Global Energy Systems Thurso ASHP

According to Global Energy Systems’ specifications, at 2C, with flow temperatures of 30/35C, the Thurso heat pump is stated to deliver a heat output of 7.88kW with power consumption of 2.67kW and a COP of 2.95, using refrigerant R410A.

So where do I begin to express my frustration with this ineffective system? I hope this review can serve as a cautionary tale to others. As the saying goes: caveat emptor… buyer beware.

In our defence, my partner and I inherited this system when we bought the house. However, we have experienced first-hand what is effectively a non-existent service, despite an annual £360 charge from Global Energy Systems, a UK designer and manufacturer of heat pumps based in the North West of England. I can understand why some people might be drawn to a UK-based manufacturer, but in my humble opinion, doing so in this case has proved to be a terrible and expensive mistake.

Looking at publicly available Companies House records today, I note that for the financial year ending 30 September 2023, the company reported zero employees. The previous year also showed zero employees, and the year before that (2021) showed two employees. There now appear to be two directors.

This raises a question for me as a homeowner: is this a semi-zombie company, surviving from quarter to quarter, potentially reliant on government pro-green incentives alongside the occasional private customer? A “UK designer and manufacturer of heat pumps” certainly sounds appealing and worthy on paper, although I have no direct knowledge of what government incentives or payments may or may not be involved behind the scenes.

Onto our issues. We live in a five-bedroom detached house in rural Cumbria, about a mile inland and roughly 200 feet above sea level. We have no access to mains gas (oh, how we wish we did) and the property is supplied via an overhead electricity line. The previous owner used oil central heating.

The house has 11 radiators in total. Apart from two bathrooms with towel rails and a kitchen with a newer single-panel tall radiator, all other radiators are dual-panel and typical of a high-temperature oil system. Two rooms, in a sandstone section of the house, have no wall insulation but are double-glazed. The rest of the house has cavity walls. In 2025, we installed 300mm of loft insulation throughout the property.

The system is a Global Energy Systems Thurso heat pump, paired with their specified UK-made World Heat CLIMACYLSS dual tank, containing 300 litres of hot water and a 100-litre buffer. A separate pump feeds the radiator circuit via approximately 22mm pipework running the length of the house through the attic, with 15mm drops to the radiators. There is a single heating thermostat in the hall.

The previous owner (let’s call him Joe) wanted a heat pump. He knew installation was expensive but believed it would save him money in the long run. We know this because we had many conversations with him before and after buying the house, following his sad and costly divorce which forced the sale.

Joe approached Mitsubishi, who told him he would need a proper heat loss survey and that most, if not all, of the radiators would need replacing. “Bugger that,” Joe thought. He knew central heating, and with oil the radiators were always hot.

Joe then discovered Global Energy Systems. According to Joe, Global Energy told him there was no problem. No heat survey was required. They referred him to one of their installers, and the Thurso model was recommended. Although the output was significantly lower than Mitsubishi had suggested, Global Energy said the Thurso would be fine. Joe accepted this advice and ordered the system. He lived with it for around three years before selling the house to us.

Global Energy charged £360 per year for an annual service and electronic monitoring. The system transmits mobile data back to them, allowing remote monitoring and adjustments. Customers have access to a summary page, but when using external control (a thermostat), you cannot remotely turn anything on or off.

Global Energy do not permit customer access to system settings. We are not allowed to adjust flow temperature, enable weather compensation or change any other parameters. All we have is the hall thermostat.

It later became apparent that the system is set to a fixed “flow” temperature of 45C, except the system is so badly under-sized that it is incapable of reaching this through the radiators, even on mild days. Most days it cannot even reach 31C.

What actually happens is this: every time the thermostat turns off, the system continues running in order to heat the buffer tank up to 45C before going into standby. This cannot be stopped. The radiator pump runs for around five minutes, then stops, after which the heat pump typically runs for another 25-30 minutes heating the buffer tank. Only then does the system shut down.

This is where things become absurd. 45C is clearly far too much for this system, particularly in cold or damp weather and it triggers multiple alarms every day. The manual provides no explanation, but the alarms include:

• Envelope Tc Low
• EVI High Superheat
• Inverter Overcurrent
• Compressor Alarm (often twice in succession)
• Lost Rotor

The system usually shuts down for around ten minutes to reset itself. By that time, the thermostat has often called for heat again, and the entire cycle of doom restarts. Occasionally (particularly in damp weather around 3-7C) the system also throws a “Major Defrost Failure” alarm and shuts down completely.

