increase steam ventilation through cupola?

[BSD]

First time boiling in a shack this year and have a 4x8 cupola, it has flip-out windows in place of the normal cupola doors. and I suspect they're framed in a way that is reducing the size of the openings.
I'm getting good amount out the windows but typically have a vapor level about 80" off the ground (height of the big door in the front). After boiling for a few hours, the roof gets saturated and then it starts raining inside. I can't keep doing this or i'll rot the building from the inside out.

is there a formula to determine the CFM of steam generated by boiling sap?
is there a good way to get a fan up in the cupola to boost ventilation? or am I better off building a hood and steam vent?

this was taken on a crystal clear, low humidity night, only boiling around 40-45gph
17643

This was last night when the humidity was sky-high.Visibility was realistically 36", and the cloud level was only 30-36" off the ground. It was a disaster. i thought i was going to have to shut down because it was so bad, couldn't see in the pans, and almost had a foam over in one of the channels. was boiling 45gph last night. this was before it "got bad".
17644.

Once the front moved through, i was able to get back to "normal" like the first picture. but cannot continue long term obviously. I need to get it resolved before i can go any faster in my pans. as i'd like to be up around 60-70 gph?

[Lethalbowman]

I have window's built into either side of my Sugar Shack that I can open to improve air flow and help get the steam rising out the cupola better. When it get't real bad I just open the door. I am looking into engineering a venthood however to really push all that steam out of the shack.17645

[maple flats]

I had very similar until I made a hood. My hood was made out of aluminum flashing and pop riveted together. I bent it on a trim brake, but back when I was in the heating business at times I bent sheet metal (stiffer than aluminum) using 3 pieces of 2x4, 2 to clamp the sheet at the spot I wanted to bend it, and a third to bend it. My hood on my 2x6 took about 90 minutes to shape and then maybe an hour to pop rivet together, drilling each hole one at a time, riveting it then doing the next. I formed a gutter on the inside edge and at the corners I used silicone caulk to seal it. I then had a small fitting for a drain to a hose, it was just a male adapter but I used a nut on each side and sealed it with silicone. On a larger hood for my 3x8 I made it out of heavier sheet aluminum and used 1x1x1 channel for the gutter. If I were doing that again I'd get 1.5 x 1.5 x 1.5 channel.
On all of my hoods including my current manufactured hood with 2 @15" steam stacks, I have aluminum stack suspended from a SS rod in the cupola and it hangs down into the stack coming up. My current on is 13" hanging into the 15" stacks. Even with it like that I get no buildup of steam in the sugarhouse, even when there is a heavy fog outside and I get almost no dripping off the underside of the steel roofing. From time to time I can see a drip where it hit the floor but it's near zero drips.
I have the telescoping method because it allows me to hoist the hood by cranking on a small boat winch and the suspended stack simply allows the bigger stack to go up without any problems.
My cupola on my 3x8 boiling about 75-85 GPH is thus venting into and out of the cupola which is only 2' across by 6' long and which has a flip down door of 4'6" x 16" on each side. Even when I get a funky breeze and can only open one side it vents perfectly.

[Haynes Forest Products]

Been there done that. Having to many windows and doors open allows the hot water vapor and the cold outside air to mix and wreak havoc on the place. I remember being in a shack that had so much fog you had to write your name one the toe of your boots to know who you were talking to.

Had a buddy with same problem and we did a quick extension down to the evap. Got some white board adout 1/8 3/16 thick 4 sheets and some 2" X 2" framing. We brought the cupola opening down 4 ft. Make it 4x12 or so don't get fancy. The other thing is try and get your make up air to NOT come in and blast into the cloud of steam. It will swirl around cooling it off causing it to drop and hover. You need to grin and bare it at start up to get the shack warm and get the Convection Current working for you. Without a hood you will have a tricky balance between hot and cold air and water vapor.

[BSD]

heres a picture at the start of a boil from a few days ago showing the windows on the cupola.
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[Sugarmaker]

First I grew up boiling in a old sugarhouse with a cupola. Steam was down at the level of the pans (a 3 x 10 Warren rig) Yea google that one! Someone would come in and not know if any one was in there unless you spoke. Used a flashlight to look through the steam to see the thermometer in the syrup pan. You wore your jacket to try to stay dry. Man was that fun!:) So 20 years ago when we decided to build our own sugarhouse we went to look at a lot of places first. Yes I like the look of a conventional cupola which screams sugarhouse and maple syrup here! But I was concerned about the steam and the rain. We wanted a place where friends and family and guests could visit and be comfortable. A sauna in the rain forest was not what we desired. Our rig is jus a little bigger than yours. I see you want to increase your boiling rate. My guess is your about there now at 60-70 gph? So here is a picture off our 3 x 10 at about 120 gph. (has steam away) Yep designed and vented hoods control about 95% of the steam in the room. No sauna and no rain inside the sugarhouse. Wasn't cheap, wasn't easy, but the results are very desirable. assuming that's the final thing you desire. BTW we have folks drop in all the time to set a spell and visit too.

Most of the steam you see on the left side is from the 30 gallons of hot condensate per hour coming off the steam away.

https://i.imgur.com/izZZiUJ.jpg

BTW you have a very nice looking sugarhouse!

