I recently spent the weekend trying to sort out a series of problems with my Gerkros 20W Woodpecker Boiler.I learned quite a bit about it as part of the process, and managed to fix it without calling Gerkros, so I thought I'd share my experiences.
How it works (very basic stuff this):
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When your boiler isn't heating water, it is on standby.
Your central heating timer/thermostat switches on the pump that pumps the water through the boiler and your radiators. When this pump is on, your boiler's water temperature thermostat is activated. If this detects that your water temperature is below a certain level, your burner starts up.
The burner takes a feed of pellets from your auger screw into it fire chamber. An element then starts to heat this chamber. Once a sufficient temperature is reached, your burners fan starts and blows air through the fire chamber. The fan should start about 4-8 minutes after the burner starts. This ignites the now scorched pellets and you have fire.
Your burner now continues to feed pellets into the fire chamber at 15-20 sec intervals. The fans keeps running and and you should have a continuous yellowish-white flame coming out of your burner and licking the fibreboard plate in the boilers main chamber. You can open the boilers middle chamber door while it is running to check this.
All the while, your pump is continuing to pump water through the boiler, where it is now coming into contact with the heat from the flame. Primary contact is made at the back-top of the boiler. The heat from the flame is funnelled onto this plate through a seris of angular metal inserts (baffles) which are inserted into a chamber at the front-top of your boiler. These baffles are not secured, so its important that you re-insert them correctly if you take them out to clean them.
When your boiler thermostat reaches a certain temperature, the rate at which the pellets are fed from the augur screw is reduced by 50%. The fan speed is also reduced. At this point, the flame should appear more like a fire you would see in your hearth, and not like the jet of flame that you saw when the boiler was running at full power.
When your boiler temperature reaches another higher temperature level, it will cut out completely and stop feeding pellets altogether. The fan will however continue for several minutes after, until this too cuts out. Your boiler will remain in this state until the water temperature drops below the trigger level and will then start up again and repeat the process described above.
What everything is:
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Front top panel
This has 2 gauges. The one on the left if the Flue Gas Temperature. This is attached to a probe that runs into the boiler chamber behind the baffles at the back top. This measures the temperature in the boiler chamber. If this rises to 250c, it generally means that there is a lot of ash in your boiler chamber and you should clean it out. You should do this at least once a year.
If this gauge isn't giving a read, it probably means the probe has worn away, which isn't a big deal, provided you clean the boiler regularly.
The gauge on the right is the water temperature gauge. This measures your water temperature. This is linked to your burner. Your burner's operation depends on the temperature given by this gauge. This gauge should always be giving a reading. If it isn't, don't use the boiler.
This panel also contains a trip switch behind a small black plastic cap. This will go if your water temperature goes over 100c. This will then prevent your burner from switching to full power mode from standy. To reset the trip, remove the cap and push the button. YOu will know it has tripped if it clicks. Youshould not do this until your water temperature has cooled to at least 40c.You should also clean out your burner fire chamber before resetting this, as it will most likely be full.
Front 2nd panel from top
This panel can be removed to give access to the baffles in the boiler chamber for cleaning. Just remove the front plate, unscrew the screws and remove the iron plate.
Front 3rd panel from top
This is just a door that gives access to the main chamber of the boiler.
Front 4th panel from top
This is the burner door plate. It can be opened to remove the ash pan and clean out the burner fire chamber
The Burner control panel
4 screws on the left
Power - this controls the amount of times the auger screw revolves when delivering pellets, and therefore the amount of pellets delivered to the fire chamber of the burner. On half power, the amount the screw revolves is reduced by 50%. You can change this while the burner is on and the change will take effect.
Start -this controls the amount of pellets delivered into the fire chamber of the burner when it switches from standby mode to full startup mode ie the
initial feed of pellets. Changes to this will only take effect after the burner has been powered down.
