what went in.

The water treatment record is only worth having if you can find it again. Manifold captures the service and commissioning detail on your phone as you work, reads the make, model and GC number off the data plate with PlateScan, and keeps the appliance history against the property, so the inhibitor dose you recorded today is still there when the two year check comes round.