I bought a Heat Pump

Mstty

akwexavante said:

My Daikin ashp has started to work harder this last few days and overall I'm very happy. Small two bedroomed house, cavity wall insulated etc. I'm happy with 16 degrees overnight and 18 during the day. I fire up a multifuel stove between 6pm and 9pm. I'm completely electric for everything otherwise. 

Before the cold snap I was using £2 to £2.50 (10 to 13kwh) a day at 17p kwh. I'm now using £4.20 to £4.60 (22 to 24kwh) a day.

My only minor issue would be that since the cold snap began the pump is much louder and I can hear it through the wall. A minor annoyance that's not keeping me awake at night though. 

My brother who lives 2 miles away tells me he's using £19 a day in gas and electric with heating set at 18 degrees 24/7. He's on the current capped rate. 

Still getting used to the idea that it takes an hour to an hour and a half to increase room temp from 16 to 18 degrees. 

I would agree with the noise certain times you cannot stop hearing it.

Ours is on the same wall as our upstairs master bedroom so can be a little irritating at times but apparently my snoring drowns it out.

Mstty

Reed_Richards said:

Mstty said:

That is an absolutely ridiculous figure.

It's ridiculous in terms of current electricity prices, yes, but it's really not so terrible in the context of my house.  We are all different and we all have different dwellings of different sizes and different levels of insulation in different locations.    

I think with that usage you could do better on your settings? 

If you are happy then leave it, if not some fettling could bring a good reduction.

Reed_Richards

I'm not really sure whet settings I could adjust.  I'm very close to the bottom end of my weather compensation line so I could turn that off and it would not make much difference.  I've been experimenting with the AI-1 setting which drops the line by a degree but I raise the temperature of my house gradually during the day and small increases are now taking several hours, indicating that there isn't much room for improvement.

I have a hot water recirculation loop which runs in the loft.  The pipes are very well insulated but it is a bit of a luxury to have hot water come promptly out of the taps.  I could turn that off for a day and see how much it saves me but it's a luxury I'm prepared to pay for.

I also have a few uninsulated heating pipes in the loft following some re-plumbing done in the spring.  I've been waiting for the dark days of winter to insulate these pipes, unfortunately those dark days have come in tandem with this unusually cold weather.  It's pretty cold now, working in the loft, but I suppose that's a good thing.     

shinytop

Reed_Richards said:

My heat pump was installed with a dedicated electricity meter so I know exactly how much power it consumes.  Yesterday the outside temperature (that I saw) varied between - 5 and -1 C.  My heat pump consumed 65.8 kWh in 24 hours, that's the largest 24 hour number I have ever seen (I don't read the meter every day, however).  Still that's less than 3kW on average for the whole house and my hot water.  And the house was nice and warm, about 20 C daytime average temperature.

12/12/22 - 51 kWh here for heating and HW. Also my record. 21 deg throughout the house. Average outside temp was -1.5 deg throughout the 24 hours. 
  
I'm happy enough with that.

Reed_Richards

I've just realised that I passed the 2-year anniversary of getting the heat pump.  My average consumption per year has been 5977 kWh of electricity.

The best comparison I can make is that my old oil boiler used 1936 litres of oil in 367 days.  That would equate to 20,032 kWh of heat if my boiler was 100% efficient.  It was a condensing boiler from 2012 so I don't know exactly what a realistic efficiency figure would be.      

Rodders53

Reed_Richards said:

I've just realised that I passed the 2-year anniversary of getting the heat pump.  My average consumption per year has been 5977 kWh of electricity.

The best comparison I can make is that my old oil boiler used 1936 litres of oil in 367 days.  That would equate to 20,032 kWh of heat if my boiler was 100% efficient.  It was a condensing boiler from 2012 so I don't know exactly what a realistic efficiency figure would be.      

You'd not be far wrong with 90% as an estimate as I doubt most oil boilers condense all the time.  Or just 18 MWh as near as makes no difference... cf 6 MWh per annum on the heat pump...  COP of 3 - rather impressive.

My circa 2006 Grant Vortex 15/26 has a claimed SEDBUK efficiency of 95% = 19 MWh and a COP of 3.17 if you would prefer the bigger number?

Today's oil price is 87-90p per litre in my area and SVT is 33.39p/kWh (both plus vat).  So oil is cheaper. but not so 'green'.

70sbudgie

It was -8 here this morning and dropped back down to -6 when I got home from work. What is your COP like in this cold weather? Is it still >1?

Reed_Richards

I don't know what my current COP is, I have no way of measuring the heat output.  However I doubt that three electric heaters at 1 kW each and distributed around my house would have been sufficient to keep it warm.

Yesterday I used only 54.8 kWh, that's 11 kWh less than the previous day without my noticing that it was significantly warmer.  I cannot account for this.   

Mstty

Reed_Richards said:

I'm not really sure whet settings I could adjust.  I'm very close to the bottom end of my weather compensation line so I could turn that off and it would not make much difference.  I've been experimenting with the AI-1 setting which drops the line by a degree but I raise the temperature of my house gradually during the day and small increases are now taking several hours, indicating that there isn't much room for improvement.

I have a hot water recirculation loop which runs in the loft.  The pipes are very well insulated but it is a bit of a luxury to have hot water come promptly out of the taps.  I could turn that off for a day and see how much it saves me but it's a luxury I'm prepared to pay for.

I also have a few uninsulated heating pipes in the loft following some re-plumbing done in the spring.  I've been waiting for the dark days of winter to insulate these pipes, unfortunately those dark days have come in tandem with this unusually cold weather.  It's pretty cold now, working in the loft, but I suppose that's a good thing.     

Every house and location is different as you say.

Just wondering if your auxillary electric heater is kicking in at the higher end of the temperatures you run. Little adjustments that don't make much difference to the house temperature or hot water temp but could shave off a few hundred kWh.

This is the fine tuning stage we are now at and it does make a difference.

Having this sustained -5oC over night and rarely getting to 0oC during the day has allowed for some good tests.

Reed_Richards

Mstty said:

Just wondering if your auxillary electric heater is kicking in at the higher end of the temperatures you run. 

I'm pretty sure I don't have an auxiliary electric heater.  My buffer tank has an immersion heater fitted but it has no electricity supply.  I'm not aware that there is anything inside the heat pump either.