Air conditioning

The bit that gets skipped

Air conditioning is sold as a box on a wall. Electrically it is one of the heaviest things you can add to a house, and the part most often got wrong is the supply feeding it.

• Board capacity — whether there is a spare way, and whether the board is suitable at all. Many are already full.
• Incoming supply — a multi-room system on top of an electric hob, a shower and a car charger adds up quickly. Diversity needs calculating, not guessing.
• A dedicated circuit — correctly rated, with RCD protection and an isolator the engineer can actually reach.
• The outdoor unit — its supply routed and protected properly, in cable rated for outdoor use rather than whatever reached.
• Condensate pumps — they need a supply too, and they are the thing that gets forgotten until water appears on a ceiling.

If a system trips the board on a hot day, it is almost never the unit. It is the circuit it was connected to.

One trade, start to finish

Refrigerant handling is regulated. Anyone working on the sealed refrigerant circuit of an air conditioning system must hold F-Gas certification, and that is an entirely separate qualification from an electrical one.

That is why most installations involve two firms: a refrigeration engineer for the units, pipework and gas, and an electrician for the supply. It also explains why so many go wrong at the join — each assumes the other has dealt with something, and nobody owns the finished job.

We hold both. F-Gas certified for the refrigerant work, NAPIT registered and City & Guilds qualified for the electrical side. One firm surveys it, installs it, wires it, commissions it and puts its name on the certificate.

What that means in practice

• One survey, one quote, and one person accountable for the whole installation
• The supply designed around the equipment rather than the equipment squeezed onto whatever circuit was nearest
• No waiting for a second trade to become available, and no gap between first and second visit
• Indoor and outdoor units sited with the cable and pipe runs planned together, which is what keeps an installation looking tidy
• Electrical certification and F-Gas records issued together on completion

What's included

• Survey and heat load assessment, so the system is sized for the room rather than guessed
• Indoor and outdoor unit installation and mounting
• Refrigerant pipework, vacuum, charge and leak testing
• Dedicated electrical circuit, isolator, containment and condensate pump wiring
• Commissioning, controls set up, and a demonstration of how to actually use it
• Full electrical certification and building control notification where required

Servicing and repairs

Air conditioning needs servicing, and most domestic systems never get it. A unit that has run for five summers with a blocked filter and a dirty coil is using considerably more electricity than it needs to and heading for a failure in the middle of a heatwave.

• Filter and coil cleaning, which is where most of the lost efficiency goes
• Refrigerant charge and leak checking — a system slowly losing gas cools worse and worse before it stops altogether
• Condensate drain and pump checks, which is what prevents water appearing on a ceiling
• Electrical checks on the supply, isolator and connections
• Repairs and fault diagnosis on systems installed by somebody else

Because the refrigerant and electrical sides are both covered, a service visit deals with the whole system rather than half of it. Annual servicing on a system you rely on is worth having, in much the same way a five-yearly EICR is.

What's worth knowing before you buy

The kit is the easy decision. What matters more is where it goes and what it is being asked to do.

• Heating as well as cooling. Nearly every modern unit is a heat pump and will heat the room too, often far more cheaply than an electric heater. Worth factoring in — it changes the sums considerably for a loft room or a garden office.
• Single split or multi-split. One outdoor unit can serve several rooms, which is tidier and usually cheaper than several separate systems. It needs planning as a whole rather than a room at a time.
• Where the outdoor unit goes. Noise, access for servicing, and how it looks from the garden. Also whether you are in a conservation area, which can restrict it.
• Loft conversions. The rooms that most need cooling are the ones hardest to retrofit. If a conversion is being done, run the supply at first fix even if the unit comes later.

If you are having building work done, get the supply in before the plastering. Adding a circuit for air conditioning afterwards costs several times what it costs at first fix.

Common questions