Octopus Cosy Tariff

[Chriswills]

Octopus energy are advertising a "Cosy" tariff for ASHP users with x2 cheap energy dips (04:00 - 07:00) and x1 high energy hike at peak (16:00 - 19:00).

Does anyone have this and/or rate it?

I thought the whole point of an ASHP was to keep it on 24/7 but with this tariif wouldnt you need to switch it off at peak time to benefit and only run it for 6 hours a day at the low rate?

Confusing!!!

[JohnMo]

Normal ill conceived, sound good to the the greater public, most of which may still be using a heat pump like the gas boiler they had before.  So may be good for them.  Until they put the oven and electric hob on for cooking the tea.

[SteamyTea]

Work out the cheap times.

[joth]

No standard ASHP controller is anywhere near advanced enough to make good use of this. You need to boost the load compensation during the cheap rates (i.e. use a higher flow rate than would be normal) and have a slightly higher target temp, and also have a set back on those parameters during the surge price. 

The current trend is to push the smarts for that "to the cloud" which has all its own drawbacks.

Doing this locally (offline) is not a simple project either. Even with my Loxone automation, making good use of this tariff would not be simple. (in large part because I can't yet control flow temperature programmatically. Next autumn's project).

 

[TW9]

We use it. We shift as much load as we can into the cheap periods (water heating, washing machine, dishwasher, car charging). We also adjust the settings on our battery to limit our use of the grid during the expensive period.

 

Our heat pump is controlled by a Tado so we have made small adjustments to the timings to try and push use away from the peak period. It's harder to do this with most heat pump controls.

 

Without an EV or a battery I think you might struggle to save more than pennies. If you're already on Octopus there's an app called Octopus Compare that tells you how much you would pay each day on different tariffs. So you could see if it's worth going for without actually moving it.

[TerryE]

4 hours ago, Chriswills said:

I thought the whole point of an ASHP was to keep it on 24/7

Not really.  The point of an ASHP to pump heat as cheaply as possible.  Two things drive this cost per kWh heat pumped: the effective CoP and the unit rate of electricity.  If you have an energy-efficient house which has a long thermal time constant (e.g if I was to lose heating now my house temp drops around 1-1½ °C per day) so it doesn't really when you pump the heat during the day, just that you pump enough day-to-day to balance out overall heat losses.  The "when" bit becomes: when I can buy it cheapest.

[ragg987]

2 hours ago, joth said:

No standard ASHP controller is anywhere near advanced enough to make good use of this. You need to boost the load compensation during the cheap rates (i.e. use a higher flow rate than would be normal) and have a slightly higher target temp, and also have a set back on those parameters during the surge price. 

I can do this with the standard Hitachi ASHP controller, provided the times for price boundaries are known. I use the flow temp compensation and variable circulator speed options.

 

Set timer to raise room temp by e.g. 2 degrees and flow temp will boost, so will flow rate.

 

Set timer to reduced room temp and either the system powers off or reduced flow temp and rate. Depends on the delta temperature.

 

I use this scheme when the external temperature is above freezing. When colder my system efficiency drops quickly so I leave the room set to a constant temperature, however the compensation control will still adjust flow to optimise for the load.

 

I am about to get a smart meter fitted and will switch to octopus intelligent soon after. My simulation suggest I will save about 25% on the bill with a few timer and behaviour changes, even allowing for a 10% increase in electrical consumption due to running less efficiently overall.

[Chriswills]

food for thought.....will have to look into the settings on my system

I have a NIBE SM0 S40 control panel and a NIBE S2125 Air Source Heat Pump

[dpmiller]

10 hours ago, ragg987 said:

I can do this with the standard Hitachi ASHP controller

 

Yep, the Carel controller on the CoolEnergy unit can do this too- four programmable time/ temp steps, for heating, cooling, and DHW at each step.

[Chriswills]

All I would do really is have timed stats for my Ufh so they turn down by 2 degrees at peak times. Is this ok?

[pudding]

Hi, I posted this a few weeks ago on the other Cosy thread:-

 

My old fixed tariff was due to expire beginning of Feb, so I moved over to Octopus in anticipation of that, and in order to get rebate payments as I've signed up to Ripples second wind turbine project. I signed up via a link to join the Cosy tariff. Got switched over to Octopus week and a half ago, and was switched onto Cosy on Thursday last week.

 

For our house we have an 8kW heat pump connected to a 300L DHW tank and a 300l buffer to tank for whole house UFH. We've also got 7kW solar, with 14kWh batteries installed last year. So, there was a lot of fiddling and tinkering with settings and timers to try and get the best out of it, and it'll take a few more days/ weeks to get the temps and timing right. But basically, the whole aim is to try and run everything ad charge everything during the 2x3hr cheap slots so we import the least amount of electricity possible at all other times. At the mo, I've got the batteries set to charge to 75% overnight which sees us through the morning and breakfast until 1pm easily enough with a bit of spare capacity for charging if/when the sun shines, and then to 100% by the end of the 1-4pm window, ready to see us through the night until 4am. The heat pump is set to come on during the cheap windows to top up the hot water tanks, and the room thermostats are set to heat the rooms only during the 3hr slots, morning up to 20/21 for bedrooms/other rooms, afternoon up to 21/22deg, so slightly warmer to keep a decent temp until they come back on at 4am. 

 

Seems to be working out quite well so far, and I think this tariff really benefits from having batteries which really take advantage of the cheap slots. I think through the year and more solar is produced I'll be able to reduce some of those battery charge levels as more and reliable solar can top them up. Plus, the heating will be off saving muchos kWhs!

 

 

Seems to be working really well and we basically use almost no electricity outside of the 2x 3hr windows, but that obviously wouldn't be the case without batteries, but even without batteries, the heat pump topping up the hot water tanks for DHW and heating is fine twice a day, although I think every now and then the DHW tank needs topping up outside the 3hr windows if baths have been used or a lot of washing up has been done. Nothing complicated control wise needed I don't think, just timers on the heat pump and thermostats really.

 

[SteamyTea]

11 hours ago, TerryE said:

If you have an energy-efficient house which has a long thermal time constant (e.g if I was to lose heating now my house temp drops around 1-1½ °C per day) so it doesn't really when you pump the heat during the day, just that you pump enough day-to-day to balance out overall heat losses. 

And you don't need a slab weighting tonnes.

My storage mass is less than 100 kg.

Pump the heat in between 4 AM and 7 AM, job done.

Edited March 9, 2023 by SteamyTea

[Chriswills]

Any idea of a good UFH thermostat to replace my exisiting Emmieti analogue ones as I want to time them to drop in temp over night.

[Luke1]

On 08/03/2023 at 17:52, joth said:

No standard ASHP controller is anywhere near advanced enough to make good use of this. You need to boost the load compensation during the cheap rates (i.e. use a higher flow rate than would be normal) and have a slightly higher target temp, and also have a set back on those parameters during the surge price. 

The current trend is to push the smarts for that "to the cloud" which has all its own drawbacks.

Doing this locally (offline) is not a simple project either. Even with my Loxone automation, making good use of this tariff would not be simple. (in large part because I can't yet control flow temperature programmatically. Next autumn's project).

 

 

You can do this with the NIbe SMO 20 controller.

It has a standard temperature / curve setting.

It has 3 separate schedules for increasing / decreasing the temperature / curve setting. 

It has a further 2 schedules for blocking the compressor from working at all.