⚙️ Testing of mechanically fed wood pellet appliances — product part PN-EN 16510-2-6

Construction PN-EN 16510-2-6

Overview

SCOPE FROM THE PKN CATALOGUE CARD, QUOTED VERBATIM (our translation): "This document applies to space heating appliances and cookers with mechanical feeding of wood pellets with a nominal heat output of up to 50 kW. These appliances are intended for space heating in residential buildings and for cooking. They may be equipped with a boiler (an integral part of the appliance containing water to be heated) for supplying hot water to central heating installations. These appliances usually use auxiliary energy, which measurement is also in this document. They may be supplied with combustion air by natural draught or assisted by a fan. These appliances burn exclusively wood pellets, according to the specification. They operate only with the fire door closed."

LANGUAGE NOTE: the sentence about auxiliary energy comes from the catalogue card in the wording that PKN gives for the English version of the standard ("która pomiar jest również w tym dokumencie" — literally "which measurement is also in this document"). The meaning is unambiguous — the consumption of auxiliary energy is one of the quantities measured according to this product part — but the sentence itself is ungrammatical in the source and we quote it verbatim, without correcting it.

THREE THINGS THAT ARE NOT IN THE OTHER PRODUCT PARTS OF THE SERIES. First — the output limit: a nominal heat output up to 50 kW, whereas product parts 2-1, 2-2 and 2-3 do not give such a numerical limit in their scope. Second — auxiliary energy: the appliances usually use it (feeder, fan, controller), and its measurement belongs to the scope of the product part. Third — an assisting fan is PERMITTED here, whereas in product parts 2-1 and 2-3 it is an exclusion. The last of these decides the choice of product part for a pellet appliance.

ONE FUEL, ONE MODE OF OPERATION. The appliances covered by this product part burn EXCLUSIVELY wood pellets according to the specification and operate ONLY with the fire door closed. There is no variant of operation with the door open here, which product parts 2-1 and 2-2 allow.

NINE TYPES INSTEAD OF SIX. The notified laboratory (Institute of Power Engineering — PIB, CUE Department) describes that for roomheaters, inset appliances and cookers with mechanical feeding of wood pellets nine types have been distinguished, whereas for appliances of product parts 2-1 and 2-2 there are six. Pellet heaters additionally have types CM50, CC50 and CC50+.

TIGHTNESS TESTED AT A DIFFERENT PRESSURE THAN FOR APPLIANCES OF PRODUCT PARTS 2-1 AND 2-2. The same source states that heaters of type CM50, CC50 and CC50+ are tested at three pressure values from 25 to 75 Pa, and the result read from the curve drawn through these points refers to a pressure of 50 Pa and should not be greater than 1 m³/h for type CC50+ and 3 m³/h for types CM50 and CC50, both these leakage values being referred to standard conditions. For comparison: appliances with a closed combustion chamber of product parts 2-1 and 2-2 are tested at overpressures from 5 to 15 Pa with reference to 10 Pa.

TEST DURATION — SIX HOURS, WITH A CONDITION OF AGREEMENT BETWEEN PERIODS. According to the same source, the test duration for mechanical heaters fired with pellets is 6 hours. At nominal heat output it may be divided into two equal periods preceded by a stage of stabilisation of the operating conditions, and each of the periods is valid only if its result does not differ from the mean value by more than 10 %. The part-load test lasts 6 hours and is a continuous process. The measurement of dust emission for this group of appliances is carried out in a 30-minute cycle, starting with a period without aspiration.

FIRE SAFETY — SENSORS IN THE HOPPER AND FEEDER. The source describes that in appliances with mechanical pellet feeding the fuel hopper and the feeder are fitted with a set of temperature sensors according to the grid given in the standard, and the test is continued until there is no further rise in the temperatures of the measuring walls. The temperature in the radiation zone in front of the heater and at its side is measured and recorded, and the recorded values must not exceed the ambient temperature by more than 65 K.

NEW SAFETY TESTS THAT THE OLD STANDARD DID NOT HAVE. The source indicates them explicitly as new for pellet heaters and cookers: the test of loss of heat removal (checking the operation of the safety temperature limiter), the test of electrical power failure and the check of the operation of the temperature controller. They result from the fact that a pellet appliance depends on auxiliary energy — a power interruption stops the feeder and the fan, but does not extinguish the fuel already in the firebox.

