To choose a good air conditioning installer in Hertfordshire, start with the one check the law makes non-negotiable: the company must hold an F-Gas company certificate from an approved body, and you can look it up. After that, pick the installer who surveys the room before pricing, explains the size of unit and why, agrees where the outdoor unit and pipework will go, and commissions and registers the system properly so the manufacturer warranty holds.

The checks that matter most

Most bad installs come down to the wrong size of unit, a poor outdoor position, an unplanned pipe run or a refrigerant circuit that was never properly tested. This is the short version of what to check.

Check	Why it matters	What a good answer looks like
F-Gas company certificate	It is a legal requirement for anyone installing split systems for customers	A certificate number you can check on the certification body’s register
Site survey	Without one, the price is a guess and extras appear on the day	A visit, or at the very least photos and measurements, before a fixed price
Sizing	Wrong size means poor comfort and higher running costs	An explanation based on the room, not just a rule of thumb
Positions agreed	Noise, looks and neighbours all depend on it	Indoor unit, outdoor unit, pipe route and condensate drain agreed in writing
Electrical work	A new circuit is notifiable building work	A named person responsible and a certificate at the end
Commissioning	Leaks and poor performance start here	Pressure test, vacuum, charge checked and a record left with you
Warranty and servicing	Most manufacturer warranties depend on both	Warranty registered for you and a clear servicing interval

Our air conditioning installation service is built around exactly these steps, and the rest of this guide explains each one so you can hold any installer to them.

1. F-Gas certification, checked not assumed

Split air conditioning systems contain fluorinated refrigerant gas. Government guidance is clear that a company, including a sole trader, must be certified by an approved body to install, repair, maintain or decommission this kind of equipment for other people. For air conditioning in Great Britain the approved bodies are Refcom, the F-Gas Register (Quidos) and Bureau Veritas. Company certificates have to be renewed every three years, and the engineers doing the work need their own personal F-Gas qualification as well.

Ask for the company certificate number and check it on the certification body’s online register. It takes a minute. A vague answer, or “we use a mate who is registered”, is a reason to stop there.

This matters even more if you buy a unit online to have fitted. Sellers of split systems are required to get the details of the qualified technician who will install them, and a handyman who is not certified cannot legally connect and commission the refrigerant side.

2. A survey before the price

A good installer looks before they quote. On a survey they should be checking:

• The size of the room, its ceiling height and how many people use it.
• Which way it faces, how much glazing it has and how well it is insulated. A south-facing loft conversion with roof windows needs far more cooling than a north-facing bedroom of the same size.
• The wall where the indoor unit will go, and what is on the other side.
• The route for the refrigerant pipes, the cable and the condensate drain, and how neat that route can be made.
• Where the outdoor unit can sit, on the ground or on wall brackets, with enough space around it for airflow and servicing.
• The consumer unit and whether there is capacity for a new circuit.

A firm price given without any of that is either padded to cover surprises or will grow on the day.

3. The right size of system

Air conditioning is sized by its cooling output in kilowatts. Getting it wrong costs you either way. An undersized unit runs flat out on a hot afternoon and still leaves the room warm. An oversized one cools the air quickly, switches off, then starts again, which wastes energy, wears the compressor and does a poor job of taking moisture out of the air, so the room feels cold and clammy at the same time.

Ask the installer how they arrived at the size they recommend. A good answer mentions the room, the glazing, the orientation and how the room is used. Also ask about heating. Most modern split systems work as air to air heat pumps, so check the heating output and the seasonal efficiency figures on the energy label (SEER for cooling, SCOP for heating) if you plan to use it in winter too. Our guide to air conditioning running costs explains how those figures turn into what you pay to run it.

4. Choosing the type of system

System	Best for	Things to know
Wall mounted split	One room: bedroom, office, living room	The most common home install. One indoor unit, one outdoor unit
Multi-split	Two or more rooms from one outdoor unit	Fewer outdoor units on the wall, but if the outdoor unit fails, every room is affected
Floor console	Rooms with no good high wall, loft rooms with sloping ceilings	Sits low on the wall, useful for heating as well as cooling
Ducted	Whole floors, where you want no visible units	Needs ceiling void space and more building work, usually planned with a renovation
Portable unit	Short-term cooling only	Not an installation at all. Much less efficient, and the exhaust hose through a window lets heat back in

5. Where the outdoor unit and pipes will go

The outdoor unit makes some noise and moves a lot of air, so its position matters to you and your neighbours. A thoughtful installer keeps it away from bedroom windows where possible, fits it on proper anti-vibration mounts, and leaves enough clearance for it to breathe and to be serviced.

