Anybody Using Hawken or Global Hydronics HE-4000?

Hi,

I have a Hawken Energy (same as Global Hydronics) outdoor wood/coal furnace. Been burning wood for the last 2 years but am now thiking of burning coal in it instead (cutting, splitting, and stacking wood is a pain!). Wanted to know if anybody had experience with these stoves and what kind of burn I can expect in a year when compared to wood (I.e. - used 10 cords of hard wood, only 5 tons of coal). I'm trying to crunch the numbers to see if it is economica to do coal. Have received 1 quote of $135/ton from a sourcein the Reading area, plus delivery (which is 200 miles one way!). If I can get away with only burning 5 tons a year the numbers work out good. The first season I burned over 12 cords of wood (not all of it seasoned and the house had almost no insulation in it). This season the house will have minimum of 6" of insulation in all walls so I'm hoping to drastically cut the amount of wood or coal I need!

Thanks for any help in advance!
Tim

Can you post pictures of the firebox and grates?

We went through this last year, it is probably a poor candidate for conversion. Anthracite requires ALL air to the fire from below in order to burn well and shakable grates to maintain it. You would be much better off selling it and getting a coal specific appliance.

coaledsweat wrote:We went through this last year, it is probably a poor candidate for conversion. Anthracite requires ALL air to the fire from below in order to burn well and shakable grates to maintain it. You would be much better off selling it and getting a coal specific appliance.

I don't have pictures of the fire box and shaker, but here is the product page.

This model is specifically designed to burn either coal or wood. What they told me was I need to burn "Lump"
coal which I take to mean "Stove" size coal. I paid a bunch extra money for this unit because of the ability to utilize either coal or wood. It is not constructed like your typical OWB, it has a very narrow and long firebox. It also has a seperate ash pan and a real heavy duty shaker system with very thick steel plates. The shakers are not very wide and the firebox has an "V" shape at the bottom. I just found that post you talked about with the woman having problems with her OWB burning coal. I tried adding a few pieces of Nut coal from the local agway with my wood fire, but it never burned right, then I read in that post you need around 3" deep of coal bed to burn effectively.

KTMDude wrote: This model is specifically designed to burn either coal or wood. What they told me was I need to burn "Lump"

They probably tested it with bituminous coal, I believe bituminous needs a similar set up as wood...someone correct me if I am wrong. Considering they are in Minnesota the chances of them having access to stove coal is unlikely. I don't even think they bag it. There's not a lot of it made and it comes at a premium price.

Go buy about 5 or 6 bags of nut and give it try with just straight coal, however if you do not have deep firebox your chances of success are not good.

See this thread for getting it lit: How to Light a Hand Fired Coal Stove

Richard S. wrote:

KTMDude wrote: This model is specifically designed to burn either coal or wood. What they told me was I need to burn "Lump"

They probably tested it with bituminous coal, I believe bituminous needs a similar set up as wood...someone correct me if I am wrong. Considering they are in Minnesota the chances of them having access to stove coal is unlikely. I don't even think they bag it. There's not a lot of it made and it comes at a premium price.

Go buy about 5 or 6 bags of nut and give it try with just straight coal, however if you do not have deep firebox your chances of success are not good.

See this thread for getting it lit: How to Light a Hand Fired Coal Stove

Richard F.Y.I. They do bag stove coal
Kimmel Reading Blaschak does & Jeddo was Not sure if they still are

markviii wrote:Can you post pictures of the firebox and grates?

First pic shows the open door. Note how it is MUCH narrower than a standard OWB. Also note the Slots where the air exits the blower motor in the door and the matching "lip" in the firebox. I assume this is to direct the air up under the coal from the ash pan area.

bottom pic you can see the first 2 shaker grates as well as the actuating rod that is attached to the handle. Also a little better shot of the "air deflection plate" (for want of a better description). I tried to get a picture of the bottom of the firebox but it was really hard to capture with the fire going and smoking. The saker grates are about the width of the door (only 18", very narrow for an OWB), but the firebox has sloped surface about 6 or 8" deep on the bottom. See the ASCII drawing below for a crude representation of the cross section of the firebox. The shaker grates are on the bottom of the little stick figure drawing. The gobs of black gook is creosote from burning wet and freshly cut wood.

