Terms of use
LAST UPDATED 26 AUGUST 2026
Using Cosydays means agreeing to what is on this page.
What Cosydays is
Cosydays is an independent app. It is not affiliated with, endorsed by, or sponsored by Octopus Energy. Octopus Energy and Cosy are trademarks of their respective owners. Cosydays talks to Octopus Energy's publicly available API using credentials you supply, and nothing here is an Octopus Energy service.
If Octopus Energy changes or withdraws that API, parts of Cosydays will stop working, and there is nothing we can do about it beyond saying so plainly in the app.
You need your own Octopus account
Cosydays reads and controls your heat pump using your Octopus API key. You are responsible for keeping that key to yourself, for having the right to use the account you connect, and for what is done with the controls once they are connected.
Controlling a heat pump
Cosydays can change your setpoint, flow temperature, schedule, hot water and mode. Some things about how that works are worth stating rather than assuming:
- Every value is clamped to the range your pump reports. If Cosydays cannot read that range, it refuses the change rather than guessing — a heat pump is a physical machine and an unclamped flow temperature is a real risk, not a rendering glitch.
- A command reaching Octopus is not a command reaching your pump. Cosydays reports what it sent and what came back, and says "sent, not yet confirmed" when that is the honest answer.
- Controls pause during an outage. When Octopus is unreachable Cosydays stops sending rather than firing into the void.
- Cosydays is not a safety system. Do not rely on it for frost protection, for a vulnerable person's heating, or for anything where a missed command matters. Your heat pump's own controls remain the authority.
Analysis, verdicts and advice
Cosydays estimates. Its efficiency figures, cost figures and weather-matched verdicts are derived from readings that arrive late, with gaps, and at half-hourly resolution. They are good enough to answer "did that change help", which is what the app is for. They are not a substitute for advice from a qualified heating engineer, and they are not a billing statement — your bill comes from Octopus Energy.
Where an AI analysis is offered, it is a reading of your own figures. Treat it as a starting point for a decision, not as the decision.
Plans and payment
There is no payment provider in Cosydays today. Where a paid tier applies, it is arranged directly and set against your account by hand. Some features are limited by how often they can be run rather than by whether you are allowed them at all; the app says which, and says so before you hit the limit rather than after.
Availability
Cosydays is provided as it is, with no guarantee of uptime. Background collection can fall behind, Octopus can refuse a request, and a deployment can go wrong. The app is built to show you when its data is stale rather than to draw a confident chart over a gap, and that is the extent of the promise.
Liability
To the extent the law allows, Cosydays is not liable for loss arising from using it — including heating costs, discomfort, or damage following a control command. Nothing here limits liability for death or personal injury caused by negligence, for fraud, or for anything else that cannot lawfully be limited.
Ending it
You can disconnect your Octopus account or stop using Cosydays at any time; see Privacy for what happens to your data. We may suspend an account that is being used to access someone else's data or to abuse the Octopus API.
Governing law
These terms are governed by the law of England and Wales.