Vaillant Arotherm heat pump: the best electricity tariff to pair with it in 2026
The Vaillant Arotherm is one of the UK's most widely installed heat pumps. It's efficient, reliable, and has a mature controls ecosystem — but the scheduling flexibility you have depends on which controller you're using. That matters enormously for tariff choice: a heat pump that can schedule around off-peak windows can save £200–£400 more per year than one that can't. Here's how the Arotherm's controls map to the available tariffs.
Why your heat pump model matters for tariff choice
All heat pumps use electricity. But exploiting time-of-use tariffs depends on whether your controller can be scheduled to run — or avoid running — at specific times. Some controllers make this easy; others require additional hardware.
The Vaillant Arotherm Plus is one of the UK's most widely installed air source heat pumps. Here's how its controls ecosystem affects your tariff options.
Vaillant Arotherm controls
VRC 700 wired controller: Standard on most Arotherm Plus installations. Supports daily and weekly heating and hot water schedules with multiple time periods per day. Sufficient to align your heat pump to any fixed-window tariff (Cosy Octopus, E.ON Next Pumped, British Gas Heat Power) without additional hardware.
vSMART app (via VR 920 WiFi module): Vaillant's smart controller add-on. Connects the heat pump to the myVAILLANT app for remote scheduling and usage history. Adds convenience without fundamentally changing scheduling capability — you set the same time-based schedules via the app that you'd set on the VRC 700.
Home Assistant / Homely: The Arotherm can integrate with Home Assistant via community-developed integrations. Homely (a heat pump optimisation platform with native Vaillant support) provides automated schedule alignment to your tariff's cheap windows without manual management.
Tariff recommendations for Arotherm owners
Cosy Octopus — recommended for Arotherm with VRC 700 or vSMART
The VRC 700's built-in scheduling maps well to Cosy's three windows. Suggested setup:
- Hot water: 04:30 start, 06:45 end (morning window). Add 13:15 top-up if needed.
- Space heating: elevated target from 03:00–15:30, then minimum from 16:00–19:00 (peak window).
The Arotherm's weather compensation mode helps significantly here: it modulates output based on outdoor temperature rather than cycling on/off, which makes preheat strategies more effective and reduces the risk of an unexpected heating call during the peak window.
Key check before going live: confirm the VRC 700 schedule prevents any heating or hot water call during 16:00–19:00. A manual hot water boost during peak hours at ~54.7p/kWh (Q3) is expensive.
E.ON Next Pumped — recommended without tight scheduling
If your installation has limited scheduling capability, or you can't reliably avoid the Cosy peak, E.ON Next Pumped's 21-hour below-cap coverage is more forgiving. The super off-peak window (22:00–06:00) covers overnight hot water. The off-peak rate (06:00–16:00) covers daytime heating at below-cap rates by default — a discount even without deliberate scheduling.
British Gas Heat Power — good with Hive integration
The Arotherm doesn't natively integrate with Hive, but if your system includes a Hive hot water controller, Heat Power's 13:00–16:00 cheap window aligns with warmer afternoon outdoor temperatures — meaning a cheaper rate and a better COP simultaneously.
EDF FreePhase — straightforward overnight scheduling
The 23:00–06:00 green window is simple to set on the VRC 700. The mild red rate at 16:00–19:00 means some peak exposure isn't catastrophic in the way it would be on Cosy. A sensible choice if you want a no-fuss overnight schedule without a severe peak penalty.
Weather compensation — the higher-value lever
All Arotherm Plus units support weather compensation as standard. It matters for tariff pairing because:
- Lower flow temperatures on mild days improve COP — more heat per kWh regardless of rate band.
- The Arotherm's modulating compressor runs at reduced power for extended periods, which suits long cheap windows better than a fixed-speed unit.
- A well-tuned weather compensation curve reduces total electricity consumption, amplifying the proportional saving from off-peak rates.
If your Arotherm is running at a fixed flow temperature rather than weather compensation, reviewing that setting with your installer is likely worth more than any tariff optimisation.
Worked example: Arotherm Plus 7kW, 3-bedroom semi
- Annual electricity consumption (heat pump + hot water): ~6,200 kWh
- SCOP: ~3.2
- Controller: VRC 700, active weekly schedule
Cosy Octopus, 70% shifted, peak avoided (Q3 2026):
- Effective blended rate: ~18.5p/kWh
- Annual cost: ~£1,147
- Saving vs standard variable (26.1p): ~£471/year
E.ON Next Pumped, natural usage pattern:
- Effective blended rate: ~20p/kWh
- Annual cost: ~£1,240
- Saving vs standard variable: ~£378/year
The £93 gap reflects the scheduling effort. For an Arotherm owner willing to invest 30 minutes setting up a good schedule, Cosy is likely the better tariff. For one who prefers set-and-forget, Next Pumped delivers strong savings without the complexity.
Compare every tariff for your home and region on Heat Pump Tariffs — using your actual half-hourly data, not a national average.