Wood pellet A1 vs A2 vs B — ENplus class differences for the 2026/2027 season
The 2026/2027 season on the Polish wood pellet market begins with the same question that comes up in trading conversations every year: A1, A2 or B — which class should you buy? The answer is: it depends on the boiler, on the end customer, and on whether you are selling a 15 kg bag to a single-family home or bulk in a tanker to a district heating plant. The ENplus class is not marketing — these are hard fuel parameters that translate into how often the burner needs cleaning, the lifespan of the heat exchanger and the number of complaints from the end customer.
At BGT we import ENplus A1 and A2 wood pellet from Kazakhstan, Vietnam and Portugal — for fuel depots, solid-fuel wholesalers and smaller heating plants. In this post we explain how ENplus A1, A2 and B classes differ, where each of them makes economic sense, how to verify a certificate so that you do not end up buying "premium pellet" from a paper bag with nothing behind it, and why the price difference between A1 and A2 is never twofold — even though some sellers occasionally try to present it that way.
We are writing from the perspective of a B2B market practitioner: less PR, more numbers. If you are looking for a short answer — scroll to the comparison table and the "Who should pick A1, who A2, who B" section. If you want to understand why 0.02% chlorine in A1 is not a whim but concrete protection against heat exchanger corrosion — read from the top.
What is the ENplus system
ENplus is an international quality certification system for wood pellet, managed by the European Pellet Council (EPC) at the European Biomass Association (Bioenergy Europe) in Brussels. In Poland the national operator is the Polish Pellet Council, which issues ENplus numbers to Polish producers and distributors (identification number in the PL-XXX format).
ENplus is not identical to a technical standard — it is based on ISO 17225-2 (the specification of wood pellet for low-emission applications), but it imposes additional organisational requirements: producer audits, chain of custody, mandatory testing in accredited laboratories, and controls on bagging and logistics. In other words: ISO 17225-2 says what the pellet should be. ENplus adds: who checks it, how often and what happens if the producer cheats.
There are three ENplus classes: A1 (highest quality — domestic boilers), A2 (good quality — domestic boilers and lower-power industrial boilers) and B (industrial quality — installations designed for higher ash content). Each class has a separate set of limit values for all critical fuel parameters.
Class A1 — parameters and application
A1 sits at the top of the wood pellet quality ladder. It is produced from clean stem wood and chemically untreated wood residues from sawmills — no bark, no boards, no recycled wood.
Key limit parameters for A1 (per ISO 17225-2 / ENplus):
- Ash content: ≤0.7% (dry basis)
- Calorific value (NCV): ≥16.5 MJ/kg (as received) / ≥4.6 kWh/kg
- Chlorine content: ≤0.02%
- Sulphur content: ≤0.04%
- Nitrogen content: ≤0.3%
- Moisture: ≤10%
- Mechanical durability: ≥98.0%
- Ash deformation temperature (DT): ≥1200°C
- Bulk density: 600–750 kg/m³
- Diameter: 6 or 8 mm
What A1 is for: domestic automatic pellet boilers (Kostrzewa, Defro, Galmet, Heiztechnik, ETA, Fröling), 5th class and ecodesign boilers, where the manufacturer requires ENplus A1 fuel in the warranty card. Retail customers, developers offering buildings with a pellet-based heat source, prosumers combining PV with a pellet boiler. Low ash content (<0.7%) means that a domestic boiler user empties the ash pan once every 2–4 weeks under normal use — not once a week.
Class A2 — parameters and application
A2 permits a broader range of raw material: chemically untreated round wood with bark and some sawmill residues may be used. The result: slightly higher ash and nitrogen content, but still fully "pellet-grade" material — safe for boilers with an automatic retort or piston burner.
Limit values for A2:
- Ash content: ≤1.2% (note: the incorrect value of 1.5% is often quoted — the ENplus limit in force since the ISO 17225-2 update is 1.2%)
- Calorific value (NCV): ≥16.3 MJ/kg / ≥4.5 kWh/kg
- Chlorine content: ≤0.02%
- Sulphur content: ≤0.04%
- Nitrogen content: ≤0.5%
- Moisture: ≤10%
- Mechanical durability: ≥97.5%
- Ash deformation temperature (DT): ≥1100°C
- Bulk density: 600–750 kg/m³
What A2 is for: pellet boilers with a tolerance for higher ash content (most modern automatic boilers 100–500 kW), smaller estate heating plants, boiler rooms in public buildings (schools, health centres). A2 is also the typical choice for fuel depots serving customers with older or structurally simpler boilers, where the price difference vs A1 realistically shifts the profitability of the heating season for the customer.
Class B — parameters and application
B is the industrial class. It permits raw material from orchard and plantation wood, recovered wood (chemically untreated) and even some bark. It is not suitable for domestic boilers — it will trigger alarms, block the burner and void the boiler manufacturer's warranty.
