Easy & Cheap Stainless Vent Hood

[schematix]

Alright live update from the brewery testing this rig. 20 gallon blichmann with 5000 w boil cool at 65%. 30 qt mixing bowl with 449 CFM 6" fan reduced downstream to 4". Simulating 10G batch with 90 min boil.

1. Excellent airflow. All the steam is staying under the hood and is venting up. Nothing outside that. EDIT: Speed controller was probably a waste of $12. The faster the steam gets out the less it condenses.

2. Within a minute I was hit by a droplet of water. This fan isn't sealed for crap. It's coming out between the fan housing. Will fix tomorrow with silicone caulk and expect that to solve.

View attachment ImageUploadedByHome Brew1422927016.944208.jpg

3. Outside its cold (25F) and it looks like a dryer vent or heater vent. Huge cloud of steam billowing out. Bad news is some is condensing in the window sill. I'll have to see how much when done to determine if that's an issue.

Will update afterward.

 

[schematix]

Overall this worked really well - all the steam went out. To confirm that, I have a copper cold water pipe overhead and it didn't develop any condensation. Last time it was raining.

The fan housing leak the whole time. I'm going to seal that up with some silicone caulk all the way around. I think a better installation method would be to orient the fan on its side, drill a tiny hole in the bottom and install a drip line. That's not an option for me though due to how close I am to the window.

The ducting didn't have any condensation at all. Very odd given how much was in the fan housing.

All in all, this is a great cheap setup.

 

[jsprinceiii]

Alright live update from the brewery testing this rig. 20 gallon blichmann with 5000 w boil cool at 65%. 30 qt mixing bowl with 449 CFM 6" fan reduced downstream to 4". Simulating 10G batch with 90 min boil.

1. Excellent airflow. All the steam is staying under the hood and is venting up. Nothing outside that. EDIT: Speed controller was probably a waste of $12. The faster the steam gets out the less it condenses.

2. Within a minute I was hit by a droplet of water. This fan isn't sealed for crap. It's coming out between the fan housing. Will fix tomorrow with silicone caulk and expect that to solve.

View attachment 253650

3. Outside its cold (25F) and it looks like a dryer vent or heater vent. Huge cloud of steam billowing out. Bad news is some is condensing in the window sill. I'll have to see how much when done to determine if that's an issue.

Will update afterward.

By chance, are you opening that window in the picture?

 

[schematix]

Yah I open the window and put the vent in the sill, then close the window in it. I then stuff a rag in the other side to prevent it from blowing back in between the panes. When I'm done I close the window, and put the vent in the other side for storage.

 

[jsprinceiii]

Can you snap a picture of it sitting in-place, just as you would use it?

 

[fman872]

So I got some videos from yesterday's brew. I'm wondering if I'm boiling to hard. I've a like a strong boil but since the move to electric I might be going to hard. I couldn't get a shot of inside the kettle boiling because of poor lighting and steam.

What percentage is everyone running there pids for a 5gal batch? What size element?

View attachment trim.E20709E5-493E-4C45-BD1F-4BC725C52558.MOV

View attachment trim.0B709291-D9FF-4AA4-B358-003B6A83F588.MOV

 

[fman872]

Alright live update from the brewery testing this rig. 20 gallon blichmann with 5000 w boil cool at 65%. 30 qt mixing bowl with 449 CFM 6" fan reduced downstream to 4". Simulating 10G batch with 90 min boil.

1. Excellent airflow. All the steam is staying under the hood and is venting up. Nothing outside that. EDIT: Speed controller was probably a waste of $12. The faster the steam gets out the less it condenses.

2. Within a minute I was hit by a droplet of water. This fan isn't sealed for crap. It's coming out between the fan housing. Will fix tomorrow with silicone caulk and expect that to solve.

View attachment 253650

3. Outside its cold (25F) and it looks like a dryer vent or heater vent. Huge cloud of steam billowing out. Bad news is some is condensing in the window sill. I'll have to see how much when done to determine if that's an issue.

Will update afterward.

I had the same leaks I used food safe silicone and aluminum tape. The problem is now it all stays in the fan. see my video above.

 

[schematix]

Can you snap a picture of it sitting in-place, just as you would use it?

It looks very similar to the previous picture I posted in post #141 on this thread. I take the drywall/vent piece out of the left side. I slide the window right-to-left to open it. I place the vent in the track on the right side, then slide the window right to close.

I'll be brewing on Saturday. I'll take a picture then.

 

[schematix]

So I got some videos from yesterday's brew. I'm wondering if I'm boiling to hard. I've a like a strong boil but since the move to electric I might be going to hard. I couldn't get a shot of inside the kettle boiling because of poor lighting and steam.

