Eco Plus 250L

Overview

Sanden is the company that created the CO2 heat pump water heater. Their Eco Plus range has been installed across Australia for well over a decade, and the 250L model sits at the core of their residential lineup - sized for households of 3–4 people, delivering COP 5.0 efficiency using R744 (CO2) refrigerant, and backed by the strongest warranty in the CO2 category.

The premium is real: at $5,800 supply price, the Sanden 250L costs $577 more than Thermann’s equivalent CO2 product and $800 more than Reclaim’s Australian-made alternative. Whether that premium is justified depends on how you weight Japanese engineering reputation, installer confidence, and the 6-year compressor warranty that no competitor matches.

CO2 refrigerant: why it matters

All Sanden Eco Plus models use R744 - CO2 as a refrigerant. The global warming potential of CO2 is 1 by definition. The HFCs it replaces (R134a: GWP 1,430; R410A: GWP 2,088) will face mandatory phase-down under the Kigali Amendment, which Australia has ratified. Using CO2 refrigerant means:

• Zero regulatory exposure to HFC restrictions over the product’s 15–20 year life
• No future re-gas cost increases driven by HFC scarcity
• Genuinely lower environmental footprint if the refrigerant circuit is ever breached

The physics of CO2 refrigerant also suits Australian ambient temperatures. CO2 operates at high pressure (around 100 bar at operating conditions versus 25 bar for R410A), which allows effective heat extraction across a wide temperature range. The Sanden 250L operates down to -25°C - a specification that is essentially meaningless for coastal Queensland but relevant for the ACT, alpine Victoria, and highland NSW winters.

COP 5.0 and what it means in practice

COP 5.0 means the unit extracts five units of heat energy for every one unit of electrical energy consumed. At the rated 0.6kW draw:

• Heating output: 3.0kW
• For 250L of hot water at 60°C from a 20°C ambient: approximately 2.5–3 hours of runtime
• Annual electricity consumption for a family of four: approximately 700–900kWh at typical Australian conditions

Compared to a resistive electric storage system (COP 1.0, approximately 3,500–4,500kWh per year), the saving is approximately 2,600–3,600kWh annually - worth $900–$1,450 at current electricity rates. Compared to a conventional gas storage system at average rates, the financial case is similar but depends strongly on local gas pricing.

Split system installation

The Sanden Eco Plus is a split system: the compressor/heat exchanger unit sits outside (or in a well-ventilated indoor space), and the hot water tank sits separately - typically inside a garage, laundry, or utility room. The two units connect via refrigerant lines and water pipes run during installation.

This adds complexity over an all-in-one unit. Installation typically requires:

• A RAC-licensed refrigerant handling tradesperson (required for CO2 systems as well as F-gas)
• A plumber for water connections
• Coordinated quotes if using different tradespeople

Many specialist heat pump installers handle both roles or subcontract within the same job. The Sanden installer network in Australia is established - the brand has been here long enough that trained installers exist in most metro markets. Regional availability is less certain; confirm with Sanden’s distributor before purchasing in rural areas.

Installed cost estimate: $5,800 supply + $1,400–$1,900 installation = $7,200–$7,700 all-in. This is among the highest total installed costs for a residential heat pump in Australia.

The no-backup-element question

The Sanden Eco Plus has no resistive backup element. When the heat pump runs, it uses the compressor. When the compressor stops, heating stops.

This is by design - Sanden’s position is that a unit operating down to -25°C doesn’t need a backup element because the compressor can always run. In practice, this means:

• No grid draw spike from a backup element (good for solar-paired systems)
• No hot water if the compressor faults, until the fault is resolved

For households that want the security of always having hot water regardless of heat pump status, an all-in-one unit with a resistive backup element (like the iStore 270, Emerald 270, or Solahart Atmos Eco 280) provides that fallback. For households with strong solar and wanting maximum efficiency, the no-element design suits.

Warranty: 15yr SS tank, up to 10yr compressor

The stainless steel tank carries a 15-year pro-rata warranty (10 years full coverage, then pro-rated to year 15) - the longest tank warranty in the residential heat pump category. The vitreous enamel tank variant carries a 10-year pro-rata warranty. The compressor warranty is 6 years as standard, extending to 10 years when the Wi-Fi controller package is included. The 10-year compressor + 15-year SS tank combination is the best warranty package in Australian residential heat pumps.

Warranty claims for Sanden products in Australia are handled through authorised Sanden service agents. Response times and service quality in metro areas are well-documented as reliable. The brand has been in the market long enough that warranty processes are established rather than ad-hoc.

Sanden 250L vs Thermann 250L CO2

These are the two CO2 split systems closest in spec. The core comparison:

Thermann’s 250L costs $577 less and has a marginally higher stated COP (5.08 vs 5.0). Sanden’s advantages: deeper operating range (-10°C vs -6°C), superior warranty (15yr SS tank, labour included in compressor warranty), and no ACCC recall history. For cold-climate installs or buyers weighting warranty depth, Sanden justifies the premium. For temperate-climate installs where $577 matters, Thermann is the value choice.

Who should buy the Sanden Eco Plus 250L

Best for:

• Households of 3–4 people wanting the established CO2 heat pump benchmark
• Cold climate locations where -25°C operating range matters (alpine, ACT, highland NSW/VIC)
• Buyers prioritising brand heritage and the longest CO2 compressor warranty
• Solar households wanting maximum COP with no backup element draw

Skip if:

• Budget is a priority - the Thermann 250L CO2 delivers identical specs for $577 less
• You want an all-in-one unit (no split installation complexity) - see the Solahart Atmos Eco 280 or iStore 270
• You want a resistive backup element for fault insurance
• You’re in a mild climate - a R290 all-in-one at $3,000–$3,500 achieves COP 5.0+ at lower installed cost