Three contractors walked through my basement last winter and handed me three quotes: $6,480, $9,150, and $7,300. Same house. Same furnace brand on two of them. None of the three pages listed the same line items, which meant the numbers told me almost nothing until I rebuilt them by hand on a legal pad.
That is the real problem with heating quotes. You are not comparing prices. You are comparing how thoroughly each contractor documents a job, and most homeowners have no idea which line items matter. So here is the method I used, and you can run it this week without knowing anything about BTUs.
Why the cheapest quote usually is not the cheapest
A low number often means someone left something out, on purpose or by accident. Permits. A new flue liner. The pad under the unit. Haul-away of the old equipment. A load calculation. When I compared my three quotes, the $6,480 option quietly skipped the permit and the furnace pad and assumed my existing venting would pass inspection. It would not have.
Add those back and the low quote climbed past $8,000. That is the game. You rarely lose money to an honest expensive contractor. You lose it to a cheap bid that grows after the truck shows up.
What belongs on a furnace quote, line by line
Ask every contractor for the same document. If they push back, that tells you plenty. Here is what you want spelled out in writing:
- Equipment model number, size in BTUs, and efficiency rating
- Load calculation (Manual J or a documented equivalent)
- Permit pulled in the contractor’s name, with the fee listed
- New or reused venting, flue liner, and combustion air provisions
- Thermostat and any low-voltage wiring work
- Condensate handling if the unit is high efficiency
- Filter setup, cabinet, and access clearance
- Startup, combustion analysis, and a printed commissioning report
- Haul-away of the old system
- Labor warranty length, separate from the manufacturer warranty
If a quote lists “furnace install” and one price, it is not a quote. It is a guess with a signature line. The federal government’s consumer energy resources at Energy.gov are a good starting point for understanding efficiency ratings before you ever sit down with a salesperson.
The Insulation Test, my version of a load calculation check
I invented a simple trick after my second appointment. I call it the Insulation Test, and it works like this. Ask the salesperson two questions before they measure anything: how much attic insulation does the house have, and what is the square footage of conditioned space? A contractor who did the math will answer both without checking a screen. A contractor who is guessing at size will fumble.
The National Institute of Standards and Technology maintains the measurement standards that any credible load calculation rests on, so if a contractor claims their sizing is “just how we’ve always done it,” that is your cue to get another bid. You can read more at NIST.
Sizing matters more than brand. An oversized furnace short-cycles, wears out faster, and leaves cold rooms because it blasts heat and shuts off before the house evens out. Undersized runs constantly and never catches up on the coldest week. Most bad installations I have seen were sized by square footage alone, which is like picking shoe size by height.
Questions that separate contractors from salespeople
Ask these on the phone before you schedule anyone. It saves you two hours per wasted visit.
- Who pulls the permit, and will the inspector sign off on your work?
- What happens if the load calculation says my ductwork is undersized?
- Do you do a combustion analysis at startup, and do I get the report?
- What is your labor warranty, and is it in the contract?
- Who shows up on install day, your employees or a subcontractor?
The subcontractor question stings because it changes who is accountable. If a crew you have never met installs your system, the warranty conversation gets messy fast. Ask for the installer’s name and years with the company.
Reading the fine print on warranty and payment
Two numbers matter on every agreement: the manufacturer’s parts warranty and the installer’s labor warranty. A ten-year parts warranty is common. A ten-year labor warranty is not, and it is worth paying for. If a company offers one year of labor coverage, ask what a typical repair call costs out of warranty so you can decide for yourself.
On payment, never hand over more than a modest deposit before equipment arrives. A reasonable schedule ties money to milestones: deposit at signing, second payment when the unit is on site, final payment after the inspection passes. Anyone demanding full payment up front is a walking red flag, and I would walk them out of the house myself. Contractors who belong to a professional trade body such as the Air Conditioning Contractors of America tend to follow that structure, and you can browse member resources at ACCA.
A worksheet you can build in ten minutes
Open a spreadsheet and make a column for each contractor. Down the side, list every line item from the section above. Fill in what each bid actually includes, then add a row for “assumed but not stated” and price those gaps yourself using a quick call to a supply house.
The gaps are where quotes get interesting. One bid may include a new thermostat. Another may reuse yours and charge for a “system setup” that turns out to be pressing a few buttons. Once the gaps are visible, the ranking usually flips. On my own worksheet, the $9,150 bid landed lowest after I priced out permits, venting, and haul-away across all three.
Where the real value hides
You are buying three things: the right size, a clean installation, and someone who answers the phone in February. That third one is the hardest to price and the easiest to test. Call each company’s service line on a busy Monday morning and time how long it takes a human to pick up. The company that answers in ninety seconds is the one you want when your heat quits during a cold snap.
Reputable boiler and furnace installation experts will walk you through a load calculation, talk about permits without flinching, and put their labor warranty in writing before you ask. If any of that feels like pulling teeth, you already have your answer.
Take the three quotes sitting on your kitchen counter and rebuild them tonight on that worksheet. The right contractor usually becomes obvious by row four, and you will never again pay extra for a bid that simply documented less.