This happened while we were away on holiday. We returned to a bleeping alarm and no heating, requiring a manual reset. During that period another water pipe froze and burst, flooding the house and costing us thousands in re-carpeting and redecoration. I cannot hold Global Energy responsible for this, but I do wonder whether that pipe would have failed had there been heat in the house.

We now rely on a jury-rigged setup of industrial fan heaters in the lofts, connected to Wi-Fi smart plugs and temperature sensors. If we are away and receive an alert that attic temperatures are nearing zero, we can switch heaters on remotely from anywhere in the world. But should any homeowner really have to live like this?

Global Energy have never contacted us to say they identified any faults. We, however, have contacted them many times. On one occasion they replied with a vague and useless suggestion along the lines of “try turning it off and on again”. After that, we emailed twice more and received no response at all. We telephoned and spoke to a lady who said nobody was available but she would make a note. Nobody ever called back.

We requested access to the system settings so we could attempt to manage it ourselves. They declined to engage. My builder contacted them, and so did his plumber, both without success. Neither was given access to the system or meaningful support.

This system is effectively useless. Customers are completely locked out, and it now needs replacing… likely along with all the radiators. Frankly, it is junk.

There was also a serious manufacturing fault. The external evaporator fins overhang the casing on the left-hand side, allowing condensate to run down between the panels and into the machinery below. Directly underneath sits the booster heater, with wiring on top, and below that the internal water pump.

The booster heater failed early on, so early that Joe did not even realise there was a booster. After we bought the house, the water ingress then destroyed the internal water pump. Global Energy charged my partner around £800 to replace it. They did replace the booster heater free of charge.

The booster remains active up to 30C, and we are not allowed to change this setting. Our only option is to turn off its circuit breaker when desired. Recently, the booster alone has accounted for roughly a third of the total electricity consumption. Global Energy did not identify the overhanging fins as a fault; it was left to me to bend them back manually to stop the water ingress.

The annual service itself was minimal. The specification includes cleaning the evaporator tray, yet a dead mouse remained there after the service. The engineer, wearing a Global Energy polo shirt, clearly did not even remove the front cover. This is disgraceful and, in my view, a discredit to the industry. We eventually cancelled the annual contract and have been on our own ever since.

So how does the system actually perform?

We are currently experiencing a cold spell, with daytime temperatures of 3-6C and nights at 0-2C. We set the thermostat to 18C from 5pm to 9:30pm, 15C overnight, and 15.5C from 7am to 5pm. We feel permanently cold.

Hot water is heated to 50C and cannot be changed. I have been meticulously recording electricity usage and recent daily consumption figures are:

44kWh, 44, 53, 49, 47, 45, 46, 53kWh.

On most days, the thermostat only reaches 16.5-17C in the evening. This is an utter failure. Without a wood burner (and a tree that came down in a storm this year) we would have been forced to move out. Before we doubled the loft insulation in 2025, the coldest days saw consumption of around 67kWh. Completely unaffordable.

There is one further oddity, although I may misunderstand the terminology. Using my own temperature probes, I can say with certainty that what the system labels as “flow” temperature appears to be the return temperature… i.e. water coming back from the radiators via the buffer tank. The actual return is typically 5-9C higher.

Yesterday evening, with an outdoor temperature of 5C and after two hours of continuous operation, the reported “flow” only reached 29.3C. Something is clearly very wrong.

The data link to Global Energy’s web portal stopped recording data nearly two years ago and never resumed. They did not query the loss of data and ignored our request to fix it. They have done almost nothing for us. I would never recommend this company to anyone.

I make no criticism of World Heat. When I contacted them directly to ask about the internal layout of the tanks, they were extremely helpful.

I am also very grateful to Mars and his YouTube videos and website, from which I have learned a great deal, as well as from my own heat pump “journey”, though why this has to be a journey at all is beyond me. I now feel almost like a professional.

The big question is this: how does one find a reputable, reliable, competent and professional installer who will do the right thing, at a fair price? How do we choose the right heat pump to heat our home as we enter retirement? If this experience is typical, then any government policy encouraging heat pumps is doomed to failure.

I fear that 2026 into 2027 may be very costly indeed.

Review published on 3 January 2026. System installed almost seven years ago.