Division C - Special CircumstancesDivision C - Special Circumstances

Division C - Special Circumstances

The input parameters and control strategies used to calculate the total annual auxiliary energy for step 2 in the method in Division B of this Part are subject to modification in the following circumstances.

1. Tanks with bottom element fitted

For systems where a bottom element is fitted in the tank (e.g. a dual element tank) the bottom element is to be used for rating purposes. The minimum boost time for a bottom element shall be nominal off-peak times of 11 pm to 6 am.

2. One-shot boosting

One-shot boosting is a manual control that allows a default boost mode (such as off-peak boosting) to be overridden so that the user can satisfy a short term high demand for hot water.

Where the system automatically resets to the default boosting mode within 24 hours of the user changing the boost mode, the one-shot boosting can be ignored.

Where the system does not automatically reset to the default boosting mode within 24 hours of the user changing the boost mode, the boosting mode activated by the manual control must be considered to be active at all times

3. SWHs with hybrid photovoltaic/thermal solar collectors

For a large SWH that utilises photovoltaic/thermal (PV/T) hybrid solar collectors, which generate both electricity and useable thermal energy from the same collector, the following testing regime must be documented.

(a) PV output

The PV output shall be assessed using a collector with the water heating part of the collector empty.

(b) Water heating output

The thermal efficiency of the collector shall be assessed in accordance with AS/NZS 2535:2007 with the PV output set to maximum power conditions. The electrical output of the collector shall not be included in the thermal efficiency assessment.

Note: A large SWH with PV/T collectors will only be eligible for STCs as a SWH in relation to the water heating component of the system.

4. Family of products

A ‘family of products’ means a combination of tanks, collectors, boosters and pumps that are used in a modular fashion to create a product range of different sizes. An interpolation or a sub-unit approach may be used for the performance rating of a family of products as detailed in the below two paragraphs.

a) Interpolation approach: interpolation of performance for a scaled family of products

An interpolation approach may be used if all members of a family of products must have the:

 same solar collector;