Daikin Altherma 3 Review: Is It the Right Heat Pump for Your Home?

The Daikin Altherma 3 is one of the most established air source heat pump ranges available in the UK, backed by Daikin’s reputation as the world’s largest manufacturer of heating and cooling systems. If you are looking for a thorough daikin heat pump review, this article covers the full Altherma 3 lineup, real-world performance data, costs, and how it stacks up against the competition from Vaillant, Samsung and Mitsubishi.

Is the Daikin Altherma 3 a Good Heat Pump?

Yes, the Daikin Altherma 3 is an excellent heat pump for larger UK homes, delivering strong performance across a wide output range of 4–16 kW. It achieves a seasonal COP of 3.3–3.9 in typical UK conditions and costs £9,000–£14,000 installed before the £7,500 BUS grant. Daikin’s strength lies in its advanced controls, including the Onecta smart app, and its well-established D1 and D1 Plus installer programmes that offer extended warranties up to seven years.

The Altherma 3 uses R32 refrigerant and includes a built-in stainless steel heat exchanger for domestic hot water, which reduces Legionella risk without relying on an immersion heater cycle. It integrates well with solar PV and offers cooling in summer — a feature increasingly valued in UK homes. The main criticism is that Daikin’s standard three-year warranty is shorter than competitors offering five years as standard, making the D1 Plus programme essential for adequate cover.

Daikin Altherma 3 Range: High-Temperature vs Low-Temperature Models

Daikin offers two distinct versions of the Altherma 3, and understanding the difference is essential before choosing. The Altherma 3 H HT (high-temperature) can deliver flow temperatures up to 70C, making it suitable for older properties with existing radiators that were sized for a gas boiler. The Altherma 3 R (low-temperature) is designed for well-insulated homes and new builds, running most efficiently at flow temperatures of 25-45C.

The high-temperature model uses R32 refrigerant and is available in 14kW and 16kW capacities. The low-temperature R model also uses R32 and comes in a wider range from 4kW to 16kW. Both are monobloc designs with all refrigerant contained in the outdoor unit.

Real-World Efficiency and COP Data

Daikin quotes an ErP efficiency of up to A+++ with a COP of 5.10 for the Altherma 3 R at A7/W35 conditions. In practice, UK homeowners are reporting seasonal COP figures between 3.0 and 4.0, depending on installation quality, flow temperatures, and property insulation levels.

Data from the Electrification of Heat Demonstration Project showed Daikin systems averaging an SCOP of approximately 3.2 across a range of UK housing stock. This is a solid real-world figure, though it does fall below the top-performing Vaillant Arotherm Plus installations which frequently reach 3.5-4.2 in optimised setups.

The high-temperature model sacrifices some efficiency for its ability to deliver 70C flow temperatures. When running at these higher temperatures, expect an SCOP closer to 2.5-3.0. This is still significantly better than a gas boiler at 0.92 efficiency, but homeowners should be aware of the trade-off. For the best results, aim to run even the HT model at the lowest flow temperature your radiators can support.

Daikin Onecta App and Smart Controls

Daikin’s Onecta app is one of the better heat pump control platforms available. It allows full remote control of heating schedules, hot water timing, holiday modes, and real-time energy monitoring. The app displays current COP, cumulative energy consumption, and heat output data.

Unlike the myVaillant app, which has been criticised for COP under-reporting, the Onecta app provides figures that align more closely with independent monitoring. It also supports integration with smart home systems and allows weather compensation curve adjustments directly from the app, which many installers find useful for fine-tuning performance remotely.

The built-in Daikin Cloud service enables your installer to monitor the system remotely and diagnose issues before they escalate, potentially reducing call-out costs. This remote diagnostics capability is a genuine advantage over brands with more basic connectivity.

Daikin Heat Pump Installed Costs in the UK

A Daikin Altherma 3 system typically costs between £10,000 and £13,000 fully installed for a standard 3-4 bedroom home. The high-temperature model tends to sit at the upper end due to its larger capacity and more complex internal components. Supply-only prices for the outdoor unit range from £3,500 to £6,500 depending on the model and capacity.

With the £7,500 Boiler Upgrade Scheme (BUS) grant, the net cost drops to approximately £2,500-£5,500 for most installations. This makes the Daikin competitive with high-end gas boiler systems while offering significantly lower running costs over the long term.

Additional costs may include a hot water cylinder (£1,500-£2,500 for a Daikin EKHWP series), radiator upgrades if needed, and any electrical supply upgrades. A full heat loss survey and system design should be completed before installation to ensure correct sizing. Request a free quote to get an accurate price for your specific property.

