MEPS Requirements for Electric Storage Water Heaters

Since 1 October 1999, unvented (displacement) electric storage water heaters manufactured in or imported into Australia must comply with Minimum Energy Performance Requirements which are set out in AS/NZS 4692.2 (originally also set out AS 1056.1 - Amendment 3).

Since 1 October 2005 the following changes and additions to water heater MEPS were made:

• MEPS levels for small main pressure water heaters (63 litres or less) were increased from the 1999 levels - the new levels are set out in the table below.
• MEPS for vented water heaters (25 to 630 litres hot water delivery inclusive) were introduced for the first time - see the equation below.
• MEPS for heat exchange water heaters with a heat storage volume from 45 to 710 litres inclusive were introduced for the first time - see the equation below.

These levels are set out in the notice of new MEPS levels for miscellaneous and mains pressure electric water heaters:   Letter from the NAEEEC Chair and are fully documented in AS/NZS4692. Note that there are a number of requirements for new models registered to revised MEPS levels that came into force on 1 October 2005 - these are fully detailed in AS/NZS 4692.2. AS/NZS 4692.2 also sets out MEPS levels for New Zealand which are different from those in Australia (these are also set out in NZS 4602 and NZS 4606.1).

The following products are exempt from MEPS:

• Water heaters that use electric resistive heating to provide less than 50% of the energy supplied in a typical year (eg heat pump and solar water heaters) when simulated to AS 4234 under Climate Zone 3 with an energy delivery of 22.5 MJ/day for an electric boosting element and energisation profile specified by the manufacturer.
• Water heaters that are not intended for electric power grid connection (eg for use in vehicles and marine applications).

Mains Pressure Electric Water Heaters

The 1999 and 2005 MEPS levels for mains pressure (unvented displacement) electric water heaters when tested to AS1056.1 are set out in the table below. AS/NZS 4692.2 set outs MEPS levels when tested to AS/NZS 4692.1.

Minimum Energy Performance Standards:
Maximum Heat Loss for Electric Storage Water Heaters
(unvented tanks without an attached feed tank)

Rated Hot Water Delivery (litres)	Maximum Allowable Standing Heat Loss (kilowatt hours/day) October 1999	Maximum Allowable Standing Heat Loss (kilowatt hours/day) October 2005
<25	N/A	0.98
25	1.4	0.98
31.5	1.5	1.05
40	1.6	1.12
50	1.7	1.19
63	1.9	1.33
80	1.47	1.47
100	1.61	1.61
125	1.75	1.75
160	1.96	1.96
200	2.17	2.17
250	2.38	2.38
315	2.66	2.66
400	2.87	2.87
500	3.15	3.15
630	3.43	3.43

Only the pre-defined hot water delivery values shown above are permitted for mains pressure models. These values may be increased by 0.2 kWh/day for each additional heating element (where there are more than 1) and 0.2 kWh/day for each temperature or temperature/pressure release valve mounted on a hot water fitting. The rated hot water delivery is defined in AS1056.1 (this is less than the hot water storage volume). It also defines the test procedures for the determination of standing heat loss.

Vented Electric Water Heaters

MEPS levels for vented electric water heaters from 1 October 2005 are set out in the following equation when tested to AS1056.1: (AS/NZS 4692.2 set outs MEPS levels when tested to AS/NZS 4692.1)

MEPS (maximum daily heat loss) = 0.255 x V^0.4032

Where:
Where V is the hot water delivery of the vented electric water heater.

The values in the above Equation apply to water heaters with a single heating unit and may be increased by 0.2 kWh/24 h for each additional heating unit and by 0.3 kWh/24 h for an attached feed tank. Vented water heaters with an attached feed tank which have a hot water delivery of less than 125 litres are exempted from MEPS.

Heat Exchange Water Heaters

MEPS levels for heat exchange electric water heaters from 1 October 2005 are set out in the following equation when tested to AS1361: (AS/NZS 4692.2 set outs MEPS levels when tested to AS/NZS 4692.1)

MEPS (maximum daily heat loss) = 0.4057 x V^0.3322

Where:
Where V is the heat storage volume of the heat exchange electric water heater.

The values in the above Equation apply to water heaters with a single heating unit and may be increased by 0.2 kWh/24 h for each additional heating unit, by 0.3 kWh/24 h for an attached feed tank, by 0.2 kWh/24 h for an expansion relief valve and by 0.1 kWh/24 h for each other water fitting (excluding a drain fitting).

A copy of the standard can be purchased from SAI Global under licence from Standards Australia.

 

This page last modified 02 February 2009

 

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