WHY THIS PRODUCT PART APPEARED ONE DAY LATER THAN THE OTHERS. Product parts 2-1, 2-2 and 2-3 were published on 01-06-2023, and product part 2-6 — on 02-06-2023. On the same day PN-EN 14785:2009 was withdrawn. Pellet appliances were therefore the only group for which the old product standard remained in force without interruption until their own product part appeared; the other groups passed in 2018 under the general part PN-EN 16510-1 before their product parts were created.

THE PRODUCT PART DOES NOT WORK ON ITS OWN. It is ALWAYS applied together with the general part PN-EN 16510-1, which contains the test methods common to the whole series. Citing product part 2-6 alone in an accreditation scope is not enough to describe the test; citing part 1 alone, in turn, does not indicate the type of appliance. Both documents should be in the report.

WHAT WE DO NOT GIVE. We did not have the text of the product part — PKN sells it (44 pages, English version). WE DO NOT GIVE: the emission and efficiency limit values, the pellet specification, the method of referring concentrations to the oxygen content of the flue gas, the grid for positioning the sensors in the hopper or the rules for calculating the results.

Method principle

The pellet appliance is installed on a test rig and run through a cycle of operation lasting many hours at nominal and partial output, while thermal quantities, the composition of the flue gas and the consumption of auxiliary energy are measured. Product part 2-6 adds to the general part of the series: a tightness test carried out at higher pressures than for appliances with manual fuel feeding, cyclic measurement of dust emission, fitting the hopper and the feeder with temperature sensors for the fire safety test, and tests of the behaviour of the appliance on loss of heat removal and on electrical power failure.

Applications

• Initial type testing (ITT) of roomheaters, inset appliances and cookers with mechanical feeding of wood pellets
• Tests of pellet appliances with an integrated boiler supplying a central heating installation
• Safety tests on electrical power failure and loss of heat removal
• Tests for the declaration of performance of a construction product in system 3
• Updating of citations in the accreditation scope after the withdrawal of PN-EN 14785:2009

Key parameters

Standard

Standard number

PN-EN 16510-2-6:2023-06 (wersja angielska; wprowadza EN 16510-2-6:2022 [IDT])

Title (PL)

Mieszkaniowe urządzenia spalające paliwo stałe — Część 2-6: Ogrzewacze pokojowe, urządzenia zabudowane i kuchenki z mechanicznym podawaniem pelletu drzewnego

Title (EN)

Residential solid fuel burning appliances — Part 2-6: Mechanically fed wood pellet roomheaters, inset appliances and cookers

Step-by-step procedure

1. Checking whether the appliance belongs to this product part

   Mechanical feeding of wood pellets and a nominal heat output up to 50 kW. A pellet appliance with manual feeding belongs to product part 2-1 or 2-3 — the method of fuel feeding decides, not the fuel itself.

2. Assigning the type of appliance

   Nine types have been distinguished for this group, including CM50, CC50 and CC50+. The leakage limit values in the tightness test depend on the type.

3. Tightness test

   Measurement at three pressure values from 25 to 75 Pa; the result read from the curve refers to a pressure of 50 Pa and is compared with the limit value appropriate to the type of appliance.

4. Test at nominal heat output

   Test duration 6 hours, after a stage of stabilisation of the operating conditions; division into two equal periods is allowed, each period being valid only if its result does not differ from the mean value by more than 10 %.

5. Test at partial output

   Test duration 6 hours, a continuous process, without division into periods.

6. Measurement of emissions and auxiliary energy

   Dust emission measured in a 30-minute cycle, starting with a period without aspiration; in parallel, measurement of CO, NOx and OGC referred to the oxygen content of the flue gas adopted in the standard and measurement of the consumption of auxiliary energy.

7. Safety tests specific to pellet appliances

   Fire safety test with sensors in the hopper and feeder, continued until the temperatures of the walls stop rising; test of loss of heat removal (operation of the safety temperature limiter); test of electrical power failure; check of the operation of the temperature controller.

8. Compilation of results citing BOTH documents

   In the report cite product part PN-EN 16510-2-6 TOGETHER WITH the general part PN-EN 16510-1. If the documentation cites PN-EN 14785:2009, the citation is outdated — the standard was withdrawn on 02-06-2023.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The test of electrical power failure is carried out with the firebox burning — after the fan stops there is a risk of flue gas escaping into the room
• The pellet hopper and the feeder are tested for burn-back — the test requires a separate risk assessment and a ready extinguishing agent
• Carbon monoxide is odourless and deadly toxic — a CO detector and effective ventilation of the test room are required
• Pellet dust in the hopper forms an ignitable mixture with air — avoid sparking when fitting the hopper with sensors
• The test lasts six hours with the appliance operating — constant supervision of the rig is mandatory

Frequently asked questions