{"id":547,"date":"2026-10-03T10:47:58","date_gmt":"2026-10-03T10:47:58","guid":{"rendered":"https:\/\/www.deltafirst.co.uk\/blog\/?p=547"},"modified":"2026-10-25T21:59:28","modified_gmt":"2026-10-25T21:59:28","slug":"air-balancing-procedure","status":"publish","type":"post","link":"https:\/\/www.deltafirst.co.uk\/blog\/air-balancing-procedure\/","title":{"rendered":"CIBSE and BSRIA aligned air balancing procedure for facilities managers"},"content":{"rendered":"<p>Air balancing is the commissioning activity that adjusts and verifies airflow so each outlet meets its design flow. Carry this out using measured AHU and terminal readings, proportional damper adjustment and documented acceptance against project tolerances. Before any measurement begins, gather the design flow rates and confirm the air handling unit is running at its intended design conditions.<\/p>\n<hr>\n<blockquote>\n<p><strong>TL;DR:<\/strong><\/p>\n<ul>\n<li>Proper pre-balance inspection, documentation, and system readiness are essential to ensure accurate airflow measurement and effective balancing.<\/li>\n<li>Selecting the correct measurement instrument depends on the terminal type and requires proper calibration and record-keeping to maintain reliability.<\/li>\n<li>Total airflow at the air handling unit must be verified before individual terminal adjustments, comparing it with the sum of branch and terminal readings for discrepancies.<\/li>\n<li>Balancing should be performed using a proportional method from the lowest-pressure branch outward, with repeated measurement after each damper adjustment to maintain stability.<\/li>\n<li>Complete commissioning records, including design data, measurement details, and remedial work, are critical for verification, future maintenance, and compliance purposes.<\/li>\n<\/ul>\n<\/blockquote>\n<hr>\n<div data-blg-cta=\"after_tldr\" data-blg-cta-layout=\"split\" style=\"margin:28px 0;font-family:-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif\">\n<div style=\"border-radius:26px;padding:min(22px,3.2vw);background:radial-gradient(circle at 100% 0%,#d7dce5 0 150px,rgba(255,255,255,0) 151px),radial-gradient(circle at 0% 100%,#d7dce5 0 130px,rgba(255,255,255,0) 131px),linear-gradient(180deg,#e4e7ee 0%,#f2f3f6 100%)\">\n<div style=\"background:#ffffff;border-radius:18px;overflow:hidden\">\n<div style=\"display:flex;flex-wrap:wrap;background:linear-gradient(104deg,#112240 0%,#0b162a 33%,#ffffff 33.15%)\">\n<div style=\"flex:0 0 30%;min-width:150px;padding:30px 10px 30px 26px;color:#ffffff\">\n<div style=\"margin:0 0 14px\"><span style=\"display:inline-block;max-width:100%;border-radius:999px;padding:6px 13px;font-size:12px;font-weight:800;letter-spacing:0.1em;text-transform:uppercase;line-height:1.3;background:#ffffff;color:#15294d\">Delta First<\/span><\/div>\n<div style=\"font-size:12px;opacity:0.75\">deltafirst.co.uk<\/div>\n<\/div>\n<div style=\"flex:1 1 300px;padding:30px 28px 30px 40px\">\n<div style=\"font-size:23px;font-weight:800;line-height:1.2;letter-spacing:-0.01em;color:#1f2937;margin:0\">Keep Air Systems Performing Safely<\/div>\n<div style=\"width:56px;height:6px;border-radius:3px;background:#1E3A6E;margin:12px 0 14px\"><\/div>\n<div style=\"font-size:15px;line-height:1.55;color:#64748b;margin:0 0 22px\">Delta First provides HVAC, compliance and planned maintenance services to help facilities managers keep commercial buildings operating safely and efficiently.<\/div>\n<p><a href=\"https:\/\/deltafirst.co.uk\" style=\"display:inline-flex;align-items:center;gap:9px;border-radius:10px;font-weight:700;font-size:15px;text-decoration:none;padding:13px 22px 13px 26px;background:#1E3A6E;color:#ffffff\">Explore Delta First services<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<h2 id=\"pre-balance-inspection-and-documents-to-gather\" tabindex=\"-1\">Pre-balance inspection and documents to gather<\/h2>\n<p>Rushing straight to a flow hood without preparation wastes time and produces numbers nobody can trust. The first job on any balancing visit is paperwork, not instruments.<\/p>\n<p>Collect the design drawings, schedule of design flow rates, control sequences and equipment data sheets before touching a damper. These documents set the target every reading will be measured against, and without them a technician is guessing rather than commissioning. Commissioning drawings showing duct routes, damper locations and test point positions save considerable time on site, particularly on systems installed years apart from any as-built record. <a href=\"https:\/\/cibse.org\/knowledge-research\/knowledge-portal\/cca-commissioning-code-a-air-distribution-systems-2024-pdf\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">CIBSE Code A<\/a> and BSRIA\u2019s commissioning guides are the reference points most specifications point to for acceptance criteria, so keep both to hand alongside the project specification itself.