@alfapat So thats a big bill! I cant help thinking that given the insulation you describe, you should be doing a lot better. Can you find your supposed heat loss calculation which i imagine should be for about the outside air temperature you had last night.

Do you know if you have a buffer vessel installed?

@bontwoody So , I would not know how to calculate that, please enlighten me .

Thete is a Tank beside s the dhw , I dont think its Buffer. I will take a picture.

 second pic shows flow setting for line pumps

@alfapat So you should have been given the heat loss calculation when you had the heat pump installed. It has to be done by the installer.

I think the smaller tank might be a buffer. Does it have four pipes going to it? They are popular with installers but there is a hit to performance if it is.

See if you can find the original documentation that you were (hopefully) given when it was fitted. Do you have an EPC? That would give an idea.

Reading back I just saw your comment about my blog. The link is below my messages

https://thegreeningofrosecottage.weebly.com/

Large tank is DHW, I think this is the info you are looking for , bear in mind I have added suspended

underfloor insulation.

@alfapat Thats the document! unfortunately I cant read it from the images, they are probably compressed for the forum. I will pm you my email address, just attch the original photos and they should come through more clearly.

Isnt the big tank your DHW? I was looking at the smaller one.

Yes mentioned that its the larger tank is DHW . I should add in the report that originally the design called for a 9kw and a 16kw . WHEN THE COMPANY abandoned me as the installer , I could not get any warranty on the pumps. as they did not service them . I did manage once to get this done bearing in mind 7 yrs ago and since found a local company that disapproved of the latout and dismissed the smaller pump and since sold it , then installed larger pipes into the house and of course charged me more for this , NIGHTMARE !

Then turned round and could not fix my my problem claiming They were not formiliar with Samsung ...,WHAT !!! I finally found an electrician that rewired the control of valves whgich were not set up right and it now looks like it needs fine tuning !

Iwill email .

@alfapat Sorry, missed the (large) tank comment 🙂

OK if the original install was for 25 kW then the 16 kW alone probably isnt oversized, but it suggests you have a very large house? Can you provide a description, bedrooms and total rooms etc. The energy use will have to be considered in conjunction with that. Do you have previous gas/oil usage costs?

I will wait for the email.

@alfapat OK. thanks for the information. It looks like your system was designed to run at 50C when at -4C outside.

The yearly electricity use for space heating is estimated at 31387 kWh and the SCOP is 2.7. that means you should be using 31387/2.7 = 11624 kWh of electricity for heating. At standard unit rate of 27p per kWh thats £3138 per year or £261 per month approx. Does that sound like what you are paying?

This amount will be heavily skewed towards the winter.

That limits your options in trying to improve things, I think the second company were right to increase pipe diameter and lose the smaller Heat pump. If the 16kW model is keeping you warm enough thats fine.

In order to improve your electricity bill, you can reduce heat loss (add insulation/stop draughts), increase the size of some radiators (probably in the room you like warmest) and try to leverage cheap electricity by solar/battery/tariff.

Depending on your house and heating system, you might be able to remove the buffer cylinder which would increase efficiency. Do you have power cuts often?

no , sorry no original costs asImoved into the house in the summerto a   design incorperating a wood burning stove and primarily an oil fired central heating boiler, linked to each other in a rather unorthordoxed system.

I think I may have found original project requirements.I will email

@bontwoody No Powercuts are not often. Do you think the buffer takes up to much energy storage wise or does it help to maintain a heat flow.

@alfapat so buffer tanks act as a big roundabout for the water. Flow comes in from the heat pump and back and water goes to the heating circuit and back. The waters mix in the tank. This lowers the flow temp to the heating circuit and so the heat pump has to run hotter to compensate.

Installers like them because the heat pump has an excellent flow rate, without having to push water around the heating circuit.

I asked about power cuts because replacing water and antifreeze with just water improves the efficiency of heat transfer. The heat pump can manage freezing temperatures as long as it has power.

If you bills are that high, it means some major work would be cost effective in the short/medium term.

The system I have in place seems  to be adequate , other than tweeks with flow temp. Perhaps the tank can be taken out of the circuit then also . Many things to think about …. as usual !