The main Greenstar families
Names change periodically; the tiering logic has been fairly consistent.
Greenstar i
The compact combi family, designed to fit a standard kitchen cupboard.
- Small footprint suits flats and tight cupboards
- Lower and mid hot water flow ratings
- Popular for straight combi-for-combi replacements
Greenstar CDi Classic
Higher output combis with stronger hot water performance.
- Suited to houses with good mains flow and heavier hot water demand
- Larger cabinet, so cupboard fit needs checking
- Chosen where a family wants faster bath filling
Greenstar Lifestyle
The upper combi tier, with the widest feature set and flow ratings.
- Best hot water figures in the combi line-up
- Fuller support for modern control strategies
- Only worth the premium if the incoming main can feed it
System and heat-only Greenstars
For homes keeping or gaining a hot water cylinder.
- Pairs with an unvented cylinder for mains-pressure hot water everywhere
- The answer for genuinely simultaneous bathroom use
- Heat-only variants suit properties keeping existing vented pipework
Where the accredited installer requirement actually bites
Manufacturer warranties on this brand are tiered, and the longest terms are conditional. Typically they require registration within a set window, a magnetic filter fitted on the return, commissioning paperwork completed, and an annual service recorded thereafter. Some longer terms are only available where an accredited installer carried out the work.
This matters more than the headline number. A boiler with a long warranty on paper and no service history behind it is, in practice, a boiler with a much shorter one.
Practical checks before choosing a Greenstar model
- Measure the incoming mains flow — it caps hot water performance regardless of range
- Check cabinet dimensions against the existing cupboard, not the existing boiler
- Confirm the flue route and terminal position work for the new appliance's kit
- Decide whether you want weather compensation, because that shapes the control choice
- Check the condensate route can be made frost-safe without an ugly external run
- Confirm the gas supply pipe can carry the new appliance's demand at full rate
Ranges get renamed, but the logic stays put: compact for tight spaces and modest demand, higher tiers for stronger hot water, system and heat-only where a cylinder earns its keep. Pick the tier your water main can actually feed.