FAQ

Frequently asked questions

On this side we help you answering some of the questions we often get in connection with purchase and installation of heating plants.Press the links below to read more.



The new Danish Wood Stove Order took effect January 26, 2015. The achievement of the new limits for CO, OGC and dust shall be made only after July 26, 2015.

 

Below here we will briefly review the most significant changes.

 

1. For all systems there need to be a test certificate. The test report can no longer be used as evidence. In return, the test certificate now must be designed in either Danish or English (§10 paragraph. 4). 

2. There are established requirements for chimney heights for plants up to and including 30 kW (§11):

  • If the roof has a roof pitch of up to 0-20 degrees, the chimney must end on at least 40 cm above the ridge, or end on at least 1 mtr. above the roof.
  • If the roof has a roof pitch of up to 21- grader, the chimney must end on at least 40 cm ridge, or has a horizontal on at least 230 cm to the roof surface.
  • The chimney has to within a radius of 15 mtr. end on at least 1 mtr above the top edges of the air intakes, windows and doors.

3. Installation of systems with a rated output of over 120 kW must be reported to the commune at least 8 weeks prior to commissioning. This can be done by submitting a copy of the test certificate (§12).

4. In exceptional emergency cases where, for example. is a risk that there may be damage to people, animals, buildings, etc. can the commune dispenses with the requirement of section 3 (§12 paragraph. 4).

5. The commune may determine exemptions from the requirements for straw boilers in terms of CO and OGC so that they must comply with EN303-5 Class 5, but only EN303-5 class 3 (§15 paragraph. 2)

6. Automatically fired boilers, which can be modulated down, must be tested only at rated maximum load. After December 31, 2019, they also have to be tested at low load as specified in the standard.

 

 

 

 PRESSURE CONVERSION

Unit Converted Designation
1 bar 1.000 mBar From bar to millibar
1 bar 100.000 Pa From bar to pascal
1 bar 1.000 hPa From bar to hectopascal
1 bar 10.200 mm H2O From bar two millimeters of water column
1 bar 10 mVs From bar to meter water column
1 bar 14,504 PSI From bar to pounds per. square inch
1 Pa 0,102 mm H2O From pascal to millimeter water column
1 mmH2O 9,8 Pa From millimeters of water to pascal

 

ENERGY CONVERSION

Unit Converted Designation
1 kWh 3,6 MJ From kilowatt hour to megajoule
1 kWh 3600 kJ From kilowatt hours kilojoules
1 kWh 861 kcal From kilowatt hours for returns kilocalories
1 kcal 4,18 kJ From returns kilocalories to kilojoules

The table below shows the different types of fuels density and energy content

Fuel Type Water Content Weight per. m3 kWh/m3 kWh/m3
Firewood, hardwood, cleaved, stored 20% 560 4,08 2284
Firewood, hardwood, cleaved, fresh 45% 660 2,61 1722
Firewood, hardwood, round, stored 20% 400 4,08 1632
Firewood, hardwood, round, fresh 45% 500 2,61 1305
Firewood, softwood, cleaved, stored 25% 420 3,83 1608
Firewood, softwood, cleaved, fresh 55% 520 2,03 1055
Firewood, softwood, round, stored 25% 300 3,83 1149
Firewood, softwood, round, fresh 55% 400 2,03 812
Straw, preshed, gray 0% 150 5,14 771
Straw, preshed, yellow 0% 150 5,04 756
Industrial wood chips, softwood 25% 200 3,83 766 
Boat wood swarf, softwood  15% 80 3,83 306 
Olive cores  15% 600 5,20 3120
Willow chips  10% 200 4,44 888
Rape cores  8% 660 6,67 4402
Grains, rye and wheet  15% 700 3,89 2723
Wood chips, softwood, stored 40% 235 2,92 686
Wood chips, softwood, fresh 55% 300 2,03 609
Wood chips, softwood, dry 25% 200 3,83 766
Sawdust, softwood 20% 250 4,22 1055
Wood pellets 7% 700 4,92 3444

The table below shows the sizes and weights of bales. The weight is only average because it depends on how hard the bales are pressed.

