Let's be honest.
Air source heat pumps can be brilliant for some UK homes. But they also have real disadvantages that people only discover after they've spent thousands of pounds.
This guide is here to tell you the truth about the downsides – in simple language – so you can decide if a heat pump is a good idea for your home, not just in theory.
We're not installers. We're an independent comparison service, so we don't need to "sell" you a heat pump. If a new boiler is better, that's fine too.
Quick Summary: Main Disadvantages
Here are the biggest air source heat pump disadvantages for UK homes:
- 💸 High upfront cost (even with the £7,500 grant)
- 🧱 You need good insulation or it can be expensive to run
- 🌡️ Radiators may need upgrading or adding underfloor heating
- 🔌 Runs on electricity, so bills don't always drop
- 📦 Needs space indoors (cylinder) and outdoors (unit)
- 🔊 Can be noisy if badly placed
- 🧰 Bad installers = bad system, and not all engineers are experts
- 🏛️ Flats, conservation areas and small gardens are harder
1. High Upfront Cost (Even With the Grant)
This is the first big disadvantage.
Typical Costs
A typical air source heat pump installation in the UK costs around:
- • £8,000–£15,000 before the grant
- • About £500–£7,500 after the £7,500 Boiler Upgrade Scheme grant
That's still a lot of money.
Even if you get the full grant, it can still feel like "a used car" level of money or "a new kitchen" type spend.
If your gas boiler is working fine and you don't have savings or access to finance, this cost can be a real problem.
👉 If you want a full breakdown of prices, you can read our air source heat pump cost guide for the UK.
2. Your Home Needs Good Insulation
Heat pumps work best in homes that hold on to heat.
If your home is:
- • Old
- • Drafty
- • No cavity wall insulation
- • Thin loft insulation
- • Single-glazed windows
…then a heat pump might struggle and your electricity bills can be higher than you hoped.
You may need to pay for loft insulation, cavity wall insulation, or sometimes floor insulation. These upgrades are good to do anyway, but they add to the total cost and effort.
If your EPC is already C or better, you're in a much better place. If it's D, E or worse, this disadvantage becomes more serious.
3. Radiators and Heating System May Need Upgrades
Gas boilers send water around your radiators at high temperatures. Air source heat pumps work best at lower temperatures.
What this means for you:
- • Some existing radiators may be too small
- • Rooms can feel cooler than you're used to
- • You may need to replace radiators with bigger ones
- • Or fit underfloor heating in some rooms
This is one of the hidden disadvantages of air source heat pumps in the UK – people think it's just "swap the box" and done.
Extra costs can include:
- • New radiators
- • New pipework
- • Underfloor heating
- • A new hot water cylinder if you have a combi boiler now
A good installer will be clear about this. A bad one will gloss over it to make the price look cheaper.
Want to Know What Your Home Actually Needs?
Get quotes from vetted MCS-certified installers who'll tell you honestly what upgrades (if any) your home needs.
4. Bills Don't Always Drop as Much as People Expect
Heat pumps are very efficient, but…
They run on electricity, and in the UK:
- • Electricity is usually more expensive per unit than gas
- • You may need to run the heating for longer periods
- • If your home is leaky, the system will work harder
So while some people see lower bills, other people see similar bills to a modern gas boiler, or even higher bills if the system is badly set up.
It depends on:
- • How well insulated your home is
- • How big your radiators are
- • Your electricity tariff
- • How you use your heating (constant gentle heat vs short blasts)
If you're expecting a heat pump to magically cut your bills in half in a cold, draughty home… that's unlikely.
5. Different Way of Heating (Takes Time to Get Used To)
This sounds small, but it's a real disadvantage for some people.
Gas Boilers:
- • Turn on
- • Get radiators very hot quickly
- • Turn off
- • House warms up fast
Heat Pumps:
- • Work best running gently for longer
- • Radiators feel warm, not scorching
- • House warms up slowly and steadily
You often need to set a stable temperature and leave it running, avoid turning it on and off all the time, and learn how your new controls work.
If you like blasting the heating for an hour in the morning and evening, this change can be annoying.
6. Noise and Outdoor Unit Placement
An air source heat pump has a big fan outside.
Modern models are fairly quiet, but:
- • They still make a humming noise when running
- • This can bother you or your neighbours if the unit is badly placed
- • Small gardens, terraces and tight spaces can be tricky
You need to think about bedrooms nearby, neighbour's windows, echo in small alleyways, and local noise rules.
A good installer will help you choose a sensible spot. A lazy installer might just stick it anywhere that's easy for them.
7. You Need Enough Space Inside and Outside
Another disadvantage: space.
