Anyone else had a bill for the recent cold snap?

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Joeboy
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Re: Anyone else had a bill for the recent cold snap?

#11

Post by Joeboy »

Oldgreybeard wrote: Tue Dec 27, 2022 12:44 pm
Bugtownboy wrote: Tue Dec 27, 2022 12:24 pm Whoops, got me wood wrong. Still got 0.3m3 in the house and the usage was for the year since April - use it outside in a cooker.

Probably over December we used about 0.75m3
Makes a BIG difference! Brings the total for the month down to somewhere around 1,770kWh, which seems a lot more reasonable. There was me thinking you must be heating a stately home to have used that much to heat it!
Maybe in the far South of the island that is a reality. As for stately 🏡. Under 2MWh to heat the first 3% maybe...? Even after airdrying my logs for 9 months there is definitely a hierarchy and an ongoing dynamic to the ebb & flow of a WBS. It has taken quite a while to know the right fuel type/ airmix to keep it chatting along within its daily burn cycle.
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Re: Anyone else had a bill for the recent cold snap?

#12

Post by Bugtownboy »

In terms of ‘accuracy’, most of the calcs for wood are based on a standard m3, either based upon cord wood or from a tightly packed m3 crate.

My estimate was basically an eyeball of the woodpile.

The only accurate one ( :roll: ) is the in-house store which is 1.2x.5x.5. Even then, it’s only loosely packed, as is the main store that I eyeball.

There again, thought we were just considering the ‘bill’ ?
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Re: Anyone else had a bill for the recent cold snap?

#13

Post by Oldgreybeard »

I guess for those lucky to have their own woodland that they can sustainably manage then the "bill" for energy from wood is free, but I'm not sure many are in that fortunate position, are they? My brother's winter business for the past 35 years or so has been supplying firewood, and he makes a good enough living from buying trees, felling them, cutting and splitting them and drying them through the year ready to sell the following winter, so for many there is a bill involved. Seems fair to try and level the playing field when making comparisons.

I was chatting to my neighbour few days ago, about the water fiasco, but his oil boiler fired up as we were chatting and he dashed in to turn it off, so the conversation drifted to bills. He was moaning that not only had the oil bill gone up a lot, but he was now paying around 30% more for logs as well. He reckons the logs are still cheaper, though, and is trying not to run the boiler unless he has to, as he's trying to get his tank of fuel to hold out through the winter. He mentioned that the cheapest he can get decent logs around here (well-seasoned, delivered by tipping trailer) is now around £100/m³, so about 5.8p/kWh. I know my brother charges a fair bit more than that, but he's down in an area where log prices have always been high. No idea what the national average price is for logs, though.
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Re: Anyone else had a bill for the recent cold snap?

#14

Post by openspaceman »

Electricity

25th Nov 2022 1169.4 Smart meter reading
25th Dec 2022 1290.8 Smart meter reading
Energy Used 121.4 kWh @ 50.63p/kWh £61.45
Energy Price Guarantee 121.4 kWh @ 17.00p/kWh -£20.63
Standing Charge 30 days @ 40.646p/day £12.19


Gas
25th Nov. 2022 297.0 Smart meter reading
25th Dec. 2022 312.0 Smart meter reading
Consumption 15.0 Units (m3)
Energy Used* 164.8 kWh @ 14.021p/kWh £23.10
Energy Price Guarantee 164.8 kWh @ 4.22p/kWh -£6.95
Standing Charge 30 days @ 27.128p/day £8.14

This latter gas bit is disappointing as it only relates to DHW, I hanker after one of those 100 litre integrated heat pump DHW units as probably suiting our needs better. Does anyone know if they can draw warm air from the house and dump freezing cold air outside?


Oldgreybeard wrote: Tue Dec 27, 2022 10:21 am
Log firewood at 20% MC is between 1,400kWh and 2,000kWh per m³ (data taken from the US government, here: https://www.forestresearch.gov.uk/tools ... -of-fuels/ ). Assuming a mean value of 1,700kWh/m³ then the wood adds about another 2,550kWh to those figures (only to put them in perspective).
That's a uk site with figures probably from the Forestry Commission, it assumes stacked wood and around 30% air space, it varies greatly with species. Softwood being at the lower end and hardwood, like beech, at the upper. I work on 4kWh per kg and this does not vary so much between species. So far this winter 3 months I have burned 1.25 solid m3 at 20% mc or below, say around 500kg, so about 2000kWh expended but probably getting 70+% into the house. That includes the cold spell when we barely kept comfortable but no other space heating.
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Re: Anyone else had a bill for the recent cold snap?

