No Hopper

Had to let the Hitzer go out last week as the temperatures were in the 60's here, I was discussing this with one of the guys in the shop who has a Surdiac he too let his go out. He told me he was going to re light Friday nite using his early and late burn method of not filling the hopper but keeping the coal level just below the hopper. He says he has much better results in warmer weather not filling the hopper having all that coal sitting above a small fire. We never had a CO alarm go off when we burned the Colebrookdale for 15 years (no hopper), but we have had alarms on warm days since the Hitzer took over. Took the hopper out this past weekend and lit the stove on Saturday, actually hand feeding through the big door is not a big deal. So far so good although it has been a little nippy at night here. I realize without the hopper the long burns can't be expected but maybe his warm weather theory of not keeping a pile of coal above the fire in a hopper would elimate the making of CO.

Hand fed stoves with internal hoppers need more / stronger draft than a hand fed stove with no hopper. The reason is; the draft needs to pull the fumes around the hopper, and then out the smoke outlet. In the case of the HITZER, the gasses are concentrated out front of the hopper, where they target the finned heat exchanger. The gasses are then pulled around the hopper, then down, and out the smoke outlet. Here is some theory to ponder; With an empty hopper, you break that solid wall of coal which extends from the fire bed, to the top of the hopper. This break allows the gasses to go directly out the smoke outlet. In other words, the draft is stronger when temps are cooler. The draft has no problem pulling gasses around the hopper (wall of coal), and out. It is part of the design for holding heat, as well as rubbing more surface area with gasses. If the chimney doesn't draft well in warmer temps; and stove gaskets are iffy, I can see how fumes may exit the stove, and into the living area. By keeping the coal below the bottom of the hopper, you break that wall. A weaker draft is able to pull the gasses directly out the stove, instead of having to pull the gasses around the hopper first. At the same time, you loose efficiency. The hot gasses go directly out the chimney.

Oliver Power,
Thanks for the technical aspects you have a great understanding of the Hitzer design, we really like the hopper principle too bad the outside north facing chimney gets lazy in the warmer weather.

What I have found works well is to leave the hopper in and just shake the ashes down in part of the bed. When you have the full bed burning you limit the heat by restricting the air to slow the burn rate. But since there isn't enough oxygen to burn the coal you end up getting more CO and less CO2. In other words the carbon is only half burnt. To make matters worse all the oxygen gets used by the coal before the air gets up to where the volitils are being given off, so they go up the stack unburnt. By just shaking the ash out of a small area all the air must pass up through that part of the bed. You end up with a small fire that produces the amount of heat you want while burning all the volitiles and all the coal that is actually burning. It's just like lining the fire box with extra bricks to make it a smaller box. But it has the advantage of being able to get your full sized fire back at any time by just shaking down the whole bed. Using this technique I have kept my stove going on 10 lbs of coal per day. With warm days and cool nights I just shake a small spot in the morning and when I get home from work, then a slightly larger area before going to bed. The air inlet is set very low but it is plenty for the small fire.