Air Handling Unit Fundamentals_1

AHU  Air  A ir Handling Unit Fundamentals

Objectives

• Review primary components compone nts of an AHU • Understand the basic progression and advantages of advanced AHU AHU control • Understand the basic control sequences • Review key operating concepts

Objectives

• Review primary components compone nts of an AHU • Understand the basic progression and advantages of advanced AHU AHU control • Understand the basic control sequences • Review key operating concepts

Why is it important? • AHU operation is fundamental to the Commercial Building HVAC Control. • Many application problems and questions are easily resolved if individuals understand the fundamentals of AHU operation • Understanding the terminology of the business is necessary to be effective in any position • ncrea ncreased sed comfort comfort and opera operation tional al effic efficien iency cy may may be achieved through advancing the control of an AHU! resulting in more sales" reduced energy costs and satisfied customers.

HA! "ystem in a Building 

HA H A! Air "ys "ystem temss • HVAC air systems are made up of# $ $ $ $ $ $ $ $

AHU ! Air handling units %ampers Coils and Va Valves lves &ans %istribution ducts and terminal bo'es (umps (u mps and and (lum (lumbin bing g Control devices and control loops Unitary equipment# fan coils" perimeter radiation" unit ventilators" unit heaters" etc.

AHU # !omponents $ %erminology

&A

RA

Return (rom "pace

'A (ilter  !ooling !oil

)A Heating

AHU components Supply fan Mixed Air    sensor 

Mixed air  dampers section

Return Air    sensor 

Heating coil & valve

Cooling coil & valve

Discharge air    sensor 

Discharge air    Duct

Return air Duct

AHU components

What are (unctions of AHU ? • &unction# Condition the air flo). $ Heat the air flo) $ Cool the air flo) $ %ehumidify the air flo) $ Humidify the air flo) $ Clean the air flo) $ %istribute the conditioned air into the building space.

• Commercial air handling units can be compared to home furnaces.

%ypes of Air Handlers • Air Handlers can be categori*ed by# $ Method of temperature control $ Method of volume control $ Method of air distribution Types :

• Mixed Air AHU • Treated Fresh Air AHU • 100 % Fresh Air AHU

%ypes of Air Handlers Air Handling Units – Mixed Air 

%ypes of Air Handlers Air Handling Units – Mixed Air 

Air )istribution "ystems • Constant Volume" Variable +emperature ,CV- • %elivered to all room areas regardless of individual room differences.

• Constant Volume" Constant +emperature ,C+$ High fan po)er costs" e'pensive installation" high energy consumption

• VAV !Variable Air Volume" Constant +emperature • /ingle 0one or %ual %uct

A *"ingle )uct+ AHU variation • +he e'haust air damper is not in this air handler1 the building air is e'hausted else)here" but the basic mi'ed air and other functions are unchanged.

Air handler variations • %he building air in the previous e,ample can  be e,hausted through wall or roof fan units remote from the AHU- or through pressure relief dampers.

'ther Air )istribution "ystems • Multi*one $ /upplies several *ones from a central system. Hot and cold dec2 temperatures are mi'ed and supplied to the *one to meet the needs of the *one

• %ual %uct $ /upply air is divided at the Central &an ! hot air 3 cold air flo) through separate ducts to the *ones ! mi'ed to meet requirements at *one

Air )istribution )esign#)ual )uct • Hot deck/cold deck AHU with *)ual )uct+ distribution. )ual ducts run through the building with many sets of 0one dampers for many individual room locations. "ill have many sets of these dual duct ta#e offs!

oned temperature control! Mixes correct amounts of hot or cool air into each room per room thermostats!

Air handler locations

)( t& unit

 Air handlers may be l!ated" #$n basement me!hani!al rms% #$n &enthuse me!hani!al rms% #'n r( t&s%

Air Handler !omponents %he damper section 1 •

Manually Operated for Outside Air/Exhaust Air

•

Motoried Modulating

•

Motoried On/Off 

•

Fire !ampers " Motoried / Fuse #in$ Operated

Air Handler !omponents %he fan section with access door open.

Air Handler !omponents (ilters 1 %ypes of Air Filters 

&re Filters



Fine Filters



HE&A Filters



U#&A Filters

Air Handler !omponents .R)/ilters # $%'%( )fficiency ! # Can filter particles of si*e upto +,% microns! # Reusa-le & "asha-le

Air Handler !omponents /ine /ilters #0%0+ ( )fficiency ! # Can filter particles of si*e upto , to 1 microns! # 2ot Reusa-le

Air Handler !omponents High )fficiency .articulate Air /ilters 4H).A5 # 00!0$( to 00!0000+ ( )fficiency ! # Can filter particles of si*e upto %!, to %!3 microns! # Used in Clean Room Applications! #2ot Reusa-le

Air Handler !omponents U6.A /ilters P*F+ ,embrane Filters Fr -tate.(.the.Art lean rm )euirements •2%(& 32oly%etra(luoro&thylene4 5embrane combines ultra#high efficiency with negligible pressure drop •High Resistance to !orrosive &nvironments 3Acid- Alkali and 'rganics4 • 6egligible 'ff#7assing 2roperties 38oron- "odium- 2otassium"ilicon4 •99.9999:; 5inimum &fficiency. 2%(& membrane filters can meet stringent semiconductor industry !lean room filtration requirements

Air Handler !omponents %he filter section.  6otice the cross stacking of the filters to increase surface area.

Air Handler !omponents %emperature "ensor 1 •

•

%emperature sensors are used for measurement of temperatur of a Room- Air )uct- Hot /!old Water'utside Air etc. 5odels are available with 2%=- 8A@!':== sensing elements.

6/1% 7 A8R DUC9 9)M.! S)2S:R 429C 1%#5

9$;,1 7 R::M 9)M.! S)2S:R 4.9,%%%