Tyler Griffin, SwiftPro. September 2026.
Two companies can quote the same house twelve thousand dollars apart and both be telling the truth. They can also be twelve thousand apart because one of them is padded. Sitting at your kitchen table with two proposals, those look identical.
Here is how I read one.
Start with the size
Find where the quote says what size system it is putting in. Three ton, four ton, whatever it says. Then ask the person who wrote it how they got that number.
If nobody measured anything, if nobody went in the attic or asked about the room over the garage or looked at how many windows face west, then that size came off the sticker on your old unit. Which means it is a guess inheriting somebody else’s guess from twenty years ago. Half the systems we get called out to fix are the wrong size, and every one of them was somebody’s brand new system once.
This one question sorts contractors faster than anything else on the page.
Then look for model numbers
“High efficiency furnace and 16 SEER2 condenser” is a category, not a product. A model number is something you can type into a search bar, compare across two bids, and hold somebody to later. When a proposal will not name the exact equipment, you cannot compare it to anything, and occasionally that is the point.
And what happens to everything the new system touches
A replacement lands on ductwork, venting, electrical, a drain and a thermostat that all already exist. The quote should say which of those are being reused and which are being replaced. Silence there is where change orders come from later, usually on the second day, usually after the old system is already in the driveway.
Two more line items worth finding. The permit, because replacements are permitted work in Northern Virginia and unpermitted work becomes your problem when you sell. And the labor warranty stated separately from the manufacturer’s parts warranty, because those are two different promises for two different lengths of time, and only one of them depends on the company still existing in six years.
Before you read anybody’s quote, check who wrote it: how to check an HVAC contractor in Virginia, from the license to the permit.
What should make you slow down
A price that expires tonight. Equipment costs do not change at midnight, and a discount that evaporates if you sleep on it was never a price, it was pressure.
A single number with nothing behind it. No equipment, no scope, no terms. That is a suggestion.
Financing brought up before the system is. The monthly payment is how you pay for the right system. It is a bad way to pick one.
And a visit that never left your living room. If nobody went into the attic or the crawlspace, that proposal describes a house nobody looked at.
Verifying Proper HVAC System Sizing
What size did you land on and what told you that. What are you doing about my existing ductwork. Who pulls the permit and is it in this price. How long is the labor warranty and who honors it.
Then the one I like best: what is on here that I could take off, and what would that cost me later. Somebody who can walk you through what each line buys, and cheerfully tell you which ones you do not need, is not padding. Somebody who gets cagey is answering the question anyway.
Know the range first
You cannot judge a number in a vacuum. Our furnace and AC prices are published, so before you open anybody’s proposal you can know that a 3 ton replacement around here runs $9,900 to $20,900 installed depending on the equipment. Now the quote in your hand is a number you can place. Top of the range with premium equipment listed on it is fair. Top of the range with builder-grade equipment on it is a conversation.
From about $165 a month at 0% APR for 60 months, the whole price financed, on approved credit. How financing works
Two minutes: see the range for your house, or if you are going ductless, price a mini split.
If a quote still feels wrong after all that, we do free second opinions on big replacement quotes. A fair amount of the time we tell people the quote they are holding is a good one. That is a fine outcome and telling them otherwise would make us the thing this whole article is about.
SwiftPro Heating, Cooling & Plumbing, 4230 Lafayette Center Drive Suite N, Chantilly, VA 20151. (703) 997-9757. Serving Northern Virginia.
Questions about HVAC replacement quotes
What should be on an HVAC replacement quote?
The system size and how it was determined, exact model numbers rather than categories, what happens to the existing ductwork, venting and electrical, the permit, and the labor warranty stated separately from the manufacturer parts warranty.
Why do two HVAC quotes for the same house differ by thousands?
Usually equipment tier and scope. A straightforward single-stage system and a high efficiency variable speed system are different products at different prices. Knowing the published range for your system size first shows whether a difference is scope or padding.
How do I know if the system size on my quote is right?
Ask how they arrived at it. If nobody measured the house, checked the attic or looked at window exposure, the size was copied off the old equipment, which repeats whatever mistake was made the last time.
Is a quote that expires tonight a red flag?
Yes. Equipment costs do not change overnight. A discount that disappears if you take a day to think it over is pressure rather than a price.
Watch real system replacements go in
Real jobs in Northern Virginia homes, filmed by our own crew. Tap one to watch.
