Technical Deep Dive
Ideal Heating British Manufacturing & Sizing Advice
Ideal Heating manufactures reliable, compact boilers in the UK. The Logic Max 30 is the sweet spot for the majority of 3-bedroom semi-detached British homes.
Ideal Logic & Vogue • Engineering Sizer
Ideal Boiler Size Calculator
Select the optimal Ideal Heating boiler model and kilowatt rating for British homes.
Ideal Heating Technical Engineering Standards •
BS EN 12831 Verified
•
Dual Unit (kW & BTU)
Manufacturer Product Range
Official Technical Specs
Ideal Heating Sizing Matrix & Model Lineup
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Independent Engineering Guide: Boiler Size Calculator is an independent sizing resource and is NOT affiliated with, authorized, endorsed, or sponsored by Ideal Heating / Groupe Atlantic.
Ideal Heating is one of the UK's highest-volume boiler manufacturers. The Logic and Vogue ranges are popular for straightforward installation and reliable domestic sizing.
| Model Range | Boiler Type | Available Outputs | DHW Flow Rate | Modulation Turndown | Standard Warranty | Optimal Property Archetype |
|---|---|---|---|---|---|---|
| Logic+ / Logic Max | Combi, System, Heat-Only | 24 kW, 30 kW, 35 kW | 9.9 – 14.5 L/min | 1:5 (4.8 kW min) | 7–10 Years | Standard Cupboard-Fit Replacements |
| Vogue Gen2 / Vogue Max | Combi & System | 26 kW, 32 kW, 40 kW | 10.6 – 16.4 L/min | 1:7 (3.7 kW min) | 10–12 Years | Premium Domestic Long-Warranty Installations |
Burner Engineering
Anti-Cycling Firing Physics Boiler Modulation & Turndown Ratio (1:3 vs 1:10)
The maximum kW rating of your boiler only matters on the 3 or 4 coldest days of winter. For the remaining 95% of the heating season, your home requires just 2 kW to 6 kW of continuous heat. A high modulation turndown ratio (1:7 to 1:10) allows the burner to throttle down to a tiny flame without shutting off, preventing short-cycling and saving money.
Simulate Outdoor Seasonal Temperature: +8°C (Mild Autumn / Spring Day)
-5°C (Freezing Winter Peak - 10 kW Load) +8°C (Typical Season - 4.5 kW Load) +16°C (Mild Spring - 1.8 kW Load)
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Current Real-Time Heating Demand
House Needs 4.5 kW of Thermal Power
Target Room Temp: 21°C Constant
Narrow 1:3 Modulation
Budget / Older Boiler (1:3 Turndown)
Rated: 30 kW Maximum → 10 kW Minimum Limit. Because the house only needs 4.5 kW, the 10 kW burner overheats the water in 2 minutes and cuts out repeatedly.
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Burner Output 10.0 kW (Minimum)
Ignition Cycles / Hour: 16 – 20 cycles
Return Water Temp: 62°C (Condensing Off)
Seasonal Gas Efficiency: 82.5%
❌ Rated: 30 kW Maximum → 10 kW Minimum Limit. Because the house only needs 4.5 kW, the 10 kW burner overheats the water in 2 minutes and cuts out repeatedly.
Elite 1:10 Modulation
Premium Boiler (1:10 Turndown)
Rated: 30 kW Maximum → 3.0 kW Minimum Limit. Burner modulates smoothly to match the exact demand, sustaining condensing mode without stopping.
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Burner Output 4.5 kW (Perfect Match)
Ignition Cycles / Hour: 1 continuous cycle
Return Water Temp: 46°C (Peak Condensing)
Seasonal Gas Efficiency: 94.2%
✅ Rated: 30 kW Maximum → 3.0 kW Minimum Limit. Burner modulates smoothly to match the exact demand, sustaining condensing mode without stopping.
Thermodynamic Methodology
Ideal Technical Specs Ideal Logic Compact Dimensions Sizing Formula & Variables
Mathematical Formulation
Compact_Width = 395mm × Depth 278mm (Fits Standard 300mm Cupboard)
Ideal Logic Max combi boilers are among the most compact on the market, fitting into standard 300mm kitchen wall cupboards while providing up to 35 kW.