FWIW I called Hawken Energy today and asked them what type of coal it as designed to burn and they said Anthracite.

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I would say give it a shot and try it.

Hard to see how the air goes under the fire.

On a separate note. I work with a guy that just throws stove coal on top of his wood to give himself some extra burn time.

Maybe you can do that?

cArNaGe wrote:I would say give it a shot and try it.
Hard to see how the air goes under the fire.
On a separate note. I work with a guy that just throws stove coal on top of his wood to give himself some extra burn time.
Maybe you can do that?

In the top pic you can see the dark area at the bottom of the door opening. There is a bent steel plate there that is preventing you from seeing the bottom of the fire in that pic. The top of the plate is flat (parallel to the shaker grates / bottom of the firebox) and then bends down at about a 45 degree angle to just in front of the first shaker grate. The air exits (seen on the inside face of the door) sit directly in front of this bent plate (right at the bottom of the door opening).

It looks like there is a air channel across the bottom of the door opening. If it seals well and ducts the air below the grates, and the grates shake, it should burn anthracite well.

coaledsweat wrote:It looks like there is a air channel across the bottom of the door opening. If it seals well and ducts the air below the grates, and the grates shake, it should burn anthracite well.

There are no seals, just the gobs of goey creosote around all the openings!

Now to just find some good coal cheap :d

I am wondering how the coal will burn like wood does, where the stove will starve the fire of air until the water temp drops, then the blower kicks on. If a coal fire smolders too long will it not reignite?

Hello KTMDude, welcome.. Does your furnace have a combustion blower that forces air through the fire?? If not, does it have an air control that opens and closes the air supply to the fire?? If you have a combustion fan, a coal fire will respond very quickly to a call for heat. If your furnace only has a draft control, then any call for addtional heat will take awhile for the coal fire to respond..

The draft of your chimney is critical, and since you have been burning wet wood, your chimney, flue pipes and passageways in the furnace will be full of creosote. Before burning coal, you must clean your chimney and your flues completely. Once you are burning coal, you won't have creosote anymore, coal only creates fly ash and heat.

You have a pretty heavy layer of creosote on the inside of the furnace firebox, this layer is insulating the walls of the firbox from the heat of the fire... ONce you get it cleaned and burning coal, you should see an increase in heat output from the furnace.

As for purchasing coal.. I would recommend going directly to a known good source of good quality coal.. buying from a coal broker is not a way to get known good coal. Buying 22 tons of 'Mystery Coal' is not something any of us recommend.. I personally truck coal all the way to Michigan, so I make sure I'm buying the best I can buy when I commit to 22-25 tons. I recommend reading the 'quality coal sources' threads, and take the advice of 'coal berner'. I've bought from Superior, UAE, Summit, Calvin Lennigs. Currently I'm buying from Superior.

Hope this helps.. Greg L

LsFarm wrote:Hello KTMDude, welcome.. Does your furnace have a combustion blower that forces air through the fire?? If not, does it have an air control that opens and closes the air supply to the fire?? If you have a combustion fan, a coal fire will respond very quickly to a call for heat. If your furnace only has a draft control, then any call for addtional heat will take awhile for the coal fire to respond..

The draft of your chimney is critical, and since you have been burning wet wood, your chimney, flue pipes and passageways in the furnace will be full of creosote. Before burning coal, you must clean your chimney and your flues completely. Once you are burning coal, you won't have creosote anymore, coal only creates fly ash and heat.

You have a pretty heavy layer of creosote on the inside of the furnace firebox, this layer is insulating the walls of the firbox from the heat of the fire... ONce you get it cleaned and burning coal, you should see an increase in heat output from the furnace.

As for purchasing coal.. I would recommend going directly to a known good source of good quality coal.. buying from a coal broker is not a way to get known good coal. Buying 22 tons of 'Mystery Coal' is not something any of us recommend.. I personally truck coal all the way to Michigan, so I make sure I'm buying the best I can buy when I commit to 22-25 tons. I recommend reading the 'quality coal sources' threads, and take the advice of 'coal berner'. I've bought from Superior, UAE, Summit, Calvin Lennigs. Currently I'm buying from Superior.