Regards,
Chris

[farmrelated]

Cracking the door or window open doesn't fix this? Our cupola makes too much draft. It'll get cold in the room even with all the heat.

[West Sumner Sugar]

We have a steam hood and 2 10" stacks with 648CFM Fantech fans in each. With both running wide open its amazing the cupola stays attached to the roof. Dial them back a little and things vent nicely. We do have to crack a few windows.

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[johnallin]

heres a picture at the start of a boil from a few days ago showing the windows on the cupola.
17646

Looking at the picture, if your stack is 10-12" the cupola doors appear to be not much taller -or maybe even shorter than 10". My guess is that for your 2.5 x 10 arch you need more open space up there. Also the vent in the gable end is just drawing cold air in and not helping you at all.

[ecolbeck]

I agree with johnallin. You need air vented in to replace air escaping through the cupola. The incoming air must be as low to the floor as possible. How warm is it inside the sugar house compared to outside? A cupola is really no different than a chimney. The greater the temperature differential (between inside and outside) the greater the stack effect (like a chimney) will be and the better the venting.

[BSD]

Looking at the picture, if your stack is 10-12" the cupola doors appear to be not much taller -or maybe even shorter than 10". My guess is that for your 2.5 x 10 arch you need more open space up there. Also the vent in the gable end is just drawing cold air in and not helping you at all.that's the problem, the windows are just too small (look nice though! but that doesn't help me).

I'll try covering up the vent on the gable end, but i don't think it's going to do much. the double doors are wide open (didn't get a chance to hang them yet). do you think there is too much cooling coming in through the front door? i've been trying to get my buddy back over to hang them for me, but favors only go so far.

at this point my options are remove the windows and frame a bigger opening. or build a steam hood i believe.

[johnallin]

the double doors are wide open (didn't get a chance to hang them yet).

Forget about the vent and the size of your cupola openings until you run it with the doorway covered over. You may as well be outside - I don't think your cupola is doing anything for you at this point.

[Woody77]

First time boiling in a shack this year and have a 4x8 cupola, it has flip-out windows in place of the normal cupola doors. and I suspect they're framed in a way that is reducing the size of the openings.
I'm getting good amount out the windows but typically have a vapor level about 80" off the ground (height of the big door in the front). After boiling for a few hours, the roof gets saturated and then it starts raining inside. I can't keep doing this or i'll rot the building from the inside out.

is there a formula to determine the CFM of steam generated by boiling sap?
is there a good way to get a fan up in the cupola to boost ventilation? or am I better off building a hood and steam vent?

this was taken on a crystal clear, low humidity night, only boiling around 40-45gph
17643

This was last night when the humidity was sky-high.Visibility was realistically 36", and the cloud level was only 30-36" off the ground. It was a disaster. i thought i was going to have to shut down because it was so bad, couldn't see in the pans, and almost had a foam over in one of the channels. was boiling 45gph last night. this was before it "got bad".
17644.

Once the front moved through, i was able to get back to "normal" like the first picture. but cannot continue long term obviously. I need to get it resolved before i can go any faster in my pans. as i'd like to be up around 60-70 gph?
A heat source will solve this problem we use either our gas stove or a construction style propane heater it goes away almost instantly. And drys the surfaces a bit.

[MISugarDaddy]

We built our sugarhouse in 2013 and have tried every idea suggested here. We have a 3' by 6' cupola, and with our previous 2' x 4' evaporator it was quite bad during a boil, but still manageable. When we went to the 2' x 6' evaporator we went with a hood immediately that we piped up into the cupola, thinking that the steam wouldn't be a problem since it was already piped up into the cupola, wrong. Finally after experimenting with different ideas which didn't solve the problem, we finally put the vent pipe from the hood through the roof of the cupola and the steam problem has now been solved. We hated to cut another hole through the roof, but it has worked great.
Gary

[maple flats]

My steam stacks end in the cupola, on my 3x8 hoods I have 2 steam stacks of 15" each, about half way up to the cupola, then I have a 13" suspended from the cupola down into the 15" ones. My hood over the syrup pan is about 14-16" above the pan and is the same 3x3 as the pan. At my usual boil rate of 75 gph and my highest rate of 81gph I get less steam that what the picture in Reply #9 by sugarmaker shows. My cupola is only 12 SF and it has 2 doors on each side that are 19"x32" each. Rarely but in some weather patterns I only open the doors on one side, but I still get no steam issues. The only time I had issues with steam was the one season I had no hood and even then the steam level was at about 7-7.5' up, the problem was the raining in there. A hood fixed that.

[BSD]

the plan right now is to replace my current arch/evaporator next season, and when i upgrade i will be incorporating a hood and pre-heater into the decision, it will go through the roof. i'm done playing with the cupola. I had another boil yesterday like the one i posted previously. after 3 hours it was flat-out raining in the building from the condensation. I did hit a personal best, sustained 72 GPH on my arch at least.

[TapTapTap]

I'm very proud of the cupola on our new sugarhouse. It works great even without a hood over our 30"x10' Leader Vortex Arch and raised flue rear pan. Lots of steam that flows nicely out the top and almost no rain! My secret is the 12:12 pitch roof, about 10 ft walls, T&G wood lining against the metal roof (not quite complete), and four 54"x32" doors. A little side ventilation from the windows helps the draft.
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