Pole Barn - Sugar Shack

Will finally be moving the evaporator inside this season. No more "blizzard boiling" ....Yahoo !!
Construction just starting on my new 28x48 pole barn; which I will partition inside into a 28x28 utility/storage area; and a 28x20 sugar shack.
Couple of design questions:
1. I plan to build a 4'x6' cupola directly over my Mason 2x4XL evaporator. The building plans call for that porous foam venting material along the full 48ft ridge (steel roof), installed before the ridge cap. Will that foam cause my rising steam to migrate along the full ridge, instead of exiting through the cupola doors? Should I delete the foam entirely, and then install a rectangular gable vent (which I could block off when boiling) at each end of the building in it's place? Maybe overthinking the venting here.
2. Before pouring my slab, I want to install a drain directly under the evaporator. Have already run a line out to a new 500 gal. drywell for gray water. Thinking about one of those 4ft long trench drains running parallel beneath my evaporator for cleaning, etc. My issue is, all the trench drains I see so far are PVC or some other non-metallic material; and if I ever get to the point of growing into a hood/steam away, etc.; the water dropping into the drain would be too hot. Maybe a trench drain isn't necessary, just a well placed cast iron floor drain?
Any and all help from the more experienced out there is appreciated.
Thanks, Bill

1. Hard to say without knowing your full plans, but could you just go with a steam hood and steam stack to avoid the cupola altogether? They are much easier to deal with for long-term maintenance.

2. Pour the cement with a lip set into it of the proper thickness and use metal grating cut to the appropriate size for the trench. Very easy to do.

It is definitely a good idea to think about the amount of hot water going down the drain now and what you might have in the future. I've seen at least a few sugarhouses where PVC was used as a floor drain that ended up melting or separating, ending up with water just pouring into gravel under the slab afterward....sometimes with very bad results. Cast iron pipe works well.

My drain is in a corner about 6ft away from the arch. Most of the hot water we get from the steam hood and pre-heater is saved in buckets for cleaning hydros etc while boiling and wash up later.
Most of the time, at the end of a boil, I pour it out onto the floor and squeegee on out an open door. It's still hot - not enough to do any damage to the pvc drain pipe - but sure does a nice job cleaning up the place!

I have a 1" hose that runs to the drain from a Y Valve for cleaning the head tank and another that I can hook up to the flue or syrup pans for cleaning. Your place is much bigger so a drain in the corner may not work so well.

About the steam and the ridge vent, regardless of the cupola or not, some steam will vent thru that type of ridge vent. A hood can all but eliminate that. I highly recommend you use a sheet goods type under the steel. If not the steel roofing will still sweat some and rain inside. I know, it has a way to always drip down the back of your neck. A hood all but eliminates that.
How large of an evaporator do you see in your future? If counting on a cupola to vent the steam, make the cupola that square foot opening. If you never see one larger than a 2x6 or maybe a 3x8, make it a 12SF or 24SF opening.
With an RO a 2x6 can do lots of taps worth of boiling, a 3x8 can do double that.

Ours is a pole barn style too. Never regretted decision to use hoods and stacks for steam. Easier to construct and to keep water tight. Neighbor built at same time and style as us. They used a cupola and have fought with snow and rain blowing in. It may look more sugarish but we like functional. Dr Tim's idea with grating is what we did, works great. Plus I can drive skid steer over it if needed.

thanks for the input! I am in the process of building a new shack. I had really planned on a cupola this time instead of a hood. I am tired of listening to a fan run the whole time. is any one using hoods with out a fan? if so how large of diameter to avoid needing fan? I plan on upgrading the evaporator in the future. so consider the size for 4 x 6 thanks in advance!

Our steam stacks dont have fans. Steam will draft up pipes no problem. Our steam stacks are 15" diameter. One for flat pans, other for flue. 3x12 evaporator.

I use the concentric exhaust design it works so good that it creates draft and sucks air in to the sugar bush. I wish I'd have plumbed a fresh air inlet in the floor that opens by my blower fan . Then it would have supplied both the fire and the hood without the breeze under the door. As for condensation I get almost nothing . Just when we first start and the room is cold but the wall heater fixes the problem fast.

I've seen lots of sugarhouses over the years, I don't think I ever saw one with a fan. My 3x8 has a cupola and after the first year I always had a hood. My steam stacks all went into the cupola and stopped even with the bottom of the cupola doors +/- 6" or so.
On my 3x8 evaporator I have a hood on the 3x5 flue pan with a 15" stack and a hood over the syrup pan 3x3, that hood is about 15" above the syrup pan, it also has a 15" stack, both stacks go up a ways, then each has a 13" stack suspended from in the cupola. That makes it possible for me to raise the hood(s) using a winch mounted on the wall. Both hoods are bolted together with the top even with the other as a single unit, being a raised flue evaporator that gives me the 15" opening over the syrup pan.