What percentage is everyone running there pids for a 5gal batch? What size element?

Wow yours is full of water. I had little droplets raining out but nowhere near that much. It looks like yours has a lip right on the inside that is holding the water. Maybe drill some pin holes in the lip so it drains? My vortex fan has smooth edges so it drips freely.

I am running my boil at 65% of 5000W for a 10G batch (11.5-14G in the kettle).

 

[theck]

I was talking to a buddy and he wondered if insulating the vent tube would help move the vapors out so that it doesn't cool fast and create water?

 

[schematix]

I was talking to a buddy and he wondered if insulating the vent tube would help move the vapors out so that it doesn't cool fast and create water?

Disclaimer: I am thinking out loud here.

I am thinking the cause of the condensation in the fan is due to the increased pressure inside the housing. If you look at a phase diagram of water you'll see that if you have steam at 100C and 1atm (which is what we have), that you can condense it back to liquid just by upping the pressure a little.

I have a friend who is very knowledgeable on steam systems. I'll run this by him and see what they do industrially to prevent this. I know steam condensation is a very dangerous problem if handled incorrectly (e.g. blowing out the end of a pipe when you have an eblow).

 

[fman872]

Wow yours is full of water. I had little droplets raining out but nowhere near that much. It looks like yours has a lip right on the inside that is holding the water. Maybe drill some pin holes in the lip so it drains? My vortex fan has smooth edges so it drips freely.

I am running my boil at 65% of 5000W for a 10G batch (11.5-14G in the kettle).

I think im going to cut the lip off entirely and boil at a lower percentage. Back to workshop. I'll report back next brew day

 

[schematix]

I spoke to my buddy who deals with industrial process control systems and got his take on this set up.

Key points:
1. He doesn't think my idea about the pressure causing condensation matters much here since the pressure differential created by the blower is actually pretty low.

2. He thinks the primary reason for the condensation in this system is temperature related. The fan housing and ducting is all relatively cool. There is also a lot of surface area inside the blower and 6" duct.

3. High velocity is key to minimizing condensation. He recommends getting the largest blower possible, and using 4" duct all the way to approx double the velocity vs 6". Going any smaller will have diminishing returns since the restriction will go up.

4. Expect condensation. All steam systems have to deal with this when they are operating under the boiling point. Typically it's addressed by collecting and draining.

5. Industrial steam systems typically run 24/7/365 so all the parts are rocket hot all the time, thus no condensation. During start-up and shutdown, special equipment is activated to get rid of the liquid water.

So with that said, I'm just going to seal my leaks, and attempt to collect / drain the condensation that is inevitable.

 

[theck]

I spoke to my buddy who deals with industrial process control systems and got his take on this set up.

Key points:
1. He doesn't think my idea about the pressure causing condensation matters much here since the pressure differential created by the blower is actually pretty low.

2. He thinks the primary reason for the condensation in this system is temperature related. The fan housing and ducting is all relatively cool. There is also a lot of surface area inside the blower and 6" duct.

3. High velocity is key to minimizing condensation. He recommends getting the largest blower possible, and using 4" duct all the way to approx double the velocity vs 6". Going any smaller will have diminishing returns since the restriction will go up.

4. Expect condensation. All steam systems have to deal with this when they are operating under the boiling point. Typically it's addressed by collecting and draining.

5. Industrial steam systems typically run 24/7/365 so all the parts are rocket hot all the time, thus no condensation. During start-up and shutdown, special equipment is activated to get rid of the liquid water.

So with that said, I'm just going to seal my leaks, and attempt to collect / drain the condensation that is inevitable.

Would it help then to insulate the lines?


-------------------
Also, curious about a 8" fan like, not much more than the 6" but cheaper than those other ones people are snagging and going from 8" to 4" right away?
http://www.amazon.com/dp/B005KMUHWY/?tag=skimlinks_replacement-20

 

[schematix]

Insulating your ducts would only help if you had an issue with condensation in your ducts. Point is, if you make your air velocity high enough, condensation can be eliminated. For a short run you should be able to go without the insulation. If you had a long run it might be needed.

That style of fan is better as a booster fan in your house. For example if you need a room far from your main blower to get better airflow. They develop very little static pressure so they don't move much air once duct is attached. Their actual air flow is WAY below what they are rated for.

 

[fman872]

I spoke to my buddy who deals with industrial process control systems and got his take on this set up.

Key points:
1. He doesn't think my idea about the pressure causing condensation matters much here since the pressure differential created by the blower is actually pretty low.

