The Ideal Logic+ C35 is the largest combi in Ideal’s Logic+ range, with 35.3kW of hot water output and 14.5 litres per minute. It’s built for busier homes, usually three or four bedrooms, where a 24kW combi would leave the shower running lukewarm.
The original Logic+ C35 is no longer the version on sale. It’s been superseded by the Logic+ Combi2 C35, which has the same outputs, a larger colour display and a few installer-friendly changes. This review covers both, so it’s useful if you own an older C35 or you’re comparing boilers before replacing one.
What Are The Ideal Logic+ C35’s Key Specs?
The Logic+ C35 gives 35.3kW for hot water, 24.2kW for heating and 14.5 litres per minute, with an A rating for both.
| Specification | Ideal Logic+ C35 |
| Boiler type | Combi |
| Fuel | Natural gas only (no LPG conversion listed for the C35) |
| Hot water output | 35.3kW |
| Central heating output | 7.1 to 24.2kW |
| Hot water flow rate | 14.5 litres per minute (35°C rise) |
| ErP rating | A for heating, A for hot water |
| Seasonal heating efficiency | 94% |
| NOx class | Class 6 |
| Dimensions (current Combi2 version) | 700mm high x 395mm wide x 278mm deep |
| Status | Original model superseded by the Logic+ Combi2 C35 |
What Is The Ideal Logic+ C35?
It’s a wall-hung condensing combi made in Hull. Like every combi, it heats water on demand straight from the mains, so there’s no cylinder or loft tank to find room for.
One detail catches a lot of people out. The “35” refers to hot water output only.
The heating side tops out at 24.2kW, the same as the C24 and C30. Ideal does this across the Logic family because most UK homes don’t need more than about 24kW for their radiators. They do benefit from a bigger burner when a shower is running, though.
A quick note on the name. Some older marketing described the “+” as standing for extra cover. In practice, the Logic+ sits between the entry-level Logic and the Logic Max, and the Logic Max adds an Ideal System Filter in the box.
What Features Does The Logic+ C35 Have?
Its headline feature is 14.5 litres per minute of hot water from a case small enough for a kitchen cupboard.
- 14.5 litres per minute of hot water, the highest flow in the Logic+ range
- Modulates down to 7.1kW on heating, which helps on milder days
- Compact case that still fits inside a standard kitchen cupboard
- Built-in filling loop
- Clear display with pressure readout and fault codes
- Quiet in use, with a published sound level of 44dB for the C35
- Works with Ideal’s own controls and most third-party thermostats
- Compatible with an Ideal System Filter
How Efficient Is The Ideal Logic+ C35?
It’s A-rated for heating and hot water, with a seasonal heating efficiency of 94%. That’s in line with most modern condensing combis.
Your running costs will depend far more on insulation, thermostat settings and your gas tariff than on the badge.
A bigger hot water burner doesn’t mean bigger bills. The boiler only fires at full rate while you’re drawing hot water, and a faster flow fills a bath sooner. On heating, it behaves almost exactly like the C24 and C30.
You can cut running costs by lowering the heating flow temperature so the boiler condenses more of the time. A smart thermostat with room-by-room or time-based control helps too.
What Are The Pros And Cons Of The Logic+ C35?
You get strong shower performance from a compact, well-priced combi, but heating is capped at 24.2kW and there’s no listed LPG option.
Pros
- Strong hot water flow for a compact combi
- Same small case as the C24, so it still fits in a kitchen cupboard
- A-rated, condensing and quiet
- Usually cheaper to buy and fit than premium combis with similar flow rates
- Spares are easy to find, and plenty of engineers know it well
Cons
- Heating output is capped at 24.2kW, which may be short for very large or poorly insulated homes
- Aluminium alloy heat exchanger rather than stainless steel
- No LPG conversion listed for the C35, unlike the C24 and C30
- Two showers at once will still share the 14.5 litres per minute
- System filter is an extra on the Logic+, whereas the Logic Max includes one
What Size Home Does The Logic+ C35 Suit?
It suits a three or four bedroom home with a main bathroom and, in many cases, an en suite. At 14.5 litres per minute, it runs a shower well and leaves some headroom for a basin or kitchen tap.
