Eco Plus 315L

Overview

The Sanden Eco Plus 315L is the large-capacity version of Australia’s reference CO2 heat pump platform. Everything that makes the 250L compelling applies here - Japanese CO2 compressor technology, COP 5.0, -25°C operating range, 10-year tank warranty - scaled to serve a household of 4–6 people where 250L would be undersized.

At $6,200, this is the most expensive residential heat pump water heater available in Australia. The price reflects engineering origin, established brand history, and warranty confidence. Whether that premium over Thermann’s equivalent ($5,800) or Reclaim’s Australian-made 315L ($5,500) is worthwhile depends on the buyer.

Why 315L instead of 250L

Hot water sizing in Australia typically follows:

• 1–2 people: 160–200L
• 3–4 people: 250–270L
• 4–6 people: 315–340L

The 315L Sanden targets larger households or those with higher-than-average hot water usage - households with teenagers, those who take long showers, homes with a bath that’s regularly filled. Going slightly oversized on tank capacity is generally better for heat pump efficiency: the unit doesn’t need to reheat as frequently, and COP is maintained across longer, less-frequent heating cycles.

For a household genuinely using 315L+ per day, the 250L would require the backup element to activate regularly during periods of peak demand - degrading efficiency and increasing running costs. Sizing correctly avoids this.

CO2 technology at this scale

The 315L model uses the same Sanden-developed CO2 compressor as the 250L. The 0.6kW nominal draw (peaking at 1.2kW during high-demand heating) produces:

• Heat output: ~3.0kW at rated conditions
• Reheat time from cold: approximately 3.5 hours (25°C ambient)
• Annual electricity consumption at typical Australian conditions: approximately 850–1,100kWh for a large household

A resistive electric 315L system at equivalent usage would draw approximately 4,500–5,500kWh per year - a saving of 3,400–4,400kWh, worth $1,200–$1,760 annually at current electricity prices.

The 315L model has a 3.5-hour reheat time, which is longer than the 250L’s 3 hours. This is expected given the larger volume. For morning peak demand households, the recommended approach is to set the timer to heat overnight during off-peak rates - the unit will have the tank fully heated before morning demand.

Split system specifics for a 315L unit

The 315L tank weighs 95kg. This affects installation in a meaningful way: it needs solid floor support and may be difficult to manoeuvre in tight laundries or small garages. The compressor/outdoor unit sits separately - connected by refrigerant lines run by a RAC-licensed installer.

The indoor-outdoor split configuration of a 315L unit has one practical advantage over all-in-one systems at this size: the compressor heat exchange happens outdoors (or in a vented space), meaning ambient air quality and temperature in the garage or laundry doesn’t affect performance. All-in-one units draw and exhaust air from the same space they’re installed in - in an enclosed garage, this can reduce performance in winter as the unit cools the air around it.

Sanden’s approach keeps the heat exchange where it should be - outside - while the tank stays in a protected indoor space.

Warranty and service

10-year tank warranty, 6-year compressor warranty. This is the best compressor warranty in the CO2 category. Sanden has been operating in Australia through authorised distributor and service networks long enough that warranty claims are processed through established channels rather than brand-new processes.

One practical note: CO2 systems require RAC-licensed technicians for any refrigerant work. This is a smaller pool of qualified technicians than for R410A/R290 systems. In metro areas this isn’t a barrier; in regional areas, confirm service availability before committing.

315L CO2 comparison

Thermann’s 315L saves $400, is 1dB quieter, and offers the same warranty. Reclaim saves $700 and is Australian-manufactured with a solar boost mode, though it’s 2dB louder. All three deliver COP 5.0.

The Sanden commands the premium on brand trust and installer familiarity - in markets where installers confidently recommend Sanden because they’ve been installing them for a decade, the recommendation network itself has value.

Who should buy the Sanden Eco Plus 315L

Best for:

• Households of 4–6 people with high hot water usage
• Cold climate installs where -25°C operating range matters
• Buyers who specifically want the Japanese CO2 heritage brand
• Situations where the installer strongly recommends Sanden and can service it

Skip if:

• Budget matters - Thermann 315L delivers the same specs for $400 less
• You want Australian-made - Reclaim 315L is domestically manufactured at lower cost
• You’re a 3–4 person household - the 250L is properly sized and $400 cheaper
• You prefer an all-in-one for simpler installation