Air Conditioning

15 articles

AC Annual Service and Maintenance: Filter Cleaning, Coil Inspection, Refrigerant Check and F-Gas Log Update

Full annual service checklist: filters, evaporator/condenser coils, condensate, refrigerant pressure (superheat/subcooling), F-Gas log update; mandatory leak check frequency by CO₂e threshold; commercial systems twice-yearly; service report format
AC Condensate Drainage: Primary vs Secondary Drain, Condensate Pump Selection and Where to Discharge

1–2 litres/hour condensate from 3.5 kW unit; primary vs secondary drain; 1:50 minimum gradient; MDPE/ABS pipe (not copper); discharge hierarchy (soil stack preferred); condensate pump head/flow sizing; check valve requirement; Part H compliance
AC Electrical Supply Requirements: Dedicated Circuit, Isolator Siting, RCD Protection and Earthing

BS 7671:2018+A2:2022; dedicated circuit sizing; Type C MCB for motor inrush; cable sizing steps; 30 mA Type A/F RCD for outdoor equipment; lockable outdoor isolator (IP44/65); earthing for TN-C-S/TT; Part P notification
AC Energy Efficiency: SEER and SCOP Ratings, ErP Directive Labels and What to Quote to Customers

SEER for cooling, SCOP for heating; ErP label reading (Class A minimum SEER 3.60, SCOP 3.40); running cost calculation; heat pump vs gas cost comparison; EPC impact; AIA replaced ECA scheme for commercial AC
AC in Listed and Heritage Buildings: Hiding Pipework, Minimal-Impact Siting and Planning Authority Liaison

Listed Building Consent required for any works; working with conservation officers; fan coil and cassette concealment strategies; reversible fixings; Historic England/HES guidance; Conservation Area outdoor unit rules; Scotland/Wales/NI equivalents
Air Conditioning and Building Regs Part F: Ventilation Requirements, MVHR Interaction and TM65 Embodied Carbon

Part F:2021 ventilation requirements; recirculating AC does not satisfy ventilation; MVHR interaction; SAP 10.2 AC declaration; Part L SEER minimums; CIBSE TM65 embodied carbon methodology
Air Conditioning Planning and Permitted Development: Outdoor Unit Siting Rules, Noise Limits and Listed Buildings

GPDO 2015 Schedule 2 Part 14 Class A conditions; 1 m boundary setback; no highway-facing walls; BS 4142 noise assessment; flats and listed buildings excluded from PD; Conservation Area rules; Scotland/Wales/NI differences
F-Gas Regulations 2024: Technician Certification, Equipment Leak Checks and Record-Keeping Obligations

UK F-Gas Regulations; CO₂e charge calculation; leak check thresholds (5/50/500 tonne CO₂e: quarterly/monthly/semi-annual); Category I/II technician certs via City & Guilds 2079; logbook requirements; HFC phase-down schedule; refrigerant recovery obligations
HVAC Commissioning and Handover: Refrigerant Charge Verification, Airflow Balancing and F-Gas Documentation

Nitrogen pressure test; two-stage evacuation to <500 microns; weigh-in refrigerant charge (±10g scales); top-up from pipe length tables; 8–12°C supply/return differential; airflow balancing ±10%; F-Gas label and log; mandatory leak test thresholds; customer handover pack
Multi-Split System Design: Outdoor Unit Capacity, Piping Length Limits, Indoor Unit Combinations and Diversity

Outdoor unit capacity vs sum of indoor units; 80–90% diversity; Refnet branch junction design; total equivalent length limits; oil trap requirements; refrigerant top-up calculation from pipe lengths; mixing indoor unit types; 10-step commissioning sequence
Portable AC vs Split System: Why Portable Units Underperform and How to Explain the Difference to Customers

Single-duct portables create negative pressure negating cooling; EER 2.0–2.5 vs 3.5–5.0 for splits; noise 52–58 dB vs 19–42 dB; running cost comparison; when portables are justified; installer opportunity converting portable users
REFCOM Certification: F-Gas Company Registration, Licence to Handle Refrigerants and Annual Returns

REFCOM company certification for F-Gas; annual returns by 31 March; REFCOM vs REFCOM Elite; Contractor Competency Scheme for natural refrigerants; how to verify contractor status; record-keeping requirements for refrigerant purchases and recovery
Refrigerant Types: R32 vs R410A vs R290 — GWP, Flammability Classes and What Each Means for Installers

R32 (GWP 675, A2L), R410A (GWP 2088, A1, being phased out), R290 propane (GWP 3, A3), R1234yf (GWP 4, A2L); ASHRAE flammability classes; A2L installation precautions; R290 charge limits in occupied spaces; phase-down timeline
Split System AC Installation: Indoor Unit Positioning, Refrigerant Pipe Sizing, Drainage and Electrical Supply

Indoor unit clearances (15 cm sides, 20 cm ceiling); outdoor unit siting and vibration isolation; pipe sizing (6.35 mm liquid/9.52 mm suction); flaring and nitrogen pressure test; evacuation to <500 microns; condensate drainage (1:50 fall); electrical supply (dedicated circuit, Type C MCB, Type A RCD, local isolator)
VRF/VRV Systems Overview: Variable Refrigerant Flow Design Principles, Piping, BCU and Controls Integration

VRF vs VRV naming; 2-pipe vs 3-pipe heat recovery; BCU function; equivalent length limits (165 m total, 50 m height); Y-junction vs header branch kits; BACnet/Modbus/LonWorks integration; commissioning software; appropriate for 5+ zones