Where two quotes stop being comparable

HomeGuide’s list of what most installation quotes include (historical cost estimate, archived source dated December 9, 2025): the outdoor unit, one or more indoor units, labor, basic electrical connections and brackets or pads, refrigerant line and basic system testing, and a standard line set of about 15 feet ^[1]. Ask each bidder to list the rest of their scope, including evacuation, charging and commissioning, in writing. That line-set length is an assumption about your house that the estimator may not have measured.

Long runs and large height differences can change what the manufacturer’s installation manual requires, so ask the installer to confirm the run against it. A quote that assumed a short run and meets a long one on the day can become a change order.

These are the items this site deliberately excludes from its own estimate, and they are excluded for the same reason they should be itemised on your quote — they vary far too much between houses to carry a default.

• line set beyond the roughly 15 ft that HomeGuide lists in most installation quotes; we could not obtain a price per foot from a source we were willing to cite, so we publish none
• a main electrical panel or service upgrade; our two sources give figures roughly three times apart, so we price neither
• removing and disposing of whatever is there now
• drywall patching, painting, and exterior siding repair around the wall penetration
• condensate pumps and any drain routing that cannot fall by gravity
• the permit fee, because we have read only one jurisdiction's published schedule

Print that list and read it down the phone. Every line is a yes-or-no question with a dollar consequence, and asking takes two minutes. The electrical item is a common surprise: if the panel is full, an electrician may have to make room, and HomeGuide puts a dedicated circuit alone at a typical $650^[2] (archived source dated November 24, 2025) before anyone touches the panel itself.

What did you size this on?

The answer you want describes your rooms — areas, orientations, window areas, insulation. The answer you do not want is a square-foot rule of thumb, because the published table this site is built on implies anywhere from 50 BTU per square foot at its smallest room size down to 17 at its largest (computed at the low end of each area band). A single multiplier is wrong at one end or the other by construction.

How long is the line set, and did you measure it?

Not estimated from the driveway. Measured, including the vertical rise between the outdoor unit and the heads, so the installer can check it against the model’s installation manual.

Who pulls the permit, and is the fee in this number?

Both halves matter. HomeGuide says a qualified installer typically manages the permit process; ask who will, and if the fee is not in the quoted figure, expect it as a separate charge.

What happens to the condensate?

A cooling head produces condensate and it has to go somewhere. Ask whether it drains by gravity or needs a pump, and whether any pump is in the quoted price.

Normalise before you compare. Write both quotes out as the same line items — equipment, heads, line set, electrical, permit, patching, disposal — and fill the gaps with the answers you got by phone. The cheaper bid can become the dearer one at this step, for example when its number assumed a short run and an available breaker.

Then look at what is left over, which is often labour and margin, and be honest that this part is not a defect. A crew that measures the line set, pulls the permit, sets the charge properly and comes back when something drips is worth more than one that does not, and the gap between them is exactly the number you were about to treat as overpricing.