Steam hood venting

[backyardsugarer]

I am going to have to put a 45 degree elbow to get my steam hood to vent. Will this restrict the flow and cause any problems? I have a 2 by 8 evaporator and I will be suspending a 3 by 7 steam hood about 18 inches over my rig. I could cut a new hole but there is already one close and I do not want to cut any more holes in my roof if I can avoid it. Thanks.

Chris

[maple flats]

What diameter stack do you plan? If large enough you will be fine.
I have a 3x8 with a 3x6 full cover hood over the flue pan and an extension of 20" over the 3x2 syrup pan that is 16" off the syrup pan. I have 2- 8" steam stack that terminate in the cupola, they don't even go out side and they work fine. The steam off the syrup pan is sucked into the hood about 99% with very little escaping even thou that part of the hood is up 16" and is 4" shorter than the pan. It still works.
Based on that I think you should be fine. I might suggest a 10" min and better a 12" stack if you will have just 1 stack, but I think most of the time a 10" will do.

[Father & Son]

I'm in the planning process of hoods for my 2x8 and was hoping 1 12" stack would do. I also will need 1 elbow want to terminate in the cupola. My only concern is the stack will only be 8' tall and I'm hoping it will have enough draw.

Jim

[backyardsugarer]

The description of the hood I bought states and 8" thimble which I thought was exhaust. If the exhaust is only 8" I am a little concerned. I am not opposed to adding an in-line fan. It is rated for 250 cfm which should help draw the steam through the hood. Any thoughts or experience with this? I bought a stainless hood and have not had a chance to pick it up yet (hence my questions). Thanks.

Chris

[maple flats]

If you plan to run a pre heater in the hood, you do not want a fan to help flow. In fact some even use a damper to slightly pressurize the hood for greater heat exchange. If you bought a commercially made hood, the 8" will be the right size, I'm sure they know what size they need. If this is a custom made from a non maple source the size might not have been tested.

[smitty76]

And if the in line fan's motor is in side the pipe and not external, the condensate with raise holy hell with the motor. I used a squirrel cage fan on mine with an external motor. I do however agree with maple flats that it may create too much flow if you have a pre-heater in the hood. It also depends on which style hood you are useing. My hoods fit onto the pans so that the fan does not drawn cold air in them( i am sure that there is some air leaking in because they are not sealed air tight around the pans) where as if your hoods are just canipes hanging over your pans. that would suck alot of cold air.

[backyardsugarer]

Smitty,

Where did you get your fan with the external motor? Home Depot carries the inline fans with the housing inside. I do not plan to use a pre-heater and my hood will be suspended.

Chris

[smitty76]

Chris,
It is just a regular squirrel cage blower, like one from a small forced hot air furnace, that I hid in the rafters. I put a 8 in stove pipe flange on the suction side of the blower and used 10 in square ducting from the discharge side of the blower to the out side of the sap house. Unfortunately, our sap house does not have a cupola so we just blow the steam out the side.

[smitty76]

Also, we ran the discharge duct with a slight slope down from the fan to get the condensate to run out side and not back into the pans.

[maple flats]

In my experience you do not need to help the steam escape, it will get out as long as the steam vent (stack ) is about the right size. Yours sounds good.
Mine sets tight on the flue pan (sort of tight) and an extension is elevated over the syrup pan. The steam gets out fine and natural draw pulls in some fresh air in at the raised part. It still gets out.

[smitty76]

We are moving our evaporator to a new location this year and are looking for differrent hoods. This new location does not have a cupola either, so we will have to figure something out. One of the reasons we added the fan was so that when the hood doors were opened, the fan would clear the steam so that there was good visibility of the sap boiling in the pans. Our guests could get a better picture of what was really going on in there. We did not need it to get the steam out, it just did a better job of it.

Smitty

[maple flats]

That visibility likely drops the rate of evaporation. You get the best rate when you slightly raise the temp in the hood. Sucking it free of steam is not doing that, it drops the temperature in the hood.

[smitty76]

I would agree. the doors of the hood are only open for show and tell. They spend 99 percent of the time closed. in theory, if the suction of the fan actually produces slight vaccum(if any, ever so slight) it will increase the rate of evaporation. However, this fan produces very, very little vaccum and probably does not make any difference. We are happy with the rate we get and our new setup will most likely not have an exhaust fan on the steam hoods.

[Linda R]

Chris hi this is Linda from Whitehall, NY My Husband John has just installed the same RO that you have. This will be his first year using RO. He wanted me to ask what do you wash RO with? He boiled 40 gals. of syrup last year and we could have boiled more but did not have RO. If you would you can email me at LdyWalleye@aol.com or go to facebook...I am Ldywalleye there too...Thanks for information5244