<\/p>\n<p>Physical readiness matters just as much as paperwork. Walk the system before measuring anything:<\/p>\n<ul>\n<li>Remove shipping guards and transit packaging from AHUs, dampers and terminal units.<\/li>\n<li>Confirm balancing dampers are fitted, accessible and free to move through their full range.<\/li>\n<li>Inspect filters, heat exchangers and outdoor-air grilles for blockage or fouling.<\/li>\n<li>Check access panels and test points are present and usable without disturbing the system.<\/li>\n<li>Verify fans, variable-speed drives and controls have been commissioned and set to their design operating points.<\/li>\n<\/ul>\n<p>Government guidance on air conditioning inspections notes that <a href=\"https:\/\/www.gov.uk\/government\/publications\/air-conditioning-inspections-for-buildings\/a-guide-to-air-conditioning-inspections\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">blocked filters, heat exchangers or obstructed outdoor-air grilles increase resistance and can reduce airflow<\/a>, which means damper adjustments made against a fouled system risk masking a fault rather than correcting it. Fix the fault first, then balance.<\/p>\n<p>Site access and health and safety arrangements need confirming before the visit too: permits, isolation procedures, working at height requirements and who holds keys to plant rooms and ceiling voids. Where the client or building control will witness sign-off, agree the date early so the report and any remedial work are ready in time. A related read on summer HVAC maintenance covers many of these same filter and fan checks as part of a routine PPM visit.<\/p>\n<h2 id=\"selecting-instruments-and-managing-measurement-uncertainty\" tabindex=\"-1\">Selecting instruments and managing measurement uncertainty<\/h2>\n<p>The instrument you choose determines whether a reading is defensible or disputable. Match the tool to the airflow path, not to whatever happens to be in the van.<\/p>\n<p>A flow hood suits most diffuser and grille terminals, giving a direct volumetric reading with minimal setup. A pitot tube traverse across a straight duct run is the standard method for total airflow in larger ducts, particularly at the AHU discharge or on branch mains where a hood cannot seal effectively. A manometer measures static and differential pressures, useful for fan performance checks and for verifying pressure relationships in critical spaces. Vane anemometers or hot-wire probes handle lower-velocity readings and awkward geometries where a hood will not seat properly, such as linear slot diffusers or perforated ceiling panels.<\/p>\n<ul>\n<li>Use a flow hood on standard ceiling and wall diffusers where a good seal is achievable.<\/li>\n<li>Use a pitot traverse for in-duct total flow measurement on AHU discharge and main branches.<\/li>\n<li>Use a manometer for static pressure, fan performance and pressure-differential room checks.<\/li>\n<li>Use a vane or hot-wire anemometer for small, irregular or high-turbulence terminals.<\/li>\n<\/ul>\n<p>Every instrument needs a valid calibration certificate, and it is worth recording the certificate reference in the commissioning file rather than just the reading it produced. BSRIA\u2019s commissioning guidance treats instrument suitability, calibration and access as part of the commissioning process itself, not an afterthought to it. Temporary test ports drilled for a duct traverse should be sealed and recorded once measurement is complete, and any permanent test point should be labelled clearly for future re-tests.<\/p>\n<table>\n<thead>\n<tr>\n<th>Instrument<\/th>\n<th>Best use<\/th>\n<th>Limitation<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Flow hood<\/td>\n<td>Diffusers, grilles, terminal units<\/td>\n<td>Struggles with linear slots and high-velocity outlets<\/td>\n<\/tr>\n<tr>\n<td>Pitot tube traverse<\/td>\n<td>AHU discharge, main ducts<\/td>\n<td>Needs a straight run and drilled test points<\/td>\n<\/tr>\n<tr>\n<td>Manometer<\/td>\n<td>Static and differential pressure<\/td>\n<td>Measures pressure, not volumetric flow directly<\/td>\n<\/tr>\n<tr>\n<td>Vane\/hot-wire anemometer<\/td>\n<td>Small terminals, irregular geometry<\/td>\n<td>Point readings need multiple positions for accuracy<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 id=\"how-to-measure-total-airflow-at-the-ahu-and-reconcile-with-branch-sums\" tabindex=\"-1\">How to measure total airflow at the AHU and reconcile with branch sums<\/h2>\n<p>The AHU reading is the baseline every branch adjustment is checked against, so get this right before any terminal work starts. A system that looks balanced at the grilles but disagrees with the fan\u2019s actual output usually has an error hiding somewhere in the method, not the ductwork.