Octopus Tariff and Energy Consumption/Costs for a Heat Pump Review (Part 3)

Octopus Tariff and Energy Consumption/Costs for a Heat Pump.  Now, you might have arrived here from our previous posts on the initial steps we took with Octopus Energy to install our heat pump, or our article regarding the actual installation.  If not, they would definitely be worth a read.

Living with the Heat Pump and Running Costs

This next part will remain a bit of a work in progress as time passes.  We’re just a short time into our heat pump ‘journey’, I’m even using the lingo 🙂

Now I’ve had a bit of time to investigate it, in other words play around with it.  I’ve mostly figured things out!  You can play a lot more with the heat pump settings with the Madoka control unit on the wall than you can with the Onecta app.  But that’s beyond the scope of what I’m writing and probably beyond what most people will wish to be involved with.  The Onecta app will let you schedule your heating days/times/temperatures and monitor your energy usage.  It’s not a perfect energy usage figure, but close enough for most.

The heat pump will adjust its temperature depending on the weather.  Not your hot water temperature, the temp of the water circulating through your radiators.  So whilst it may be running at 50 degrees during a chilly winter day, it might only be at 35 degrees at other points in the Spring/Autumn.  Basically the colder the weather is, the hotter it will run to compensate.  Running hotter is less efficient if it doesn’t need to be hotter – it makes clever adjustments automatically. 

Our installation happened at either the best or the worst time of year depending on your point of view.  Mid to end of November 2023.  I liked the timing, others may hate it.  Mainly because once installed, you could really feel the benefit, a bit like when your mum says “don’t keep your coat on indoors, you won’t feel the benefit”, probably.  

So, here’s a couple of ideas of electricity usage from the app over the first couple of months.  The first showing some minus 6 overnights (minus 9 one day), and minus 2 during the day.  The second showing a bit of a frost overnight and 5 or 6 during the day.  There’s a lot of difference, some days will be a bit pricey, don’t fret, most aren’t like this in the UK.  We haven’t yet reached spring, so no ideas on that as yet.

Screenshots from the Onecta App

I have included all the screenshots, with a little explanation on each – and lots more writing below (so don’t forget to scroll down to read that).

Just a quick to explain the following screenshots.  The daily used kWh figures – the larger number is that day’s usage whereas the smaller number is the same day the previous week.

Octopus Tariff and Energy Consumption/Costs
Winter – Cold current week versus previous really cold week



Octopus Tariff and Energy Consumption/Costs
Winter – Average Cool Week


Heat Pump Octopus Tariff and Energy Consumption/Costs
Really Cold Overnight and Start of Day (two hourly periods) it was -9 that night!


Octopus Tariff and Energy Consumption/Costs for a Heat Pump
This was our first full week after the heat pump installation.


We’ve signed up to the Cosy tariff with Octopus – cheap between 4-7am, 1-4pm, expensive 4-7pm.  The idea is that you avoid the 4-7pm period and reduce your heating during this point.  I’ll be honest, I tried reducing my heating between 4-7pm and the house was cooling down a smidge too much, so I’ve stopped doing that for now.  I’m still taking advantage of the two cheaper periods to warm things up more though.  Maybe outside of winter this would work better when the house loses less heat.   A battery would be perfect to tide the house over these expensive 3 hours, maybe that should be a future addition, with or without solar, maybe!  That’s a whole different post 🙂

Photos from Octopus’ Thermal Imaging Camera (FLIR)

On the theme of the house losing heat, I’ve been on an Octopus waiting list to borrow a thermal camera (FLIR) for a while, and one has just turned up with DPD!  Quite timely, so now I have a week to check my house for any heat loss I could improve on, or maybe also take comedic photos of the cats.  I think it’s a great scheme, there’s a bit of a wait as they’re understandably popular.  Check out a couple of photos from this next.  You probably have an inkling that some areas of your home could do with some energy efficiency tweaks.  This certainly helps verify where you might want to spend your money!

1 year old double glazed window above, approx 20 year old double glazed not in peak condition below! 

You can see the lower window is much brighter – ie leaking more heat out.

It might just give you a kick to fit the draught stripping (that’s definitely not sat in the cupboard currently) to your brand new back door, see the very obvious blueness at the bottom, cold leaking in. This photo is taken from the inside.

See also the cold caused by the cat flap!

Also, our front door and glazing above is pretty much all blue, meaning it’s freezing round here!  The door is the original Edwardian door with stained glass above.

Octopus FLIR thermal imaging camera
This photo is also taken from the inside – maybe time to replace this door.

I have another couple of random (but interesting photos).  Firstly an image of part of underfloor heating.

Thermal imaging photos Octopus


Secondly a thermal image of of one of our cats (look at those cold ears!):

Thermal imaging of cat


Initial Thoughts on Running Costs of the Heat Pump

We’re currently just a couple of winter months into our ownership of the Daikin (EDLA09DA3V3)/Octopus heat pump (early Feb 2024).  We have our thermostat set at 23 degrees all day from 5am-10pm, 16 degrees overnight, we both work from home.  Some rooms (teenagers esp), have their radiator TRVs turned right down to 15 degrees for reasons best known to teenagers. 

These will be the most expensive months to own a heat pump, so absolutely don’t just multiply these figures by 12 and assume that’s what a year will cost.  So what’s it costing to heat our house?  January is the only complete uninterrupted month so far, and it’s used 75kWh to heat the water, 1001kWh to heat the house.  Obviously energy prices change so the final cost will depend upon those – and at what point you read this article.

Incidentally, I compared this January 2024 overall household electric usage with January 2023 and it’s within a few kWh of each other.  You might think this is bad, but previously our house was bloomin’ cold most of the time, the electric panel heaters I spoke of took the chill off the bedrooms just before bedtime, and the downstairs was kept less cold!  Now, we are comfortable all the time for the same cost, so I count this as a win.  That’s not massively scientific I grant you, but it’s how we’ve experienced it.  I suspect we’ll see greater savings with milder winter and early spring months to come, watch this space.

Is the Heat Pump Noisy?

Also, it’s quiet, sometimes really quiet!  It’s a bit noisier in the depths of winter, but unless you’re having a January barbecue like me, you won’t be outside to hear it!  When it’s just ticking along and it’s milder outside, it is really quiet!

Please note – the crunching is my feet on the new gravel.  Note also the birdsong at the end of the video.  I am stood about a metre away from it at this point.


The Heat Pump Defrosts Itself

It will look like this periodically, it’s just defrosting itself, no cause for alarm.  Occasionally you will get a large plume of steam from it when this occurs.  Still no alarm needed, though the first time you see it happening,  you may think it’s on fire!




Please see all our posts in our Octopus Heat Pump series:

Initial Steps

Actual Installation of Heat Pump

Octopus Tariff and Running Costs for the Heat Pump

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