@littlered Looks like your model is a 9kW unit - EDLA09DA3V3 

https://www.daikin.eu/en_us/products/edla09-16d3v3.table.html

@littlered 

Hi LittleRed,

Thanks for the photo's, they are excellent. It would appear that you have a 9kW ASHP, which is what I would have expected for a property of the size of yours, in fact a smaller sized heat pump would probably have been adequate.

How much snow do you normally get in your area? If you get a large quantity of snow then they should have raised the ASHP up from ground level and also installed a snow shield above.

I suspect that your ASHP is badly sited, in that it is at the side of your home in a fairly enclosed area. ASHP's need as much area around them as possible, particularly at the front and the sides.

Let me explain. As the name implies, an ASHP extracts energy from the outside air, and in the Winter requires a great deal of air to extract sufficient energy to keep your home warm. So the outside unit draws in air at the rear and one side, and pushes the air out at the front after extracting some of the heat energy. The air coming out at the front is therefore colder than the ambient air temperature. If the ASHP is located within an enclosed area, some of this colder air can be drawn back into the ASHP, but because it has already had some of its heat energy extracted, it has less heat energy to supply, so the heat pump has to work harder. As you will no doubt realise, this is now a vicious circle, the air coming out gets colder, which in turn means that the air going in is now colder, so the heat pump has to work harder and harder, and costs a kings ransom to run.

It is easy to check if this is the case. Obviously carry out the test with the ASHP running.

If you or one of your neighbours has a thermometer, measure the ambient air temperature well away from your ASHP, then measure the air temperature at the rear of your ASHP. If you find that there is a large difference between the two readings, then it would appear that your ASHP has been incorrectly sited, and will struggle to operate in an efficient manner.

Are your neighbours heat pumps located in a similar position?

@derek-m Installation manual page 8 tells the story. I'd say there is a pretty strong case of going back to the developer to move this ASHP as its been put in a poor location.

@derek-m Thanks, yes all the bungalows have pumps sited down the side of the house. I will check out the snow cover option.

Not sure these Daikin links work.  This is from the Installer Rererence guide.  

Thanks to everyone who has contributed to trying to help me so far. Just had the developers in and they have changed the thermostat settings for day and night comfort levels, checked the settings in the loft and informed us that we would only need a snow cover if on higher ground as where we are is not subject to snow drifts. They said the siting of it is fine too, that this has been checked and approved by Daikin. We are now going to give it a week on the new settings and monitor our usage with our neighbours. It is such a new technology, quite hard to take in that it is less efficient when most needed on days like we have all had this week. Illogical to have a system that is less efficient when needed the most and not sure on my current experience that unless I was eco crazy I would opt for one over gas.

@littlered what are the settings?!? and how would you go about changing them? Have they shown you?

@batalto They have shown us how to set the heating on and off and at what temperatures (to suit our needs) on the individual thermostatic controls in each room. They checked the pipes and the unit in the loft and said we did not need to touch them, so we are following their guidance and testing out the settings they have recommended for us. It will be set to 20 during the day coming on at 7 and overnight at 16. Cost wise we just have to accept that the unit cost is affecting our overall costs right now. They said we do not need a snow cover as we are not in a high snowfall or snowdrift area, and that there is sufficient air flow around the unit, all recommended by Daikin. We have to follow what they say as we are not experts on this system at all and have no desire to be adjusting water flows or monitoring graphs. Only time will tell.

Posted by: @littlered

Thanks to everyone who has contributed to trying to help me so far. Just had the developers in and they have changed the thermostat settings for day and night comfort levels, checked the settings in the loft and informed us that we would only need a snow cover if on higher ground as where we are is not subject to snow drifts. They said the siting of it is fine too, that this has been checked and approved by Daikin. We are now going to give it a week on the new settings and monitor our usage with our neighbours. It is such a new technology, quite hard to take in that it is less efficient when most needed on days like we have all had this week. Illogical to have a system that is less efficient when needed the most and not sure on my current experience that unless I was eco crazy I would opt for one over gas.

Hi LittleRed,

Of course your developer is going to say that the heat pump is correctly sited, it will cost time and money to have them all moved. On one of the photo's, did I see ice on the heat exchanger fins?

I'm afraid changing a few settings on the thermostats is not going to resolve your problems. Ask your developer for the heat loss calculations for your home, and the name of the person at Daikin who approved the siting of your ASHP.

I live in the vale of York and remember having snow drifts in the past, and I think that you are more likely to get them than me.

If you carry out the temperature test that I suggested, it will soon prove whether or not your heat pump is incorrectly sited.

@derek-m Ok, we are going to follow their instructions for a week and with several neighbours are monitoring the situation. We have made a note of what you have said and are compiling a list of questions for the developer as we cannot trust them entirely as you rightly note, they would say that.

@littlered from what you've said you aren't going to save much money at all. They've adjusted the thermostats, not the heat pump water temperature settings <- this is what you need to adjust. What costs is bringing the heating hot water up to temperature and this is exponentially more expensive the higher the water flow temperature is - especially when its colder outside and the air contains less heat. Its important to remember a gas boiler works at 75 degrees, punches out a load of heat and turns off. An ASHP can't get that hot (or shouldn't as its ruinously expensive). So you want to run it more often at a low temperature. From what you've said you'll get lots of expensive cycling in the day, as the unit heats up the house again. Then you'll lose that heat at night, so the unit will have to work hard again in the morning. You have UFH, so you should be able to have the most cost efficiently heating flow temperatures.

You cannot run a heat pump like a normal boiler. I don't want to be the harbinger of doom, but I wouldn't hold my breath on saving money if I was you. They've just fobbed you off.

@batalto Not sure I explained myself very well. It wont be going off, it has just been set at one temperature in the daytime and another overnight. They checked the water flow and the heat pump water settings and they remain as they set them in accordance with the Daikin instructions. We were using it all wrong, turning it up and down manually and in different rooms at different times, so we have probably inadvertently contributed to the costs we have experienced, so we are going to try out their new thermostat settings to see what difference it makes. If there is still a problem after that, well back to them to check what you say and a few other things mentioned by Derek.