Part L and air handling units | Archive Titles

Part L: Fan and system efficiencies for a typical AHU
Unit reference	AHU 1 SUPPLY	AHU 1 EXTRACT
Design criteria
Design capacity (m3/s)	22	17.1
Design static (Pa)	1089	696
Quantity of velocity pressures	1	1
Max w/l/s	2.5	2.5
Max system input power / kw	55	42.75

Preselection criteria
Max discharge velocity	12	12
Nominal dynamic (based on above discharge velocity)	86.4	86.4
Nominal total pressure	1175.4	782.4
Nominal required system efficiency to meet pressure	47.02%	31.30%

Selected fan data
Dynamic (Pa)	112	107
Shaft power (kW)	28.4	15.84
Installed motor power (kW)	2 x 30	2 x 15
Fan shaft efficiency	93.04%	86.69%
Based on	2 x 800	2 x 710
Motor efficiency (nominal)	93.40%	93.40%
Based on
Belt drive efficiency (nominal)	94.00%	94.00%
Based on	belt drive	belt drive
Inverter efficiency (nominal)	96.50%	96.50%
Based on Danfoss VLT6000 at 75% load
Total tolerance of fanset components	0.00%	0.00%
Based on	Not considered	Not considered
Actual system input power (kW)	33.52	18.7
Max actual system input power (kW including tolerances)	33.52	18.7
System heat loss per volume flow rate (W/ l /s)	1.52	1.09
Max (W/ l/s) including tolerances	1.52	1.09
Total system efficiency	78.82%	73.44%
Worst case total system efficiency including tolerances	78.82%	73.44%

Reselection criteria
Max static (Pa based on above component efficiencies)	1858.6	1729.1
Max total pressure (Pa based on above component efficiencies)	1970.56	1836.11
System heat loss per volume flow rate (W / l /s)	2.3735
(with supply and extract powers/supply air vol)
Heat wheel heat recovery	Winter	74.30%
	Summer	76.00%

Air Pressure drop on the AHUS
Volume (m3/s)	22	17.1
External static pressure (Pa)	300	250
Louvre (Pa)	INC	INC
Damper (Pa)	40	75
Electric frost (Pa)	20	0
Panel/bag AHU 1 clean (Pa)	188	87
Thermal wheel (Pa)	158	117
Cooler & eliminator (Pa)	209	0
Electric heater (Pa)	20	0
Atmospheric attenuation (Pa)	16	14
Non-return dampers (Pa)	70	70
Diffuser (Pa)	50	45
Jobside attenuation (Pa)	18	38
Totals	1089	696