Limit values for B:
- Ash content: ≤2.0% (dry basis)
- Calorific value (NCV): ≥16.0 MJ/kg / ≥4.4 kWh/kg
- Chlorine content: ≤0.03%
- Sulphur content: ≤0.04%
- Nitrogen content: ≤1.0%
- Moisture: ≤10%
- Mechanical durability: ≥97.5%
- Bulk density: 600–750 kg/m³
What B is for: professional heating plants, co-firing CHP plants, industrial installations with a moving grate or an automatic ash removal system, high-power burners (500 kW and above). Class B rarely ends up in 15 kg bags for the individual customer — it is more often sold in bulk, by tanker or in big bag 1000 kg.
Comparison table — A1 vs A2 vs B
| Parameter | ENplus A1 | ENplus A2 | ENplus B |
|---|---|---|---|
| Ash (dry basis) | ≤0.7% | ≤1.2% | ≤2.0% |
| Calorific value (NCV) | ≥16.5 MJ/kg | ≥16.3 MJ/kg | ≥16.0 MJ/kg |
| Chlorine | ≤0.02% | ≤0.02% | ≤0.03% |
| Sulphur | ≤0.04% | ≤0.04% | ≤0.04% |
| Nitrogen | ≤0.3% | ≤0.5% | ≤1.0% |
| Moisture | ≤10% | ≤10% | ≤10% |
| Mechanical durability | ≥98.0% | ≥97.5% | ≥97.5% |
| Ash deformation temp. (DT) | ≥1200°C | ≥1100°C | no requirement |
| Bulk density | 600–750 kg/m³ | 600–750 kg/m³ | 600–750 kg/m³ |
| Diameter | 6 or 8 mm | 6 or 8 mm | 6 or 8 mm |
| Length | 3.15–40 mm | 3.15–40 mm | 3.15–40 mm |
| Application | domestic boilers | domestic + small industrial | district heating, industry |
How to verify an ENplus certificate
An ENplus certificate is not a sticker you can generate in Photoshop. Every producer, bagger and distributor has a unique identification number in the format country code + number, e.g. PL-XXX (Poland), AT-XXX (Austria), PT-XXX (Portugal), KZ-XXX (Kazakhstan), VN-XXX (Vietnam).
Step by step:
- Check the number on the bag or in the delivery note. It should be visible next to the ENplus logo in the ID + class code format.
- Go to the register: enplus-pellets.eu → "Find certified pellets" section.
- Enter the number. The system will show the full data: company name, country, certificate class, expiry date and status (active / suspended / withdrawn).
- Compare with the label. If the bag reads "PL-042 A1" but the register shows "PL-042 = A2" or the status "suspended" — you are dealing with an outdated or counterfeit marking.
An ENplus number does not identify a single producer forever — it applies to a specific plant and class. One company may hold several numbers if it runs several production lines. The bagger's number differs from the producer's number — for the end customer the bagger is what matters, because they are responsible for the quality of the pack on the pallet.
Pellet ISO 17225 vs ENplus — which standard to follow
ISO 17225-2:2021 is the international technical standard describing wood pellet parameters. The classes in ISO 17225-2 are called A1, A2 and B — the same abbreviations, the same numerical thresholds. You can come across a producer saying: "we meet ISO 17225-2 class A1, we don't have ENplus because it's too expensive".
The difference lies in the control system:
- ISO 17225-2 is a declaration of parameters. The producer can test it themselves (or not at all). A system certificate is not required.
- ENplus is a system based on ISO 17225-2 + mandatory external audits + reports from accredited laboratories + bagging controls + a public register.
For a heating plant signing a contract for 5000 t per year the difference is fundamental: ENplus provides an appeal body (the Polish Pellet Council, EPC) to which a quality complaint against the producer can be filed. ISO 17225-2 without system certification does not. In practice: ENplus for bags and smaller boiler rooms; ISO 17225-2 may be sufficient for industry, provided your contract stipulates SGS/Intertek testing at every delivery.
Price vs class — is A2 twice as cheap as A1
Short answer: no. The actual price spread A1 vs A2 in the 2026/2027 season on the European market (loco terminal Gdańsk / Świnoujście, bulk) ranges between 8–15% — meaning that if A1 costs PLN 1150/t, A2 will be PLN 985–1060/t. The reason: the raw material base partially overlaps (the same pine sawdust, the same pressing process), the difference lies in the selection of the input material and ash control.
The spread B vs A1 is higher — 15–25%, because the raw material for B (orchard wood, bark, some residues) is cheaper and more widely available.