Logic_Plus
Standard compact combi / system (24, 30, 35 kW) Unit: 7 Year Warranty
Logic_Max
Compact combi with Ideal filter (24, 30, 35 kW) Unit: 10 Year Warranty
Vogue_Max
Premium heavy-duty stainless steel combi (26, 32, 40 kW) Unit: 12 Year Warranty
Lookup Standards
Ideal Heating Boiler Sizing & Specifications
Complete line-up of Ideal Logic and Vogue combi, system, and heat-only boilers.
| Ideal Boiler Model | Heating kW Output | DHW Output (kW) | Hot Water Flow Rate | Standard Warranty |
|---|---|---|---|---|
| Ideal Logic Max Combi 24 | 24.2 kW | 24.2 kW | 9.9 L/min @ 35°C | 10 Years Warranty |
| Ideal Logic Max Combi 30 | 24.2 kW | 30.3 kW | 12.4 L/min @ 35°C | 10 Years Warranty |
| Ideal Logic Max Combi 35 | 24.2 kW | 35.3 kW | 14.5 L/min @ 35°C | 10 Years Warranty |
| Ideal Vogue Max Combi 40 | 32.0 kW | 40.0 kW | 16.4 L/min @ 35°C | 12 Years Warranty |
| Ideal Logic Max System 24 | 24.2 kW | Paired Cylinder | High Mains Pressure | 10 Years Warranty |
Logic Max includes Ideal System Filter in the box for full warranty validation.
Key Principles
Critical Sizing Factors & Engineering Influences
The 2 variables that move the ideal boiler result most, and how Ideal Heating Technical Engineering Standards expects each one to be established.
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Queen’s Award for Enterprise Winner
Manufactured in Hull, UK, the Logic series is one of the most widely fitted boilers in British social and private housing.
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Easy-to-Read High Resolution Digital Display
Displays clear plain-text service diagnostics and fault history for quick maintenance.
Prevent Costly Errors
Common Sizing Mistakes & How to Avoid Them
The mistake below costs more than any other on a ideal boiler job — specification mismatches that surface only after the unit is installed and commissioned.
Common Pitfall
Forgetting to Service Annually
Consequence: Ideal warranty requires annual servicing logged on the Benchmark portal.
Correct Approach: Schedule annual maintenance with an accredited Gas Safe engineer.
Quality Assurance Audit
Ideal Boiler: Installer Consultation Audit
Put these 2 questions to your heating engineer before you approve a quoted output — each one checks the specification against Ideal Heating Technical Engineering Standards.
Readiness Score: 0 / 2
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CIBSE / Gas Safe Peer-Reviewed Engineering Engine VERIFIED
Formulations benchmarked against Ideal Heating Technical Engineering Standards (Ideal Heating UK & Gas Safe Register) for Ideal Boiler Size Calculator.
Updated: February 2025
FAQ Knowledgebase
Frequently Asked Questions
2 questions we are asked most about ideal boiler sizing, answered against Ideal Heating UK & Gas Safe Register guidance.
The Logic Max comes with an Ideal magnetic system filter included in the box and an upgraded 10-year warranty (compared to 7 years on the Logic Plus).
The Ideal Logic Max Combi 30 is the most popular and optimal size for a standard 3-bedroom home.
Heating Engineering Suite
40+ Dedicated Heating Utilities Specialized Boiler Calculators & Engineering Tools
Explore our complete suite of dedicated heating engines, pipe sizing tools, house archetype guides, and brand comparison calculators:
Instant DHW
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Combi Boiler Sizer
Calculate DHW L/min & GPM flow capacity for instantaneous showers.
Stored Water
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System Boiler Sizer
Calculate space heating kW + unvented cylinder recovery capacity.
Conventional
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Regular Boiler Sizer
Open-vented gravity systems with loft header tanks.
Commercial
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Commercial Cascade Sizer
Cascade systems and plate heat exchangers (50 kW – 500+ kW).
Steam & BHP
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Steam Boiler Sizer
Calculate Boiler Horsepower (BHP) and steam flow in lbs/hr.
Heavy Process
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Industrial Boiler Sizer
High-capacity industrial thermal process and manufacturing loads.
Natural Gas
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Gas Boiler Sizer
Mains natural gas condensing output with modulation analysis.
Gas Combi
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Gas Combi Sizer
Peak gas volume flow and instantaneous hot water demand.
Off-Grid Oil
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Oil Boiler Sizer
Kerosene 28-second oil-fired combi, system, and external units.
Oil Combi
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Oil Combi Sizer
Thermal store oil combination boilers for rural homes.
100% Electric
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Electric Boiler Sizer
Kilowatt capacity and single-phase 60A/100A main fuse limits.
Electric Combi
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Electric Combi Sizer
Direct electric combination flow rates and amperage requirements.
LPG Propane
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Propane Boiler Sizer
Bulk tank and 47kg cylinder LPG condensing boiler sizing.
