The Worcester Bosch Greenstar 36CDi Compact is the most powerful boiler in Worcester’s CDi Compact range, giving around 12.9 litres of hot water a minute at a 40°C rise. It suits three and four bedroom homes with a bathroom and an en-suite, where there isn’t much room for the boiler.
It’s still available from UK merchants in 2026, in natural gas and LPG versions. Its heating output is 24kW, the same as the smaller CDi Compact models, so it’s a hot water upgrade rather than a bigger heating boiler. Below, we explain what that means for your home, what it costs to fit and how it compares with the newer Greenstar 8000+.
What Are The Worcester Bosch 36CDi Compact’s Key Specs?
It’s a 36kW gas combi with a 24kW heating output, 12.9 l/min of hot water at a 40°C rise and a casing just 280mm deep.
| Specification | Greenstar 36CDi Compact |
| Boiler type | Wall-hung gas condensing combi |
| Hot water output | 36kW |
| Central heating output | 24kW |
| Hot water flow rate | 12.9 l/min at 40°C rise (about 14.7 l/min at 35°C rise) |
| ErP rating | A for heating, A for hot water |
| Dimensions (H x W x D) | 690 x 390 x 280mm |
| Fuel | Natural gas or LPG (separate LPG model) |
| Controls | Bosch EasyControl compatible, works with most smart thermostats |
| Status | Still available in 2026; the Greenstar 8000+ is Worcester’s newer high-output combi |
What Is The Worcester Bosch Greenstar 36CDi Compact?
It’s the top model in Worcester’s CDi Compact range, which covers the 28CDi, 32CDi and 36CDi, all built into the same 690 x 390 x 280mm casing.
Few combis with this much hot water fit inside a standard kitchen wall cupboard, which is the main reason installers recommend it.
The number in the name refers to the hot water output. At 36kW, the boiler heats mains water fast enough to give a strong shower while someone else runs a tap.
The heating side is capped at 24kW, which suits most well-insulated three bedroom homes and many four bedroom ones, but not every larger property.
If you already own a 36CDi Compact, you’ve got a well-known Worcester model that engineers service all the time. Parts are easy to get hold of. Once yours is over 8 years old, though, efficiency has usually dropped and a new boiler is often the better option.
What Features Does The 36CDi Compact Have?
Its key feature is about 29% more hot water than the 28CDi from exactly the same cupboard-sized casing.
- High hot water output in a small box. That extra hot water comes with no change in size.
- Fits a kitchen cupboard. At 280mm deep, it slots into a standard wall unit.
- Hot water pre-heat. This keeps the hot water side warm for quicker delivery at the tap, and you can turn it off.
- Smart controls. It works with Bosch EasyControl and most smart thermostats, including Hive and Nest. See our smart thermostats page.
- Solar compatible. It accepts pre-heated water from solar thermal panels.
- LPG option. There’s an LPG model for homes off the gas grid. Our LPG and oil boilers page has more on this.
How Efficient Is The Worcester 36CDi Compact?
It’s ErP A-rated for both heating and hot water, and paired with an internet-connected Bosch EasyControl the heating package can reach A+.
A bigger hot water output doesn’t mean bigger gas bills on its own. The boiler only fires at high output while you’re drawing hot water, and the heating output is the same 24kW as the smaller models.
Setup is what really drives running costs.
A flow temperature of 55 to 60°C, weather or load compensation and a magnetic filter all help it stay in condensing mode and use less gas.
If your home has low mains flow, the extra hot water capacity will go unused, and a 28CDi or 32CDi will perform just as well for less money.
What Are The Pros And Cons Of The 36CDi Compact?
You get strong hot water from a cupboard-sized boiler, but the 24kW heating output can fall short in large or draughty homes.
Pros
- Strong hot water flow for its size
- Fits in a standard kitchen cupboard
- Good choice for homes with a bathroom and an en-suite
- Natural gas and LPG versions
- Well known to engineers, with good parts availability
Cons
- Heating output of 24kW may be too low for large or poorly insulated homes
- Two showers at full flow at the same time is still a stretch
- Needs a good mains flow rate to deliver its rated hot water
- Older display and features than the Greenstar 8000+
What Size Home Does The 36CDi Compact Suit?