Fan Hi - the speed of the fan on full power
Fan Low - the speed of the fan on half power
Temperature Gauge - this controls the water temperature at which the burner starts up. It is what is known as a potentiator. This means that is is not a precise measure of temperature but gauge of temperature relative to other factors. You can however think of it has a precise measure of tempeature. The more you turn it to the right, the hotter your water temperature will be.
The 3 lights
When your boiler is on standby, the top one will blink every 5-10 secs; when your boiler is starting up, the top one will blink every 1 secs; when your boiler is on full or half power, the top one will remain on; when your boiler reaches its cut out temperature, the top one will remain off.
When your boiler is running on half power, the second light will be orange and remain on.
When you boiler encounters a a fault that causes the burner to stop, the third light will be red and remain on.
The feed pipe
This is the metal pipe with the bend that is connected to your augur screw. Along its side you will find a metal casing that contains a thermostat connected to a trip switch. If the temperature in the pipe reaches a certain level, this switch will trip and power to the burner will be shut off. You then need to remove the casing and reset the trip switch. This pipe sould never get hot. If it is, your burner is getting too many pellets. More about this anon.
The feed pipe also houses a deflector plate which is held in place by an exterior screw. This slows the velocity of the pellets entering the fire chamber so that they don't shoot out straight into the boiler chamber (which prevents them from being burned). Longer pellets can sometimes get jammed between the deflector plate and the edge of the feed pipe.
The fire chamber
This is the circular pipe in the burner in which the pellets burn. If you look into it you will be able to see 2 small holes at the back near the bottom.
Through one of these you will see the element and through the other the light sensor. The light sensor detects the amount of light coming from the flame. If too many pellets build up in the chamber, the light sensor can see less of the flame and shuts down the burner.
At the font of the pipe you have a removable stop plate. This prevents pellets from shooting out into the boiler where they are not burned.
The cables
There are 3 cables on the left of the burner. Nearest front powers the auger screw; middle powers the burner itself; back is connection from water temperature thermostat that controls the operation of the burner.
The back of the boiler
2 thing to look out for here, and both are on the flue.
The draft regulator doesn't really effect the operation of the burner, but if not set correctly, it can allow condensation to build up in the flue, which
reduces efficiency. This is particularly important for flues that are over 2m in length. It should be more of less open when the boiler is running.
The flue fan is also important. This sends your smoke up the flue, and should obviously be working. If it isn't, your boiler chamber will overheat and your burner will eventually cut out.
What can go wrong:
##################
The boiler is a pretty simple piece of engineering, and as long as the component electronics are working, the only thing you need to worry about it getting your fuel and temperature levels right.
Burner runs out of pellets
You haven't filled the hopper; no pellets getting to the burner; it shuts down and red light goes on.
You need to fill the hopper; disconnect the auger screw from the feed pipe and direct the auger screw feed into some sort of recepticle; disconnect the burner and auger power cables from the burner; connect these to each so that the augur screw runs continuously; when the feed of pellets is continuous, disconnect the cables from each other so that the augur screw stops; reconnect everything as was; turn off the burner and switch it on again. Red light should go out and you can start the heating again.
Burner getting too many pellets
If your burner is getting more pellets than it can burn your burner will eventually stop. This will happen for one of two reasons.
The first is that your light sensor detects too many pellets in the chamber and cuts out. The second is a little more dramatic. Your burner will continue to burn pellets until the cut out temperature is reached. However, the excess pellets remaining in your burner, and maybe backed up in your feed pipe, will continue to burn, causing your water temperature to keep rising and the temperature in your feed pipe to rise. Eventually, a thermostat will kick in and shut every thing down, but if you still have burning pellets in your fire chamber, your water temperature may well rise to 110-120c. At this point, your pipes will start clanking and the steam pressure valves on your heating system will started shooting out boiling steam. If this happens, don't panic. Don't try and interfere with the operation of the burner. The pellets will eventually burn out and the water temperature will decrease.
Obviously then its important to get the rate of delivery of pellets spot on. This would have been set when your boiler was commissioned, but if for any reason it has become unset, here's what you do.