Type H x W x L (cm) Weight (kg) Energy Content (kWh)
Small bales 36 x 48 x 90 12 49
Round bales Ø110 x 120 95 391
Round bales Ø140 x 120 150 618
Round bales Ø180 x 120 250 1030
Round bales Ø200 x 120 310 1277
Mini-big bales 85 x 80 x 160 160 659
Mini-big bales 85 x 80 x 180 180 742
Mini-big bales 85 x 80 x 200 200 824
Mini-big bales 85 x 80 x 240 240 989
Big bales (Heston) 129 x 122 x 240 500 2060

A boiler with under combustion is designed with a fuel hopper, wherein the fuel rests on a grate. The combustion air is added as primary air under the grate and as secondary air over the grate on the place, where the developed gasses leave the fuel. By this principle it is only approximately the bottom 20 cm of the fuel layer hight, which is on fire, because the smoke and the gasses together with the flames pull out under the bottom edges of the magazine walls (the so-called water noses) and out in the smoke turner of the boiler. It is on this place the highest temperatures are found, because there are both found embers and flames, and it is on this place the secondary air has to be added in plentiful amounts, so the gasses are mixed effectively with air and can be ignited and burned completely.

From here the smoke flows out in the smoke turners and out of the boiler into the chimney.

From here it is possible to obtain a clean combustion, when just there are filled fresh fuel on, before the fuel is sunk down under the water noses. If first there are filled fuel on after the fuel layer is reached under the water noses, the fresh fuel will develop a lot of gasses, which will not be able to be ignited, because the temperature is not sufficiently high, whereby the combustion will become sooting and incomplete, until the fuel has come on fire and the ignition temperature has been reached.

In an under combustion boiler there can also be burned coke and cinders. In that case the secondary air supply will be turned off, because this is unnaunnecessary and only leads to a deterioration of the heating economy.

A boiler for  through combustion is designed with a fuel hopper, wherein the fuel rests on a grate. The combustion air is added under the grate and flows up through the fuel. The combustion will therefor also take place up through the fuel, so the total fuel layer catches on fire. The smoke flows out the fuel above and out from the boiler. Gradually as the fuel burns off, the fuel layer sinks down towards the grate, where the ashes fall through the grate and down in the ash drawer.

After kindling or refilling of fresh fuel, there will always take some time before the fuel layer has been completely ignited, and there will therefore, in this period flow unburnt gases in the flue gas of the boiler, since there is no such high temperatures present in the fuel layer upper part, the gases ignite.

It is therefore necessary to use so-called gas carbon fuels - coke and cinders - in such boilers. These fuels develops little gas.

In through-combustion boilers gaseous fuels - coal, lignite and wood not used as they during heating develops large quantities of flammable gases will be lost with the smoke out of the chimney and cause soot, smoke and odors. There may further be explosive blows in the boiler soot-fire in the
chimney and poisoning by leaking chimneys and boilers.

After June 1, 2008 it is under the stove Directive and building regulations for small houses and commercial buildings, forbidden to install through-combustion boilers for the purpose of burning coal and wood (gaseous fuels).

A boiler with under combustion is designed with a fuel hopper, wherein the fuel rests on a grate. The combustion air is added as primary air under the grate and as secondary air over the grate on the place, where the developed gasses leave the fuel. By this principle it is only approximately the bottom 20 cm of the fuel layer hight, which is on fire, because the smoke and the gasses together with the flames pull out under the bottom edges of the magazine walls (the so-called water noses) and out in the smoke turner of the boiler. It is on this place the highest temperatures are found, because there are both found embers and flames, and it is on this place the secondary air has to be added in plentiful amounts, so the gasses are mixed effectively with air and can be ignited and burned completely.

From here the smoke flows out in the smoke turners and out of the boiler into the chimney.

From here it is possible to obtain a clean combustion, when just there are filled fresh fuel on, before the fuel is sunk down under the water noses. If first there are filled fuel on after the fuel layer is reached under the water noses, the fresh fuel will develop a lot of gasses, which will not be able to be ignited, because the temperature is not sufficiently high, whereby the combustion will become sooting and incomplete, until the fuel has come on fire and the ignition temperature has been reached.

In an under combustion boiler there can also be burned coke and cinders. In that case the secondary air supply will be turned off, because this is unnaunnecessary and only leads to a deterioration of the heating economy.