When a seller offers A1 at the A2 price (spread <5%), it is worth asking for the ENplus number and checking the register. When they offer "premium A1" 30% above the market average — we ask what exactly "premium" means and whether it is an additional parameter beyond ENplus (e.g. bulk density >720 kg/m³, ash <0.4%) or just a better marketing brochure.
Pitfalls: counterfeit bags, no certificate, producer's declaration
The three most common quality problems the market brings back to BGT:
-
Counterfeit bags with the ENplus logo. A classic: a PL-XXX number belonging to another producer, printed on a bag without the number holder's consent. Verification: the enplus-pellets.eu register. If the number does not belong to the company on the bag — file a complaint and report it to the Polish Pellet Council.
-
"Class A1" with no certificate. The producer declares A1 parameters but has no ENplus number. Technically legal, but there is no independent verification. In practice: the parameters often drift over the course of the season, and at the heating plant this becomes visible in the ash pan.
-
Producer's declaration instead of a certificate. An A4 sheet signed by the producer with parameters "≤0.7% ash, ≥16.5 MJ/kg". No accredited laboratory, no auditor, no register. Worth as much as the paper it is printed on — we do not accept this as proof of quality in BGT contracts.
An additional pitfall when importing from outside the EU (Kazakhstan, Vietnam): the ENplus certificate for non-European supplies must be issued by the national operator (e.g. KZ-XXX, VN-XXX). It happens that the producer shows an ISO 17225-2 certificate but claims it is "the same as ENplus". It is not. For BGT deliveries from Kazakhstan and Vietnam we require an ENplus certificate + an SGS/Intertek test report for every delivery — parameters confirmed by an independent laboratory before customs clearance.
Who should pick A1, who A2, who B
A1 — take it if:
- you sell 15 kg bags to individual customers through a fuel depot,
- your customers have modern 5th class / ecodesign boilers with "ENplus A1" written into the warranty,
- you want to avoid "too much ash" complaints,
- high margin > volume.
A2 — take it if:
- you run a wholesale operation serving a mixed market (domestic boilers + small boiler rooms),
- customers ask about price but still have an automatic burner,
- you want to optimise the profitability of the season (price spread vs A1 = 8–15%),
- you have industrial off-takers <500 kW.
B — take it if:
- you supply a district heating plant in bulk or in big bags,
- your off-taker has a moving grate or a burner designed for 2% ash,
- the buyer is a professional energy company with its own inbound laboratory,
- volume > margin.
FAQ
1. Is A1 pellet from Kazakhstan the same as A1 from Portugal? By parameters — yes, if both hold a valid ENplus A1 certificate (KZ-XXX vs PT-XXX). In practice: differences may occur in bulk density, pellet length and wood type (pine vs eucalyptus). Calorific value ≥16.5 MJ/kg — both meet it. For the end customer usually indistinguishable.
2. Can I mix A1 and A2 pellet in one silo? Technically yes — after mixing the fuel will have parameters worse than A1, better than A2. Formally, however, you lose the right to sell it as A1 or A2 (mixing classes is not permitted when selling with a class marking). For your own heating plant — no problem, provided the boiler tolerates the higher ash content.
3. What does "mechanical durability 98%" mean? The share of pellet that survives the tumbling test (per ISO 17831-1) without breaking up. Below 97.5% in a domestic boiler means a lot of dust in the burner, more frequent auger blockages and higher particulate emissions in the flue gas.
4. Can ENplus A1 have 0.3% ash? Yes — the threshold is ≤0.7%, but good A1 pellets (e.g. from mountain pine, sapwood) actually run at 0.3–0.5%. This is the marketing boundary of "premium A1" — some producers sell it as a separate product, but formally it is still ENplus A1.
5. Have the ENplus thresholds changed for the 2026/2027 season? No. The ENplus thresholds are harmonised with ISO 17225-2:2021 and have not changed since the 2021 update. The next revision of the standard is in consultation, but before the 2027/2028 season the limit values remain identical to the table above.
Summary and BGT recommendation
For 90% of pellet buyers in Poland in the 2026/2027 season we recommend class A1 for retail bags and A2 for bulk / tanker / big bag for industry <500 kW. Class B is worthwhile only in professional heating plants with automated ash removal — beyond that it generates more operational problems than real savings.
When ordering, what matters:
- The ENplus number visible in the offer and verifiable at enplus-pellets.eu,
- A test report from an accredited laboratory for every delivery (SGS, Intertek, Bureau Veritas, ITB),
- A complaint clause in the contract — parameters deviating from ENplus should result in a price reduction or return of the batch.
BGT imports ENplus A1 and A2 wood pellet from Kazakhstan, Vietnam and Portugal, in bulk and in big bag 1000 kg, delivery loco terminal Gdańsk / Świnoujście or with road / rail transport to the customer's depot. We are happy to discuss orders for the 2026/2027 season — with concrete numbers, SGS test reports and a delivery schedule.
