Hi, No problem at all! This forum is designed for anyone with Plumbing and Gas Issues  

here as per NZS 5261:2003 2.6.6

Where a gas appliance  is installed in a room or enclosure, that room or enclosure shall be ventilated. Where the total input of open flued gas appliances exceeds 3MJ/h for each cubic metre of the room or enclosure volume, the area shall be ventilated in accordance with clauses 2.6.6.1.

2.6.6.1 states: Two permanent openings shall be provided each with a minimum free ventilation area as calculated using the following formula:
A=F x T where

A= the minimum free ventilation area (mm-square)
F= the factor given in Table 3
T= the total gas consumption of all gas appliances (MJ/h)

Although a room sealed appliance draws required air from the outside, ventilation of the room may be required to prevent an excessive rise in ambient temperature.

Please refer to the manufacturers specification and consult a registered Gas fitter to ensure the appliance is suitable for its purpose and installed correctly.  

Hope this helps

that's pretty much it.. To establish wether the required air is to be provided by adventitious openings or additional ventilation openings, the total input of the gas appliances in the room/enclosure in MJ/h is divided by the room/enclosure volume in cubic m. well done..