What should be in an air conditioning quote

Most domestic air conditioning quotes are a single figure and a model number. That is not enough information to compare two of them, and it is not enough to tell whether the job has been thought about.

Here is what a real one contains, and what to ask when it does not.

Before anybody quotes: what the survey covers

A quote produced without a visit is a price for an imagined installation.

Four things cannot be established remotely, and every one of them can change the price after work starts:

• Where the outdoor unit can actually go. Not just whether there is a wall, but whether that wall is the one facing a highway, whether the property is listed or in a conservation area, and whether anything is already mounted on it. The planning checker will tell you which provision applies to your property before anybody comes round.
• The pipe run. The distance between indoor and outdoor units, and what the refrigerant lines have to pass through to connect them. Long runs cost more and, past a point, cost capacity.
• Condensate drainage. An indoor unit produces water and it has to go somewhere with a fall. Where that is not available, a pump is added, and a pump is a component that can fail and can be heard.
• The electrical supply. Whether the consumer unit has a spare way, and whether the circuit is adequate.

How many units, and why the answer is per room

This one causes more disappointment than anything else on this page.

An indoor unit conditions the room it is in. It does very little for the room next door, because there is a door in the way and a doorway is not a duct. So the count of indoor units is the count of rooms you want conditioned, not a figure derived from the size of the house.

The capacity of each one is a separate question, and it is the room’s heat load rather than its floor area. The room cooling calculator works that out from the fabric, the glazing and the orientation, which is what actually decides it.

Outdoor units are the other way round. A multi-split system runs several indoor units from one outdoor unit, which is the normal domestic arrangement and also the one that keeps you within Class G, where a detached house may have two outdoor units and everything else, flats included, may have one.

So the usual domestic shape is several indoor units and a single outdoor one. A quote proposing an outdoor unit per room on a terrace is proposing something that is not permitted development.

What the quote itself should say

Line by line, and if any of these are missing, ask:

The exact model, indoor and outdoor. Both halves. A model number for the indoor unit alone does not identify the system, and the outdoor unit is the one with the planning consequence, because Class G limits its volume.

Whether it is reversible. This is the single most consequential fact about the machine. A cooling-only unit is never permitted development in England and attracts no grant. One that also heats is usually permitted and attracts £2,500. That is set out in the grant piece, and it is the first thing to check on any quote.

Whether the grant is already deducted. Two prices that look close may be thousands apart underneath.

Both certifications. F-Gas, which the law requires for anybody opening a refrigerant circuit, and MCS, which the Boiler Upgrade Scheme now requires of anybody claiming the grant for you. They are different schemes and a firm may hold one without the other. Ask for the registration numbers and look them up.

Making good. Who fills the holes, who paints, who moves the furniture, and what the wall looks like afterwards. This is the most common source of an argument at the end of an otherwise competent job.

Commissioning. What paperwork you get on completion. On a refrigerant system there should be something recording that the circuit was pressure tested and correctly charged.

What is deliberately not on this page

A price. Not a range, not a typical figure, not a rule of thumb per unit.

Installation prices depend on the pipe run, the number of indoor units, the building and the region, and any national figure printed here would be used to argue with a quote it knows nothing about. What this page can do is tell you what the quote should contain, so that two of them can be compared on the same basis.

Once you have two quotes with all of the above in them, the cheaper one is genuinely the cheaper one. Before that, it usually just has less in it.