Two quotes, thousands apart: which lines explain the gap?

A total tells you what a contractor will charge. It does not tell you what you will get. Two bids at different prices may both be fair, because they describe different jobs.

The way to compare is to read each quote for the same set of lines. Anything missing from a quote is a question for that contractor, not a saving.

This guide goes through the lines in the order that matters. Keep a pen handy and tick them off.

Each quote should name the equipment by model and give its capacity. Then ask how that capacity was chosen. The answer should be a load calculation, with a worksheet you can keep.

New York's residential code calls for sizing under ACCA Manual S from loads calculated under Manual J, or another approved method. If a quote names a size and no basis, ask for the basis. Our guide on sizing explains what the worksheet should show.

A condensing furnace or boiler cannot vent into an old masonry chimney. Oak Ridge National Laboratory lists the usual alternatives: a new side wall vent, a new vent run up through the house, or the old chimney reused as a chase for the new pipe. It says each adds cost compared with swapping like for like.

Then look at the water heater. If a gas water heater shares the chimney, the new furnace leaves it alone in a flue sized for two. The laboratory says the draft may then be too weak and the exhaust can spill back into the basement. The federal checklist for furnace replacement says a contractor must tell the homeowner the fix, a chimney liner being its example.

Look for the words liner, draft inducer or water heater on the quote. If you see none of them, get the contractor to state in writing how the water heater is handled, even if the answer is that nothing needs to change.

Ask also where a side wall vent will exit. It has to clear windows and doors and sit above the highest snow, drifts included. Ask to be shown the spot on your house.

The best equipment is wasted if the ducts or pipes cannot carry what it delivers. A quote should say whether the ducts were measured, and list any changes: a new return, a larger trunk, a sealed run.

For a boiler, the equivalent is the piping, the circulator and the radiators. A quote that replaces a boiler and says nothing about the system it feeds leaves you guessing what stays.

If a bid is silent on this, ask a simple question: what did you check, and what did you find? A contractor who looked can answer in a sentence.

Scope is what leaves the house and what arrives. It should name removal of the old unit, any tank or old piping that goes with it, the new equipment, the connections for gas, power and drain, and the start-up. Ask what is excluded, and what would change the price.

Ask about cleanup. Ask who is on site and when. A short list in plain words is better than a long page of terms.

Your town or village decides whether a permit is needed for replacement work. State rules let a local program exempt some like-for-like equipment swaps, and each municipality chooses. Ask the contractor who files the permit and when you will see it, and ask your own code office if the answer is unclear.

New York has no statewide HVAC contractor license. The Department of State says licensing is a local matter. The city of Syracuse runs its own Board of Mechanical Examiners, and publishes a list of license holders. Ask each contractor for the local license, if your municipality has one, and for their insurance certificate.

We do not vouch for any contractor's credentials, so ask for each paper yourself.

The quote should give a start date or a range, the steps at which payments are due, and the person to call about a problem. Read the payment steps and ask what happens if the schedule slips.

If any quote asks for a large payment before work starts, ask what it covers. You can decide whether that suits you.

A good quote names what you are buying. Look for the make and model of the main unit, and for the matching parts: the coil that goes with an outdoor unit, the thermostat, any controls. A quote that says only a high efficiency furnace or a three ton air conditioner leaves you unable to compare it with another.

Once you have the model names, you can look up each unit's published ratings yourself. For a heat pump, look for its output at low outdoor temperatures. For a furnace, look for its venting category and what it needs for a vent. Ask the contractor to confirm anything you cannot find.

Several quote habits are worth asking about. A price that expires in a few days is a question: why that deadline? A line that says miscellaneous is a question: what is in it? A scope that says as needed is a question: needed when, and who decides?

You do not have to treat these as accusations. Ask them in the same calm tone you would use to ask about the date. The answer tells you how the contractor works.

Compare lines. Count how many of the lines above each quote fills in.

If two quotes have the same size basis, the same vent plan and the same duct notes, the difference is in price. If one leaves out the vent plan or the water heater, the difference is in scope. Ask each contractor to list in writing everything that is not included.

Make a simple grid. Down the side, list the lines: size, vent, water heater, ducts or pipes, scope, permit, papers, dates. Across the top, write one column for each quote.

Fill each cell with a tick, a blank or a note. After ten minutes you can see which quote is the full job and which is missing lines. A quote with blanks is a list of questions.

If you want help with the questions, send your details. We do not price the work and we do not install it. We give you the questions and introduce a local contractor, and you choose whether to book.