Here, the independent monitoring of one of the UK’s first Daikin Altherma hybrid heat pumps is examined; highlighting the cost-saving benefits it provided to a three-bedroom semi-detached family home in Cargenbridge, Dumfries.
With its unique combination of an air-to-water heat pump and a high efficiency gas combi boiler, the Daikin Altherma hybrid is the most advanced domestic heating system available today.
When Chris Kirk, his wife and two children moved into the 126m2 Cargenbridge house, they were pleased with the spacious interior but not the outdated and inefficient electric storage radiators and immersion heater hot water system.
Chris Kirk said: “It was an old heating and hot water system, due for replacement. The heat was patchy and you could only ever run half a bath. We were always cold and wanted a gas central heating system, like we’d had before.
“Stephen Thomson of Coolheat Energy Services in Dumfries introduced me to the Daikin Altherma hybrid heat pump. I was interested in energy saving and was looking at other things like biomass, but he suggested the Hybrid would work better and would save us money.
“With the Hybrid you don’t have to feed it fuel – it just sits there and does the job for you. It’s all computerised and works in the background to give us constant heating throughout the house, and keep the costs down.”
Coolheat installed an 8kW Daikin Altherma hybrid system with the air-to-water heat pump at the side of the Kirk’s house, and a combi boiler with combined Hydrobox, wall mounted in a utility room. The house has a design heat loss of 7.9kW at -3.4°C and the new system has a design flow temperature of 50°C at -3.4°C.
New radiators were fitted throughout and the redundant domestic hot water tank was removed to provide additional space. In addition, the system was installed and configured for cost-efficient energy usage at whatever temperature the Kirks set on their thermostat controller.
Developed to meet the need for gas boiler replacement, the Daikin Altherma hybrid is the most efficient and advanced new heating solution for customers replacing mains gas or LPG combi boilers.
In addition to blending renewable energy with intelligent use of natural gas, the system uses smart logic that automatically selects the most energy efficient and cost effective mode of operation, based on the user’s energy tariff.
Unlike any other hybrid system on the market, in the Daikin Altherma hybrid heat pump, the gas combi boiler and air-water heat pump operate in series and are combined into a single indoor unit. The heat pump provides low flow temperatures and the boiler provides support for higher flow temperatures.
As one of the first Daikin Altherma hybrid installations, the Kirks’ was included in an independent metering and monitoring project in the 11 months to 31 March 2015.
Demonstrating the efficiency of the system, the results show that the heat pump achieved an annual Seasonal Performance Factor of 4.0 and was able to provide 80% of the space heating requirements – 8,448kWh of the 10,610kWh total. In addition, the primary energy efficiency of the whole system was 131%.
As the heat pump was fitted with appropriate electricity and heat meters, it is eligible for the government’s domestic Renewable Heat Incentive (RHI) and consequently, the Kirks’ installation earned £472 in RHI payments. Furthermore, running costs for space heating were £292 – against an estimated £405 if only a gas boiler was used instead, translating to a running cost saving of 28%.
“The benefits for the whole family have been great,” said Chris Kirk. “The bedrooms are warm, there’s a nice steady temperature all night and plenty of hot running water.
“The system is very quiet. I don’t even hear the gas kicking in or the noise from outside. The neighbours don’t hear any noise either. They were very interested to see it for themselves once it was installed as they also were due for a gas replacement. They seemed very impressed with the system.
“I would definitely recommend the Hybrid system to anyone thinking about a new gas boiler.”
The Kirks’ hybrid system was monitored by Dr Anne Stafford, Senior Research Fellow at the Centre for the Built Environment at Leeds Beckett University.
Dr Stafford said, “Independent field trials, including detailed performance monitoring, are vital because they allow us to understand the actual real-world performance of the systems, not just calculated or ideal performance. They also help to quickly identify and understand any issues arising in individual systems, and therefore to improve overall performance consistency.”
*The running costs were calculated based on the gas and electricity consumption in kWh (meter readings). Energy prices used were i) Electricity= 10p/kWh ii) Gas=2.94p/kWh.