Do Heat Pumps Work in the UK? 10 Common Problems & Fixes
Yes. Heat pumps work. Millions of them are running right now across Scandinavia, Germany, France, and the UK heating homes reliably, efficiently, and in some cases in temperatures well below 20°C.
But here’s the honest truth: heat pumps are not plug-and-play appliances in the way a gas boiler is. They are a heating system and like any system, the results depend heavily on how well it’s been designed, sized, and set up for your specific home. Get those things right, and a heat pump will keep you warm, cut your carbon footprint, and reduce your energy bills. Get them wrong, and you’ll be cold, confused, and reaching for a helpline.
At Aquila, we install and maintain air source heat pumps across Cheshire, Warrington, and Greater Manchester every week. In this guide, we’re going to give you the straight answers: how the technology actually works, why some customers struggle, and most importantly how every single one of those problems can be fixed.
| 300–400% Efficient for every 1 unit of electricity used, a heat pump produces 3–4 units of heat. A gas boiler produces less than 1 unit per unit of gas burned. |
How Does an Air Source Heat Pump Actually Work?
Think of it like a fridge but in reverse. Your fridge takes heat from inside and dumps it out into your kitchen. A heat pump does the opposite: it takes heat from the outside air and brings it into your home.
Even on a cold winter’s day, the air outside contains usable heat energy. The heat pump passes that air across a special fluid called a refrigerant. The refrigerant absorbs the heat, gets compressed (which makes it hotter), and then transfers that heat into your central heating and hot water system through a heat exchanger.
The result: for every unit of electricity the heat pump uses to run the compressor and fan, it delivers 3 to 4 units of heat into your home. That’s what SCOP means Seasonal Coefficient of Performance and a good installation should achieve a SCOP of 3.0 or above across a full UK heating season.
| 💡 The Key Difference from a Gas Boiler A gas boiler burns fuel to create heat instantly and at very high temperatures (70–80°C). A heat pump extracts heat from the air and works at lower, steadier temperatures (35–55°C). That’s not a weakness it’s how the efficiency is achieved. But it does mean the system needs to be designed differently to your old boiler. |
Modern heat pumps are designed to operate in outdoor temperatures as low as 15°C to 25°C depending on the model. The UK’s typical winter low in the North West sits around 5°C to 8°C. A properly specified heat pump handles that comfortably and has done so, reliably, in countries far colder than ours for decades.
So Why Do Some Customers Have Problems?
Almost every heat pump complaint we encounter comes down to one of three root causes:
- Poor design: The system wasn’t sized or specified correctly for the property.
- Poor installation: Shortcuts were taken wrong radiator sizes, incorrect settings, or no proper commissioning.
- Boiler habits: The customer is using their heat pump like a gas boiler and it doesn’t work that way.
None of these are faults with the technology. They are fixable. Below, we’ve listed the ten most common issues we hear from customers and exactly what the solution is in plain English.