The pipe run between the indoor and outdoor units has to stay within the manufacturer’s limits for length and height difference, and shorter is better. Ask whether the pipes will be hidden in trunking, run through a cupboard or boxed in, and where the condensate water will go. It has to drain somewhere suitable, either by gravity to a drain or through a small condensate pump if gravity is not possible.

Check planning too. Many straightforward home installations go ahead without an application, but flats, listed buildings and homes in conservation areas are treated differently, and many Hertfordshire towns have conservation areas. A good installer raises this at survey. If in doubt, ask your local council before work starts.

6. The electrical side

Most split systems need their own circuit from the consumer unit. Under the Building Regulations in England, installing a new circuit is notifiable work, so it must be done by an electrician registered with a competent person scheme who can self-certify it, or be notified to building control. Ask who is doing the electrical connection and make sure you receive an electrical installation certificate at the end. If your consumer unit is old or full, the survey should pick that up, and we can deal with it at the same time.

7. Commissioning, paperwork and warranty

This is where corners get cut, because the homeowner cannot see it. A proper installation includes:

1. Pressure testing the refrigerant pipework with dry nitrogen to prove there are no leaks.
2. Pulling a deep vacuum on the pipework to remove air and moisture before the refrigerant is released.
3. Checking the refrigerant charge for the length of pipe run and recording it.
4. Testing cooling and heating, checking the condensate drains and showing you the controls.
5. Leaving you a commissioning record and registering the manufacturer warranty.

Manufacturer warranties usually depend on correct installation and regular maintenance. One leading manufacturer, for example, states that its warranty is only valid if annual maintenance is carried out, and recommends that owners clean the filters every couple of months. Ask your installer what your chosen unit needs, and whether they offer air conditioning servicing afterwards.

Comparing quotes

Put your quotes side by side and check each one names the make and model of both indoor and outdoor units, the cooling and heating output, the positions agreed, the pipe run allowance, the electrical work, making good, commissioning, the warranty and the labour guarantee. Our checklist of what an air conditioning quote should include goes through it line by line.

Red flags

• No F-Gas company certificate number, or a vague answer about who holds it.
• A fixed price with no survey, no photos and no questions about the room.
• No make or model on the quote, just “10,000 BTU unit”.
• An offer to connect a unit you bought online without being certified.
• No mention of commissioning, warranty registration or servicing.

How we price it

Installations are quoted as a fixed price after a free survey, so the price you agree is the price you pay. You can start with our online air conditioning quote and we confirm the details before booking. Every rate is on our prices page. We are Refcom F-Gas registered (REF1024550), and our air conditioning installations carry a 12 month labour guarantee alongside the manufacturer’s warranty on the equipment.

Frequently asked questions

Does an air conditioning installer need to be F-Gas registered?

Yes. A business that installs, services or repairs split air conditioning for other people must hold an F-Gas company certificate from an approved body, and its engineers need personal F-Gas qualifications. Ask for the certificate number and check it on the certification body’s register.

Do I need planning permission for air conditioning?

Many straightforward home installations do not need a planning application, but it depends on the property and the position of the outdoor unit. Flats, listed buildings and homes in conservation areas usually need more care and sometimes consent. A good installer checks this at survey, and your local council can confirm.

How long does it take to install air conditioning?

A single wall mounted split system in a straightforward room is usually a one day job. Multi-room and ducted systems take longer, and the survey should tell you how long yours will take.

Can air conditioning heat my home in winter?

Most modern split systems can heat as well as cool, working as an air to air heat pump. Check the heating output and the SCOP figure on the energy label for the model you are offered.

How often does air conditioning need servicing?

Manufacturers generally recommend a professional service once a year, and some make it a condition of the warranty. In between, clean or vacuum the indoor unit’s filters every couple of months, or as your user guide says.

Air conditioning installation across Hertfordshire

If you are comparing installers in Hertfordshire, Bedfordshire or Cambridgeshire, we will survey your room and give you a fixed price with no pressure. We are based in Stevenage, Refcom F-Gas registered (REF1024550) and rated 4.9 on Google. See our air conditioning installation page or call 01462 506374.