When everything is off, set your temperature gauge (the potentiator), your Power dial and your Start dial to 9 o clock. Start up your heating. Note the number of times the augur screw turns when it delivers the start does of pellets. If your burner doesn't fire up and remain fired up after the fan starts, this does maybe too low. Adjust it upwards, reset the burner and restart the heating. Keep doing this until your burner fires up and remain running for at least 5 minutes.
When you have your start dose right, your burner will keep firing and start delivering pellets at 15-20 sec intervals. Note the number of turns of the auger screw as it delivers pellets. After each delivery, remove the plastic augur pipe from the burner feed pipe and have a look into the feed pipe. You should be able to see the deflector plate but you should never be able to see any pellets. If you can, you are delivering too many pellets, and you should reduce the Power dial. This will have the effect of reducing the amount the augur screw revolves at each delivery, which means the burner gets fewer pellets.
If your feed pipe gets blocked, your burner will either cut out because it isn't getting fuel, or the blockage will eventually clear, delivering an excessive load of pellets into the chamber, wherein the light sensor will shut the burner down.
If your burner is getting enought pellets, it should keep running. If not, your flame will appear weak and the burner will stop before its gets to half
power. If this is the case, gradually increase the rate of pellet delivery.
Once you have your start does and delivery rate properly set, you can gradually being increasing the water temperature. As you increase the water temperature, you should proportionately increase your start dose and power until the burner is running normally at your desired temperature.
Components
If none of this is getting you anywhere, you probably have a component failure. Most common failure is the ignition switch or the element. Probes and gauges can also fail. If this happens, contact Gerkros.
Cleaning
Empty the ash pan and clean out the burner at least once a week. Remove ash from boiler chamber and baffles at least once a year, or more often for greater efficieny. You don't need a Gerkros engineer to do this.
Just open up the 2 doors and the baffles panel on the front, remove the fibreboard plate from its housing and hoover up as much ash as you can. Be careful with the fibreboard, however. Its delicate and you don't want to damage it.
Have fun.
How it works (very basic stuff this):
#####################################
When your boiler isn't heating water, it is on standby.
Your central heating timer/thermostat switches on the pump that pumps the water through the boiler and your radiators. When this pump is on, your boiler's water temperature thermostat is activated. If this detects that your water temperature is below a certain level, your burner starts up.
The burner takes a feed of pellets from your auger screw into it fire chamber. An element then starts to heat this chamber. Once a sufficient temperature is reached, your burners fan starts and blows air through the fire chamber. The fan should start about 4-8 minutes after the burner starts. This ignites the now scorched pellets and you have fire.
Your burner now continues to feed pellets into the fire chamber at 15-20 sec intervals. The fans keeps running and and you should have a continuous yellowish-white flame coming out of your burner and licking the fibreboard plate in the boilers main chamber. You can open the boilers middle chamber door while it is running to check this.
All the while, your pump is continuing to pump water through the boiler, where it is now coming into contact with the heat from the flame. Primary contact is made at the back-top of the boiler. The heat from the flame is funnelled onto this plate through a seris of angular metal inserts (baffles) which are inserted into a chamber at the front-top of your boiler. These baffles are not secured, so its important that you re-insert them correctly if you take them out to clean them.
When your boiler thermostat reaches a certain temperature, the rate at which the pellets are fed from the augur screw is reduced by 50%. The fan speed is also reduced. At this point, the flame should appear more like a fire you would see in your hearth, and not like the jet of flame that you saw when the boiler was running at full power.
When your boiler temperature reaches another higher temperature level, it will cut out completely and stop feeding pellets altogether. The fan will however continue for several minutes after, until this too cuts out. Your boiler will remain in this state until the water temperature drops below the trigger level and will then start up again and repeat the process described above.
