How long should my oven last

Tips and Tricks
around the stove

Help, my stove is not burning!

Antje B. from Oberursel is actually quite satisfied with her stove. If the stove is in operation, it gives off a cozy warmth and the wood burns and crackles behind the pane.

"Unfortunately, you can't see the fire because the pane keeps getting black," regrets Antje B.

In most cases, this can be remedied. Sometimes a few tricks are enough to improve the function of a stove.

Who can do it best? Chimney sweep! That is why master chimney sweep Kevin Mielke from Hanover answers the most urgent questions and gives you valuable tips on the topic of wood-burning stoves.

 

Sooty windows

A known problem with wood-burning stoves and fireplaces with glass doors. The exhaust gases condense on the (relatively) cold pane and blacken the inner surface. Note the following: Put the firewood all the way back against the back wall. Never position the logs with the front side facing the pane. Most of the wood gas escapes there. It is better to put the logs across the oven. Use only dry, untreated wood. Well-designed stoves prevent the panes from blackening by preheating the combustion air, which is guided along the pane from inside (secondary air). However, this system only works if the primary air (air flow through the ash drawer to under the flame) is completely closed or throttled at the same time. The primary air should only remain open during the heating-up phase. If these tips are of no use, then your stove is either leaking (so-called "false air" penetrates the combustion chamber through the doors and ash drawer) or your stove is structurally not equipped with a functional "window flush". In the area of ​​the window frame, the secondary air sliders only allow cold air curtains to reach the window and usually only keep the window transparent in places. With some stoves, the secondary air cannot be regulated. A throttle valve in the exhaust pipe can help here, which prevents uncontrolled burning of the fuel if the chimney draft is too strong.

Firewood partner tip * ²:
Slightly sooty panes can be easily cleaned with a damp cloth that has been dipped into the cold ash beforehand. Particularly stubborn or thick layers of tar can be removed with a ceramic hob cleaner or, if necessary, carefully scraped off with a razor blade. Avoid chemical clubs. These can drip down when sprayed and leave permanent traces. You can also use special and expensive special cleaners.

 

Smoke formation when adding wood

This problem occasionally occurs with stoves with large door openings. When the door is opened, a negative pressure is created in the entire door opening area if the door is opened during operation. The chimney suddenly has to convey up to eight times the amount of air. This is only able to do this if it has a sufficient cross-section and sufficient effective height. Before buying a stove, it is advisable to have your master chimney sweep check whether the chimney is suitable for a stove with a panoramic window. If this is not the case, you can switch to ovens with a split or smaller door. Do you already have the "wrong" stove in your living room? Then the following tricks can help:

 

  • In a few models, the upper baffle plate (mostly made of fireclay) is very wide ex works and does not allow enough exhaust gas to pass through. This baffle plate can possibly be shortened by a few centimeters in order to reduce the resistance on the exhaust gas side. Ask your stove builder or manufacturer.
  • Place the wood all the way back across the combustion chamber, use a pair of pliers (part of the fireplace tools).
  • Basically, a vertical flue gas outlet towards the top has a more positive effect on the function of a stove than an outlet towards the rear.
  • Check that the connection between the stove and the chimney is clean. Check whether any throttle valve in the connection piece is in the correct position (open).
  • First open the door a crack and wait a few seconds, then slowly open the door as far as necessary and add the wood.

Firewood partner tip * ²:

If in doubt, please ask your chimney sweep on site (he can check the chimney and the stove) or your stove builder / manufacturer.

 

No draft in the oven

The cause is often a dirty connector or the chimney. Check whether any throttle valve in the connection piece is in the correct position (open). Smoke can often push back during heating up because the chimney has not yet received any heat. A chimney can only “draw” properly if it is warmer inside than outside. Chimneys guided on the outer wall may need a little jump start. This is where grandma's home remedies can help in the event of an accident: Loosely crumple up newspaper and light it in the firebox, then immediately put on kindling. If this remains unsuccessful, there is only the uncomfortable alternative. Put some paper in the lower cleaning opening of the fireplace and light it. Then immediately use the buoyancy that has just been generated in the furnace for the heating process. It is possible that the cross-section of the chimney is not sufficient or the stove door is too large (see above: smoke when adding wood).

