AHU REFURBISHMENT GUIDE

Avoiding expensive replacements and improving the efficiency of AHUs

As time passes, technologicalimprovements lead to greaterefficiency, lower costs and betteroverall performance – all of which youwill miss out on if you fail to upgradeyour HVAC equipment.

Conventional wisdom dictates that airhandling units (AHUs) should bereplaced every 10 to 15 years, dependingon use and maintenance over that time.There is, however, a potentially far morecost-effective way to proceed thanreplacement – refurbishment and/or upgrade.

The cost of disposing of the old unitcould easily run into thousands ofpounds. And then there are the costsassociated with commissioning a newunit to consider.

One of the best routes to sustainabledevelopment in the HVAC sector isthrough retrofitting and refurbishment ofheavy-use equipment like air handlingunits and condensers. Retrofitting is,

essentially, the addition of newtechnology or features to older systemsand refurbishment refers to the processof returning something to a good state ofrepair (which can include retrofitting aspart of the mix).

The Carbon Trust says: “Nearly allrefurbishments offer opportunities toreduce carbon emissions beyond thestandards set by building regulations.However, conventional refurbishmentprojects often miss the opportunitiesavailable, leading to unintentional andunnecessary increases in energy use andassociated emissions.”

Relatively simple measures can make abig difference. For example, HVACsystems have made considerableprogress in the last two decades and newcontrol technology (including variablespeed drives) can be retrofitted to boostenergy efficiency and reduce operatingcosts.

Retrofitting HVAC equipment can saveenergy, but its benefits don’t end there. Itcan also allow you to:

l Accelerate your return on investmentbecause you can retrofit equipment ata fraction of the cost of replacing it.

l Extend the life of an older system.

l Reduce the disruption caused byreplacing large pieces of HVACequipment, especially in city centre locations.

l Improve comfort conditions byensuring more consistenttemperatures and better-controlledhumidity.

See also the box for more advantages ofrefurbishment. Refurbishment can beanything from simply re-sealingcondensate pans, chamber floors andother surfaces to replacement ofcontrols, or a complete overhaul. Even inthe latter case, refurbishment is typicallyfaster than replacement.

As HVAC equipment ages, itinevitably costs more andmore to run and isincreasingly likely to breakdown. Refurbishment andrepair can, however, give yourclients’ air handling units anew lease of life and savethem money.

01635 244100 www.ecex.co.uk

And, in the process of refurbishment, theexisting specification of the AHU can beimproved with, for example, theinstallation of the latest electronicallycommutated energy saving fans orboosting filter performance.

Refurbishment refers to the process of returning something to a good state ofrepair (which can include retrofitting).Retrofitting is, essentially, the addition of new technology or features to older systems.

A well-executed refurbishment can add 15to 20 years working life to equipment. ManyAHU components can be removed andreplaced including fans, filters, heaters andcooling coils, dampers and burners.

l Fans – These can often be replacedwith the latest energy efficient directdrive EC (electrically commutated)fans which are inverter controlled.Replacing old forward curved fanswith new plug fans can use 15-20%less energy.

l Filters – Many older units have poorlyfitting filters allowing bypass ofunfiltered air. Specialist Site Servicescan replace filter frames to preventthis and often fit higher-grade filters.

l Coils – For units with restrictedaccess, replacement coils can beprovided in sections which are thenjoined on site, replacing valves andactuators as required. Coils can alsobe flat-packed to suit restrictedaccess situations.

l Dampers – These can jam and thisone of the biggest causes of poor AHU operation.

An AHU is essentially a metal box withfans, heaters and/or cooling elementsinside to distribute and condition air inconjunction with heating, ventilating andair conditioning systems. Typically fittedto existing ductwork in the building,some AHUs – referred to as packagedunits or rooftop units – are positionedoutside on roofs.

Whatever your AHU needs, it pays toconsider them in association with areliable, knowledgeable partner with anestablished track record.

Indeed, the key to a successfulretrofitting, refurbishment ormaintenance project is to get the rightpeople on board before you start rulingout options, and even before you set afinal budget. And, of course, the rightpeople include experts in retrofitting,repair and refurbishment of HVAC systems.

01635 244100 www.ecex.co.uk

For more information, call 01635 244100 or email sales@ecex.co.uk.Visit www.ecex.co.uk forour full range of productsand services.

01635 244100 www.ecex.co.uk

WHAT ECEX OFFERS

ECEX offers a comprehensive AHUrefurbishment and repair service,helping businesses keep essentialequipment operational, improvingenergy efficiency and preventingbreakdown with minimal impact today-to-day operations.

The AHU refurbishment and repairservice offers many benefits, includinga big improvement in energyefficiency; the prevention ofbreakdowns; less disruption to theoperation, and – as a result – astronger bottom line.

Our extensive services also include onand off-site repairs of all tube and finheat exchangers, and the manufactureof coils to existing patterns or bespokenew designs.

These services complement thecompany’s comprehensive designservice for coils as well as on andoffsite maintenance and cleaning.

The company also offers coil filteringin the form of ECEX Air Intake

Screens, which extends the life andincreases the reliability of coils.Condenser and evaporator coils arenormally left unfiltered, leading to abuild-up of seasonal debris such asleaves and pollen.