What everything is:
###################
Front top panel
This has 2 gauges. The one on the left if the Flue Gas Temperature. This is attached to a probe that runs into the boiler chamber behind the baffles at the back top. This measures the temperature in the boiler chamber. If this rises to 250c, it generally means that there is a lot of ash in your boiler chamber and you should clean it out. You should do this at least once a year.
If this gauge isn't giving a read, it probably means the probe has worn away, which isn't a big deal, provided you clean the boiler regularly.
The gauge on the right is the water temperature gauge. This measures your water temperature. This is linked to your burner. Your burner's operation depends on the temperature given by this gauge. This gauge should always be giving a reading. If it isn't, don't use the boiler.
This panel also contains a trip switch behind a small black plastic cap. This will go if your water temperature goes over 100c. This will then prevent your burner from switching to full power mode from standy. To reset the trip, remove the cap and push the button. YOu will know it has tripped if it clicks. Youshould not do this until your water temperature has cooled to at least 40c.You should also clean out your burner fire chamber before resetting this, as it will most likely be full.
Front 2nd panel from top
This panel can be removed to give access to the baffles in the boiler chamber for cleaning. Just remove the front plate, unscrew the screws and remove the iron plate.
Front 3rd panel from top
This is just a door that gives access to the main chamber of the boiler.
Front 4th panel from top
This is the burner door plate. It can be opened to remove the ash pan and clean out the burner fire chamber
The Burner control panel
4 screws on the left
Power - this controls the amount of times the auger screw revolves when delivering pellets, and therefore the amount of pellets delivered to the fire chamber of the burner. On half power, the amount the screw revolves is reduced by 50%. You can change this while the burner is on and the change will take effect.
Start -this controls the amount of pellets delivered into the fire chamber of the burner when it switches from standby mode to full startup mode ie the
initial feed of pellets. Changes to this will only take effect after the burner has been powered down.
Fan Hi - the speed of the fan on full power
Fan Low - the speed of the fan on half power
Temperature Gauge - this controls the water temperature at which the burner starts up. It is what is known as a potentiator. This means that is is not a precise measure of temperature but gauge of temperature relative to other factors. You can however think of it has a precise measure of tempeature. The more you turn it to the right, the hotter your water temperature will be.
The 3 lights
When your boiler is on standby, the top one will blink every 5-10 secs; when your boiler is starting up, the top one will blink every 1 secs; when your boiler is on full or half power, the top one will remain on; when your boiler reaches its cut out temperature, the top one will remain off.
When your boiler is running on half power, the second light will be orange and remain on.
When you boiler encounters a a fault that causes the burner to stop, the third light will be red and remain on.
The feed pipe
This is the metal pipe with the bend that is connected to your augur screw. Along its side you will find a metal casing that contains a thermostat connected to a trip switch. If the temperature in the pipe reaches a certain level, this switch will trip and power to the burner will be shut off. You then need to remove the casing and reset the trip switch. This pipe sould never get hot. If it is, your burner is getting too many pellets. More about this anon.
The feed pipe also houses a deflector plate which is held in place by an exterior screw. This slows the velocity of the pellets entering the fire chamber so that they don't shoot out straight into the boiler chamber (which prevents them from being burned). Longer pellets can sometimes get jammed between the deflector plate and the edge of the feed pipe.
The fire chamber
This is the circular pipe in the burner in which the pellets burn. If you look into it you will be able to see 2 small holes at the back near the bottom.
Through one of these you will see the element and through the other the light sensor. The light sensor detects the amount of light coming from the flame. If too many pellets build up in the chamber, the light sensor can see less of the flame and shuts down the burner.
At the font of the pipe you have a removable stop plate. This prevents pellets from shooting out into the boiler where they are not burned.
The cables
There are 3 cables on the left of the burner. Nearest front powers the auger screw; middle powers the burner itself; back is connection from water temperature thermostat that controls the operation of the burner.
The back of the boiler
2 thing to look out for here, and both are on the flue.