<\/p>\n<ol>\n<li>Record fan speed, motor current and nameplate data before taking any flow reading.<\/li>\n<li>Measure static pressure across the filter, coil and fan to confirm the system is operating within its design resistance.<\/li>\n<li>Carry out a pitot traverse on a straight section of main ductwork to establish total AHU airflow.<\/li>\n<li>Cross-check the traverse figure against the fan\u2019s published performance curve at the measured pressure and speed.<\/li>\n<li>Sum all branch and terminal readings and compare the total against the AHU figure.<\/li>\n<li>Investigate any discrepancy above the project\u2019s stated tolerance before proceeding to terminal adjustment.<\/li>\n<\/ol>\n<p>A traverse reading and a summed set of terminal readings rarely match exactly, and a modest gap is normal given duct leakage and instrument variance. A large gap points to a leak, a miscounted terminal or a fan operating away from its design point, and BSRIA\u2019s guidance is clear that terminal readings without fan and controls verification miss systemic faults that grille-by-grille measurement alone will never reveal.<\/p>\n<p>Document the test conditions alongside every figure: fan speed setting, outdoor air conditions on the day, filter condition and whether the building was in occupied or unoccupied mode. A reading taken with a half-loaded filter and a reading taken after a filter change will differ, and without that context a repeat test months later cannot be compared meaningfully against the original.<\/p>\n<h2 id=\"terminal-measurement-techniques-and-sequencing\" tabindex=\"-1\">Terminal measurement techniques and sequencing<\/h2>\n<p>Terminal readings are where most of the visible balancing work happens, and where poor technique does the most damage to a report\u2019s credibility.<\/p>\n<ol>\n<li>Measure critical spaces first, such as clean rooms, isolation rooms or areas with a specified pressure relationship, before general office or corridor terminals.<\/li>\n<li>Work through the largest diffusers on each branch before the smaller ones, since large terminals affect branch pressure the most.<\/li>\n<li>Take multiple traverse points across grille faces rather than a single centre reading, and apply the manufacturer\u2019s area or \u201cAK\u201d correction factor where the grille geometry requires it.<\/li>\n<li>Label every terminal with a unique reference that matches the drawing and the commissioning sheet, recording design flow, measured flow and the instrument used.<\/li>\n<li>Re-measure the terminal immediately after any damper adjustment rather than waiting until the end of the run.<\/li>\n<\/ol>\n<p>Flow hoods need a firm seal against the ceiling or wall face to avoid leakage around the edges, and a hood held at an angle or against an uneven tile will under-read. Where a hood cannot seat properly, a multi-point traverse with a vane anemometer across the grille face, corrected with the manufacturer\u2019s factor, is the more reliable option.<\/p>\n<p>Some terminals resist standard measurement altogether. Perforated ceiling diffusers, narrow linear slots and active chilled beams all disturb airflow in ways that make a hood reading unreliable, and manufacturer test data or a specialist attachment is often the only practical route to a trustworthy figure on these units. Where the specification calls for a chilled beam or active diffuser to perform to a manufacturer\u2019s stated flow and throw, verify against that manufacturer\u2019s data rather than forcing a generic method to fit.<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790667321957_Specialist-attachment-measuring-active-chilled-beam-airflow.jpeg\" alt=\"Specialist attachment measuring active chilled beam airflow\"><\/p>\n<p>Re-run every affected terminal after each round of adjustment, because a damper change on one branch shifts pressure and flow at every other terminal downstream of the same main. The <a href=\"https:\/\/deltafirst.co.uk\/glossary\/index.html\" target=\"_blank\" rel=\"noopener\">building services glossary<\/a> is a useful reference if a term such as grille correction factor or AK factor needs clarifying mid-survey.<\/p>\n<h2 id=\"proportional-balancing-procedure-for-branch-dampers-and-final-tuning\" tabindex=\"-1\">Proportional balancing procedure for branch dampers and final tuning<\/h2>\n<p>Balancing is an iterative process, not a single adjustment followed by a final reading. The proportional method exists because moving one damper changes the pressure everywhere else in the system, so small, deliberate steps beat large corrective swings every time.<\/p>\n<p>The principle is straightforward: start from the index run, the branch with the least available pressure, and work back towards the fan, adjusting each damper only enough to bring its branch closer to its proportional share of design flow. Large single adjustments tend to overshoot and destabilise branches that were already correct, creating a chase that never settles.