UK Aircon Response installs F-Gas certified air conditioning systems that cool rooms rapidly, filter air quality, and provide winter heating (heat pump mode). We calculate BTU requirements (room volume × insulation × sun exposure), specify SEER-rated equipment (energy efficiency 8.5+ A+++ rating), mount indoor/outdoor units with refrigerant pipework, vacuum-test for leaks—then commission system and register F-Gas compliance certificate.
Survey week 1. Equipment ordered week 2. Outdoor unit mounted day 1. Indoor unit installed day 2. Pipework + electrical day 3. Vacuum test + refrigerant charge day 4. Commissioned week 2.
F-Gas certification required by law for refrigerant handling (engineer qualification—only F-Gas certified engineers can install/service AC legally). Typical 3.5kW (12,000 BTU) split system costs £1,200-1,500 installed. Cools 12-15m² bedroom. SEER 8.5 (Seasonal Energy Efficiency Ratio—higher = cheaper to run). Mitsubishi/Daikin/LG inverter units (variable speed compressor, quieter + 40% more efficient than fixed-speed). Running cost: 25p/hour at 24p/kWh electricity (1kW average draw in cooling mode). Building Regs Part F compliance if replacing window/wall ventilation. Planning permission not usually required (permitted development) unless listed building/conservation area.
From BTU calculations to F-Gas certification
Most common domestic AC: 3.5kW (12,000 BTU) capacity, cools 12-15m² bedroom or 18-20m² living room. Cost: £1,200-1,500 installed including VAT. System components: outdoor unit (compressor, condenser coil, fan), indoor wall-mounted unit (evaporator, fan, filters), refrigerant pipework (copper, insulated, 3-5m typical run), condensate drain, electrical supply (dedicated 16A circuit from consumer unit). Installation: outdoor unit fixed to external wall (bracket bolted to brick), core drill 65mm hole through wall for pipework, indoor unit mounted 2m high (optimal for air circulation), refrigerant pipes lagged + clipped, vacuum pump test (removes moisture/air from system—critical for efficiency), refrigerant charged (R32 gas, 1.2kg typical), system commissioned. Brands: Mitsubishi Electric MSZ-AP (quietest, 19dB indoor), Daikin Sensira FTXC (best value, £950 trade price), LG Artcool (stylish black glass panel, £1,100). SEER rating: 8.5+ for A+++ energy label (means 8.5kWh cooling per 1kWh electricity—very efficient). Running cost: 1kW average draw in cooling mode = 24p/hour at 24p/kWh electricity (£1.92 for 8-hour night).
Undersized AC can't cool room, oversized wastes energy and short-cycles (inefficient). Correct sizing critical. BTU (British Thermal Units) measures cooling capacity—12,000 BTU = 3.5kW. Calculation factors: room volume (length × width × height in m³), insulation quality (modern double-glazed = 50% less heat gain than single-glazed), sun exposure (south-facing rooms gain 30% more heat), occupancy (100W heat per person), equipment (TVs/computers add 200-400W heat). Formula: BTU needed = (room m³ × 150) + (sun exposure factor × 500) + (occupancy × 340). Example: 12m² bedroom (3m ceiling = 36m³), south-facing, 1 occupant = (36 × 150) + (1 × 500) + (1 × 340) = 5,400 + 500 + 340 = 6,240 BTU = **2kW unit sufficient**. But we recommend 3.5kW (12,000 BTU) for headroom on hot days (32°C+) and faster cooldown. Oversizing risk: unit short-cycles (reaches setpoint quickly, switches off, switches back on frequently—wears compressor, doesn't dehumidify air properly). Undersizing worse: runs continuously, never reaches setpoint, high electricity bills. We conduct room-by-room heat gain surveys to size accurately.
Inverter AC uses variable-speed compressor (ramps up/down to maintain temperature). Fixed-speed is on/off only (full power or off). **Inverter benefits:** 40% lower running costs (compressor runs at 30-70% capacity most of time vs 100% with fixed-speed), quieter (30dB vs 45dB when running low), longer lifespan (less wear from on/off cycling), better dehumidification (continuous low-speed running removes moisture gradually). **Cost difference:** Inverter £1,200-1,500, fixed-speed £800-1,000 (£400 premium). **Payback:** £80/year electricity saving (based on 500 hours/year usage) = 5 years. Worth it if using AC regularly (>300 hours/year). Example inverter models: Mitsubishi MSZ-AP35 (3.5kW, SEER 8.6, £1,350 installed), Daikin FTXC35 (SEER 8.5, £1,200), Panasonic Etherea (SEER 9.0, £1,600—best efficiency but pricey). Fixed-speed still sold but being phased out (Ecodesign regulations favor inverters). We recommend inverter for all residential installs—£400 extra is justified by comfort + efficiency.
