There seems to be a general misconception that combination coal and wood stoves can't burn wood cleanly or efficiently. Generally that has been the case, but there was one combo stove made that did both very well and achieved EPA status, the Harman "E" CW30. In another thread there seems to be some interest in learning more about this stove. I didn't want to get off topic in the other thread, so I thought I'd start a new one about this stove. Unfortunately, Harman stopped making this great little stove, but the engineering is still interesting...
Here is the original thread:
https://www.hearth.com/talk/threads/20970/
[quote author="BeGreen" date="1217918329"]Great find. Front, back, top and interior views would be great. I am particularly interested how they manage the air flow and options provided for top (wood) or bottom (coal) burning. Is there a removable grate system for the coal?[/quote]
There is no removable grate system, everything sits on the shakers.
The stove has two doors in the front. The traditional larger front loading door and then a smaller door below it which houses the ash pan and the lever that controls the air flow. This lever at one extreme controls the air flow for coal ("C") and wood ("W") at the other. The lever sticks through the lower ash pan door and can only be set to the either wood or coal with the door closed as there is a piece of metal cast into the door which blocks the lever from mistakenly or accidentally being pushed over to the wrong position. You simply slide the lever one way or the other to adjust the airflow for the selected fuel, much like you would for a traditional stove. As you slide this lever, it opens or chokes down the air flow either going into an air path that leads under the shakers for coal fuel, or upwards across the main loading door while burning wood.
There is also a damper at the top of the stove which bypasses the secondary combustion while burning wood. You open this damper for starting the fire, when reloading the stove, or while burning coal.
When you switch from wood over to coal, all you do is open the lower ash pan door, switch the airflow lever from wood to coal, re-close the door, then open the upper damper for burning coal (so it bypasses the secondary combustion path)... it's that simple. You can obviously switch from one fuel and back to the other without the fire ever going out. To shake the ashes while burning wood or coal, you just move the shaker lever on the side of the stove and the fine ash gets disturbed and falls into the ash pan below.
The stove was so cleverly designed, I'm amazed the concept never really took off.
Here are a couple of pages copied from the owners manual which will give you a better idea of what I'm talking about, I'll post actual pictures of the stove in a couple of months when I yank it out of the garage...
![[Hearth.com] Harman "E" CW30, the only EPA wood/coal combo stove ever made...](https://www.hearth.com/talk/attachments/stovemanual1-webp.179625/ "[Hearth.com] Harman \"E\" CW30, the only EPA wood/coal combo stove ever made...")
![[Hearth.com] Harman "E" CW30, the only EPA wood/coal combo stove ever made...](https://www.hearth.com/talk/attachments/stovemanual2-webp.179626/ "[Hearth.com] Harman \"E\" CW30, the only EPA wood/coal combo stove ever made...")
![[Hearth.com] Harman "E" CW30, the only EPA wood/coal combo stove ever made...](https://www.hearth.com/talk/attachments/stovemanual3-webp.179627/ "[Hearth.com] Harman \"E\" CW30, the only EPA wood/coal combo stove ever made...")
Here is the original thread:
https://www.hearth.com/talk/threads/20970/
[quote author="BeGreen" date="1217918329"]Great find. Front, back, top and interior views would be great. I am particularly interested how they manage the air flow and options provided for top (wood) or bottom (coal) burning. Is there a removable grate system for the coal?[/quote]
There is no removable grate system, everything sits on the shakers.
The stove has two doors in the front. The traditional larger front loading door and then a smaller door below it which houses the ash pan and the lever that controls the air flow. This lever at one extreme controls the air flow for coal ("C") and wood ("W") at the other. The lever sticks through the lower ash pan door and can only be set to the either wood or coal with the door closed as there is a piece of metal cast into the door which blocks the lever from mistakenly or accidentally being pushed over to the wrong position. You simply slide the lever one way or the other to adjust the airflow for the selected fuel, much like you would for a traditional stove. As you slide this lever, it opens or chokes down the air flow either going into an air path that leads under the shakers for coal fuel, or upwards across the main loading door while burning wood.
There is also a damper at the top of the stove which bypasses the secondary combustion while burning wood. You open this damper for starting the fire, when reloading the stove, or while burning coal.
When you switch from wood over to coal, all you do is open the lower ash pan door, switch the airflow lever from wood to coal, re-close the door, then open the upper damper for burning coal (so it bypasses the secondary combustion path)... it's that simple. You can obviously switch from one fuel and back to the other without the fire ever going out. To shake the ashes while burning wood or coal, you just move the shaker lever on the side of the stove and the fine ash gets disturbed and falls into the ash pan below.
The stove was so cleverly designed, I'm amazed the concept never really took off.
Here are a couple of pages copied from the owners manual which will give you a better idea of what I'm talking about, I'll post actual pictures of the stove in a couple of months when I yank it out of the garage...