Firewood partner tip * ²:

Talk to your chimney sweep about this the next time you sweep the house.

          

Oven gets too hot, wood burns away quickly

Most wood-burning stoves have a heat output of approx. 6 - 8 kW. Much too much for a living room of approx. 30 m² (heat requirement in a new building at -10 ° C = approx. 2 kW). The result is a room temperature of 30 ° C and more. One possibility is to put less wood on it and keep the flame small. Other sources of error can be leaky door seals or the pane frame if the furnace can no longer be properly throttled. If the window rattles when you tap it, the sealing frame must be tightened. The door seal is a wearing part and should be checked regularly for its function. The door handle should press the door firmly into the seal as it locks. The ash drawer must seal completely at the stop. If all else fails, the door may be warped or the stove has large manufacturing tolerances. This problem often occurs with very simple wood-burning stoves with low quality requirements.

Firewood partner tip * ²:

Talk to your chimney sweep about this the next time you sweep the house.

 

Wood does not burn completely

After the fire has gone out, there are often unburned pieces of wood in the firebox. There are two reasons for this: Most of the time, the firewood was not completely dry when it was thrown into the fire. Then only the part burns that was directly in the bed of embers of the existing fire. The rest goes out as soon as the additional heat source is cold. Another cause can be either the construction of the fireplace or incorrect operation: Wood should not get any air from below (via the grate) during combustion. The pieces of wood are literally burned away as soon as they are directly over the grate. The ends then remain unburned. Burning in a bed of embers (like a campfire) is ideal. The combustion air comes from above and from the sides. For heating up you usually have to add air from below (primary air) so that the wood burns. Then you should close the lower air supply as quickly as possible and only regulate with the secondary air (air from above). With good wood-burning stoves, the pane also stays clean.

Firewood partner tip * ²:

Leave the scraps of wood in the fireplace. They usually form an optimal bed of embers for the next heating process.

 

Fireclay bricks broken

Thin cracks often form in the fireclay on stoves and chimneys. This is normal when you consider that the firebricks can reach temperatures of over 600 ° C. The high temperatures ensure optimal afterburning of the exhaust gases and prevent condensation and tar formation in the combustion chamber. It only becomes critical when parts of the fireclay come off and fall into the oven. This can lead to damage to the jacket of the fireplace or (in the case of chimneys) to excessive heating of the rear wall of the building.

Firewood partner tip * ²:

In this case, have the fireplace checked by a specialist immediately.

 

Gloss black in the furnace and in the stovepipe

Black carbon in the oven or connector always means that you are heating with wood that has not been properly dried. There is an acute danger that this soot could ignite and cause a chimney fire.

Firewood partner tip * ²:

In this case, have the fireplace checked by a specialist immediately.

 

Throttle, what is it?

Anyone who buys a wood-burning stove cannot avoid buying so-called "exhaust accessories". The exhaust accessories consist of a connector, wall lining and a ring collar. Alternatively, the exhaust pipe is offered with an integrated throttle valve. It reduces the free cross-section of the pipe by approx. 65%. The "throttling" of a fire by means of a throttle valve requires that the amount of combustion air cannot be reduced in any other way. Good wood-burning stoves have custom-fit doors and ash boxes, and the primary and secondary air slides can be perfectly regulated. If there is only embers in the firebox, you can close all the slides to keep the embers as long as possible. A throttle valve has no additional effect here.

There are stoves that let the fuel burn happily even though the air damper is closed. The cause is leaks, mostly in the area of ​​the ash pan or the door and window seals. Some manufacturers do not regulate the secondary air at all. Here you shouldn't do without a throttle valve.

Remarks:

* ²The firewood partner tip is without guarantee, in case of doubt please always ask your master chimney sweep, fireplace builder or stove manufacturer.