<\/p>\n<ol>\n<li>Identify the index terminal or branch, typically the one furthest from the fan or with the lowest measured-to-design ratio.<\/li>\n<li>Set that branch\u2019s damper fully open and treat its measured flow as the reference point for the rest of the balance.<\/li>\n<li>Move outward branch by branch, closing each damper incrementally to bring its flow proportionally in line with the index branch.<\/li>\n<li>Re-measure after every adjustment rather than after several changes at once.<\/li>\n<li>Repeat the sequence across the full system until every terminal sits within the project\u2019s stated tolerance.<\/li>\n<li>Confirm the AHU total still matches the summed terminal readings once the branch balance is complete.<\/li>\n<\/ol>\n<p>Acceptance tolerance is set by the project specification, not by a blanket industry percentage, and CIBSE Code A and BSRIA\u2019s guidance are the references most specifications lean on to define what \u201cacceptable\u201d means for a given system type. A hospital isolation room and a warehouse office will carry different tolerances for good reason, so check the specification before deciding a reading is close enough.<\/p>\n<p><strong>Pro Tip:<\/strong> <em>Log every damper movement and its measured effect on a running sheet as you go: it turns a balancing visit into a repeatable record instead of trial and error, and it saves the next technician from redoing work that was already correct.<\/em><\/p>\n<h2 id=\"how-vav-pressure-differential-and-decentralised-plant-change-the-procedure\" tabindex=\"-1\">How VAV, pressure-differential and decentralised plant change the procedure<\/h2>\n<p>A constant-volume method applied to a variable system produces a result that looks complete on paper and fails the moment the building\u2019s load changes. System type dictates the test, not just the target flow.<\/p>\n<ul>\n<li>VAV systems need testing at more than one operating point, since a terminal that meets design flow at full load can still fail at minimum load if its control response is not verified across the range.<\/li>\n<li>Pressure-differential rooms require both a flow reading and a pressure relationship check, because a room can hit its design airflow while still failing to maintain the pressure cascade the specification calls for.<\/li>\n<li>Fan coil units, chilled beams and other decentralised terminals often rely on manufacturer performance data rather than a generic traverse, particularly where the unit\u2019s geometry defeats standard flow hood measurement.<\/li>\n<li>Balancing should pause until controls commissioning is complete when a VAV box, damper actuator or sensor is not yet responding correctly, since measuring against an uncommissioned control loop produces a false baseline.<\/li>\n<\/ul>\n<p>CIBSE Code A separates constant-volume, variable-air-volume and pressure-differential systems for exactly this reason, requiring verification of controls and terminal response across the specified operating range for VAV rather than a single-point reading. Where building automation is involved in driving terminal response, a facilities team may find it useful to understand how building automation systems coordinate that control range, since a balancing result is only as good as the control sequence behind it.<\/p>\n<p>Remedial work on ductwork, actuators or sensors should always happen before a final balance, never alongside it. A damper adjusted against a faulty actuator will need repeating once the actuator is fixed, doubling the site visits for no good reason.<\/p>\n<h2 id=\"what-a-complete-commissioning-record-should-contain-and-how-to-present-it\" tabindex=\"-1\">What a complete commissioning record should contain and how to present it<\/h2>\n<p>A balancing job without a report is a job that cannot be verified later, disputed with confidence, or handed to building control with any credibility. The record is the evidence that the work was actually done to specification.<\/p>\n<ul>\n<li>As-installed flows against design flows for every terminal, with the deviation and any action taken clearly stated.<\/li>\n<li>Instrument details and calibration certificate references for every measurement device used on site.<\/li>\n<li>Test conditions: fan speed, filter condition, outdoor air conditions and whether the building was occupied.<\/li>\n<li>Fan and control settings at the time of test, including VSD frequency and any setpoint changes made.<\/li>\n<li>Photographic evidence of test points, damper positions and any remedial work carried out.