It suits three and four bedroom homes with one main bathroom and an en-suite, and up to around 12 to 14 radiators depending on insulation. It copes well with a shower running while someone uses the kitchen tap.
Two things decide whether it’s right for you.
First, your mains supply needs to deliver at least 13 litres a minute for the boiler to reach its rated output, and your engineer should measure this. Second, your home’s heat loss needs to sit within the 24kW heating output. Larger homes with lots of radiators may need something like the Greenstar 8000+, which offers up to 33.7kW to the heating.
If two showers often run at the same time, a combi may not be the best fit, and a system boiler with a cylinder could serve you better. Our guides on how to size a combi boiler and the best system boilers can help you decide.
How Much Does It Cost To Install A Worcester 36CDi Compact In 2026?
A like-for-like combi swap typically costs £2,500 to £3,300, while relocations and conversions from tank-fed systems cost more.
The total depends on the work involved, because moving the boiler or converting a system takes more time and materials.
| Type of job | Typical installed price (guide only) |
| Combi to combi swap, same location | £2,500 to £3,300 |
| Combi swap with relocation or new flue | £3,000 to £3,900 |
| System or regular boiler to combi conversion | £3,400 to £4,800 |
These guide ranges include VAT, a system flush, a magnetic filter and standard controls. Prices vary with access, the flue route, pipework condition and your choice of controls. For more detail, see our guide to how much a new boiler costs, or spread payments with boiler finance.
What Are The Best Alternatives To The 36CDi Compact?
The 32CDi Compact suits homes with moderate mains flow, and the Greenstar 8000+ 36kW suits larger homes that need more heating output.
- Worcester Bosch Greenstar 32CDi Compact. Same casing, slightly less hot water at 11.5 l/min at a 40°C rise. It’s a good choice if your mains flow is moderate. Read our 32CDi Compact review.
- Worcester Bosch Greenstar 8000+ 36kW. Worcester’s current premium combi, with a touchscreen, 13.5 l/min at a 40°C rise and a 33.7kW heating output. It’s a larger boiler, so check your space.
- Worcester Bosch Greenstar 34CDi Classic. Now discontinued, but plenty of homes still have one. See our 34CDi Classic review if you’re replacing one.
- Other high-output combis. Our best combi boiler reviews compare Worcester with Vaillant, Ideal and Baxi.
Is The Worcester Bosch 36CDi Compact Worth It?
Yes, for a busy home with a bathroom and an en-suite but limited space, it’s hard to beat.
You get strong hot water from a boiler that hides in a kitchen cupboard, but check that your mains supply and heat loss suit it before you commit.
Choose it if
- You need strong hot water but the boiler must fit in a cupboard
- Your mains flow rate is 13 l/min or better
- Your home’s heating needs sit within 24kW
Look elsewhere if
- Your home is large or poorly insulated and needs more heating output
- Your water pressure is low, as a smaller combi will do the same job
- Two showers regularly run at the same time
Get A Free Boiler Quote From Clever Energy Boilers
Clever Energy Boilers installs Worcester Bosch combis for homeowners and landlords across the North West, Yorkshire and the Midlands.
As Worcester Bosch accredited installers, we test your mains flow and work out your heat loss first, so you get the right model for your home.
Long, market-leading warranties are available through Clever Energy on our Worcester Bosch boiler installations.
Get a fixed price in a few minutes with our online boiler quote tool. There’s no obligation.
Frequently Asked Questions
Is The Worcester Bosch 36CDi Compact Discontinued?
No, it’s still available from UK merchants and installers in 2026. The Greenstar 8000+ is Worcester’s newer high-output combi if you want the latest design.
What Flow Rate Does The 36CDi Compact Give?
About 12.9 litres a minute at a 40°C rise, or roughly 14.7 litres a minute at a 35°C rise. Your actual flow depends on your mains water supply.
How Many Radiators Can A 36CDi Compact Run?
Typically around 12 to 14 radiators. The heating output is 24kW, so larger homes should have a heat loss check first.
Is The 36CDi Compact Good For Two Bathrooms?
Yes, for a bathroom plus an en-suite that aren’t often used at the same time. Two showers running together at full flow will be a stretch for any combi of this size.
Does The 36CDi Compact Fit In A Kitchen Cupboard?
Yes, at 280mm deep it fits most standard kitchen wall units. Your installer will check the clearances for servicing and the flue route.