F-Gas regulations control refrigerant handling to prevent greenhouse gas emissions. **Engineer qualification:** Only F-Gas certified engineers can install/service AC containing fluorinated gases (R32, R410A). Certification requires exam + practical assessment (2-day course, £800-1,200 cost to engineer). Cowboys without F-Gas cert install illegally—system not insured, warranty invalid, £5,000 fine if caught. **Refrigerant types:** R32 (most common now, GWP 675—lower environmental impact), R410A (older, GWP 2,088—being phased out), R290 (propane, natural refrigerant, flammable so limited use). **Installation compliance:** Refrigerant leak test before charging (vacuum pump to -1 bar, hold 30 mins—if pressure rises, leak present), charge by weight (scales measure exact refrigerant amount—overcharging reduces efficiency), log serial numbers + refrigerant quantity (legal requirement for systems >3kg refrigerant). **Annual checks:** Systems >3kg refrigerant (5kW+ units) require annual leak checks by F-Gas engineer (£80-120/year service contract). Domestic 3.5kW systems exempt (under 3kg). **Decommissioning:** Refrigerant must be recovered (not vented to atmosphere—£5,000 fine). We use recovery machine to pump gas into cylinder (recycled/destroyed properly). F-Gas certificate issued on installation completion—keep for property records (proves legal install if selling house).
**Multi-split:** One outdoor unit powers multiple indoor units (2-5 rooms from single compressor). Cost: £3,500-6,000 for 2-room system (e.g., 2 × 2.5kW units on 5kW outdoor unit). Benefits: single outdoor unit (less visual clutter on facade), centralized control, cheaper than multiple single-splits (saves £800-1,200 vs 2 separate systems). Drawbacks: all rooms on same system (can't cool bedroom while heating living room—all units must be in same mode), if outdoor unit fails, all rooms lose AC. Best for: homes needing AC in 2-3 rooms, limited outdoor space for multiple units. **Ducted systems:** Central AC unit in loft/basement, ducts distribute cooled air to multiple rooms via ceiling vents. Cost: £8,000-12,000 for whole-house (4-5 rooms). Benefits: invisible (no wall-mounted units), even temperature distribution, can integrate with MVHR ventilation. Drawbacks: expensive, requires ceiling void depth (200mm+), harder to zone (whole house cools/heats together unless motorized dampers fitted—adds £1,500). Best for: new builds or major renovations where ducting can be integrated, open-plan layouts. We recommend multi-split for most retrofit situations (ducted only viable if loft conversion or major refurb planned).
Modern AC units are reversible heat pumps—cool in summer, heat in winter. **Heating performance:** 3.5kW unit produces 4-5kW heat output (COP 4-5, same efficiency as dedicated air source heat pump). Cheaper than electric heaters (£1/hour vs £2.50/hour for 2.5kW panel heater). **When to use:** Shoulder seasons (spring/autumn) when full central heating overkill, bedrooms that get cold (heat individual room without heating whole house), backup heating if boiler fails. **Limitations:** Output drops below 7°C outdoor temp (at -5°C, 3.5kW unit only produces 2kW heat—not sufficient for very cold days), doesn't produce hot water (only space heating), noisier in heating mode (outdoor fan runs faster). **Cost comparison:** Heating bedroom 3 hours/evening at 15°C outdoor temp: AC heat pump £0.72 (4kW output, 1kW input, 24p/kWh), gas radiator £0.54 (80% boiler efficiency, 6p/kWh gas), electric heater £1.80 (2.5kW, 24p/kWh). So AC heat pump is middle option—cheaper than electric, more expensive than gas, but convenient for single-room heating without firing up whole central heating system. We install AC primarily for cooling but heat pump mode is useful bonus feature (not replacement for central heating).
Legal compliance required for refrigerant handling
Tell us your room size and we'll calculate BTU requirements