BENEFITS OF REFURBISHMENTOVER REPLACEMENT

l Rapid and demonstrable return oninvestment due to greatly improvedenergy efficiency

l Minimal disruption, reduceddowntime

l Refurbishment typically costs lessthan new replacement

l Problems of installing differentsized plant are eliminated

l Logistics (e.g. crane lift) associatedwith transporting new plant to roofor plantroom are eliminated

l Reduces ongoing maintenance time and cost

l Helps AHUs adhere to energyefficiency standards defined in theErP (Energy-related Products)directive. Equipment that does notmeet defined minimumrequirements can no longer bemarketed in the European Union.

l Ensures more compact AHUsbecause the ErP Directive appliesonly to ventilation systems installedafter January 1, 2016. This meansheat recovery (in the form of athermal wheel, crossflow heatexchanger or run-around coils) –which increase AHU size by around20% – is not required.

l Cuts downtime from around 10 weeks for replacement with a new unit to between two and four weeks.

l Can result in energy savings of 26to 38% because of new fan designsand savings on drive belts, motorand fan pulleys replacement.

l Extends lifespan of existing unit

l Typically costs less than areplacement AHU

l Overcomes transport and accessdifficulties of replacing units

l Removes need for cranes and road closure

l Latest energy efficient EC plug fans and components

01635 244100 www.ecex.co.uk

THE IMPACT OF ECODESIGN

All new residential and non-residentialventilation units are now subject to the requirements of the EcodesignDirective. This establishes aframework for the setting of eco-design requirements forenergy-related products and theirimplementation.

As of January 2016, all ventilation andfan products have had to comply withEcodesign and must be labelled withthe relevant CE marking. The directiveis designed to drive carbon-emissionreductions and help the EU achieve itsenergy and climate change objectives.Equipment that does not meet thedefined minimum requirements canno longer be marketed in the EU.

In most industrialised countries, HVAC

equipment is responsible for around athird of total energy consumption. Themain purpose of heat recoverysystems is to mitigate the energyconsumption of buildings for heating,cooling and ventilation by recoveringthe waste heat.

Under the directive, AHUs mustadhere to certain energy efficiencystandards. To achieve these, they oftenrequire some form of heat recovery,whether with a thermal wheel,crossflow heat exchanger or run-around coils.

Since these need to be attached to theAHU, this makes the units bulkier andincreases their footprint; new unitsare typically 20% larger than existingplant. This is to cope with the

increased heat recovery surfacerequired to achieve compliance.

However, the legislation applies only toAHUs installed after January 1, 2016.Refurbishment comes under separateguidance which means that you don’thave to comply with Ecodesign so theAHUs can remain smaller.

POTENTIAL SAVINGS OFREFURBISHMENT

The savings associated with airhandling unit refurbishment can bedramatic. For example, on a recentAHU upgrade project, we calculatedthat we could provide an estimated22% – 33% energy saving simply byupgrading the fans.

There were also additional savings asbelts and pulleys would no longer

need replacement, as well as muchreduced maintenance time.

On another job, we quoted to replacethe fans with new direct drive ECenergy efficient fans complete withnew auto changeover function andpotentiometer. New electricalisolators, air pressure switches andair flow tubing were also to be

installed to match the new fan design.

On top of this, general refurbishmentincluded full deep clean, replacementbackdraft shutters, replacementinternal insulation lining and new roofplate fixings as the existing aredamaged. We calculated that all thiswould result in an energy saving of28% - 38%.

01635 244100 www.ecex.co.uk

IDENTIFYING SUITABLE CANDIDATES FOR REFURBISHMENT

There are several signs that will helpdetermine whether refurbishment isthe right option for a particular HVACsystem.

For example:

l The system is in a decent conditionand has a clear history of beingregularly maintained.

l Energy consumption is starting to climb.

l Comfort levels in the building are declining.

l The HVAC installation is in adensely populated area wherereplacement would causeexpensive disruption to thebuilding’s neighbours.

l The application has strictrequirements for precisetemperature and humidity control –for example, food processing,storage of perishables, chemicalprocessing and storage, andcomputer rooms.

l Management plans to keep theexisting system for at least afurther 18 months.

The larger the system, the greater theopportunities are for energy savingsthrough refurbishment. The sameargument applies to usage; the morehours the system runs, the greater theprospects for energy saving.

THE IMPORTANCE OFMAINTENANCE

Before even thinking aboutrefurbishment or replacement,enlightened and progressive buildingowners and operators put in place aneffective maintenance strategy. Run tofailure has long been a discreditedapproach so the service options arelimited to predictive and/or preventivemaintenance.

As its name suggests, predictivemaintenance is designed to predictwhen equipment failure might occurand to prevent its occurrence viaappropriate servicing. If the predictivemaintenance plan is working well,

machines are only serviced whenrequired. Predictive maintenance toolssuch as vibration analysis, infraredthermography, ultrasonic testing andmotor current analysis can be used todiagnose problems in advance.

Predictive maintenance helpspreclude problems before they occur.However, preventive maintenanceshould be at the heart of any plan toensure optimum HVAC equipmentperformance. Essentially, preventivemaintenance is servicing that isregularly performed on a piece ofequipment to lessen the likelihood of it

failing. It is in two parts – makingcertain that the system is operating atits highest possible efficiency andmaintaining this performance.

There will, however, inevitably come atime when maintenance is no longerworking. The choice is then to replacethe asset or repair and overhaul it. Butbeware – it is a myth to assume thatolder assets exhibit higher failurerates; a well-treated HVAC system willhave a lower failure rate than an ill-treated one, regardless of age.Treatment, in this context, means howwell they are maintained.

Unit H, Venture House, Bone Lane, Newbury, Berkshire RG14 5SHT 01635 244100 E sales@ecex.co.uk W ecex.co.uk

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