High Electric Bills with new ASHP

Gerry1

deantrina said:

Gerry1 said:

Why have you chosen a needlessly expensive tariff with Bulb?

Is it absolutely impossible to get mains gas?

Happy to take suggestions on companies / tariffs to look into for when i get conclude 

Start comparing with Citizens Advice and 'Which? Switch', entering your annual kWh usage derived from actual meter readings a year apart.  Just compare annual costs, always ignore all projections and savings claims.

Also have a look at the customer service ratings on Citizens Advice and the 'Add your feedback on energy supplier xxxx....' threads here on the forum: Symbio are cheap but might not be the best choice !

Reed_Richards

I have a 12 kW LG heat pump.  The heat requirement assessed for my house is is 27722 kWh per year for space heating and 9855 kWh per year for hot water.  The latter assumes 45 litres of hot water used per day and the tank temperature being 50 C.  The former assumes that the outside temperature is is -3.7 C and the rooms are at standardised temperatures between 18 C for bedrooms and 22 C for bathrooms, the radiators run at 50 C flow and 45 C return.  I cannot find the total heat output from my radiators under these conditions but from memory it was about 10.5 kW.  So that's a 12 kW heat pump matched to a 10.5 kW radiator heat output when the outside temperature is -3.7 C.  I can give you more figures @deantrina but for starters see how these compare with yours.      

matelodave

All you need to know is the deltaT output spec of your radiator to be able to work out its heat output at lower temperatures

Have a look at this which shows you the conversion factor to apply when derating your rads from a nominal deltaT of 60degrees (although a lot of manufactures also give it at 50 nowadays to suit lower condensing boiler temperatures) down to your your delta T or approx 27.5 (room temp of 20 and rad temp of approx 47.5)

If you want to do the sums from first principles then have a look at this (you can use the calculator to do the hard work)
https://www.engineeringtoolbox.com/heat-emission-radiators-d_272.html

Reed_Richards

Some more figures for comparison:
In the 3 months since it was installed my heat pump has consumed 3881.5 kWh, an average of 43.5 kWh per day.  Since 21st February when I changed the flow water temperature from 50 C to 40 C the average has been 26.3 kWh per day.  I calculate that the average heat output of my old oil boiler was 59 kWh per day over the entire year.  For my heat pump to achieve a price match with oil I would need my yearly average to be about 20 kWh per day of electricity.  

matelodave

I cant accurately measure my heatpump consumption over long term a the clamp on energy monitor loses data when we have power cuts (of which there are quite a few, only short duration but it causes stuff like the router and data logger to drop out and reboot)

However,our total annual leccy consumption is around 7200kwh and, based on my summer consumption, we use approx half (3600kwh) on household stuff (cooking, washing machine, dryer, dishwasher, lighting etc) and half by the heatpump 3600kwh. In the summer it only uses about 2-3kwh a day to heat the hot water tank. However I'm guessing that this year we'll have used more than our average because winter has been a bit colder than the last couple of years (and we are getting a bit older and feeling the cold a bit more than we used to) Although that said, I did find that the thermostat in my wife's craft room had been "tweaked" and was set to 20 degrees 24/7 - its been reset back to it's normal 20 during the day and 18 overnight

Reed_Richards

matelodave said:

I cant accurately measure my heatpump consumption ...

You have clearly had it a while.  These days it is mandatory to meter your heat pump electricity consumption if you want to claim the RHI.  

matelodave

I've had mine  for ten years, the RHI came into effect in April 2014 and I got my first payment in July 2014. The last payment is due in April 2021. 
My RHI payments have totalled just over £5,000. My RHI is calculated on a "deemed" COP of 2.5 based on my EPC energy requirement - here is the calculation

Heat Pump (providing space and water heating):
Space heating: 12,565kWh
Water heating: 2,759kWh
Total heat demand: 15,324kWh
SPF: deemed 2.5 SPF calculation: (1-1/SPF), (1-1/2.5) = 0.6

Estimated annual renewable heat = 15,324 x 0.6 = 9,194kwh. I reckon my heatpump uses around 3500kwh a year which is about half of my total leccy consumption

Do you have to submit both your energy consumption and generated heat output. I assume that you've also got a heat meter. If so you can work out your actual COP by dividing your heat output by the electricity consumption

deantrina

matelodave said:

I've had mine  for ten years, the RHI came into effect in April 2014 and I got my first payment in July 2014. The last payment is due in April 2021. 
My RHI payments have totalled just over £5,000. My RHI is calculated on a "deemed" COP of 2.5 based on my EPC energy requirement - here is the calculation

Heat Pump (providing space and water heating):
Space heating: 12,565kWh
Water heating: 2,759kWh
Total heat demand: 15,324kWh
SPF: deemed 2.5 SPF calculation: (1-1/SPF), (1-1/2.5) = 0.6

Estimated annual renewable heat = 15,324 x 0.6 = 9,194kwh

Do you have to submit both your energy consumption and generated heat output. I assume that you've also got a heat meter. If so you can work out your actual COP by dividing your heat output by the electricity consumption

I cab see a definate drop in £££ now i have made some tweaks like turning the stats temps down, using the wake up , stop , restart & go to sleep settings . When i got in tonight reading was £4.40 instead of £7.50 ( Mrs & girl home all day) but that is probably partly due to sunny day hitting the PV panels as well . I think i will get a sprraed sheet up & runing to monitor a few things each day & can then look back over a period of time . Have now sent of the ref numbers & await the voucher so as thats £5k off my install bill. Have just applied for the feedback tarrif with Bulb ,will get that up & running then reseacrh who i will be swapping to. Now need to apply for the RHI .

matelodave

The more data you collect the better you'll understand how it works and how tweaks affect your consumption and comfort. Gald to see that you are seeing some improvements

Reed_Richards

matelodave said:

Do you have to submit both your energy consumption and generated heat output. I assume that you've also got a heat meter. If so you can work out your actual COP by dividing your heat output by the electricity consumption

Neither.  I do not have a heat meter.  My RHI payments are calculated the same way as yours, except that my COP is about 3.  Heat meters are only required in some exceptional circumstances.  The meter for electricity consumption must be required so you know how much of your electricity bill the heat pump is responsible for.  That's important in cases like this where the user finds their bill is too high.