From knowledge of the building's age and the desired heated area, the required boiler capacity is calculated from the diagram below. Effect of hot water and loss (2kW) has been recognized. The diagram shows both the necessary performance for heating a building that meets the requirements bygningsreglementetes for the isolation and for the elderly, poorly insulated buildings.

If an oil burner is included in the installation, this can be used as reserve-peak. In this case, it is not necessary to dimension the boiler to the housing dimensioned heat loss. There a more optilmal operation if the boiler underdimensioneres for example. 75% of the rated heat loss.

When selecting the stoker should also dimension from approximately 75% of the house-sized heat loss. This should be done to ensure that the stokeranlægget pausefyrer little as possible.

Nødvendig Kedelydelse Baseret På Boligens Areal Og Alder

From knowledge of the building's annual oil consumption or in kWh for heating, the required boiler capacity of the boiler is calculated from the diagram below. Effect of hot water and loss (2 kW) has been recognized.

If the dwelling has been heated by electricity, correspond 1 kWh of electricity to 0.13 liters of oil.

Example: The annual electricity consumption for heating totals 30,000 kWh. This is equivalent to 4000 liters of heating oil. If the appliance must be able to heat the dwelling alone, the boiler output is 16 kW.

If an oil burner is included in the installation, this can be used as reserve-peak. In this case, it ikek necessary to dimension the boiler to the housing dimensioned heat loss. There a more optilmal operation if the boiler underdimensioneres for example. 75% of the rated heat loss.

When selecting the stoker should also dimension from approximately 75% of the house-sized heat loss. This should be done to ensure that the stokeranlægget pausefyrer little as possible.

Nødvendig Kedelydelse Baseret På Årligt Olieforbrug

POWER REQUIREMENT TO HEAT WATER

In order to calculate the power requirement is necessary in order to heat the water, it requires the following parameters:

T = (water temperature required) - (water current temperature)

L = Number of liters desired heated

Example: We want to heat 2,000 liters of water from 40 to 90 degrees:

T = 90 - 40 = 50

L = 2000

Energy requirement = (T * L) / 860 = (50 * 2000) / 860 = 116.3 kWh

Attention! The calculation is an ideal situation, irrespective of system efficiency.

BY KILO BIOMASS TO BE USED TO HEAT WATER

In order to calculate the number of kilograms of biomass to be used in order to heat the water, it requires the following parameters:

T = (water temperature required) - (water current temperature)

L = Number of liters desired heated

V = boiler of efficiency thanks

K = The energy content of the desired biomass measured as kWh / kg.

Example: We want to heat the 2000 liters of water from 40 to 90 degrees. We use wood pellets for heating (see the section of Alcon School of fuels density and energy content):

T = 90 - 40 = 50

L = 2000

V = 0.88 (efficiency 88%)

K = 4.92

Biomass = (T * L) / (860 * K * V) = (50 * 2000) / (860 * 4.92 * 0.88) = 26 kg.

Degree days are a measure of how cold it was and how much energy is used for space heating. Degree-day figure can help consumers compare the energy consumption per. month with a normal month for each. years with a normal year.

Energy consumption for water is not included because it is not dependent on the outside temperature.

One graddag is an expression of a difference of 1 ° C between the "inner" daily mean temperature of 17 ° C and the exterior daily mean temperature for one day. Diurnal degree-day figures therefore calculated as the difference between 17 ° C and the outside daily mean.

Below are a few examples of the calculation of degree days:

-5 ° C outdoor temperature = 22 degree days.
+ 2 ° C outdoor temperature = 15 degree days.

> The individual days of degree-day figures summed to weekly, monthly, annual and seasonal values.

The heating season started in the autumn, when the exterior daily mean temperature reaches 12 ° C or lower for at least 3 consecutive days and ends in the spring when it reaches 10 ° C or higher for at least 3 consecutive days.

If after the heating season start should be at least three days where the temperature reaches above 12 ° C ceases degree days counting until the temperatures again goes down below 12 ° C, and in the spring, if the temperature goes down below 10 ° C for at least three days resumes degree days count.

Press the link below to go to the DTI's website and learn more about degree days.

http://www.teknologisk.dk/graddage/pressemeddelelse/492

If you did not receive an answer to your question, please feel free to contact us.