Hope this helps.. Greg L

Greg,

The boiler (like all the OWB I've looked into) has a blower motor in the door of the furnace. There is also a small solenoid that has a small plate attached to it that covers the air port. When the aquastat senses the water is too cold, it activates both the solenoid and the blower motor at the same time. As far as I can tell the two can not operate independent of each other so there is no "draft" control other than the blower motor itself.

The chimney itself doesn't really exist on an OWB. There is a short section (maybe 16" long) of 10" steel pipe going out the top of the unit. The only thing you do is put a rain cap on it, otherwise there is nothing really to consider as a chimney, which is one of the selling points of OWB's (no more chimney fires!). While there is a bunch of creosote in the stove it tends to gather around the door, ash pan area, and on the chimney cap (where the temps are coolest). It also has a lot to do with the time of year. Right now with wood, the blower may only turn on 5 or 6 times a day for only a few minutes each time to maintain temps. With the wood sitting and simmering all day the creosote tends to get thicker cause there is no time when you have a really nice hot fire going. Believe it or not the actuall walls of the firebox where the water jacket is don't really have a lot of creosote on them. The first season after I shut it down (after 8 months of continuous burning) I tried cleaning the layer of creosote out, but it was back with a few days after I started burning this last season. I honestly don't think that creosote layer is effecting the efficiency of the furnace a whole lot (at least with wood). When I shut down on wood I will clean out the chimney cap and remove any really heavy layers from around the door and ashpan. Once the furnace cools off it's dang near impossible to chisel the creosote off!

It seems like if I can get Superior coal I will, hopefully they will return my calls!

Once again, thanks for all the help!

Hi KTM,, you will have a hard time keeping a fire going in your OWB without some steady draft pulling air through the coalbed. You will probably have to add about 6-9 feet of pipe to the boiler to get some draft. Even this is pretty iffy.. a hand feed stove/boiler/furnace usually needs about .05"wc of draft to keep the fire going.. You will have to prop open the flapper that closes off the inlet to the fan, unless there is another source of air to the underside of the fire.

There are a lot of hand feed boilers and furnaces that don't use a combustion blower,, but all are hooked to a chimney,, I missed that your unit is outside and used as an OWB,, This alone is going to make burning antharacite a challenge. You may have to add a low speed blower to force a draft to keep the fire idling, then let the aquastat turn on the current blower/flapper for heat calls.

The way coal burns is much different than wood. A wood fire is hotter,, it may be able to force heat across the insulating layer on the boiler waterjacket.. but a coal fire is cooler, much more consistant and longer burning. But it needs a clean water jacket because of the lower firebox temperatures. I designed my 'BigBertha' boiler to have all surfaces accessable to scrapers to remove creosote, and flyash.. My Axeman Anderson boiler is self scrubbing/cleaning.. the heat exchanger stays clean all season long. Makes for very high efficiency.

Let us know how it does on coal.. I like the grates, and the wide bottom of the firebox.. the tapered 'V' of the side firebrick is nearly vertical from what I can see in the photos,, this is very good news.. with a chimney, and maybe a firebox reducer, you may have a good coal burner there...

Greg L
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Well, today I let the wood mostly burn off and removed 2 ash pans worth of ashes (4 15 gallon alvanized trash cans worth!). There was a couple of big chunks of wood still left in there. I pushed them to the back and made sure the shaker grates were clean. I then went to agway and bough 10 40 lb bags of nut coal(they had Blaschak). I put 5 bags in it and it barely covered the bottom of the stove to a depth of around 2 inches maybe. I turned off the blower for a while in an attempt to pull some heat of the furnace. I turned the heat up in the house and took a nice long shower to get the coal dust off me. After around an hour the temp had dropped to about 160F (I'm talking about the water temp inside the jacket). I turned on the blower to see if I could get the coal to light. It smoked pretty hard for around 10 minutes before I got bored of watching it. I cam back about 20 minutes later and noticed there must have been a little explosion!
I'm hoping this isn't something normal! I'll see what happens in the AM, I'll know if it stayed lit if in the morning if it's not freezing when I get up!