#15

Post by Oldgreybeard »

I looked at one of those integrated heat pump water tanks, years ago, looked impressive to me. That was at the home building centre in Swindon, where there was a UK firm selling what they claimed to be a UK made product, but was really just a badged product from China. They seem very popular in China, Alibaba is awash with various models.

It's absolutely fine to draw warm air from the house and dump it outside with these, if you can arrange to draw extract air from the bathroom or kitchen (or both) then so much the better, as that recovers a bit of waste heat from the used hot water as well. The only issue I remember is from around ten years ago, where a chap on a now-defunct self build forum had the stainless tank corrode. IIRC, he lived on Skye, though, and my guess is that the water up there might have been a bit acidic. I believe these things have a replaceable protective anode now, to reduce that risk.

They should be as reliable as a fridge, as I looked at the innards of the one on display and it looked to be a standard fridge compressor sat on the top (under the lid) but with a radiator and fan instead of the free-air cooled condenser on the back of a fridge. There didn't seem much to go wrong with them at all.

The only reasons I didn't buy one was at that time there was no easy way to integrate it with an MVHR system (I believe there is now) and I got put off by the company being a bit misleading as to the fact that they were just importing something from Alibaba and sticking a label on it saying it was UK made (there were absolutely identical models for sale on Alibaba at that time). No idea if this is still the case, but either way I'm not so sure it would bother me now, given these things have been around so long.
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Re: Anyone else had a bill for the recent cold snap?

#16

Post by Stinsy »

openspaceman wrote: Tue Dec 27, 2022 4:12 pmI hanker after one of those 100 litre integrated heat pump DHW units as probably suiting our needs better. Does anyone know if they can draw warm air from the house and dump freezing cold air outside?
I’ve looked at those. Bulky and expensive beasts. I get the attraction but a standard cylinder with an immersion, solar and a ToU tariff makes more sense. And: yes you can extract warm air from your house and expel cold air to outside.
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Re: Anyone else had a bill for the recent cold snap?

#17

Post by Oldgreybeard »

Stinsy wrote: Tue Dec 27, 2022 4:42 pm
openspaceman wrote: Tue Dec 27, 2022 4:12 pmI hanker after one of those 100 litre integrated heat pump DHW units as probably suiting our needs better. Does anyone know if they can draw warm air from the house and dump freezing cold air outside?
I’ve looked at those. Bulky and expensive beasts. I get the attraction but a standard cylinder with an immersion, solar and a ToU tariff makes more sense. And: yes you can extract warm air from your house and expel cold air to outside.
The one I looked at was about the same diameter as an ordinary pre-insulated hot water cylinder, but maybe about a foot or so taller? The gubbins was all under the top cover, and not any bigger than a fridge or freezer compressor from what I remember. It also had a standard immersion heater (two, I think) so in summer it could be used with an Immersun or similar with the heat pump bit just ignored.

Main issue with them when running in heat pump mode was the somewhat slower re-heat. I think the compressor was rated at around 500W or so, and because of the warm intake air the COP was pretty high, around 4:1. Still around 30% longer re-heat time compared to an immersion though. Does save a lot of energy in winter if run on off-peak electricity.

Pricing is a bit oddball. They are not that expensive in China, typically they sell for between $500 and $800 at one-off prices. Certainly a bit more costly than a standard unvented cylinders with immersions etc, but not massively so. The UK importer (that may now have a design or manufacturing input I believe) is this company: https://www.earthsaveproducts.com/products/ecocent and they do stick a fair markup on the price, but then they are providing UK support, plus they have most probably ensured compliance with UK safety requirements, something I'd be wary of if buying direct from Alibaba,
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Re: Anyone else had a bill for the recent cold snap?

#18

Post by openspaceman »

Stinsy wrote: Tue Dec 27, 2022 4:42 pm
I’ve looked at those. Bulky and expensive beasts. I get the attraction but a standard cylinder with an immersion, solar and a ToU tariff makes more sense. And: yes you can extract warm air from your house and expel cold air to outside.
Oh well I may stick with my vented tank and immersion, it is all we need for half the year. Problem is the 3ft immersion only has an 18" thermostat so only the top 18" gets fully hot.

