Introduction
This paper provides an overview of the principles of flueing for natural draught flue systems and the factors that contribute to good flueing practice. It is primarily aimed at gasfitting practitioners, from trainees to craftsmen.
Effective elimination of products of combustion is an important aspect of any gas appliance to ensure its safe and efficient operation. While so-called flueless gas appliances are designed to operate safely indoors under certain conditions,1 or to operate outdoors, many gas appliance types are intended to operate with a flue.
An effective natural draught (or atmospheric) flue will rapidly establish draught conditions that allow safe elimination of products of combustion, and avoid excessive spillage of products of combustion into living spaces. Flues, in particular powered flues, can also be important in purging the combustion chamber of some appliances on startup.
This guide is intended to complement, not replace, the mandatory requirements in the Gas Regulations and Part 1 of NZS 5261, and the means of compliance in Part 2 of NZS 5261.
This guide takes as a starting point that in New Zealand gas appliances are required to be:
- designed and constructed in accordance with NZS 5262; and
- installed in accordance with NZS 5261 – including:
- reference to relevant manufacturers instructions,
- existing conditions of installation, and
- commissioning and testing to verify safe operation.
Powered or fan assisted flues are outside the scope of this paper. Such flues are used where the appliance is designed for fan assisted flueing or in cases where natural draft is not effective or adequate. Advice should be sought from the manufacturer and/or a specialist in installing powered flues when a powered flue is considered for a natural draught appliance.
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