Had my own construciton co. for a while.
Now with construction, writing a bid is more complicated than it is for installing ac and heat. So about half of my bids were big enough that I had to go away to figure out a price and either call, stop back, or mail my price.
But for small projects such as decks, roofing, siding, windows, etc. I had some rules of thumb in my "price book" and could write a proposal on the spot.
I found that if I go away and make up some numbers, they seem made up. If they come out of an official price book (whick I made up), they are immediately accepted as the CORRECT price.
To tell you the truth. Home owners don't know they need a load calc. done. And the wholesale price difference between a 3 ton and 3-1/2 ton isn't that big.
I'd have a square foot price figured out for each unit available (one economy, one consumer grade, one delux...or whatever you call it). A price for lineset by the foot, a flat fee for disposal of the old unit, etc. etc. The more items included, the less shocking the price is.
And then write the proposal on the spot, get an committment on the first visit too. Either a yes or no. But get an answer.
Estimating equipment by sq foot is going to be pretty close and you can do a real load calc back at the shop. Make your proposal read "a/c capacity to be calculated according to blah blah blah standards as found in blah blah, article blah. Price high enough so that if you estimated a 3 ton and have to put in a 4, you still make a profit.
Just my humble opinion.
Ryan
Maintenance Guy
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naysayer, skeptic, conspiracy theorist