Yes I too am Finding a huge electricity bill and with a new installation.  And this is with a warmish autumn.  Tonight it’s -1 and the ASHP is working overtime.  I’m terrified to look at the meter. 

Your system should be set up so that it operates at the lowest flow temperature but as the weather gets colder this temperature increases. 

Does your property have the correct  amount of insulation? If your  rooms are not warm enough it’s likely that the insulation could be improved.

my instinct is to turn the temperature down at night but I’ve been told not too.

will be interested in what those who have more experience say.

That does seem high levels of usage. To compare, we used about 50kwh on 28th Nov (yesterday) - which is c. £12 in money too - but we are heating a 6 bed, 3 storey house at c. 21degrees.

We find that it is most cost effective to ignore the individual room thermostats (set them to something like 25 degrees so that they are constantly calling for heat) and then rely upon the ASHP controller to manage the house temperature. Ironically, it runs more efficiently heating the whole house to the same temperature than just some rooms.

What make of ASHP do you have?

@littlered 

Hi and welcome to the forum.  We have a 4 bed bungalow build in 1990, with an ASHP and radiators.  In theory, yours (2 bed, new, ufh) should be cheaper to heat. Yesterday was our most expensive heating day this year at 44.4kWh/£9.  The house was warm throughout at 21-22C.  We currently have the heating on 24 hrs.

You should be able to do better than £12; ASHPs all work the same way and Daikin is a good make.  Is that £12 for just the ASHP or everything? Can you see how much energy (kWh) your ASHP uses for heating and hot water?

Unfortunately you won't get better than 21p/kWh for now.

Kev

@hjd Can you explain what the ASHP controller is? We have been told that we only need to control our heating by the thermostats. I think maybe turning them down and up is causing our over usage? Should we be leaving the thermostats on at a constant temperature 24 hours a day?

@mikefitz We turned our thermostats down in the main rooms but now think we might experiment and leave them on. What constant temperature do you think it is best to leave them at and do you leave them at the same in all rooms?

@derek-m Thanks for all the replies so far. It is a Daikin Altherma 3M. The bungalow has 2 average sized bedrooms, an en-suite shower room, bathroom, a living room, kithchen/diner which is partly a sun room (solid roof, not glass, but glass walls), wide hall and a garage. It is brand new, only lived here a month and we are at the mercy of the developer's information which is limited. We understand it has all been installed to Daikin's approval with sufficient insulation - not sure what that means. The loft looks very well insulated - much deeper than any we have seen before, but not sure what goes in the walls. There are no radiators, just all under floor. Each room as its own thermostat.

We were told not to turn the thermostats down more than 4 degrees at the 'comfort temperature', so during day 20-21, then in the evening, we turn the main two rooms down to 15-16. The bedrooms and bathrooms, we keep at around 16. We tried leaving the thermostats on in most rooms overnight at 18, but it was very expensive, and we lowered them to 14 in main rooms and that took an age to heat up and was very expensive. 

What we are hoping to find out is which is the best, that is cheapest, way to maintain a comfortable level of heat, is it by leaving the thermostats permanently set at around 20 (which is a temperature that suits us) or lowering them overnight. 

This morning I got up around 4.30am to check and in the main rooms where we had lowered the temperature to 14, the thermostats indicated the heating was on and now at almost 9am, they are still only at 15, which makes us think we should have left them higher, but how high, or is this the right way is what we are trying to establish.

@kev-m Hi, yesterday somehow we used 60 kw. We did not feel warm either. Do you find it cheaper to leave the thermostats on overnight and if so at what temperature do you set it overnight? Do you lower the heat output overnight or is it best to leave it? We are currently lowering it but finding it takes an age to heat up. Looking for the cheapest solution really. Our smart meter only shows the total KW usage.