<\/li>\n<\/ul>\n<p>An outlet register in table form gives clients and building control a format they can check at a glance:<\/p>\n<p>BSRIA\u2019s BG 49 guidance sets out the functional testing, setting to work and proportional regulation procedures this kind of record should reflect, and treats documentation as inseparable from the commissioning process rather than a summary written after the fact. A report that lists only terminal readings without fan and controls evidence falls short of what BG 49 describes as complete commissioning.<\/p>\n<p>Acceptance criteria should reference the project specification first, then CIBSE Code A and BSRIA\u2019s BG 49 where the specification defers to industry guidance. Sign-off should involve whoever the specification names as witness, often the client\u2019s representative or the consulting engineer, and the finished pack should include an entry in the building logbook alongside the commissioning sheet itself, so the next contractor to touch the system has a starting point rather than a blank page.<\/p>\n<h2 id=\"typical-failure-modes-that-undermine-balancing-and-how-to-fix-them\" tabindex=\"-1\">Typical failure modes that undermine balancing and how to fix them<\/h2>\n<p>Balancing a system that has an underlying fault only produces a result that will drift out of tolerance again within weeks. Diagnose before you adjust.<\/p>\n<ul>\n<li>Reduced airflow across a branch is most often dirty filters, a blocked outdoor-air intake or a fouled coil, all of which increase resistance and starve downstream terminals regardless of damper position.<\/li>\n<li>Duct leakage shows up as a gap between the AHU total and the summed terminal readings that does not close after correct proportional adjustment.<\/li>\n<li>Collapsed or kinked flexible ductwork restricts flow at a single terminal in a way that no amount of damper opening will fix.<\/li>\n<li>Incorrectly installed balancing dampers, fitted backwards or seized in one position, will not respond to adjustment and need physical correction, not recalibration.<\/li>\n<li>Control faults, such as a sensor mounted in the wrong location or an actuator not reaching its commanded position, produce readings that look wrong even when the ductwork and dampers are fine.<\/li>\n<\/ul>\n<p>GOV.UK\u2019s inspection guidance is direct on this point: blocked filters, heat exchangers and obstructed grilles increase resistance and can reduce airflow, and the same guidance frames improving airflow delivery and controls as a genuine route to lower energy use, not just a comfort fix. Fixing a fouled coil before balancing rather than compensating for it with a wide-open damper protects both the result and the running cost.<\/p>\n<p>Sensor and actuator faults usually need a controls specialist rather than a balancing technician, since the fix is electrical or programmatic rather than mechanical. A quick check with a multimeter or the building management system trend log will usually confirm whether the fault sits with the sensor or the damper before a specialist visit is booked. Where the diagnosis points to a fan, coil or ductwork repair, that work is best scheduled as PPM if it is wear-related and predictable, or as urgent reactive work if it is stopping the system meeting its duty now. Our piece on <a href=\"https:\/\/deltafirst.co.uk\/blog\/air-conditioning-consulting\" target=\"_blank\" rel=\"noopener\">air conditioning consulting<\/a> covers fault diagnosis in more depth for teams building out a wider maintenance strategy.<\/p>\n<h2 id=\"delta-firsts-applied-checklist-and-what-clients-receive-in-a-handover\" tabindex=\"-1\">Delta First\u2019s applied checklist and what clients receive in a handover<\/h2>\n<p>Delta First\u2019s engineers follow the same sequence on every commissioning and PPM visit: design documentation review, health and safety and site access checks, then physical inspection of filters, fans, dampers and controls before a single measurement is taken. Our vans carry calibrated flow hoods, pitot traverse kits and manometers, so the right instrument is available for AHU, branch and terminal readings without a return visit.<\/p>\n<p>A typical commissioning or PPM visit includes inspection of the system\u2019s physical condition, full flow measurement at AHU and terminal level, minor remedial work carried out on the spot where it falls within scope, and a written report with recommendations for anything beyond that scope. Where a coil needs cleaning or a damper needs replacing rather than adjusting, we flag it clearly rather than working around it.<\/p>\n<p>The handover pack a facilities manager receives includes the outlet register, instrument calibration references, test conditions and photographic evidence, in a format ready to sit in the building logbook or to hand to building control. Where remedial work is identified, we agree realistic timelines for the repair and the re-test that follows it, so the balance is confirmed once the underlying fault is actually fixed rather than assumed.