How to compare furnace replacement estimates beyond the price

Compare furnace estimates by the equipment and work included, then compare their totals. Ask each installer to identify the model, explain how the capacity was selected and put installation changes in writing. Two prices are not directly comparable if one includes work the other leaves undecided.

If you are still deciding whether to replace the unit at all, start with repair or replace: when an old furnace is worth fixing. This checklist is for the next step, when you have replacement proposals in front of you.

What should the contractor check before quoting?

Expect questions about your existing system, uncomfortable rooms and the house itself. ENERGY STAR’s contractor-selection guide recommends a home evaluation that considers insulation, windows and the duct system. Its guidance also calls for checking duct leakage and airflow, rather than choosing equipment only from the old unit’s label.

Prepare a short note with the current model, maintenance history and rooms that feel too hot or too cold. Mention changes since the system was installed, such as replacement windows or a newly finished space. These are useful inputs to the sizing discussion, not instructions to buy a larger furnace.

Which details should match across proposals?

Build a comparison sheet with one column for each estimate. Mark missing information as “not specified” instead of assuming it is included.

Item	Question to put to the installer
Equipment	What exact model and capacity are being supplied?
Sizing	What evaluation or load calculation supports that selection?
Efficiency	What efficiency does the proposed model have, and what assumptions support any savings estimate?
Installation	What connections, venting or duct changes are included?
Controls	Is the existing thermostat compatible, or is a replacement included?
Administration	Who handles applicable permits and inspection arrangements?
Removal	Is removal of the old equipment and cleanup included?
Completion	What startup checks and homeowner instructions will be provided?

The purpose is to make differences visible. If one proposal includes a duct modification, ask what observation led to it. If another omits it, ask how that proposal addresses the same condition.

Should the replacement have the same capacity as the old furnace?

Not automatically. Ask the installer to explain the selection for the house as it is now. ENERGY STAR cautions that a larger system is not necessarily an improvement and connects sizing to the house’s characteristics. Its home-evaluation guidance is a useful starting point for that conversation.

Avoid deciding from floor area alone. Have the proposal document the basis of the choice so you can compare the reasoning, not just two model numbers.

What should be settled before signing?

Ask for a written scope, a proposed start window, payment milestones and a process for additional work. Record any promised equipment or labor coverage in the agreement, including who you contact if a problem develops. Ask which items depend on a site check or approval and what happens if the equipment selection changes.

A verbal assurance is difficult to compare later. Keep the proposal, any revisions and the final equipment details together.

Common questions

Can I compare two different brands?

Yes. Compare the specified capacity, efficiency, controls and installation work alongside the model information. A brand name does not tell you whether the two proposals cover the same job.

Should I choose the smaller total?

First resolve missing scope. Ask both installers to price the work you actually need and explain optional items separately. That gives you a clearer choice than comparing totals with different inclusions.

What information should I have ready for a visit?

Have the system model, service records if available, access to the equipment and a list of comfort problems. You can learn about our furnace replacement service or request an estimate. Our heating and cooling guides cover related planning questions.