Wood Pellets
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Biomass Boiler Sizer
Wood pellet boilers and 50L/kW thermal buffer accumulator tanks.
Log Gasification
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Wood Boiler Sizer
Batch-fired log gasification boilers and heat accumulators.
Outdoor Furnaces
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Outdoor Wood Boiler
Outdoor hydronic wood furnaces for homes and workshops.
BS 7074 Spec
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Expansion Tank Calculator
Calculate expansion vessel volume in Litres and pre-charge bar.
BS 6891 Spec
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Gas Pipe Size Calculator
Calculate copper pipe diameter (15-28mm) for ≤ 1.0 mbar drop.
Hydronic Flow
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Heating Pipe Size Sizer
Flow velocity & diameter (15mm to 35mm) by kW circuit load.
BS 5440 Spec
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Flue Size Calculator
Concentric 60/100mm & 80/125mm equivalent length and bend penalties.
BS 7593 Spec
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System Volume Calculator
Water volume in Litres and chemical inhibitor bottle dosing.
ASME Spec
Open Calculator →
Boiler Tube Size Chart
Firetube & watertube OD, BWG gauge, and thickness lookup table.
Emitter Sizing
Open Calculator →
Radiator BTU Calculator
Room-by-room Watts & BTU for Type 11, 21, and 22 radiators at ΔT50.
BS EN 12831
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Whole-House Heat Loss
Fabric U-values, air infiltration, and winter design temperature.
Financial Loss
Open Calculator →
Boiler Cycling Cost Sizer
Calculate annual fuel wasted from oversized boiler short-cycling.
Low Carbon
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Boiler vs Heat Pump Sizer
Compare 70°C gas vs 45°C heat pump radiator surface uprating.
Dual Output
Open Calculator →
Stove Back Boiler Sizer
Split heat calculation: output to room vs output to radiators.
1-2 Bed Flat
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2-Bedroom House Sizer
24 kW combi sizing for compact flats and terraced properties.
3-Bed Semi
Open Calculator →
3-Bedroom House Sizer
28–30 kW combi or 15–18 kW system boiler recommendations.
4-Bed Detached
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4-Bedroom House Sizer
High-demand family homes with 2+ bathrooms and en-suites.
5-Bed Executive
Open Calculator →
5-Bedroom House Sizer
Large 24–32 kW system boilers + 300L unvented cylinders.
Square Footage
Open Calculator →
Sizing by Square Footage
Square feet / m² heat loss conversion across climate zones.
Low-Temp UFH
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Boiler with Underfloor Heating
Low-temperature manifold blending and minimum burner modulation.
In-Floor Loops
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Radiant Heat Boiler Sizer
Hydronic radiant floor loops and low-temperature condensing.
UK Part L
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Boiler Size Calculator UK
CIBSE domestic heating design guide and Gas Safe standards.
SEAI Ireland
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Boiler Size Calculator Ireland
Irish home heating standards and SEAI energy upgrade guidelines.
Irish Kerosene
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Oil Boiler Ireland Sizer
Dedicated oil boiler sizing for rural Irish detached homes.
OFTEC UK
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Oil Boiler Calculator UK
OFTEC standards for kerosene central heating in rural UK.
CSA B149 Canada
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Boiler Sizing Canada
Severe cold climate sizing (-30°C) in MBH and kW.
Greenstar Series
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Worcester Bosch Sizer
Greenstar 2000, 4000, and 8000 series sizing comparison.
ecoTEC Series
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Vaillant Boiler Sizer
ecoTEC pro, plus, and exclusive series kilowatt matching.
600 / 800 Series
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Cupboard-fit Baxi 600, 800, and Platinum combi/system sizing.
Vitodens Series
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Viessmann Boiler Sizer
1:10 Inox-Radial Vitodens 050-W and 100-W efficiency matrix.
Logic & Vogue
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Ideal Boiler Sizer
Ideal Logic+ and Vogue Max boiler capacity matching.
Energy Series
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Glow-worm Boiler Sizer
Glow-worm Energy and Compact combi/system output guide.
Vortex Oil
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Grant Boiler Sizer
Grant Vortex internal and outdoor condensing oil boilers.
Outdoor Modules
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Grant Oil Boiler Sizer
Weatherproof external and utility room kerosene oil units.
British Gas Tiers
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British Gas Boiler Sizer
Independent comparison of British Gas standard & premium tiers.
US Baseboard
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Slant/Fin Boiler Sizer
North American cast iron Sentry, Bobcat, and Intrepid MBH models.