£2000 a quarter electricity bill

Coprolyte

Hi all,  I live in a bungalow (built 1980's, breezeblock, 200sq m) and my quarterly electricity bill Nov-Jan was £2000, don't have gas.   

We have underfloor heating and air source heat pump, fitted 10 yrs ago.  There are two people living here, we run a large freezer, american syle fridge freezer and fridge, fish tank and the computer is on most of the day.  Cooking is minimal, mainly microwave. All the lights are LED, standard loft insulation and I believe the walls are cavity insulated. 
There is occasional use of a dishwasher and washing machine.  The dishwasher always after 11.30pm

Since that bill I've taken some drastic measures and had the heating largely off all day and a lot of nights!   

Here are some consecutive days readings of units used, taken from the meter at 9am 20th March to 2nd April 2023.

1) Daytime 7.30am - 11.30pm  19  24  18  14  20  20  21  29  21  25  44  20  18  16        2) Nightime 11.30pm - 7.30am   8  12  13  14  11 10  8  18  15  17  24  15  15  24 

Do these readings for day time(1) and economy night time usage(2) seem reasonable and the variations normal?  The bill is still going to be coming in around £1200 a quarter as far as i can calculate.  I'm not very electrically savvy though so any comments or corrections would be appreciated.   

EssexHebridean

You look like you're borderline suitable for E7 at those use figures - have you done the maths on whether you'd be better off on single rate? And have you also checked whether there is a supplier whose day/night rates might suit you better based on how you use your electricity? 

Remember to make sure things like showers etc are dealt with on the off peak rate where possible - and also how is your water heated, standard immersion heater? If so then making sure that also runs on the off-peak will help with the figures too. 

markin

What was the usage and rates for Nov-Jan?

A heat pump works 24/7 but most of your power seems to be day time, The most efficient time to heat the hot water is the warmest part of the day 11am - 2pm

Mouldymeat3

Assuming the ASHP heats the water, is there an excessively long pasteuriation heater setting?

Is there an accelerator heater on the ASHP? 

matelodave

I'd have said that the last thing you need is E7 for a heatpump. We've got one and it uses most of its energy during the day/evening and least overnight when its turned down a bit. Even heating water with the HP overnight wouldn't justify E7.

You really need to sort out how the system is set up so you understand what is going on but TBH those readings aren't a million miles different to mine in terms of kwh consumption however how much are you paying for peak and off peak consumption.

add your day and night consumption figures together and multiply by 0.35 to get a rough idea of what a single rate tariff would cost you compared with what you are paying on the dual rate.

my monthly consumption over the past six months was 
oct = 499kwh cost at 0.35p,kw = £174.69
nov = 720 = £252
dec = 1149 = £402.15
jan = 1135 = £397.25
feb = 875 = £306.25
mar = 993 = £347.55

so just over £1700 plus the standing for six months.

My average annual consumption based on 13 years worth of weekly data is just under 7500kwh which at 0.35p comes to £2625 plus the standing charge

ours is 140m2 bungalow, underfloor heating, cavity wall insulated, 30 year old double glazing and 300+mm of insulation in the loft.

No fish tank, separate tall upright fridge and freezer, washing machine, tumble dryer (both used a couple of times a week), dishwasher(3-4 times a week) Two computers on a virtually all day, my 3D printer gets used quite a bit as does my wifes embroidery machine. cooking is done with an air fryer, microwave and induction hob with occasional use of the main oven. .

The heating runs virtually continuously from October through to April and has weather compensation turned on - we aren't cold.

Patrol

I don't think there is enough information to do more than provide general suggestions. It doesn't sound like you should have a particularly high use if the heat pump is hardly in use so I'd be checking each item individually to see if there is a culprit or at least to get an understanding of use

• Do you have a smart meter so you can see base load (trough) and peak use
• Does the heat pump record operating hours (my ground source does for both hot water and heating)
• Do you use a lot of hot water, and does the heat pump provide it
• Do you have a plug meter so you can check individual devices
• Do you have a tv, soundbar, stereos etc. No electric heaters, fan heater, hair dryer, power shower, external security lights?
• How efficient is your computer. They vary hugely and if under load could be using more than you think
• Are devices left on standby
• Is your fish tank tropical (heated). e.g. a 300w heater stuck on could easily be 1/3 to 1/4 of your daily consumption without you realising it
• If those daily figures are with the heat pump mostly off, how long is it on for
• Have you lived in the house for more than a year (consumption similar but unit cost e.g. tripled)
• Were the Nov and Jan start/end figures both from readings, or estimates

With a heat pump you will use a lot more electricity during that time. e.g. for my ground source pump I see about 1-2kWh a day during the hottest days and 15-20kWh a day during the coldest days. I think an air source pump may be even more pronounced than that. Also, I found counter-intuitively it was most efficient when left to run 24/7

Patrol

Oh, and what temperature was your house. The running cost between say 18c and 22c would be noticeable

Coprolyte

This is a lot of info to take in and questions to answer.  Thanks all for taking the time to reply

I have got the basic idea correct I hope – if I run a 2kw electric fire for an hour it’s 2x .45p so 90p an hour during the day.