| 📌 A Note Before You Read On The issues below are common but they’re also largely preventable. That’s why choosing an MCS-certified installer who carries out a proper heat loss survey and system design before quoting is the single most important decision you’ll make. Check any installer’s MCS status at mcscertified.com before you sign anything. |
The Top 10 Heat Pump Issues and How to Fix Them
| Issue 1 My House Isn’t Warm Enough |
| ❌ What’s happening This is the most common complaint, and almost always it traces back to design rather than the technology. The heat pump may have been sized too small for the property’s actual heat demand. Or the radiators sized for a gas boiler running at 70–80°C are too small to deliver enough heat at the lower flow temperatures a heat pump uses (typically 35–55°C). A draughty or poorly insulated home makes this worse. |
| ✅ The fix A qualified engineer should carry out a proper heat loss calculation (required under MCS standards) before any installation. This tells them exactly how much heat your home needs on the coldest design day and ensures the heat pump and radiators are sized correctly. If you’re already installed and cold, ask your installer to check: (1) whether the heat pump is achieving its design flow temperature; (2) whether radiators have been correctly sized and balanced; and (3) whether the weather compensation curve is set correctly. In many cases, adjusting the control settings or upgrading a few key radiators solves the problem entirely. |
| Issue 2 My Heat Pump Runs All the Time |
| ❌ What’s happening Customers used to a gas boiler expect the heating to come on hard, get the house hot quickly, then switch off. A heat pump doesn’t work like that. It’s designed to run continuously at a low output gently maintaining a steady temperature rather than blasting heat in cycles. Some customers mistake this normal behaviour for a fault. |
| ✅ The fix This is expected behaviour in most cases not a problem. Heat pumps are most efficient when running steadily and consistently, rather than cycling on and off like a boiler. Think of it like the difference between sprinting and a brisk walk: the walk covers the same ground with far less energy. Set your heat pump to maintain a constant background temperature (around 19–20°C) rather than scheduling it to blast on and off. If the system is running flat-out and still not reaching target temperature, that points back to Issue 1 sizing or settings. |
| Issue 3 My Electricity Bills Are Higher Than Expected |
| ❌ What’s happening This catches customers out when they haven’t been given realistic expectations at the sales stage. A heat pump uses electricity not gas and while it’s 3–4 times more efficient than a gas boiler, electricity is currently priced higher per unit than gas. Running a heat pump on a standard electricity tariff without optimising settings can result in higher than expected bills, particularly if the flow temperature has been set too high. |
| ✅ The fix First, check your flow temperature setting. Every 5°C you can reduce the flow temperature increases efficiency by roughly 5–10%. The heat pump should be running at the lowest flow temperature that still keeps your home comfortable typically 40–50°C for radiator systems. Second, look at your electricity tariff. Octopus Energy’s Cosy tariff and similar smart tariffs are specifically designed for heat pump users offering significantly cheaper off-peak electricity rates that align with how a heat pump naturally operates. As an Octopus Energy Approved Partner, Aquila can advise on tariff optimisation as part of every installation. |
| Issue 4 The Hot Water Isn’t Hot Enough |
| ❌ What’s happening Heat pumps heat domestic hot water differently to a gas boiler. In standard operation, the hot water cylinder is kept at around 50–55°C warm enough for comfortable use. Some customers find this feels less ‘scorching hot’ than what they were used to, or they run out of hot water if the cylinder is too small for their household demand. |
| ✅ The fix Most heat pump systems include a hot water cylinder (often called a buffer or thermal store). The cylinder must be correctly sized for your household typically 200–250 litres for a family of four. Ensure the cylinder has a good quality immersion heater for a weekly legionella pasteurisation cycle (where the water is heated to 60°C to kill any bacteria). This runs automatically and uses a small amount of electricity. If hot water is consistently insufficient, ask your installer to check the cylinder size, the priority settings on the heat pump controls, and whether the flow rate to the cylinder is adequate. |
| Issue 5 My Radiators Don’t Feel as Hot as They Used to |
| ❌ What’s happening This is almost always a deliberate design feature, not a fault though it surprises many customers who’ve lived with gas central heating for years. A gas boiler heats radiators to around 70–80°C. A heat pump heats them to 40–55°C. They feel warm rather than hot to the touch. If the radiators have been correctly sized for the lower temperature, the room will still reach the same comfortable temperature it just takes longer and the radiator surface isn’t scalding. |
| ✅ The fix If rooms are reaching the target temperature, the radiators are working correctly. The system is designed to operate at lower temperatures and the radiators should have been sized accordingly. If some rooms are not reaching temperature, the radiators in those rooms may need upgrading to larger double-panel or triple-panel convectors, which have more surface area and can emit more heat at lower temperatures. Ask your installer to recheck the room-by-room heat loss calculation and confirm radiator adequacy. |