The draft regulator doesn't really effect the operation of the burner, but if not set correctly, it can allow condensation to build up in the flue, which
reduces efficiency. This is particularly important for flues that are over 2m in length. It should be more of less open when the boiler is running.
The flue fan is also important. This sends your smoke up the flue, and should obviously be working. If it isn't, your boiler chamber will overheat and your burner will eventually cut out.
What can go wrong:
##################
The boiler is a pretty simple piece of engineering, and as long as the component electronics are working, the only thing you need to worry about it getting your fuel and temperature levels right.
Burner runs out of pellets
You haven't filled the hopper; no pellets getting to the burner; it shuts down and red light goes on.
You need to fill the hopper; disconnect the auger screw from the feed pipe and direct the auger screw feed into some sort of recepticle; disconnect the burner and auger power cables from the burner; connect these to each so that the augur screw runs continuously; when the feed of pellets is continuous, disconnect the cables from each other so that the augur screw stops; reconnect everything as was; turn off the burner and switch it on again. Red light should go out and you can start the heating again.
Burner getting too many pellets
If your burner is getting more pellets than it can burn your burner will eventually stop. This will happen for one of two reasons.
The first is that your light sensor detects too many pellets in the chamber and cuts out. The second is a little more dramatic. Your burner will continue to burn pellets until the cut out temperature is reached. However, the excess pellets remaining in your burner, and maybe backed up in your feed pipe, will continue to burn, causing your water temperature to keep rising and the temperature in your feed pipe to rise. Eventually, a thermostat will kick in and shut every thing down, but if you still have burning pellets in your fire chamber, your water temperature may well rise to 110-120c. At this point, your pipes will start clanking and the steam pressure valves on your heating system will started shooting out boiling steam. If this happens, don't panic. Don't try and interfere with the operation of the burner. The pellets will eventually burn out and the water temperature will decrease.
Obviously then its important to get the rate of delivery of pellets spot on. This would have been set when your boiler was commissioned, but if for any reason it has become unset, here's what you do.
When everything is off, set your temperature gauge (the potentiator), your Power dial and your Start dial to 9 o clock. Start up your heating. Note the number of times the augur screw turns when it delivers the start does of pellets. If your burner doesn't fire up and remain fired up after the fan starts, this does maybe too low. Adjust it upwards, reset the burner and restart the heating. Keep doing this until your burner fires up and remain running for at least 5 minutes.
When you have your start dose right, your burner will keep firing and start delivering pellets at 15-20 sec intervals. Note the number of turns of the auger screw as it delivers pellets. After each delivery, remove the plastic augur pipe from the burner feed pipe and have a look into the feed pipe. You should be able to see the deflector plate but you should never be able to see any pellets. If you can, you are delivering too many pellets, and you should reduce the Power dial. This will have the effect of reducing the amount the augur screw revolves at each delivery, which means the burner gets fewer pellets.
If your feed pipe gets blocked, your burner will either cut out because it isn't getting fuel, or the blockage will eventually clear, delivering an excessive load of pellets into the chamber, wherein the light sensor will shut the burner down.
If your burner is getting enought pellets, it should keep running. If not, your flame will appear weak and the burner will stop before its gets to half
power. If this is the case, gradually increase the rate of pellet delivery.
Once you have your start does and delivery rate properly set, you can gradually being increasing the water temperature. As you increase the water temperature, you should proportionately increase your start dose and power until the burner is running normally at your desired temperature.
Components
If none of this is getting you anywhere, you probably have a component failure. Most common failure is the ignition switch or the element. Probes and gauges can also fail. If this happens, contact Gerkros.
Cleaning
Empty the ash pan and clean out the burner at least once a week. Remove ash from boiler chamber and baffles at least once a year, or more often for greater efficieny. You don't need a Gerkros engineer to do this.
Just open up the 2 doors and the baffles panel on the front, remove the fibreboard plate from its housing and hoover up as much ash as you can. Be careful with the fibreboard, however. Its delicate and you don't want to damage it.
Have fun.