EssexHebridean

Looks like it would cost more to go on a 24/7  35p rate on my calculations, see Matelodave comment.

The hot water is a big boiler heated by the air source heat pump, so that’s going to be hot 24/7

I did ask the guy who serviced the heat pump and he said they were quite efficient, he’s not the one who sold us it!

Markin

Not sure if I can time control the water heating part of the system to just go during the day

MouldyMeat3

I’d have to check the pasteurisation heating setting length

Matelodave

For March we used 705 during the day, 623 at night on 45p and 12p respectively which gives £317 and £75, total £392.  1328 at .35 gives £465.  As the day time figures are for 16 hours use and nightime 8 aren’t we using nearly twice as many units at night per hour than during the day.

I’m getting confused, is the above correct?

Patrol

Not got a smart meter, do you recommend them?

It doesn’t record operating hours, the system is 10 years old.

I’d say we use very little hot water. Two showers, the odd dish (mainly dishwasher a few times a week and always after 11.30pm).

I’ll try a plug in meter for the various items in use during the day.  The computer is around 4 yrs old and is mainly used for gaming so quite high on energy usage I imagine. 

We have two large tv setups with soundbars, sky etc which are always on standby if not being used.

Everything is on standby

The fish would be dead if the heater was on full time though no doubt the heaters are working harder as the house is colder now

The heat pump is hardly on at all to be honest and really not at all during the day, I’ve even been turning it off at the wall thermostats in each room on most nights.  As you might imagine the house is bloody cold, a lot of unused rooms at 12-16 others around 18 which is too cool to be comfortable but we can’t afford bills of 2k a quarter.  This is what worries me as I’m not going to benefit a whole lot when it gets warmer if the heating isn’t on much now anyway.

All figures from readings

I can’t seem to find a definitive answer on the timed as opposed to 24/7 debate

Spoonie_Turtle

Coprolyte said:
The heat pump is hardly on at all to be honest and really not at all during the day, I’ve even been turning it off at the wall thermostats in each room on most nights.  As you might imagine the house is bloody cold, a lot of unused rooms at 12-16 others around 18 which is too cool to be comfortable but we can’t afford bills of 2k a quarter.  This is what worries me as I’m not going to benefit a whole lot when it gets warmer if the heating isn’t on much now anyway.

This is why single rate is recommended with heat pumps, they need to be working during the day and you don't want them using expensive daytime electricity. 

The hot water should be set to 50℃ so the immersion doesn't need to kick in (unless for a legionnella cycle once a week, which you may or may not feel is necessary.  The risk is minimal, but whether you're prepared to take even a minimal risk is up to you and your family). 

You can set the times to make sure the hot water is only heated during a certain time, you'll have to find a video for your controller.  Night time is of course best if you're adamant at staying on dual rate, the loss of efficiency is outweighed by the lower cost of nighttime electricity.

What is the heat pump doing at night if it's on more then than in the day?  Is it kicking in for heating?  And/or circulating for frost protection?

Possibly the heat pump at night, along with your base load, the things that are always on standby and the things that are always on (pond pump) are what's making your bills high, to be honest.  Energy monitoring is your friend here.

Also lightbulbs - all LED, or do you have halogen spotlights?  Those tend to guzzle energy, especially when there are a lot of them.  They're nearly as bad as incandescent lights.  Btw I've reread your post and you say they are LED, but when I first came here I thought ours were all LED too, but then I looked more closely and it turns out a couple of room bulbs were halogen and most CFL.  We're slowly replacing the CFL as they die, but the halogen ones were replaced very quickly!

The American FF is likely a culprit too.

You really do need to do a full energy audit, find out how much every item and appliance uses, as far as possible, and work out what can be turned off, what can be replaced, to reduce your usage overall.  It's no good being cold when you're quite possibly spending money on other things that are less important (of course what is or isn't important will differ between households).

macman

Why did your original installer not advise you to switch to single rate when you had the ASHP installed? Did they even check what tariff you were on?
What you need to post is your annual kWh usage on each register. you can them easily do the maths to see what the comparative costs are on E7 vs single rate. One winter quarter is not sufficient, because that's when the heat pump will be working hardest.

markin

March is often getting warmer and nights getting warms and the split tends to move so could be misleading look at the Nov-Feb split, and annual for as many years as you can.

That energy use is not of a cold house, even the waste heat will be heating the house, not so good in the summer though.

Is the tank inside the home, or outside, if outside frost protection will use a lot of energy.


Is the underfloor heating all wet no electric anywhere? 

Underfloor heating has to heat up the slab first and is better on long times with low heat, 35c - 40c, Same with the heatpump, not used in short bursts like with a radiator Gas system.