Noise Levels and Planning Considerations

Noise is one area where the Daikin Altherma 3 is not class-leading. The outdoor unit produces 54-62dB at 1 metre, which translates to approximately 42-50dB at 3 metres depending on the model. The larger 14kW and 16kW models are the loudest.

Under permitted development rules, the unit must not exceed 42dB at the nearest neighbour’s property boundary. For detached homes with generous gardens, this is rarely an issue. For semi-detached and terraced homes, careful positioning is essential, and the larger models may require planning permission if the 42dB limit cannot be met.

Daikin offers a quiet mode that reduces the fan speed, bringing noise levels down by approximately 5-8dB. This is useful for overnight operation but does reduce heating capacity, so the system needs to be sized with this in mind if quiet mode will be used regularly.

Daikin Altherma 3 vs Vaillant, Samsung and Mitsubishi

Choosing between the top heat pump brands in the UK often comes down to specific property requirements. Here is how the Daikin compares to its closest rivals on the factors that matter most.

The Vaillant Arotherm Plus edges ahead on refrigerant choice (R290 vs Daikin’s R32) and maximum flow temperature (75C vs 70C). It is also quieter in most models. However, the Daikin typically costs £500-£1,500 less installed and has a marginally better app experience.

The Samsung EHS Gen 7 undercuts both on price while matching the Vaillant on R290 refrigerant. It is also the quietest option at 35dB in quiet mode. The trade-off is a lower maximum flow temperature of 65C and a shorter UK track record.

The Mitsubishi Ecodan remains the most widely installed heat pump in Britain, with the largest installer network. It is a safe choice with proven reliability, but its R32 refrigerant and 60C maximum flow temperature are less future-proof than the Vaillant or Samsung alternatives.

Who Should Choose the Daikin Altherma 3?

The Daikin Altherma 3 is an excellent choice for homeowners who want a well-proven, reliable system from the world’s largest heat pump manufacturer. The high-temperature model is particularly suited to older UK properties that need 60-70C flow temperatures to work with existing radiators without expensive upgrades.

It is also a strong option for homeowners who value app-based monitoring and smart controls. The Onecta platform is genuinely useful for tracking performance and optimising settings, and the remote diagnostics capability can reduce long-term maintenance costs.

If you are building a new home or have already invested in good insulation, the low-temperature Altherma 3 R paired with underfloor heating will deliver the best efficiency figures. For existing homes, consider combining the heat pump with insulation upgrades and potentially solar panels to maximise the return on your investment.

The Daikin may not be the best choice if noise is your primary concern, as it is louder than the Samsung and Vaillant alternatives. It also lacks the R290 refrigerant that the Vaillant and Samsung use, though R32 is still a significant improvement over the older R410A.

Frequently Asked Questions

Is the Daikin Altherma 3 suitable for a poorly insulated home?

The high-temperature H HT model can deliver up to 70C flow temperatures, making it workable in less well-insulated homes. However, the efficiency will be lower at these temperatures, and running costs will be higher. It is always worth improving insulation before or alongside a heat pump installation to get the best performance and lowest bills.

What warranty does Daikin offer on the Altherma 3?

Daikin provides a standard 5-year warranty on the Altherma 3 range when installed by a Daikin-approved installer. Extended warranties up to 10 years may be available through certain installer schemes. Annual servicing is required to maintain the warranty, costing approximately £100-£180 per year.

Can I use my existing hot water cylinder with a Daikin heat pump?

In most cases, no. Heat pumps require a cylinder with a larger coil surface area than standard gas boiler cylinders. Daikin recommends their own EKHWP series cylinders for optimal performance, though third-party heat pump-specific cylinders from manufacturers like Telford and Mixergy are also compatible.

How much does it cost to run a Daikin Altherma 3 per year?

For a typical 3-bedroom UK home, annual heating and hot water costs with the Altherma 3 are approximately £750-£1,100 at current electricity prices. This assumes an SCOP of 3.0-3.5 and annual heat demand of 10,000-15,000kWh. Adding solar panels can reduce this by £200-£400 per year.

Does the Daikin Altherma 3 qualify for the Boiler Upgrade Scheme?

Yes. All Altherma 3 models are MCS-certified and eligible for the £7,500 BUS grant. The grant is deducted from your installation cost by your MCS-certified installer. Get a free quote to find out the net cost for your home after the grant is applied.