Hood/Ductwork Over Harman Mark2

Hi
Glad to find a forum like this one been good for learning ect.
I just instaled a hood above my coal stove 8" pipe with a fan
about ten feet from stove .Hood is 2 inches above stove does
not over hang on any side.My problem is the mark2 has that
gap on the bottom of window for more air will this with the inline
fan can it pull up carbon or other fumes ? seems to work just
need to get all pipe to 8" to get some of the heat from basement
to first floor any help in this area would be great I will post pics
soon . safety first is on my mind.

thanks bick

If your chimney is pulling a normal draft, for a hand fired stove, that would be about .05-.06" wc, then there is no way that your hood and fan can pull any CO or fumes out of the stove's door/glass vent..

Pulling hot air out of the room is a big help but you need to provide a return duct for the cool air from upstairs to return to the stove. This creates the all-important circulation loop that improves efficiency.

Greg L

Thanks greg
I have the correct pull from chimney I have not instaled cold air return until I had the anser on the first ? my problem is I go from 8 to 6 inch
pipe it kills the warm air flow you can feel it on the pipe.I will fix that mide week with 8" all the way then 6"to each floor vent.My next idea
is I have a coustom bent pipe round and crimped on one end oval on other I got a knock out for the the hood this will let this half moon pipe
collect heat from one of the air output on one side of stoves blower to hood the other side will blow in to basement.The door still clears fine
this will put a lot of heat into hood and keep stack temp down .

sorry for spelling/grammer not my thing

thanks bick

Bick, we need to see some pictures of your hood design!!!!!

PS : You beat me!!!

Hi Bick, I recommend focusing on a cold air return from the upstairs to the inlet of the distribution fan on the stove.. You basicly make the coal stove into a hot air furnace when you duct cool air returned from upstairs to the fan, the fan forces it around the stove, and your custom ductwork sends it back upstairs..

There are many threads on this subject on the forum, and creating the circulation loop really works..

I am also anxiously awaiting photos !!

Greg L

This type of setup works very good, I built a cabinet around my hitzer and did the 8" pipe, and ducted it. It works really well, but the cold air return is essential, otherwise you got a vacuum and you can tell, it isnt where it needs to be for most efficency. Try to balance the cfm's of the fan in the hood, to the cold air return fan.

i Here are pics keep in mind im using the door to hold up the what I call heat tube(for pic only stove is not running) until I get the knock out from work .
This cold air return has got me a bit confused even with a 1 inch gap at the door and the hall way reg not hooked up not
enough? I need help. when I hook up the heat tube upload another pic
countain on the blower that comes on the stove to pump some heat up into duct work.when in final spot bottom is infront of heat
outport of mark2 .

Hi
People I know with wood stoves just have a floor reg at a point far away from heat so the cold air sinks back down
to stove but you people are talkin fans . If this will get more out of the stove I want to know more it sounds like
regular forced air furnace type of duct work please tell me more .my basement is 70 upstairs 63 thats cold forcing
me to run wood all the time in cold maine.

Thanks Bick

You said you have a fan in the 8-inch duct, and also on the stove. That's good because I wonder if the stove fan itself would move enough air. You said you would also capture the output from one of the blower outlets on the stove and get that into the hood as well. Why not capture both outlets instead of just the one? Is it a finished cellar and do you need the 70 degree heat in the cellar? If not, route it all upstairs, not just half of it. You will get a great deal of heat in the cellar just from radiation off the stove and the plenum and the ducts.

I think the reason people suggest a cold air return duct, is so that you will be losing less heat to the cellar if you channel that upstairs air directly back to the stove, rather than let it flow all over the cellar. It looks like you have an uninsulated concrete-wall cellar, which will suck up huge amounts of heat just trying to warm the concrete. By the same token, maybe you could extend your hood down around the sides of the stove to capture that heat as well, rather than let it warm the cellar. The Mark II puts out lots more heat from its sides than from the top, so a lot of it is getting away from you!

I don't know how wedded you are to the Mark II, but there are stoves more suited to serving as a hot-air furnace.

When you have an open floor register that dumps upstairs air into the basement, this does provide a pathway for air to return from upstairs to downstairs. However, the returning air is dumped into the basement, so the basement is being used as a very large, very cold duct to return the air to the stove..

What you want is to put a 6-8" duct from that floor register to the inlet of the fan on the coal stove. This way, the return air is not using the basement as a duct, but is being returned directly to the fan on the stove. With a duct installed this way, the basement will be cooler, it will not be heated by the return air. The air feeding the stove will be warmer, and therefore will result in hotter air leaving the stove and going upstairs. If the duct is ended either just at or if it is attached to the fan inlet, then the duct will PULL cool air from the upstairs.. a huge increase in circulation and efficiency is the result.

Greg L

hi
rberg I hate this stove to be honest kinda 1)I cant get the long burn times they said . 2)it runs great for 3 4 or5 days the bang
wake up its out . 3) checked all compments using hard coal drives me crazy im better than last year 4)needs to be shaken more
often than they said when got stove so on weekends when home I walk by it shake it runs great

prob me people I know with same stove swear buy it I swear at it.

bick

ps buying somthing else not in budget love to have a big stoker