Best tariff for heat pump (no ev or batteries)

barker77

stripling said:

barker77 said:

Looking to shortly get an octopus heat pump (daikin) installed. Wonder if anyone has done similar and what tariff would recommend ? 

I was on Tracker for many years but jumped ship recently. My heat pump is a 6kw Daikin. I don't use a room thermostat - I use pure weather compensation (Leaving Water Temperature Control Daikin call it) and I have it programmed to reduce the flow temp by -2º at night, increase it  to +1º  at 6am and increase to +2º at 16.00.  I didn't want to start reducing temperatures just as it was getting cold at 4pm so I can't be bothered with the Cosy tariff. I like a warm - 21/22º minimum house

I'm on a fix with Fuse Energy at 21p kwh and it suits me fine. It has a good simple but clear app for monitoring energy use, which I back up with the Bright app for more detail. The fixed tariff means I know exactly where I am with it all. If I had solar and/or batteries it would be different. 

My 🐙 installation was very good, I can run my heat pump at 39º design temp and be super warm and so far it’s not costing me too much.   One tip - get as much radiator acreage as possible. The more water volume the more efficient & cheaper your system. 

Fuse looks interesting but shame rhey hace very little renewable in their power purchasing. In terms of your radiator sizes did you get octopus to upgrade higher than they were going to originally or upgrade them yourself ?

TroubledTarts

Another vote for Cosy this past winter.

No EV and no batteries averaging 17pkwh but prices go up 1st April 2025.

However we switch between Agile and Cosy now. Suspect Agile for the summer and in fact will switch to Agile for a few days from today.

Realistically the long term solution is to get batteries as a starting point and charge them up overnight on a cheap tariff, enough capacity for 70-80% of the worst day in winter with the heat pump.

NedS

TroubledTarts said:

Another vote for Cosy this past winter.

No EV and no batteries averaging 17pkwh but prices go up 1st April 2025.

However we switch between Agile and Cosy now. Suspect Agile for the summer and in fact will switch to Agile for a few days from today.

Realistically the long term solution is to get batteries as a starting point and charge them up overnight on a cheap tariff, enough capacity for 70-80% of the worst day in winter with the heat pump.

Pretty much the same here (except we can't quite match your 17p import rate - well done!).

I have been following Agile closely, but because we have solar I don't really see that we can take advantage of the cheap prices. Lately they have either been cheap during the day when we are not importing anything due to solar, or are cheap overnight when we are only importing minimal background usage, so for now we are staying on Cosy and it's guaranteed cheap slots.

Like you, we are looking to add battery storage with sufficient capacity to last from one Cosy cheap period to the next (so a 13.5kWh battery, with 40-50kWh daily usage in winter). If we are able to add that, the plan will be Cosy in winter, and one of the cheap overnight EV tariffs (cough, although we don't have an EV) once our usage falls to around 20kWh/day in spring which can be covered by cheap rate battery and daily solar generation. For us, it's too expensive to add 40-50kWh of battery storage to rely only on a cheap overnight tariff in the depths of winter, when a 13.5kW battery can be cycled 3 times per day in Dec-Feb.

barker77

Must admit the peak prices for cosy put me off and then the Scottish power and edf ones start to look more appealing. That said I don’t know as I don’t have a heat pump yet how much id use off peak either 11am-4pm (better for afternoon but not morning heating?) with Scottish power or the 4am-7am 1pm-4pm with edf (covers morning and afternoon peak heating?

NedS

barker77 said:

Must admit the peak prices for cosy put me off and then the Scottish power and edf ones start to look more appealing. That said I don’t know as I don’t have a heat pump yet how much id use off peak either 11am-4pm (better for afternoon but not morning heating?) with Scottish power or the 4am-7am 1pm-4pm with edf (covers morning and afternoon peak heating?

Yes, a lot can depend on how you use your heat pump. [Rhetorical] Are you intending to run it constantly or will you utilise set backs (which may also depend on whether it is oversized or not for your property). Which TOU tariff best fits your lifestyle. Can your property tolerate a 3h set back during peak rates or will it simply get too cold. Maybe you are always out between 4-7pm due to lifestyle/work. Do you have solar on an east or west facing roof that generates more in the morning or afternoon. So many factors can affect the decision that there is no one right answer for all.

barker77

I’ll have over Specd radiators a bit so hoping can run at 40c. They aren’t underfloor so will still need on I think - will be in property from 5 but planning to use set back as don’t need to heat between 8-5 

matelodave

With a bit of experimentation and tweaking and not letting the place get stone cold. Running it longer with a bit of set back on the flow temp when you aren't there (setback by a couple of degrees, not off) and perhaps a bit of uplift before the peak hours you might be able to get the flow temp down even lower.

Now I've taken off all the zone valves, set the unit to run virtually continuously with weather compensation I've managed to get my flow temps down to between 28-34 and the place is much warmer and more comfortable than when we had the stats and zones all trying to fight each other. I set back the flow temp by 4 degrees overnight which is a bit more than most advise but we don't seem to lose too much heat.

Mind you it can take a couple of days to get the place back up to temp with very low flow temps if we let it get stone cold

Our consumption has also gone down by around 10%.

There's not much point in our having a special tariff as I can't persuade SWMBO to use stuff in the off-peak periods or avoiding the high peak periods.

barker77

Edf offering 20p kWh flat rate or other e7 tariffs of 27p day 11 overnight. Anyone worked out if better on cheaper overall vs night e7 etc ? 

matelodave

barker77 said:

Edf offering 20p kWh flat rate or other e7 tariffs of 27p day 11 overnight. Anyone worked out if better on cheaper overall vs night e7 etc ? 

In the end you have to decide how you want to run the system and adjust your lifestyle to suit a TOU tariff

You can crank it up and down to suit the tariff or you can do what I do leave it on a the cheapest fixed tariff I can find.

The system runs all day and all night if it needs to. I dont get grief from SWMBO because she's getting cold if you have to shut it down during the high cost periods and TBH there is no way I could get her to do the washing ironing or vaccying at 2am or not having our main meal between before 4pm or after say 8pm to suit something like Octopus Cozy.

My days of playing silly things and continuous tweaking  to extract the ultimate performance and lowest cost have long since gone especially when they get thwarted by my wife who wont play.