Posted by: @kev-m

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Posted by: @mjr

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Posted by: @bob77

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My energy costs about 33% less overnight, which of course coincides with time I don’t need the house so warm. But should I leave the heating running through the cheap period so it’s not playing catch-up at peak rate? 

Interesting. My E7 is about 67% cheaper overnight at the moment. But there's still little point heating rooms as much while everyone is under duvets, so I don't leave the heating running through the cheap period, but I do heat some water up and start heating soon enough to catch up before peak rate (or at least that's the aim: was 30 minutes late catching up this morning!).

This is going to be a common variable and isn't yet generally understood how to include it in heat pump settings. Octopus are rumoured to be developing a heat-pump-user-specific tariff with two cheaper-rate periods (early-morning and early-afternoon) and a higher evening peak rate and I expect their variable-by-half-hour Agile will return one day, too.

 

@mjr is this the Octopus tariff you mean?

https://octopus.energy/smart/cosy-octopus?fbclid=IwAR0B_KhYcBSGnI50qIhS3Kr_T4fGXpqu77t9HR3U8J70KGtR36dDr8SY9a4

 

 

Yes. I didn't know it had been finalised and prices displayed yet. 

@mjr 

that Octopus tariff would work well for me I think.  I don't have a smart meter but I'm going to try and switch and have Octopus install one. 

We are with Octopus but they can't install a smart meter for us.  We ring our meter readings in to them.

Posted by: @kev-m

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I don't have a smart meter but I'm going to try and switch and have Octopus install one. 

At the risk of sounding like a tin foil hat conspiracy theorist, I have 100% resisted having a smart meter installed, despite heroic attempts by my energy supplier (EDF) to get me to have one. I say heroic, but really they are just dishonest, repeatedly claiming I have to have the 'essential' upgrade, when of course there is nothing essential about it, and I absolutely do not (yet) have to have one.

My principal objection to smart meters is not EMFs and all that, but that we are sleepwalking into a social credit system. Firms like Octopus (just like Tesco with their club card scheme) bribe and coerce people into signing up to whatever part of the social credit system it is that they are trying to implement. In Tesco's case, the bribe is significantly lower prices, the cost is Tesco know everything there is to know about your grocery shopping, from how many units of alcohol your household consumes weekly, to what your grocery carbon foot print is. There are already credit cards that allow you to (voluntarily for now) set a limit on your carbon spending, when you go over that limit, 'the card says no'...

The bribe with smart meters is lower tariffs, the cost is partly you tell your energy supplier how much energy you use and when, but the real cost is you give your supplier the ability to shut off your supply remotely. You want to warm up the house a bit? When you try to do so, you find 'the smart meter says no'... 

You can extend the dystopia very easily. What if the energy industry implodes in a not so distant energy crisis, and the government effectively nationalises the industry (as happened with the banks during the financial crash, point being these things can and do happen). The government now has remote access to control your energy supply. Is that something you really want to allow?

I've tried running 24/7 with 18degC general space temperature. Lounge is boosted with a log burner the trickles heat upstairs too. It has been very cosy but in this really cold weather my kWh consumption all-in per day has been unsustainable at 48-54kWh/day on default price cap tariff. So I'm knocking my ASHP off from 10pm to 4am each night and seeing what I will save. I'll load the log burner in the lounge last thing at night to retard the house temperature drop. The lounge has a couple of large windows and the heat does disappear rather quickly!

I'll have to accept slightly cooler starts in the morning and the ASHP 'saw-toothing' up to weather compensated flow temperature while it starts from cold and cycles in defrost. I've upped the WC curve from a max of 40degC to 42degC to improve the pre-heat time in the morning, but that's still quite low for wet rad system.

I've also changed the hot water charge time to mid day, when the loss of heating for an hour is least disruptive. For the hour after I've knocked the ASHP off so that the Solar PV iBoost can also top up the water beyond the 45degC stat setting.

We had a 90 minute power cut last night anyway, the first of many we'll get this winter, thanks to 'NO-rthern PowerGrid' so I definitely saved some money there!!