It isn’t a replacement for stored hot water in a house where two bathrooms get heavy use at the same time.
Two showers running together will split the flow. That won’t match a system boiler with an unvented cylinder. If that sounds like your household, our guide to the different types of boiler explains the options.
Your mains supply matters as well. To get the full 14.5 litres per minute, your incoming cold main needs to deliver at least that much. We measure flow and pressure on every survey, and if your supply is weak, a bigger combi won’t fix it. Our article on how to size a combi boiler covers this.
How Much Does A Logic+ C35 Cost To Install In 2026?
Expect a guide price of £2,000 to £2,800 for a like-for-like swap, including VAT. Relocations and system-to-combi conversions cost more.
| Type of job | Guide installed price |
| Like-for-like combi swap, same position | £2,000 to £2,800 |
| Combi swap with boiler relocated | £2,600 to £3,500 |
| Conversion from system or regular boiler to combi | £3,100 to £4,400 |
Treat these as a starting point only, because every job is different. Flue length, gas pipe upgrades, condensate routing and controls all affect the final figure.
Larger combis often need a 22mm gas supply run back to the meter. If your existing pipe is 15mm, that adds cost. A good installer will spot it at the survey, not on the day. There’s more detail in our guide to how much a new boiler costs.
What Are The Best Alternatives To The Logic+ C35?
The Logic Max C35 is the closest alternative, with identical outputs and a system filter in the box.
- Ideal Logic Max C35: identical outputs with a system filter included. Read our Ideal Logic Max C35 review.
- Ideal Vogue Max C32 or C40: Ideal’s premium range, with a stainless steel heat exchanger and higher heating outputs of 26kW and 32kW.
- Ideal Logic+ C30: 12.4 litres per minute, a sensible middle ground for three bedroom homes with one bathroom.
- A system boiler with a cylinder: the better choice for two bathrooms in regular use. See our best system boilers.
Is The Ideal Logic+ C35 Worth It?
Yes, for a family home with one main bathroom and perhaps an en suite. It’s a solid, cost-effective combi.
You get a big step up in hot water over the C24 without a bigger case or a big jump in price. If you want stainless steel or more heating output, the Vogue Max is the upgrade. Our Ideal boiler comparison sets the ranges side by side.
Choose It If
- You have a three or four bedroom home with one bathroom, or a bathroom plus en suite
- You want good shower performance from a compact combi
- Your home’s heat loss sits comfortably under 24kW
- You want a well-priced boiler from a UK manufacturer
Look Elsewhere If
- Two showers regularly run at the same time
- You’re on LPG
- Your home is large or draughty and needs more than 24kW of heating
- You’d prefer a stainless steel heat exchanger
Get A Free Boiler Quote From Clever Energy Boilers
We install Ideal combis for homeowners and landlords across the North West, Yorkshire and the Midlands. Our team are experienced, professional and registered installers.
We size every boiler from a proper look at your home, not a guess based on the number of bedrooms.
Find out more about our Ideal boiler installations, or get a fixed-price boiler quote online. Clever Energy can also arrange long, market-leading warranty cover on your new boiler.
If the C35 is more boiler than you need, or not enough, we’ll say so and quote the right model.
Frequently Asked Questions
Is The Ideal Logic+ C35 Still Sold?
No, not in its original form. It’s been superseded by the Logic+ Combi2 C35, which has the same 35.3kW hot water output and 14.5 litre per minute flow rate, plus a larger colour screen.
How Many Bathrooms Can A Logic+ C35 Run?
One bathroom plus an en suite, as long as both aren’t used heavily at once. For two bathrooms in regular simultaneous use, a system boiler with a cylinder usually works better.
Why Is The Heating Output Lower Than 35kW?
Because 35kW is the hot water output. Heating output is 24.2kW across all Logic+ sizes, which is enough for most UK homes.
Can The Logic+ C35 Be Converted To LPG?
No, there’s no LPG conversion listed for the C35. The C24 and C30 can be converted, so off-grid homes should look at those or at our LPG and oil boilers.
Does The Logic+ C35 Need A System Filter?
Yes, we’d strongly recommend one, and we suggest it on every installation we quote for. A magnetic filter catches sludge and protects the heat exchanger.