When two quotes for the same furnace or heat pump replacement are thousands of dollars apart, the difference usually isn't one contractor's markup. More often the two are pricing different jobs: different equipment, a different size and a different idea of what's included. One quote covers a chimney liner, a new return duct and the permit; the other leaves them out or never mentions them.
The way to compare is to line the quotes up item by item before looking at the totals. Get model numbers for every piece of equipment, check that capacity and efficiency ratings match, confirm what each contractor includes and excludes, and only then decide which price is better. If you want a sense of what drives the totals themselves, our breakdowns of new furnace costs in Massachusetts and heat pump costs go through the numbers. This guide is about making two or three quotes comparable.
Where the differences come from
Most price gaps trace back to a handful of things, and each one is easy to check once you know to look.
Equipment tier and model line
Manufacturers sell several lines of the same kind of equipment, from basic single-stage models to variable-speed systems with their own communicating controls. A "95% gas furnace" on a quote could be a single-stage unit with a standard blower or a modulating furnace with a variable-speed one, and the price difference between them can be large. The same goes for heat pumps and air conditioners, where a single-stage outdoor unit and a variable-speed one sit at very different prices. Unless both quotes name exact models, you can't tell whether they're comparable.
How the system was sized
A contractor who runs a heat load calculation (ACCA's Manual J is the industry standard) bases the size on your house: its insulation, windows, air leakage and layout. A contractor who copies the nameplate of the old unit is repeating a decision made 20 years ago, before the new windows and the attic insulation. The two methods often land on different sizes, and a bigger system costs more, so sizing alone can explain part of a price gap. Ask each contractor how they arrived at the size they're proposing.
Scope that's easy to leave out
This is where most surprises come from. A lower quote isn't necessarily missing anything, but these are the items worth checking for by name:
- Venting changes, including a chimney liner when a gas water heater is left alone in the chimney after a furnace switches to plastic venting
- A condensate pump where there's no floor drain near the equipment
- Pads, wall brackets or snow stands for outdoor units
- Refrigerant line sets, whether new or reused, and how long the runs are
- Plenum and transition work to connect new equipment to the existing ducts
- Duct changes, such as a larger return or replacing leaky sections
- Electrical work: a new circuit, a disconnect or a panel upgrade
- The thermostat or system control
- Permits and inspections
- Removal and disposal of the old equipment
When one quote lists these and the other doesn't, the cheaper one may simply describe less of the job. The unlisted work still has to happen, and it can come back later as a change order.
Labor and time on site
Two crews can install the same equipment very differently. A careful installation includes the unglamorous steps that take time: pressure-testing and evacuating refrigerant lines, verifying the charge, checking airflow, testing combustion on a furnace or boiler, and sealing duct connections. A price built around a quick in-and-out may skip some of that. It's fair to ask how many people will be on the job, how long they expect to be there and what they test before they leave.
Matched indoor and outdoor components
A split air conditioner or heat pump is two pieces of equipment, an outdoor unit and an indoor coil or air handler, designed to work as a pair. AHRI, the industry group that runs the certification program, certifies the performance of the system rather than the individual units, and each certified combination gets its own Certified Reference Number. The SEER2 or HSPF2 rating on a quote only holds if the exact combination being installed is a certified match. Ask for the AHRI reference number or certificate for the system in each quote. It confirms the pairing, gives you a fair basis for comparing efficiency, and may be required when you apply for a rebate. Mass Save, for one, calculates heat pump rebates from the AHRI-rated capacity.
Manufacturer warranty registration
Equipment warranties come from the manufacturer, and with several large manufacturers the length depends on registration. Register within a set window after installation, commonly 60 or 90 days, and the parts coverage can run 10 years; miss the window and it may fall back to a shorter base term, often 5 years. A manufacturer's parts warranty also generally doesn't cover the labor to replace the part. When you compare quotes, ask who registers the equipment and when, whether you'll get a confirmation, and what each quote says about labor on repairs in the first few years.
What a good quote lists
A quote you can compare is specific. At a minimum it should show:
- The make and model number of each component: furnace or air handler, outdoor unit, indoor coil and thermostat
- Capacity (BTUs or tons) and efficiency ratings (AFUE, SEER2, HSPF2), with the AHRI reference number for split systems
- The scope of work, line by line, including venting, electrical, ductwork and disposal
- Permits and inspections, and who arranges them
- What's excluded, in plain words
- A start date and how long the work will take
- Payment terms: the deposit, when the balance is due and how changes are priced
None of this is an unusual request. A quote that won't commit these details to paper is a quote nobody can be held to.
Red flags
A few patterns should make you slow down. The first is a price given without a visit, or after a visit where nobody looked at the venting, the ducts or the electrical panel and nobody measured anything. Sizing and scope can't be right if no one looked. The second is a price that's good only today. Equipment costs do change, but a legitimate quote holds for a reasonable period, and a deadline measured in hours exists to keep you from comparing.
Vague wording is another. "Replace heating system, $9,800" doesn't say what you're buying, and it leaves room for a lower-grade unit or a skipped chimney liner. Be wary, too, of any suggestion that a permit isn't needed. In Massachusetts, gas work can only be done under a permit issued to a licensed plumber or gas fitter, and electrical work has to be done by a licensed electrician under a permit. The permit is what brings an inspector to check the work. Finally, treat pressure of any kind, such as a discount that disappears unless you sign tonight, as a reason to take your time.
Questions to ask every contractor
- How did you size the system, and can I see the load calculation?
- What are the exact model numbers, and what's the AHRI reference number for this combination?
- What does the price include, and what would cost extra if you find it once work starts?
- Will the job be permitted and inspected, and who makes the gas and electrical connections?
- When can you start, and how many days will the work take?
- Who registers the manufacturer warranty, and who pays for labor if a part fails in the first few years?
- For a heat pump: are you in the Mass Save Heat Pump Installer Network, and is this equipment on the Mass Save qualified products list? Both are required for the 2026 rebates.
How a contractor answers matters as much as the number at the bottom. Specific, unhurried answers usually come from someone who has actually thought through your job.
How OniFix approaches it
OniFix looks at the system and the house before pricing a replacement, and you get the estimate up front, before any work starts. Nothing begins until you agree to it. The page on how a visit works lays out each step. If you already have quotes in hand and want another to set beside them, request a quote and OniFix will get back to you to set up a visit.
Sources: AHRI, how and why of certified ratings; Mass Save, air source heat pump rebates; 248 CMR 3.00, plumbing and gas fitting work; Mass.gov, electricians consumer fact sheet.