Posted by: @allyfish

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I've tried running 24/7 with 18degC general space temperature. Lounge is boosted with a log burner the trickles heat upstairs too. It has been very cosy but in this really cold weather my kWh consumption all-in per day has been unsustainable at 48-54kWh/day on default price cap tariff. So I'm knocking my ASHP off from 10pm to 4am each night and seeing what I will save. I'll load the log burner in the lounge last thing at night to retard the house temperature drop. The lounge has a couple of large windows and the heat does disappear rather quickly!

I'll have to accept slightly cooler starts in the morning and the ASHP 'saw-toothing' up to weather compensated flow temperature while it starts from cold and cycles in defrost. I've upped the WC curve from a max of 40degC to 42degC to improve the pre-heat time in the morning, but that's still quite low for wet rad system.

I've also changed the hot water charge time to mid day, when the loss of heating for an hour is least disruptive. For the hour after I've knocked the ASHP off so that the Solar PV iBoost can also top up the water beyond the 45degC stat setting.

We had a 90 minute power cut last night anyway, the first of many we'll get this winter, thanks to 'NO-rthern PowerGrid' so I definitely saved some money there!!

This is very similar to what I do. I have a coal stove (sorry!) and no upstairs but the same idea. I reckon it saves 20% or so.

Posted by: @cathoderay

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but the real cost is you give your supplier the ability to shut off your supply remotely. You want to warm up the house a bit? When you try to do so, you find 'the smart meter says no'... 

They can already shut off supply and if we get to that dystopia, smart metering and shutoff will simply be installed on the energy company's side of the boundary.

There are problems with UK smart meters, not least customer access to our own data, but they are not worse than dumb meters could be.

Posted by: @cathoderay

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but the real cost is you give your supplier the ability to shut off your supply remotely. You want to warm up the house a bit? When you try to do so, you find 'the smart meter says no'... 

They can already shut off supply and if we get to that dystopia, smart metering and shutoff will simply be installed on the energy company's side of the boundary.

There are problems with UK smart meters, not least customer access to our own data, but they are not worse than dumb meters could be.

Isn't the important variable here is the average temperature of the house over the 24 hour period? If you turn it off for 3 hours, and the temp drops 3 degrees from 21C to 18C say, then turn it back on and it takes 3 hours to raise the temp back up to the set point again, then the average temperature of your house for the full 24 hours will be slightly lower (20.5C or so). Your heating requirement will therefore be slightly lower, as the Delta T between inside and outside temperatures is slightly lower. So yes you should save energy because you're effectively setting the thermostat to be half a degree lower.

The loss in efficiency from turning off and on the heat pump once per day is surely negligible compared to the reduced energy requirement from having the temp of your house be 0.5C lower.

@kev-m That Cosy Octopus tariff is really interesting. We are currently on Octopus Go and it expires in March, when it looks like the tariff will be much higher. 

With an EV though, it becomes a difficult decision of whether to go for Intelligent Octopus or Cosy Octopus. It would be really useful if they had a calculator that told you the most efficient tariff for you. 

@knukes these are my rates. Pretty interesting if you have a heat pump and batteries. Not much use to me as my current rate is 7.5p/kW for 4hrs a day and 39p for the rest. But once that ends, it'll be very interesting. Two lots of charging would be great

@scrchngwsl Not in every house. I think it is different with well insulated houses.

When I run my house for 4-6 hours a day from about starting at 11am-4-5pm with a fix flow around 35-36c it turns of when reaches 21C. Then the temp still climbs as the 19tonne of concrete we put down takes time to heat but then it radiating the heat all the way up to about 22.5c. So it is off for the coldest part of the day. Then at 11 am kicks back in. Usually it is never under 20c at that time. So thankfully it does not drop 1 degree an hour. It is off for 17-18 hours and I louse about 2- max 3 c? 17-18 hours (so that's is about 0.16C/hour).

I have to say that is when at night is as low as 0c, during the day goes up to about 5-6. I have not run a test when it it was this cold as lately.