<\/p>\n<p>If your building is due a re-balance, or you have never had one carried out against the original design flows, request a survey and we will scope the work properly before a single damper is touched.<\/p>\n<h2 id=\"balancing-as-evidence-not-guesswork\" tabindex=\"-1\">Balancing as evidence, not guesswork<\/h2>\n<p>Too many balancing visits are treated as a box-ticking exercise: a few grille readings, a note that \u201cflows are acceptable\u201d, and a report nobody checks against the original design intent. That approach misses the point entirely. Balancing is functional commissioning, and its value lies in the evidence it produces, not the adjustment itself.<\/p>\n<p>The buildings that stay comfortable and efficient over years are the ones where balancing happened early, against real design figures, with a proper record kept for the next contractor to build on. The energy savings, the reduced comfort complaints and the fewer emergency call-outs all follow from that discipline, not from any single clever adjustment. Get commissioning involved at design and installation stage, not as an afterthought once occupants start complaining.<\/p>\n<blockquote>\n<p><em>\u2014 Ashley<\/em><\/p>\n<\/blockquote>\n<h2 id=\"getting-your-system-properly-balanced-and-kept-that-way\" tabindex=\"-1\">Getting your system properly balanced and kept that way<\/h2>\n<p>A trusted building services contractor delivers air balancing as part of a wider HVAC installation, commissioning and maintenance service, so the same team that measures your system can also fix the fault behind a poor reading, rather than handing you a report and a list of someone else\u2019s jobs to book separately.<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/07\/1783116648075_deltafirst.jpg\" alt=\"Delta First\"><\/p>\n<p>A typical engagement runs from site survey through measurement, any remedial work identified, a re-test to confirm the fix, and a handover pack you can file against your compliance records. The core engineering team is directly employed, with specialist subcontractors brought in only where needed, so the same faces who surveyed your plant room are likely to be the ones who come back to close it out.<\/p>\n<ul>\n<li>Planned preventive maintenance contracts including balancing checks as part of scheduled visits.<\/li>\n<li>Reactive maintenance and emergency call-out services for faults found during balancing surveys.<\/li>\n<li>Compliance management and reporting services suited to building control and audit requirements.<\/li>\n<\/ul>\n<p>To speed up your quotation, have your design drawings, equipment data and preferred access windows ready when you get in touch. <a href=\"https:\/\/deltafirst.co.uk\" target=\"_blank\" rel=\"noopener\">Request a quotation or planned maintenance survey<\/a> and the work will be scoped against your actual system, not a generic checklist.<\/p>\n<p><strong>Need support with mechanical or HVAC maintenance?<\/strong> Delta First delivers planned and reactive mechanical maintenance across Essex, Suffolk and London, using certified specialist partners for gas and refrigerant work, with 24\/7 emergency cover. Call 01206 237422 or <a href=\"https:\/\/www.deltafirst.co.uk\/#contact\">request a quote<\/a>.<\/p>\n<h2 id=\"sources\" tabindex=\"-1\">Sources<\/h2>\n<ul>\n<li><a href=\"https:\/\/www.gov.uk\/government\/publications\/air-conditioning-inspections-for-buildings\/a-guide-to-air-conditioning-inspections\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Gov<\/a><\/li>\n<li><a href=\"https:\/\/cibse.org\/knowledge-research\/knowledge-portal\/cca-commissioning-code-a-air-distribution-systems-2024-pdf\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">CCA Commissioning Code A: Air distribution systems (CIBSE, 2024)<\/a><\/li>\n<\/ul>\n<h2 id=\"faq\" tabindex=\"-1\">FAQ<\/h2>\n<h3 id=\"is-air-balancing-worth-it-for-an-existing-building\" tabindex=\"-1\">Is air balancing worth it for an existing building?<\/h3>\n<p>Yes, particularly where a system has never been balanced against its original design flows or has had significant alterations since installation. Correcting airflow reduces the energy wasted by fans working against unnecessary resistance and cuts the comfort complaints that generate reactive call-outs.<\/p>\n<h3 id=\"how-much-does-an-air-balance-cost\" tabindex=\"-1\">How much does an air balance cost?<\/h3>\n<p>Cost depends on the number of terminals, system type and how much remedial work is needed before balancing can proceed, so there is no single published figure. Delta First provides a price after reviewing your design documentation and site access, available on request through a quotation.<\/p>\n<h3 id=\"how-do-i-balance-airflow-in-a-building-with-several-room-types\" tabindex=\"-1\">How do I balance airflow in a building with several room types?