2. He thinks the primary reason for the condensation in this system is temperature related. The fan housing and ducting is all relatively cool. There is also a lot of surface area inside the blower and 6" duct.

3. High velocity is key to minimizing condensation. He recommends getting the largest blower possible, and using 4" duct all the way to approx double the velocity vs 6". Going any smaller will have diminishing returns since the restriction will go up.

4. Expect condensation. All steam systems have to deal with this when they are operating under the boiling point. Typically it's addressed by collecting and draining.

5. Industrial steam systems typically run 24/7/365 so all the parts are rocket hot all the time, thus no condensation. During start-up and shutdown, special equipment is activated to get rid of the liquid water.

So with that said, I'm just going to seal my leaks, and attempt to collect / drain the condensation that is inevitable.

Hmmmm. So with a 6" fan would it be better to use 4" duct?

 

[jsprinceiii]

I believe reducing to a 4" duct will increase back pressure, and decrease CFM.
I also do not believe increasing the CFM (larger blower) is going to work.
Some suggestions..

• 6" Duct end to end, not reduced.
• Insulate the duct work.
• reduce 90 degree bends, make them 45's. This will reduce static pressure
• Make sure the vent cap is sized properly, and if it has a damper that it is functioning
• do not use a dryer vent cap.
• Makeup air inlet should be the same size or larger than exaust.
• make sure your makeup air inlet is not near the fan, preferable 10+ feet away, and lower than kettle.

 

[schematix]

I believe reducing to a 4" duct will increase back pressure, and decrease CFM.
I also do not believe increasing the CFM (larger blower) is going to work.
Some suggestions..

• 6" Duct end to end, not reduced.
• Insulate the duct work.
• reduce 90 degree bends, make them 45's. This will reduce static pressure
• Make sure the vent cap is sized properly, and if it has a damper that it is functioning
• do not use a dryer vent cap.
• Makeup air inlet should be the same size or larger than exaust.
• make sure your makeup air inlet is not near the fan, preferable 10+ feet away, and lower than kettle.

I agree with most of your points - less restriction will lead to a greater volume of air flow.

However, I don't think insulating the duct work is going to help much unless the duct is going to be in an especially cold area. There is very little heat in the steam so your duct work is going to settle just a touch above the air temperature you're pumping through it. The difference between a 50 degree duct surface and 70 degree duct surface is going to be minimal. It won't hurt anything, but I don't think for most installations its going to have a real performance benefit for the cost.

As far as 4" vs 6" velocity, all I can offer is that the air velocity was noticeably higher once the reducer was on. Sure the total CFMs went down, but now that steam was spending close to half as much time in the duct before exiting. My 4" duct was bone dry... not so much in the fan housing.

 

[schematix]

Hmmmm. So with a 6" fan would it be better to use 4" duct?

I suspect this is going to be a contentious issue, but I was told this afternoon by a licensed Professional Engineer who designs piping systems for a living (and who I consider to be an "A" grade mechanical engineer) that the best thing to do was to get the highest CFM fan possible, and use 4" duct. Counter intuitive in some regards, but the argument is that reducing duct size increases the velocity, decreases surface area, and will give less time for condensation.

My 4" ducts were pumping a ton of steam outside, and when done my 6" fan housing was dripping with water and my 4" ducts were bone dry.

 

[stickyfinger]

I suspect this is going to be a contentious issue, but I was told this afternoon by a licensed Professional Engineer who designs piping systems for a living (and who I consider to be an "A" grade mechanical engineer) that the best thing to do was to get the highest CFM fan possible, and use 4" duct. Counter intuitive in some regards, but the argument is that reducing duct size increases the velocity, decreases surface area, and will give less time for condensation.

My 4" ducts were pumping a ton of steam outside, and when done my 6" fan housing was dripping with water and my 4" ducts were bone dry.

That's a nice piece of empirical evidence. I have been using some duct calculators and the info at this site in particular:

http://custom-wheels-blowers.centralblower.com/Asset/Determining-Static-Pressure.pdf

Whenever I use 6" duct vs. 4" duct in my calculations, the actual air velocity comes out almost exactly the same (the 6" velocity is usually just a bit higher.) I wonder if there is something wrong with the calculations or if the fan I am using is just more hindered by the 4" duct (I used the fan performance curves to calculate CFM at the calc'd static pressures.)

For example, for 3 elbows, 10' of duct run and a 20 inch diameter round hood, I calculate an actual air flow of 214 and 231 FPM when using 4" and 6" duct, respectively. The 4" takes a huge hit in static pressure, which reduces the CFM, and thus the air velocity quite a bit.