Outside:
- • A clear space for the outdoor unit
- • Enough room for airflow
- • Solid base or wall brackets
Inside:
- • A hot water cylinder (if you have a combi now)
- • Sometimes a buffer tank
- • Wall space for controls
In a small flat or tiny house, this can be a big problem.
If you have no airing cupboard, no loft space, no spare corner, or a tiny yard or balcony – then fitting a full system becomes much harder.
8. Installer Quality Really Matters (and Varies a Lot)
This is one of the biggest real-world disadvantages of air source heat pumps in the UK.
The technology is good. But the design and installation can be:
- • Excellent
- • Average
- • Or terrible
When it's badly done, people complain that rooms never feel warm enough, bills are much higher than promised, system keeps breaking down, and noise is annoying.
The problem is often not the heat pump itself. It's that:
- • The system was wrongly sized
- • Radiators were not upgraded
- • Controls were set up badly
- • Insulation wasn't checked properly
This is why we always say: Don't just get one quote from a random company. Compare multiple MCS-certified installers and ask questions.
Avoid Bad Installers
We only match you with vetted, MCS-certified installers. Compare up to 3 quotes and choose the one you trust.
9. Planning, Flats and "Awkward" Homes
For many normal houses, you don't need planning permission for a heat pump (it's often permitted development).
But there are exceptions:
- Flats – you may need freeholder or building management permission
- Conservation areas – extra rules about where the unit can go
- Listed buildings – need full listed building consent
- Tight terraces – with no private outdoor space
In these cases, the process can be slower or more complex. Sometimes it's not possible at all. If you're in a flat or special area, this disadvantage really matters.
So… Are Air Source Heat Pumps a Bad Idea?
Not at all. But they're also not magic.
✓ They are a great idea if:
- • Your home is reasonably well insulated
- • You can access the £7,500 grant
- • You're happy to upgrade radiators if needed
- • You're okay with gentle, steady heating
- • You choose a good MCS-certified installer
✗ They may be a bad idea right now if:
- • Your home is very draughty and cold
- • You can't or don't want to improve insulation
- • You have no space for a cylinder and outdoor unit
- • You don't qualify for the grant
- • Your existing gas boiler is new and working well
If you want a deeper "yes/no" view, you can also read our "Are air source heat pumps worth it?" guide.
How to Reduce These Disadvantages
Here's how to make the downsides smaller:
- ✅Get proper insulation first – especially loft and walls
- ✅Use the £7,500 grant – don't install without it if you can avoid it
- ✅Get at least 2–3 quotes from MCS-certified installers
- ✅Ask about radiators and underfloor heating before you sign
- ✅Ask to see their heat loss calculations for your home
- ✅Think about where the unit will go – for noise and looks
- ✅Make sure you understand the running costs on your tariff
You don't need to become an engineer. You just need clear info and honest quotes.
Independent Help Choosing the Right Option
We built our service for people who feel like this:
"I don't want a sales pitch. I just want to know what this would really cost for my home, and whether it's a good idea or not."
Here's what we do:
- • We help you check your grant eligibility
- • We match you with up to 3 vetted, MCS-certified installers
- • You can see real quotes and what's included
- • You compare boiler vs heat pump options if both are possible
- • You choose what you want – or walk away
No pressure. No pushy sales calls from us. You never pay us a penny.
Frequently Asked Questions About Air Source Heat Pump Disadvantages
What are the main disadvantages of air source heat pumps in the UK?
The main disadvantages are: high upfront cost (even with the grant), need for good insulation and sometimes new radiators, different heating style (slow and steady, not quick blasts), electricity prices can limit savings, noise and space issues for the outdoor unit, and quality of installation varies a lot between companies.
Will a heat pump make my house colder?
It shouldn't, if the system is correctly sized, properly designed, and paired with the right radiators/underfloor heating. But if the installer cuts corners, you may feel your home is less "toasty" than with a gas boiler, especially if your radiators are too small.
Can a heat pump increase my bills?
Yes, it can increase bills if your house is very poorly insulated, the system is badly designed, you use it like a gas boiler (short, hot bursts), or your electricity tariff is very expensive. In a well-insulated home, set up well, on a good tariff, bills are often similar or lower vs a gas boiler.
Are these disadvantages the same everywhere in the UK?
The disadvantages are similar everywhere, but colder areas need better design and insulation, some councils are stricter on planning and noise, and rural homes often have more garden space, which helps.
Next Step: See If a Heat Pump Makes Sense for Your Home
Reading about disadvantages is useful. But the real question is:
"What would this actually look like for my house and my budget?"
We can help you:
It takes about 90 seconds to start. No obligation. No pressure. Just clearer answers.
