heat pumps anyone ?

There are a variety of tariffs available, from giving you fixed overnight hours (eg 4-5h per night) to those where they communicate with your car or charger (ie they tell it when to charge based on whether it's better to charge at 11pm or 3am, but you always wake up with a full battery). Or you can ignore EV charging completely and go to something where the price varies based on wholesale rates either on a daily or half-hourly basis (but may be overall cheaper than the standard tariffs).

If you don't have other uses for E7 like storage heaters, it's worth investigating because the day rates on E7 can be very high.

Theo

Octopus have two tariffs for EVs

6 hours - 7p/kWh but controlled(??) after 11:30pm by Octopus, otherwise

https://octopus.energy/ev-tariffs/

Most old systems would have been designed for a higher flow temperature than 60C. My condensing boiler fitted a few years ago had a factory default setting of 75C.

The advice at the start of the fuel crisis about reducing the flow temperature to 60C didn't provide enough heating for many :)

They also have a standard E7 tariff, which is useful if either car or charger are not yet compatible with their scheme.

Chris

I'm not sure over how many months the SCOP figure is calculated but the figure would be very misleading if months outside the real heating season were included. Including the summer months would push the SCOP figure higher.

Even within the geographical range of Cornwall to the lowlands of Scotland the difference in average weather conditions (temperature) would make the economics of an ASHP very different. With a reference location and all manufactures using the same regional figures the SCOP gives a comparison between models.

We are being told with the climate catastrophe we can expect many more periods of extreme weather, many more beasts from the East! No use designing for the average weather if the system doesn't work or it cripples you financially when the COP figures approach unity :) Having the COP figures rather than SCOP means that you can establish if a ASHP is financially sensible for you.

There seems to be some assumptions in the pricing that the householder has a suitable hot water tank and the rest of the system has been well maintained. The householder also has to supply valid Energy Performance Certificate.

I don't know what the cost would be if trying to swap a combi boiler with instant hot water with their ASHP. Grants don't apply to hybrid systems.

On web sites promoting ASHP they indicate £11k is the very bottom end for higher temperature heat pump installations.

https://freeimage.host/i/2BBb5j2

https://freeimage.host/i/2BBb5j2

If your car or charger aren't compatible you can't have the 'controlled' tariff (Intelligent Octopus), but you can have the regular fixed-hours EV tariff.

Theo

You don't want Legionaires Disease. It's very nasty - I write from personal experience. I was lucky to escape.

They're not particularly high for us at present. We've been on Economy 7 for yonks and, until we had the plugin hybrid car, we usually about broke even compared with not having Economy 7. We heat our water (immersion heater) overnight, run the dishwasher, do clothes washig, etc.

Is that EV only, or can one use it for other things?

Which is where I came in! We're on the standard E7 tariff.

The quoted SCOP figure is all year. When summer months are included the SCOP goes *down*. The reason is that in the summer the ASHP is only making hot water, which has a lower COP because it has to heat the water hotter than it would do for central heating purposes. That makes the SCOP annual average worse. If you have another source for summer hot water (eg solar) you get a better SCOP calculation as the ASHP isn't running so much in the summer..

Indeed. It's not perfect, but also we aren't comparing Florida and Minnesota - the climatic difference across the UK isn't that large.

I agree we want proper data, and I hope that will be available if you're a prospective customer.

Yes, if you don't have a hot water cylinder it'll cost more. The actual cylinder is about £1k, but it depends what extra work is needed where it is to go, and extra plumbing.

Theo

You can use it for anything in the given hours. You need to have an EV to get on the tariff (I suppose they check) but you don't need to use it for the EV. Basically it's like 'economy 5' but with much lower rates.

The Intelligent Octopus needs to have a car or charger they can chat to, but I don't think they discriminate what you use the energy for. Even if those things tell them how much power you're taking, they aren't certified meters they can use for billing, and only your whole-house meter is.

Theo

From their FAQ (their 5 hours at 8.5p offering) I assume the four hour should actually read five hours

Quote Can I use my cheap charging period for anything other than charging my car?

Of course! During this four hour period, any electricity you use will be charged at 8.5p/kWh.

You can even automate stuff to come on using smart plugs and neat, simple to set up integrations with Alexa and IFTTT – check out some smart home hacks from our brilliant customers. /Quote

The tariff is reliant on having a working smart meter.

Unfortunately, many people's gas systems were designed for the (at the time) standard boiler temperature of 82°C and will need much larger radiators (at least twice the size), may need larger bore piping and will need a larger hot water cylinder (two to three times the volume, as the lower temperature hot water is used up faster than hotter water).

Of course many homes removed hot water cylinders completely in recent years, as they had better uses for the space.

For the last 12 months, we have charged our EV on OVO Anytime - often right up to 100%, knowing that I have a long journey the nexy day. We have never had a failure to charge to what we've set, by the time we've set (as long as we've been sensible about not starting to charge too late at night). We even get low cost charging at times during the day.

We pay less than 7.5p per unit for charging, with no increase (above standard OVO rates) for standing charge or non-charging units.

Which is best depends unon how much electricity you use for other purposes during the E7 period.

With OVO, we have a standard Smart meter and an OHME charger. The charger *IS* used for billing - we pay for all our electricity at OVO's standard rate, but have our bill reduced by how much we use for charging (reported by the charger), bringing charging units down to 7p.

No

Very simplistic numerical example Assume 2 data points each of 100 days (a long winter and a long summer)

2) outside temperature is 20C, DHW needs to be heated to 50C giving a typical COP figure of 4.5

Assume that the incoming water temperature is always constant as its come through miles of underground pipes. Assume that it requires 1kWh each day to heat the water. Assume a household uses the same amount of DHW each day in the 200 day year

The 100 day winter output needs to be 100kWh but with a COP of 2.5 the ASHP input is 40kWh

The 100 day summer output needs to be 100kWh but with a COP of 4.5 the ASHP input is 22kWh

The SCOP for both seasons is 200kWh/66kWh = 3 The SCOP for just the winter is 100kWh/40kwh = 2.5

Include the summer months and the SCOP figure becomes more favourable

Obviously the above is not that realistic as heating which only occurs in the winter months dominates the SCOP figures (assuming that the SCOP figures are not calculated with the house being cooled by the ASHP in the summer)