My actual run will likely be 1 elbow, 4' total run and 20 in. diameter hood, which calc's out to 497 vs 508 CFM for 4" vs 6" and 228 vs 233 FPM for 4" vs 6". I shouldn't have to run the fan on full power, even for full boil (5500 W.)

This is all just calculations based upon some empirical input though, so it might all be garbage. I'm right at the point of deciding how to run and what size to use, so I think I'll just try to plan for placing my fan horizontally with the capability to have it drip on the floor if needed to be safe and use 6" duct that is well-sealed. Though, I'm tempted to switch to 4" for less space taken up and similar performance. The CFM is lower of course, but it's still really high. l The overhead might allow me to see no condensation in the fan or pipes.

 

[schematix]

I put a speed controller on my blower and it was probably a waste of $12. It can only be adjusted down maybe 20% before the steam isn't fully captured any more, and its still loud. For the 90 minutes it's on, might as well just run it full blast and use a $1 switch.

I'm not an expert in sizing blowers. I'll do some research and see if there is an explanation here.

I guess if your performance numbers say all else is equal, might as well go the cheaper route.

 

[stickyfinger]

I refurbished an old "Variac." It's super quiet from 0 - 110V and has pretty decent fan control, though, I don't know how low I will be able to run it and still get good exhausting.

 

[Hello]

I'm curious, is there any reason I could not use this duct fan through the bowl? I have the bowl, not the fan. My thought was to just do that, use ducting, then outside and buy the vent for the outside of my building.

http://www.amazon.com/dp/B005KMUHWY/?tag=skimlinks_replacement-20

 

[stickyfinger]

The manufacturer of that fan says it can be used for indoor grow rooms, but I don't know how good it would be with super high humidity conditions. If you have a short run, it might be able to move enough air. I bet it has a very poor performance curve, meaning the longer your run, the greater number of elbows and the smaller the ducting, it will drop off in CFM very quickly compared with a nicer fan. If you don't mind risking $26 to try it, it might work for a short run. I think someone else in this thread tried one or thought of trying one.

 

[theck]

I think I'm going to build a box out of 2x2s and cover the inside with galvanized duct then punch a hole in the side and use a 8" duct fan like http://www.amazon.com/dp/B005KMUHWY/?tag=skimlinks_replacement-20 not connected directly to the box but maybe a little ways off... I figure I might be able to do a drip edge as well and collect the water down a tube or ?

 

[schematix]

The manufacturer of that fan says it can be used for indoor grow rooms, but I don't know how good it would be with super high humidity conditions. If you have a short run, it might be able to move enough air. I bet it has a very poor performance curve, meaning the longer your run, the greater number of elbows and the smaller the ducting, it will drop off in CFM very quickly compared with a nicer fan. If you don't mind risking $26 to try it, it might work for a short run. I think someone else in this thread tried one or thought of trying one.

This style of inline fan has a high theoretical CFM with nothing attached, but they develop very little static pressure and so get bogged down very quickly when you put anything on them. Mfr says this 8" fan develops a mere 0.1 inH2O. The 6" vortex makes 250% more. Static pressure is your friend when you want to get high CFMs.

 

[Hello]

This style of inline fan has a high theoretical CFM with nothing attached, but they develop very little static pressure and so get bogged down very quickly when you put anything on them. Mfr says this 8" fan develops a mere 0.1 inH2O. The 6" vortex makes 250% more. Static pressure is your friend when you want to get high CFMs.

The manufacturer of that fan says it can be used for indoor grow rooms, but I don't know how good it would be with super high humidity conditions. If you have a short run, it might be able to move enough air. I bet it has a very poor performance curve, meaning the longer your run, the greater number of elbows and the smaller the ducting, it will drop off in CFM very quickly compared with a nicer fan. If you don't mind risking $26 to try it, it might work for a short run. I think someone else in this thread tried one or thought of trying one.

Oh that makes more sense now that I read about static pressure. I just saw it and thought it was an option. I'll stick to the 440 cfm vent fan that has been linked here. Thank you both.

 

[orangehero]

I've seen a small plastic tote used for the hood. Definitely easier to cut. I don't think it's necessary for it to be round or stainless.

 

[schematix]

That thin stainless bowl was a bitch to cut. Ate up 3 jigsaw blades and took about 15 minutes. Even my nice cobalt step bit was having a slow time getting my pilot hole cut.

I thought about using a plastic tote, but I have built a stainless steel shrine in by basement and didn't want to tarnish it

 

[orangehero]

Spray paint.