| Issue 6 I Can Hear a Noise from the Outside Unit |
| ❌ What’s happening The outdoor unit contains a fan and a compressor both of which produce some noise during operation. This is normal. Modern heat pumps are considerably quieter than older models, typically operating at around 40–50 decibels at one metre similar to a quiet dishwasher. Problems arise when the unit is positioned too close to a bedroom window, a neighbour’s boundary, or a solid wall that reflects sound. |
| ✅ The fix If noise is genuinely excessive (not just audible), ask your installer to check: whether the unit is sitting on anti-vibration mounts; whether any pipework is transmitting vibration into the building fabric; and whether the unit positioning complies with the permitted development noise limits (42dB at one metre from a neighbour’s window). Positioning the unit away from bedrooms and solid reflective surfaces makes a significant difference. Under MCS permitted development rules, your installer must have assessed noise compliance before installation if this wasn’t done, raise it with them directly. |
| Issue 7 Ice Is Building Up on the Outside Unit |
| ❌ What’s happening This alarms customers who’ve never owned a heat pump before but surface frost on the outdoor unit in cold weather is completely normal. When outside temperatures drop, moisture in the air freezes on the heat exchanger. All heat pumps have an automatic defrost cycle built in: the system briefly reverses to melt the ice, then resumes normal heating. You may notice a temporary drop in output and a small amount of steam or dripping water during this process. This is all entirely expected. |
| ✅ The fix Surface frost and automatic defrost cycles are normal and nothing to worry about. The system manages this itself. Where ice buildup becomes a problem is if the unit is blocked by leaves, garden furniture, or snow preventing airflow. Keep a 300mm+ clearance around all sides of the outdoor unit at all times. If the unit is freezing solid and not completing defrost cycles, that does indicate a fault possibly a blocked coil, low refrigerant, or a defrost sensor issue and you should contact your installer or service engineer. |
| Issue 8 The System Seems Less Efficient in Very Cold Weather |
| ❌ What’s happening This is technically correct and it’s physics, not a fault. The colder the outside air, the harder the heat pump has to work to extract heat from it. At 0°C, efficiency is noticeably lower than at 7°C or 10°C. At 10°C, a heat pump may achieve a COP (coefficient of performance) of around 2.0–2.5 rather than its peak of 3.5–4.0. Some systems include an electric immersion backup element that kicks in during extreme cold to maintain output. |
| ✅ The fix Understand that some efficiency variation is normal and built into the SCOP rating, which averages performance across the whole heating season including cold spells. For UK conditions, a wells-pecified heat pump handles everything the North West can throw at it. The backup immersion element is there precisely for the rare extreme cold events it costs more to run but operates rarely. The key mitigation is good insulation: every improvement to your home’s fabric (loft insulation, draught proofing, cavity wall fill) reduces the demand on your heat pump and lifts seasonal efficiency. |
| Issue 9 My Heat Pump Controls Are Too Complicated |
| ❌ What’s happening Heat pump control systems are more sophisticated than a standard boiler thermostat and not all installers take the time to walk customers through them properly at handover. Customers who aren’t confident with the controls end up setting things incorrectly: too high flow temperatures, frequent overrides, or heating schedules that work against the system’s natural efficiency. |
| ✅ The fix A proper handover session is part of every quality installation and is required under MCS standards. Your installer should explain: how to set the heating schedule; how weather compensation works and why you should leave it enabled; how to set and adjust the hot water schedule; and what the different modes and error codes mean. If you didn’t get this at handover, ask your installer for a follow up walkthrough any reputable company will provide this. Smart controls compatible with heat pumps (such as those from Daikin, Vaillant, or Worcester Bosch) also have user friendly apps that simplify day to day management. |
| Issue 10 My Heat Pump Seems to Have Stopped Working |
| ❌ What’s happening A heat pump that has shut down completely may have a fault displayed via an error code on the controller, or it may have tripped a safety cutout. Common causes include: power supply issues; a pressure fault in the water circuit; a refrigerant fault; a sensor failure; or the outdoor unit being physically blocked (by snow, debris, or an object placed too close). |
| ✅ The fix First, check the outdoor unit is clear and unobstructed. Then check the controller display for an error code note it down and look it up in your user manual, or contact your installer with it. Check that no circuit breakers have tripped in your consumer unit. If it’s a pressure issue, some systems allow you to repressurise the circuit yourself (similar to a boiler) your installer should have shown you how to do this. Do not attempt to access the refrigerant circuit yourself this must only be done by an FGas certified engineer. For any fault you’re unsure about, call your installer or service provider. |
Heat Pump or Air Conditioning: Which One Actually Cools Your Home?
