A2W Heat Pump - High Bill

AnswerIs42

I was wondering if someone could confirm if my bill is as what you would expect for this time of the year. This is our first winter with the HP so maybe it is normal.

The bill is for 2 months from early December to early Feb. It says the house used 2900 units which has cost €580.

The bill from October -> December was only €130 euro with 655 units used.

Obviously December -> Feb is colder meaning the HP works harder but nearly 5 times harder?

The house is 200 square meters with UFH downstairs and rads upstairs all working of the 9kwh A2W heat pump. 2 adults and a baby living here. Downstairs is zoned and controlled via thermostat that never has it's temp changed. (Set to 20 C)

I wondering if there is a setting on the HP that I should change to help tackle the bill? Or maybe this is normal usage for winter?

Thanks for any help

antoinolachtnai

The first thing you need to do is read the meter.

read it today and read it again every day or so for the next seven days (which are likely to be cold enough. That will give you a clear idea of what is actually going on. (Easiest way is to take a photo of the meter.)

And then check whether the meter was read or just estimated in early December.

Meters are read three or four times a year. My suspicion is that your meter was read only once, in february.

There is a thing that is used to compare weather conditions called 'heating degree days'. It is a bit of a palaver but basically it gives you an estimate of how much heating is required in one time period compared to another time period by looking at the temperatures. Using this method and a temperature of 15.5, the degree days for the last year were:

Month starting HDD
2019-02-01 224
2019-03-01 254
2019-04-01 218
2019-05-01 157
2019-06-01 96
2019-07-01 33
2019-08-01 36
2019-09-01 79
2019-10-01 192
2019-11-01 274
2019-12-01 288
2020-01-01 281

So, according to the theory, December would take 50 percent more heat than October to keep the house comfy.

Now, depending on what reference temperature you use, you will get very different heating degree days tables, so take it all with a pinch of salt.

We would expect a typical household to use 4300 units or so over a year, so 700 units every two month period on average, excluding heating.

If your house were heated with oil, you likely would have bought a tank of oil by now, which would have cost you 620 euros. So I don't think you are too badly off for keeping a 200 sq m house at 20 C.

There might be value in you getting a night saver meter but wait until you have some meter readings to see where you are.

Your heat pump might have some built in monitoring, or it might not. You need to look at the manual. You could put a separate submeter (your own private electricity meter basically) on it to monitor its consumption, if you were worried about it.

AnswerIs42

antoinolachtnai wrote: »

The first thing you need to do is read the meter.

read it today and read it again every day or so for the next seven days (which are likely to be cold enough. That will give you a clear idea of what is actually going on. (Easiest way is to take a photo of the meter.)

And then check whether the meter was read or just estimated in early December.

Meters are read three or four times a year. My suspicion is that your meter was read only once, in february.

There is a thing that is used to compare weather conditions called 'heating degree days'. It is a bit of a palaver but basically it gives you an estimate of how much heating is required in one time period compared to another time period by looking at the temperatures. Using this method and a temperature of 15.5, the degree days for the last year were:

Month starting HDD
2019-02-01 224
2019-03-01 254
2019-04-01 218
2019-05-01 157
2019-06-01 96
2019-07-01 33
2019-08-01 36
2019-09-01 79
2019-10-01 192
2019-11-01 274
2019-12-01 288
2020-01-01 281

So, according to the theory, December would take 50 percent more heat than October to keep the house comfy.

Now, depending on what reference temperature you use, you will get very different heating degree days tables, so take it all with a pinch of salt.

We would expect a typical household to use 4300 units or so over a year, so 700 units every two month period on average, excluding heating.

If your house were heated with oil, you likely would have bought a tank of oil by now, which would have cost you 620 euros. So I don't think you are too badly off for keeping a 200 sq m house at 20 C.

There might be value in you getting a night saver meter but wait until you have some meter readings to see where you are.

Your heat pump might have some built in monitoring, or it might not. You need to look at the manual. You could put a separate submitter (your own private electricity meter basically) on it to monitor its consumption, if you were worried about it.

Hi antoinolachtnai,

You are correct that the reading in December was an estimate and the one in Feb was an actual reading.

I'll take a reading each day over the next week and see how many units I'm using each day.

It's a samsung HP and I'm not sure if they have a monitoring system but I'll have a look through the manual and see what it says.

Thanks for the pointers

0lddog

Also, you. May be paying ( a lot ) more for your 'leccy than you need.
1 look at getting a day / night meter
2 compare your supplier charges with other suppliers ( use bonkers.ie or similar )

AnswerIs42

0lddog wrote: »

Also, you. May be paying ( a lot ) more for your 'leccy than you need.
1 look at getting a day / night meter
2 compare your supplier charges with other suppliers ( use bonkers.ie or similar )

Thanks for the advice 0ldday

1. A day/night meter may the way to go. Its worth considering. I'll try and take readings at 11 pm and 7am each day for the next week to see if it would work.
2. I'm paying 14.99 cent so according to bonkers, that's a good rate so not sure there is any improvement to be made there.

0lddog

AnswerIs42 wrote: »

..... It says the house used 2900 units which has cost €580.....

Suggest an effective rate of 20c/unit incl standing charges ?

AnswerIs42 wrote: »

.. I'm paying 14.99 cent so according to bonkers, that's a good rate so not sure there is any improvement to be made there.

