Just over three months ago, we moved from sunny West Sussex to a new build, 4 bed, 3 bath detached house, of brick/slate construction in the Welsh borders. The property is south facing, with a floor area of approximately 228sqm and an EPC showing an Energy Efficiency Rating of B (87). Our home is double glazed and highly insulated.
The heating and hot water is provided via a Grant Aerona 3, single fan 10.5kW air to water, air source heat pump (ASHP) system. The fan’s dimensions are 850x 882cm, and the unit is installed against an east facing wall.
Underfloor heating runs throughout the ground floor, radiators heat the first floor with a 250 litre, 46kW pre-plumbed hot water cylinder. Room temperatures are set via digital thermostats, one in each ground floor room and one stat serving all bedrooms and bathrooms.
Being novices to ASHPs we found that having had a full briefing on operating the system by the installer was essential. We also found it important to:
1. Not compare the ASHP system to our former traditional gas fired radiator heating system and its performance/heating costs.
2. Be patient in allowing the system time to get rooms up to a comfortable temperature, several days in some instances.
3. Trust the installer’s advice to leave the system at a comfortable – in our case 20/21C, 24/7 – to optimise running costs.
We are one of four new build homes at the edge of a village and each owner reports being concerned about potential high running costs, all of us watching our smart meters ticking over rapidly on colder winter days. Particularly noticeable was on very cold days with -3/4C daytime temperatures, daily electricity usage was as high as 64kWh per day, whereas on days that were at 8-10C, usage was as low as 21kWh. I would add that this does also include normal electrical appliance /lighting usage, as well as heating and hot water.
Our experience of our Grant ASHP system performance to date:
Having seen various comments on My Home Farm’s user comments about ASHPs including noise of fans, ability to heat all rooms, and running costs, we have been pleased that our Grant system is not intrusive, even when running overnight in colder temperatures.
It maintains most rooms to a pleasant 20/21C, although on a few very cold days with overnight temperatures of -4C it did struggle to heat the rooms furthest away from the unit above 19C. This is worse when the wind was an easterly in our case.*
Our electricity usage over January/February 2021 looks to be around 1,100kWh per month. We currently pay 17.65p per kHh (plus VAT) with a daily standing charge of 21.56p (plus VAT), with Eon. We will be looking to switch to a better tariff given our high usage.
These costs represent more than three times the cost of our previous traditional gas fired heating and electricity bill for a similar sized property. One does have to wonder how such expensive ‘green’ systems can be ‘sold’ to the general populous going forward. Also, how can it be ‘green’ if it is using three times as much energy? I have written to my local MP on this matter.
One disappointment was finding that the RHI scheme does not apply to new homes unless they are custom builds. The scheme would have been very helpful in offsetting such large annual energy bills for seven years.
We do, however, enjoy the ambient constant temperature achieved without the need for ‘red hot’ radiators.
In conclusion, all the above points do not detract from the love of our great new -build home with views and quiet countryside setting.
*At the time of writing and after approaching Grant UK about cold weather performance, they have offered to place a logging monitor in our property and will monitor system performance over a 7-day period and report back on their findings.
Editor’s note: You can read an interview with Kevin Ellis, renewables sales manager at Grant UK, where he addresses the noise, costs and future of air source heat pumps.