@littlered below are the codes you need to access the units settings

Looks like this should be your controller

This is the user guide - HERE

This is the installer guide - HERE - Page 28 onwards talks about the controller settings

@littlered,

as @batalto said on the other thread, you may not be using the system the best way.  ASHPs are like cars; they are most efficient when pootling along at a moderate pace.  A lot of heating up/cooling down will make them less efficient.  But it's a bit of a balancing act because when it's not running, the ASHP uses no power at all. 

Because you have underfloor heating (ufh) and, I assume, concrete floors, it will take a long time to heat your house up.  It's probably best to keep the house at the lowest constant temperature you are happy with during the day and dial it down a bit at night - 2 or 3 degrees.

The other point that @batalto is getting at is that it also works much more efficiently at lower flow temperatures.  So, you need to find out what flow temperatures it's set at.  Weather compensation is just the term used to describe how the ASHP varies the flow temperature according to how cold it is outside.  Using it is usually the most efficient way of running an ASHP.  You will need to have a look at your controller using the links @batalto posted.

It really is poor that the developer didn't tell you more.  But then they probably don't know know any more than you about ASHPs.

Posted by: @littlered

Hi, just moved into a brand new 2 bedroom bungalow with a Daikin ASHP and am shocked at how expensive it has been costing so far. We have been in a month and today we used £12.50 in a single day and were not even warm. Each room is thermostatically controlled and it is all under floor. We do not know what temperature it is best to turn it all down to overnight or if we need to keep it a set temperature all the time so any advice appreciated. We are with Eon and the tariff is 21p per kw and according to moneysavingexpert this is the cheapest rate we can currently get. We have just retired and on a fixed budget so were not expecting such high fuel bills. So just looking for expertise on how best to use it most efficiently please.

From my own personal experience (although I am no expert) I found that with the two options:

1. Lowering the room temps at night and raising them in the evening.

2. Maintaining a constant room temp 24 hours.

They will both use around the same amount of energy, but the latter gives you a much more comfortable environment.

Having said that, this situation might change depending on your properties construction and heating system, (i.e.thermal mass of UFH for example).

As you are retired and potentially someone is going to be at home all day, option 2 would probably suit you better.

I and other ASHP owners have found that using the weather compensation curve gets the most efficiency out of the system, but setting this up does require some tinkering over a period of time.

It's an unfortunate truth that a mains gas boiler is far cheaper to run than any ASHP. Currently mains gas is approx 4p/kWh and electricity is 20p. This means the ASHP would need to run with a COP of at least 5 in order to be comparible. Currently at 2.4ºC outside I'm getting 3.3 COP and the colder it gets the lower the COP goes and the more electricity the ASHP needs to use.

@littlered 

Hi LittleRed,

For the time being, I suggest that you set your thermostats at 20C during the day and maybe 19C or 18C at the lowest overnight, whilst we get you conversant with the controls of your ASHP.

You should have received the manuals for your ASHP in the handover package when you purchased your bungalow, so if you do not have these then chase the developer. Also ask for a copy of the heat loss calculations, on which the size of your heat pump was selected. You should also ensure that you get copies of the manuals for all the other equipment that has been installed within your heating system.

For us to be able to help you in the most efficient manner, we need to know how familiar you are with modern technology and how to make adjustments where necessary. If you are not tech savvy, then it may be best for you to go to the developer and inform them that your ASHP has not been correctly commissioned and that you wish it to be set for weather dependent operation.

If possible, please download the following manual and read section 11 Configuration from page 123. Then let us know what you understand and don't understand.

EBLA09-163V3(3W1,V3,W1),EDLA09-16DV3(3W1,V3,W1)_4PEN620241-1_Installer reference guide_English

To proceed further we will need to know the kW size of your ASHP and the floor size of your bungalow in square metres or square feet.

A list of all the thermostats or controllers detailing manufacturer and model number would be useful.

@batalto Thank you. All our new neighbours are having similar issues, so will share all the advice I get here with them. One of them seems to think the water flow is too low? Although on here, someone has just said it should be low. We have contacted the developer for more help.