Saving a total of £200 a year on not using gas doesn't justify much spending and even at a COP of 3 I would have to use electricity from the grid in winter to run the air to water heat pump.

OGB's pricing looks good as a direct import and the space is available, Why not continue to run the heat pump on solar pv and then just boost with the immersion?
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Re: Anyone else had a bill for the recent cold snap?

#19

Post by Joeboy »

Oldgreybeard wrote: Tue Dec 27, 2022 4:03 pm I guess for those lucky to have their own woodland that they can sustainably manage then the "bill" for energy from wood is free, but I'm not sure many are in that fortunate position, are they?
I dont do luck, i do fortune. I have no idea who is fortunate and who is not here or in which realm this falls whether it be in realm of river access, geography, house design, woodland access or a myriad of other variables.

It's not all easy to qualify or simplify at any point. I have no idea who trades what for which and its not always easy to quantify those secondary values. An example. I have a friend who has a forest. He can't be bothered with it so I fell trees, process and cart them off. In return for this I offer goods & services (meals, wine, labour, kindling etc to a minimum of twice the value of the felled trees). I do this to return what he offered me at no cost and free to take, the logs are purely a bonus. I am literally rewarding him for his selflessness. I write the cost off in my mind and thus the logs are 'free'. I also have other sources. As I said, not simple! :D

I won't extend the point but the same can be said for any fortunate circumstance. Hence best to stick to the bills in £'s I think? Otherwise we'd be trying to build a value into a fortunate Southerly aspect at 15 degrees, or is that more terroir? :?
Last edited by Joeboy on Tue Dec 27, 2022 6:25 pm, edited 1 time in total.
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Re: Anyone else had a bill for the recent cold snap?

#20

Post by Oldgreybeard »

openspaceman wrote: Tue Dec 27, 2022 5:30 pm
Stinsy wrote: Tue Dec 27, 2022 4:42 pm
I’ve looked at those. Bulky and expensive beasts. I get the attraction but a standard cylinder with an immersion, solar and a ToU tariff makes more sense. And: yes you can extract warm air from your house and expel cold air to outside.
Oh well I may stick with my vented tank and immersion, it is all we need for half the year. Problem is the 3ft immersion only has an 18" thermostat so only the top 18" gets fully hot.

Saving a total of £200 a year on not using gas doesn't justify much spending and even at a COP of 3 I would have to use electricity from the grid in winter to run the air to water heat pump.

OGB's pricing looks good as a direct import and the space is available, Why not continue to run the heat pump on solar pv and then just boost with the immersion?

To be honest, I couldn't make the sums add up either at the time, so initially I fitted a normal hot water cylinder and immersion. My thoughts have evolved over the years, though, and I had a sort of deep internal conflict about why I was doing the things I was trying to do. I started off on the low environmental impact thing decades ago with a fairly techie enthusiasm for ways to reduce both our energy use and to make what energy we did use less harmful to the planet, very much the whole renewable energy ethos, so did Hugh Piggott's course, and that led to meeting someone that was active on the "other place", which in turn led to an interest in solar, and that led to an interest in batteries.

At the same time, ever since a lucky chance over 30 years ago that led to a walk around Mole Manor, I was absolutely convinced that I wanted to build a low energy home. That started as a desire to have low running costs, then I realised that focussing on that just made me a selfish arse, and that if I really wanted to reduce the impact we have on our fragile planet there would be a cost involved, and I'd have to get away from the crazy, "let's get something for free and bugger the consequences" mindset and invest in making the planet a better place for our kids and grand kids.

That, sort of indirectly, led to me making a lot of changes, one of which was the decision to invest money in more efficient water heating, as well as investing in a better insulated house and a more airtight one, and investing in a more expensive heat recovery system and then, much later, investing in a small electric car. We have spent a lot of money that we won't get back, but what we have, I hope done, is play a miniscule part in making the planet more likely to be habitable for our descendants.

I can't put a price on that, or say what we've done has made any difference, but we have tried, and continue to try, as it seems to me that if we don't try to make our lives less dependent on resources that both aren't renewable and that harm the ecosystem we rely on, then as a species we are doomed. Heat pumps aren't the answer, but they are a way of using less non-renewable energy, and that's a tiny little step along what I think is the right path to take. Others may not agree, that's fine.

The real key thing for me, though, is trying hard to not be selfish, and do stuff because it's the right thing to do, not because it's cheap or gives me a buzz for having gamed the system somehow.
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