Home Methodology
How we build every page EPA data first and gaps marked
Every number on this site comes from one of four places: the EPA Certified Wood Heater Database, the federal rule itself, the maker's own documents, or a government source such as the IRS or USDA. We link the source next to the value and date it. When we can't find a source, the value reads not yet verified.
Where the Numbers Come From
| Data | Source | How we use it |
|---|---|---|
| Tested heat output range, HHV efficiency, particulate, carbon monoxide, firebox volume, test fuel | EPA Certified Wood Heater Database, from its Excel export | Copied as listed; where a listing prints the low and high output in reverse order, we put the smaller first |
| Emission limits, test methods, labels, fuel rules | eCFR, 40 CFR 60 subparts AAA and QQQQ | Quoted with a section link |
| Maker claims: advertised BTU, heating area, efficiency, burn time, logs, hopper, price | Product pages, brochures, owner’s manuals and certification reports from each maker | Quoted as claims, with the document linked |
| Tax credit status and rules | IRS and ENERGY STAR | Summarized with links; not tax advice |
| Fuel heat content | USDA Forest Products Laboratory Fuel Value Calculator | Gross heat values used in the calculator |
| Rulemaking schedule | Unified Agenda, RIN 2060-AU07 | Deadlines as published |
Every value on a stove page carries a link to its source and the date we checked it. The current data set was checked on October 21, 2026. A script cross-checks every EPA figure on our stove pages against the EPA export before each update goes live.
We Don’t Test Stoves
We don’t run hands-on tests. Output, efficiency and emissions on this site are the EPA certification results, measured by EPA-approved labs. Everything else, including burn times and heating area, is the maker’s claim, labeled as such. Where neither exists, we say so. We think the certification record is the fairest comparison there is, because every stove was measured the same way, and you can check each number yourself.
Reading an EPA Listing
Each listing in the EPA database covers a model line, which can include several names and an insert version. From each listing we take:
- Heat output range (BTU/hr). The lowest and highest heat output measured across the test burn rates. It’s the best single guide to sizing. See stove BTU ratings explained.
- Efficiency. The weighted average overall efficiency across the burn rates, on the higher heating value (HHV) basis, measured under CSA B415.1-10 (40 CFR 60.534). See HHV vs LHV.
- Particulate emissions (g/hr). The certified weighted average, compared against the 2020 limits of 2.0 g/hr on crib wood or pellets and 2.5 g/hr on the cordwood option.
- Carbon monoxide (g/min), firebox volume (cu ft), test fuel and 2020 compliance, as listed.
When a maker’s page and the EPA listing disagree, we show both and say which one is current. When a model has more than one listing (a newer version, say), we name the other one.
How We Compare Claims
On every stove page, the “Maker Claims vs the EPA Listing” section lines up the maker’s own words with what’s on file. We work out two simple ratios for every stove:
- Advertised ÷ tested: the headline BTU figure divided by the EPA maximum output.
- Tested BTU/hr per advertised square foot: the EPA maximum divided by the top of the maker’s heating area claim. Castle’s manual sizes at 35 BTU/hr per square foot for post-1982 construction; every area claim in our database works out below that.
The Calculator
The calculator uses only figures from the sources above: each stove’s EPA maximum output and HHV efficiency, USDA’s gross heat content for seasoned firewood (20 million BTU per cord at 20% moisture) and premium pellets (16.4 million BTU per ton), and the fuel prices you enter. We don’t publish fuel prices because they vary too much by region and season.
Community Research
We read r/woodstoving, r/PelletStoveTalk and the hearth.com forums through their public RSS feeds to learn what buyers ask and how they describe it. We quote threads with a link; we never use forum posts as a source for specs.
“Not Yet Verified”
A value marked not yet verified means we haven’t found a primary source for it. It doesn’t mean the feature is missing. We’d rather leave a gap than fill it with a retailer listing or a guess.
Affiliate Disclosure
Stove Specs may earn a commission when you buy through some retailer links, at no extra cost to you. As of October 21, 2026, the site has no affiliate links; every stove page has a “Where to buy” box ready for them. When links are added, they’ll be marked “Check Price” with a disclosure right beside them, and they’ll use rel="sponsored". Commissions will never change our data, our picks or the order we list stoves in, and every stove gets the same box whether or not it earns us anything.
Corrections and Updates
Makers revise specs and EPA adds listings. If you spot an error, the fix is to point us to a better source; we update the value and the checked date.
- October 21, 2026: launched with 12 stoves, the full EPA database (306 listings), a heating and fuel calculator, 5 comparisons and 7 guides. All data checked October 21, 2026.
Glossary
- BTU/hr: British thermal units per hour, the rate of heat output. One BTU heats one pound of water by 1°F.
- HHV / LHV: higher and lower heating value. HHV counts the energy in the water vapor from combustion; LHV doesn’t, so LHV efficiencies read higher.
- Crib wood: the standardized test load of dimensional lumber used in most certification tests.
- Cordwood: split firewood. The 2020 rule allows a cordwood test option with a 2.5 g/hr limit.
- Catalytic / hybrid / non-catalytic: whether the stove burns its smoke with a catalytic combustor, a combustor plus secondary air, or secondary air alone.
- Step 2: shorthand for the 2020 emission standard.
- QMID: Qualified Manufacturer Identification Number, required on 2025 returns to claim the 25C credit.