The Last Furnace pages are written to be accurate, useful and honest about where each number comes from, and about what an estimate cannot know. This page sets out how that works and where its limits are.
How a page is made
- Research. We start from primary sources and from our rules and cost registers, and note what they do and do not settle.
- Writing. A draft is written from that research under the name The Last Furnace.
- Fact-check. A separate check compares each price, rate, rebate, date, rule and specification with its source, and reworks every sum on the page.
- Graphics. Any charts or diagrams repeat figures from the text and add no new facts.
- Final review. A last read looks for errors, gaps, unsafe advice and any lean toward one answer. If it finds a serious problem, the page is fixed and reviewed again. We do not publish a page with a serious problem still open.
Each page ends with the date its sources were checked. No process catches everything, so please tell us if you find a mistake.
Neutrality: the furnace gets a fair hearing
Our name leans toward heat pumps. Our pages must not. Our about page explains what the name asks, and these rules keep it a question:
- We say plainly when a furnace wins. Pages in our furnace or heat pump guides say when a furnace is the better call, with the numbers.
- The final review of those pages asks one question: would a reader who should keep the furnace leave knowing that?
- Calculators treat both results alike. A negative saving means the furnace costs less to run, and the page says so.
- Going back to gas is written up as a normal decision.
- Sellers’ claims are reported as claims, with a link to the sheet. State programs that promote heat pumps are reported with their stated assumptions too.
- A rated COP is never written as what a home will get.
Our sources
Every price, rate, tax rule, rebate, limit, date, specification and safety statement links to a primary source at the claim. We use sources such as the tax code and the IRS, Department of Energy program notices, EPA rules and the Federal Register, state program and utility documents, the Energy Information Administration, ENERGY STAR, NOAA, and makers’ data sheets and manuals.
Installed prices are the exception, because most have no primary source. Those live on our sister site CostPlain. When one appears here, it is a named, dated published estimate, labelled with what it measures, and never averaged with others. Rules differ by state and utility, so we name the places we have read and never state a national rule that does not exist. If we cannot confirm something, we leave it out or say plainly that it is unconfirmed. Our how we estimate page explains the method.
What we do not claim
- We have no crew and install nothing. We never say “we tested” or “we installed”, and we do not claim to have done the work we describe.
- We do not invent authors, quotes, homeowner stories or technician comments.
- We do not publish “best” rankings of brands, products or installers.
- We never tell you that you qualify for a program, that a price is fair or that a purchase is worth it. We give estimates. A qualified installer, the program or a tax professional decides.
- Photos are stock images chosen to illustrate a topic. They do not show jobs we have done or homes we have seen.
Safety
Heating equipment involves refrigerant, high voltage and combustion gases, so a how-to can do harm. We follow these rules:
- Refrigerant. No page tells you to add, top off, recover, vent or charge refrigerant, or to open a line. That work is for technicians certified under EPA Section 608. Low refrigerant means a leak and a technician.
- Electrical. Your checks stop at what the maker’s manual allows, such as thermostat mode, the filter and clear airflow. Capacitors, contactors, control boards, disconnects and wiring go to a technician or licensed electrician. We quote the maker’s electrical figures, not circuit or breaker sizes of our own.
- Carbon monoxide. Removing a furnace can leave a gas water heater on a flue that no longer suits it. That is a must-check for a qualified person. Capping gas lines and removing oil tanks are jobs for licensed trades, with no how-to here.
- Frozen pipes. We flag the risk when combustion heat is shut off, as a question to ask before the work starts.
- Ice and snow. We follow the maker’s manual: no chipping ice, no hot water, and no opening the unit unless the manual says so.
- Emergency heat. We explain what it is and why it costs so much, and we do not suggest living on it instead of getting a fault fixed.
- Lower-flammability refrigerants. We describe them as lower flammability and give no charge limits. A leak-detector alarm is a matter for the maker’s manual and a technician.
- Permits. No page advises skipping a permit or inspection. Where we have not read the local rule, we say to ask the local building department.
Calculators
Our calculators are formulas with named inputs and shown working, and each formula is checked against answers worked by hand before it goes live. Every default that is a price, rate, efficiency, temperature or capacity says where it comes from and when, or that it is our assumption, and you can change it. Calculators print numbers only, so read the notes on the page around them. No calculator replaces a load calculation for your house.
Updates and corrections
Rebates are rechecked monthly, other rules at least every three months, and prices through the heating season as new data come out. Rebates that change on 31 December get a recheck in mid-December and again in January. A page shows an updated date only when its content really changed. Errors are fixed and recorded on our corrections page.
Advertising and independence
Display advertising pays for this site, and advertisers have no say over what we publish. We use no affiliate links, accept no paid placements, sell no leads, give no quotes and make no installer referrals. Our disclaimer sets out the limits of what we publish.