Yes, seems like a good rate. Any idea how they manage to run that basic rate up to 20c/unit ? ( bit of a puzzle to me )

( BTW in winter months night rate charging starts at 23:00 hrs and finishes at 08:00hrs )

AnswerIs42

0lddog wrote: »

Suggest an effective rate of 20c/unit incl standing charges ?



Yes, seems like a good rate. Any idea how they manage to run that basic rate up to 20c/unit ? ( bit of a puzzle to me )

( BTW in winter months night rate charging starts at 23:00 hrs and finishes at 08:00hrs )

Correct, it's 19.98 cent to get the €580 but then they apply a discount to bring it down to the €500 mark or so. It says on the bill that this translate to 14.99 cent

0lddog

AnswerIs42 wrote: »

Correct, it's 19.98 cent to get the €580 but then they apply a discount to bring it down to the €500 mark or so......

Puzzle solved

AnswerIs42

I mapped out the readings over the last few days to get an average of how many units I am consuming. I tried to take the readings at the roughly same time but life got in the way so this is what I ended up with.

On average I take 46 minutes to consume 1 unit.

I'm not sure if this is good or bad so I guess my question is would anybody know if that average is a good return or if it may point to a problem?

Date/Time|Reading|Time diff between reading|Time diff in minutes|Unit difference|1 unit every x minutes
14/02/20 18:06|9136||||
14/02/20 23:36|9142|05:30|330|6|55
15/02/20 06:57|9154|07:21|441|12|36.75
15/02/20 19:45|9170|12:48|768|16|48
15/02/20 23:29|9175|03:44|224|5|44.8
16/02/20 09:16|9188|09:47|587|13|45.1538461538462
16/02/20 22:34|9209|13:18|798|21|38
17/02/20 07:13|9221|08:39|519|12|43.25
17/02/20 17:03|9230|09:50|590|9|65.5555555555556
18/02/20 07:22|9254|14:19|859|24|35.7916666666667
18/02/20 16:54|9266|09:32|572|12|47.6666666666667

John.G

Don't know if this includes water heating but even if it doesn't maybe not too bad?.
You are consuming ~ 1.3 kw/hr so assuming a few different COPs then a COP of 3 means you require 3.9 kw/hr to heat your house, a COP of 3.5 = 4.6 kw/hr and a COP of 4 = 5.2 kw/hr.

AnswerIs42

It does include hot water.

Excuse my ignorance but what does COP mean?

John.G

COP means coefficient of performance, if you have a COP of 3, it means that for every 1 kw of compressor power that you extract 2 kw ("free") from the air by extracting heat from it by lowering its temperature, add this to the 1 kw compressor power (as heat) and you get the COP of 3. It can be higher or lower than this depending on ambient temperatures and the compressor discharge temperature (the lower the better).

0lddog

Are the readings from some display on the heat pump or are they from the ESB meter ?

( If ESB meter then they include things like fridge, freezer, alarm, entertainment....do you have an electric cooker ? .... etc )

AnswerIs42

They are ESB readings so yes they would be for the whole house. The house is a standard enough house, all the kitchen appliances are new with at least A rating.

Looking at the data, I'm averaging 32 units a day which seems high from what little knowledge I have.

From the sounds of it, there is no problem with the HP anyway so I guess I'll look into measuring the power consumption of other items in the house and see if I can lock it down to something else.

Thanks for the help

antoinolachtnai

AnswerIs42 wrote: »

They are ESB readings so yes they would be for the whole house. The house is a standard enough house, all the kitchen appliances are new with at least A rating.

Looking at the data, I'm averaging 32 units a day which seems high from what little knowledge I have.

From the sounds of it, there is no problem with the HP anyway so I guess I'll look into measuring the power consumption of other items in the house and see if I can lock it down to something else.

Thanks for the help

Well 12 per day would be normal without heating.

So 20 for heating. 3 or 4 euros a day on cold days. It’s not terrible for a house that size.

0lddog

AnswerIs42 wrote: »

...
From the sounds of it, there is no problem with the HP anyway .....

antoinolachtnai wrote: »

.... 3 or 4 euros a day on cold days. It’s not terrible for a house that size.

Yup, thats how it appears to me too


If your consumption of electricity was even over a 24 hour period then I think a night meter would save you around 80c per day at this time of year ( winter ) .... less in summer

antoinolachtnai

0lddog wrote: »

Yup, thats how it appears to me too


If your consumption of electricity was even over a 24 hour period then I think a night meter would save you around 80c per day at this time of year ( winter ) .... less in summer

Yep and if you knocked the unit off at 5 or 6 pm and relied on the heat stored in the floor for that period and then turned it on again at midnight to charge the system up again with heat overnight you might save even more.

Muise

You should definitely be on nightsaver electricity. 1/2 price per unit.
Thinking of going for underfloor heating Air to water would you recommend?

AnswerIs42

Yes I would. I think the UFH is great by itself and the HP has worked well for us.

The service is 180 euro a year for the system which I think is reasonable enough and if i can get solar panels installed, the house will be in a good place going forward.

ColemanY2K

AnswerIs42 wrote: »

Yes I would. I think the UFH is great by itself and the HP has worked well for us.

The service is 180 euro a year for the system which I think is reasonable enough and if i can get solar panels installed, the house will be in a good place going forward.

PV combined with a battery and you'll cut your bill significantly. At present the government is drafting legislation which will do away with the 12 square metre PV limit. It should be signed into law by the end of the year. A 5KW array facing south along with a battery (either on roof or garden) would cut the average family bill to next to nothing. A big outlay but big reward.

In addition a feed in tariff is finally about to be introduce although word is the rate will be paltry.