<\/h3>\n<p>Start with the design flow rates for every space, then measure total airflow at the air handling unit before moving to terminal readings. Balance proportionally from the index branch outward, re-measuring after each damper adjustment, and treat rooms with a specified pressure relationship, such as isolation rooms, as a separate check against both flow and pressure.<\/p>\n<h3 id=\"what-equipment-is-needed-for-air-balancing\" tabindex=\"-1\">What equipment is needed for air balancing?<\/h3>\n<p>A flow hood for most diffusers and grilles, a pitot tube for duct traverses, a manometer for static and differential pressure, and a vane or hot-wire anemometer for smaller or irregular terminals. Every instrument needs a current calibration certificate recorded in the commissioning file.<\/p>\n<h3 id=\"how-often-should-air-balancing-be-repeated\" tabindex=\"-1\">How often should air balancing be repeated?<\/h3>\n<p>There is no fixed universal interval, since it depends on system alterations, occupancy changes and the tolerances set in the original specification. A re-test is generally warranted after any ductwork change, refurbishment or persistent comfort complaint, and can be scheduled as part of a planned preventive maintenance visit.<\/p>\n<h2 id=\"recommended\" tabindex=\"-1\">Recommended<\/h2>\n<ul>\n<li><a href=\"https:\/\/deltafirst.co.uk\/blog\/air-conditioning-consulting\" target=\"_blank\" rel=\"noopener\">Air conditioning consulting for facilities managers: UK guide<\/a><\/li>\n<li><a href=\"https:\/\/www.deltafirst.co.uk\/blog\/summer-hvac-maintenance\/\" target=\"_blank\" rel=\"noopener\">Summer HVAC maintenance: a guide for facilities managers<\/a><\/li>\n<li><a href=\"https:\/\/www.deltafirst.co.uk\/blog\/bms-maintenance\/\" target=\"_blank\" rel=\"noopener\">BMS maintenance: the practical checklist for facilities managers<\/a><\/li>\n<\/ul>\n<h2>Talk to Delta First<\/h2>\n<p>Delta First Building Services is a Colchester-based M&amp;E contractor working across Essex, Suffolk and London, with commercial work in Norfolk. Our directly employed electrical team is supported by vetted specialist subcontractors where extra certification is needed, and we offer genuine 24\/7 emergency cover. <a href=\"https:\/\/www.deltafirst.co.uk\/#contact\">Get in touch<\/a> to arrange a survey or quote.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Practical air balancing for facilities managers with step by step field actions, calibrated instruments and CIBSE and BSRIA acceptance records.<\/p>\n","protected":false},"author":2,"featured_media":858,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","footnotes":""},"categories":[13,4],"tags":[855,609,117,57],"class_list":["post-547","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-facilities-management","category-mechanical","tag-air-balancing","tag-commissioning","tag-facilities-managers","tag-hvac-maintenance"],"blocksy_meta":[],"uagb_featured_image_src":{"full":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/df-078-air-balancing-at-grille.jpg",1600,900,false],"thumbnail":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/df-078-air-balancing-at-grille-150x150.jpg",150,150,true],"medium":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/df-078-air-balancing-at-grille-300x169.jpg",300,169,true],"medium_large":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/df-078-air-balancing-at-grille-768x432.jpg",768,432,true],"large":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/df-078-air-balancing-at-grille-1024x576.jpg",1024,576,true],"1536x1536":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/df-078-air-balancing-at-grille-1536x864.jpg",1536,864,true],"2048x2048":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/df-078-air-balancing-at-grille.jpg",1600,900,false]},"uagb_author_info":{"display_name":"Delta First Editorial Team","author_link":"https:\/\/www.deltafirst.co.uk\/blog\/author\/deltaeditor\/"},"uagb_comment_info":0,"uagb_excerpt":"Practical air balancing for facilities managers with step by step field actions, calibrated instruments and CIBSE and BSRIA acceptance records.","_links":{"self":[{"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/posts\/547","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/comments?post=547"}],"version-history":[{"count":6,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/posts\/547\/revisions"}],"predecessor-version":[{"id":1114,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/posts\/547\/revisions\/1114"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/media\/858"}],"wp:attachment":[{"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/media?parent=547"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/categories?post=547"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/tags?post=547"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}