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Octopus Cosy Heat Pump Owners & Discussion Thread

AndrewJ · 2025-10-23T11:37:06Z

I'd like to discuss how you find it, how you run it and so on.

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Air Source Heat Pumps (ASHPs)

Last Post by AgentGeorge 4 weeks ago

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AndrewJ

(@andrewj)

Reputable Member Member

Joined: 1 year ago

Posts: 220

Topic starter 16/05/2026 7:57 pm

@swwils mine is mostly off now. Hot water for an hour 02:30 to 03:30 then heating to 21c from 03:30 to 05:30 although in reality it will only come for a short period to bring the house temp back up to that temp. This is giving overall COPs of <4 with the OAT in single figures right now, but a quick calc of the heating only COP from this morning gives 4.08 at 7.4c.

What would be very useful is if you could describe your system, in some detail: how you have it set up, how you run it, hub parameters etc.

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AgentGeorge

(@agentgeorge)

Estimable Member Member

Joined: 1 year ago

Posts: 172

17/05/2026 8:46 am

@swwils there is no logic to oversizing a heat pump. It wastes energy keeping a large compressor and heat exchanger running.

you got the 9kW cosy as the smaller 6kW was not suitable for your properties heat loss

its not just the COP you look at, its the energy consumption in kWh per day.

My Cosy6 was running full operation the first winter as i hadn't completed the insulation in the new kitchen extension roof.

This winter period, the Cosy6 was much quieter, insulation makes a huge difference to heat loss. My rear extension is fully insulated, floors, ceiling, walls, to 150mm. It is always 2C warmer than the rest of the house

This Autumn, after the wall insulation is installed in the Lounge/Kitchen I will be rebalancing the UFH towards the Lounge

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