Mechanical Ventilation - Lochinvar Mini Copper-Fin MCW91CE Installation, Commissioning And Maintenance Instructions

Gross Net
Model Input Input
(kW) (kW)
MC271CE 79.1 71.3
MC316CE 92.3 83.1
MC361CE
105.5 95.1
MC401CE 117.2 105.6
MC501CE 146.5 132.0
TABLE 9.2

9.2 MECHANICAL VENTILATION

To comply with the relevant installation standards, (BS5440-2:2009 for appliances with net heat inputs below
70kW and BS6644:2005 for appliances with net heat inputs between 70kW and 1.8MW) combustion ventilation
must be provided for all open flued appliances. In situations where this cannot be provided by the means of
ventilation grilles, combustion air can be supplied by a fan. The minimum flow rate for the fan should be in
accordance with Table 9.3.
If required, extract air can also be through the use of a fan. When sizing the extract fan, the extract flow rate
should be calculated by subtracting the difference volume (from Table 9.3) from the actual supplied volume of inlet
air. If therefore, a larger than required inlet volume is provided, the extract flow rate will need to be increased
accordingly.
If the ventilation discharge from the plant room is through the means of simple openings relying on thermal effects,
the minimum free areas of the openings and any associated grilles should be as specified for natural ventilation
(see separate "Free Area Requirements – Combustion" specification sheet). The ventilation openings shall be at
high level and the air supply shall be at low level.
Ventilation must not be provided through natural inlet and mechanical extract as this will cause a negative
pressure within the plant room and may lead to the products of combustion being drawn into the plant room.
When using mechanical ventilation systems, an automatic control should be used to cause a safety shut-down of
the burner in the event of failure of air-flow either inlet or extract ducts.
NOTE: VENTILATION MUST NOT BE PROVIDED THROUGH NATURAL INLET AND
MECHANICAL EXTRACT AS THIS WILL CAUSE A NEGATIVE PRESSURE WITHIN THE PLANT ROOM AND
MAY LEAD TO THE PRODUCTS OF COMBUSTION BEING DRAWN INTO THE PLANT ROOM.
Appliance Type
With draught diverters
Without draught diverters.
(with or without draught stabilisers)
TABLE 9.3
Worked Example – Mechanical inlet/natural discharge:
Lochinvar MC361CE
Heat input (net):
Minimum combustion air flow rate:
Ventilation grille size (high level):
Plant Room
Low Medium
Summer Use Summer Use
High Low High Low
(cm ) (cm ) (cm ) (cm )
2 2 2 2
143 286 214 357
167 333 250 416
190 380 285 475
212 423 317 528
264 528 396 660
COMBUSTION VENTILATION REQUIREMENTS MC271CE – MC501CE
Flow rate per kW total rated net input (m
Minimum Inlet Air
(Combustion, Ventilation)
2.80
2.60
MECHANICAL VENTILATION FLOW RATES
= 95.1 kW
= 95.1 x 2.8 m
= 192 cm
2
High Low
Summer Use Summer Use
High Low High Low
(cm ) (cm ) (cm ) (cm )
2 2 2 2
286 428 357 713
333 500 416 831
380 570 475 951
423 634 528 1056
528 792 660 1320
Difference between Inlet and Extract Air
(Inlet minus Extract Ventilation)
2.07 ± 0.18
1.35 ± 0.18
= 266.28 m
/h
3
Enclosure
Medium High
Summer Use Summer Use
High Low High Low
(cm ) (cm ) (cm ) (cm
2 2 2 2
428 785 500 856
500 916 583 999
570 1045 665 1140
634 1162 740 1268
792 1452 924 1584
/h)
3
/h
3
14
)