Heat pumps and air conditioning get talked about as if they’re interchangeable, but they’re not quite the same thing. A wall-mounted split system, which is technically an air-to-air heat pump, cools your home in summer and heats it in winter. An air-to-water heat pump connects to your radiators and replaces a gas boiler but won’t cool your bedroom on a 34°C night.
Knowing the difference before you spend anything saves a lot of frustration. We’ve covered both in detail, including running costs, efficiency figures, and which qualifies for the £7,500 Boiler Upgrade Scheme grant, in our guide to heat pumps vs air conditioning: what really works in a UK heatwave 2026.
Quick Self Help Checklist Before You Call Anyone
| 📋 Run Through This First These simple checks resolve a surprising number of heat pump complaints and take less than five minutes. |
- Outdoor unit: Is it clear of leaves, snow, garden furniture, or any obstruction? Clear a 300mm+ gap all round.
- Power supply: Check your consumer unit has any circuit breaker tripped?
- Controller display: Is there an error code showing? Note it down.
- Flow temperature setting: Is it set higher than 55°C? Try reducing it to 45–50°C for radiator systems.
- Heating schedule: Is the system set to ‘boost’ or ‘holiday mode’ accidentally?
- Thermostatic radiator valves (TRVs): Are any TRVs turned fully down or off in rooms you want to heat?
- Radiator balance: Are some radiators cold at the top? They may need bleeding.
- Hot water cylinder: Is the cylinder temperature showing correctly on the controller?
The Bottom Line: Heat Pumps Work When Done Right
The evidence is clear. Countries far colder than the UK Finland, Sweden, Norway have been running heat pumps as the primary heating technology for decades. In Finland, over 60% of homes use a heat pump. The technology is proven, mature, and improving every year.
The issues covered in this guide are real but every single one of them is either preventable with a quality installation or fixable with the right support. The heat pump itself is almost never the problem. The problem is almost always how it was designed, installed, or set up.
That’s why MCS certification matters. Every MCS-registered installation must follow strict design standards including a full heat loss calculation, room by room emitter sizing, and a proper handover to the customer. When that process is followed, a well installed air source heat pump is a reliable, efficient, and genuinely comfortable heating system.
| 🏆 Aquila’s Promise Every ASHP installation Aquila carries out is MCS certified from survey to signoff. We size the system correctly, set it up properly, and walk you through the controls before we leave. If you have questions after installation, our team is here to help. That’s not just good practice it’s what MCS requires of us. |
Thinking About a Heat Pump? Start with a Free Survey
Whether you’re ready to go or just exploring your options, the best starting point is a free, no-obligation home survey. We’ll assess your property’s heat loss, check your existing radiators, and give you an honest recommendation including whether your home is heat pump ready right now, or whether a few simple improvements would give you a better outcome.
As an MCS certified installer, Worcester Bosch Accredited Partner, and Octopus Energy Approved Partner, Aquila is among the most accredited heating and renewables contractors in the North West. And with the £7,500 Boiler Upgrade Scheme (BUS) grant available right now, there has never been a better time to make the switch.
For independent heat pump guidance, visit the Energy Saving Trust. To verify any installer’s MCS status, visit mcscertified.com. For BUS grant eligibility, visit gov.uk Boiler Upgrade Scheme.
Aquila Heating & Plumbing Ltd
MCS · Gas Safe · NICEIC · OFTEC · Worcester Bosch Accredited · Octopus Energy Approved · HEIS
Serving Warrington, Cheshire & Greater Manchester | WA · CH · M · WN · SK · CW · L