There are now more than 170 heat pumps connected to the leaderboard. Most are in the UK. A high ranking can help installers sell their services to customers, adds Hudson. This is crucial because a badly installed heat pump can leave homeowners shivering or facing massive energy bills.
If you want to add your own heat pump to the online leaderboard, you need to attach a small array of temperature and electricity meters to your heating system. These record electrical input and heat output data in real time, with measurements transmitted automatically to OEM every 10 seconds. It’s possible to track your heat pump’s COP over months or even years, but the kit required isn’t exactly cheap. A typical monitoring setup could cost between 500 and 700 pounds, says Hudson, all on top of the price of the heat pump system itself.
Still, getting an idea, albeit not peer-reviewed analysis, of how well heat pumps can work in the UK is valuable, suggests Hudson—in the aggregate, the dataset could help researchers and policymakers study heat pump performance on a larger scale than before. Having access to live data also means installers can quickly spot when the devices develop faults. Tracking performance is also just fun. “It’s bonkers,” Hudson says of Ritchie’s high COP. “It’s hard to comprehend that.”
HeatPumpMonitor.org is a unique resource at present. It can be difficult to locate data on live heat pump performance. WIRED spent weeks scouring the web and speaking to experts to find examples of heat pump systems that could beat Rob Ritchie’s current SCOP and found only a handful of possible contenders.
“There are a couple of organizations that are trying to get more real-world performance data on heat pumps, but it’s tough to find,” says Kevin Kircher, who studies heat pump efficiency at Purdue University in the US.
Rewiring America, a nonprofit focused on electrifying homes and businesses, says it is working on 100 heat pump installations that it hopes, eventually, to study in terms of their efficiency. There are additional challenges in measuring heat pump performance in the US. Most US home heating systems rely on forced-air distribution, rather than the water-filled radiators common in Europe. It is easier to attach a temperature monitor to a water pipe.
Back in the UK, the independent research body Energy Systems Catapult has published data on a sample of heat pump installations, with the best ones achieving a 365-day SCOP of around 4.4.
“If you can set that standard across the whole of the UK, you’re laughing. That’s where you should be aiming,” says Harland Guscott, a plumber in the southeast of England who became vegan and switched to installing heat pumps instead of gas boilers in order to protect the environment. He says his own heat pump installations tend to reach SCOPs above 4.
Some of the key elements in achieving a high SCOP include keeping the flow temperature low; enabling weather compensation, so you don’t heat too much when it’s mild outside; adding large radiators that distribute heat efficiently into rooms; or using technology to intelligently defrost heat pumps during cold, damp weather, since that tends to make them ice up.
“We developed some algorithms that can anticipate when frost is going to go up,” says Kircher, who explains that small, proactive defrost cycles can boost overall efficiency. Bennett at Viessmann adds that the heat pump in Ritchie’s installation includes a buffer that allows it to defrost itself without interrupting indoor heating, therefore helping it to maintain room temperatures while running at a continuous, gentle pace.
Lambda, an Austria-based heat pump manufacturer, says its latest air-source models, soon to be released, could achieve SCOPs of 6 so long as they are used in properties with relatively low heating demand—a house with underfloor heating, for example, which can run on a modest flow temperature of 35° Celsius.
But Lambda’s heat pumps are “not the cheapest” admits Manuel Krall, product manager: “If somebody’s not really into the topic or doesn’t know what COP means, then they will not buy us, usually.”
Lambda’s heat pumps use R290, or propane, as a refrigerant, which is considered both more efficient and more environmentally friendly than some older refrigerants on the market. R290 may also be helpful in buildings where low-temperature heating isn’t an option, since it could enable heating of radiators to say, 50° Celsius, while still retaining reasonably good SCOPs.
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