GVH Drying Method

[GVH_Dan]

So, my question is, what is the SP curve for hop bed depth?

You and me both...I have some data but its sketchy at best. I've built a new test rig for this year that should answer most of my questions, I hope.

Part of it is that the sp changes through the drying process. Think of it this way, as you get close to dry, those cones open up. As they open up, the sp increases, which means less airflow but that's OK. Towards the end of the drying cycle, you don't need as much airflow.

 

[GVH_Dan]

Hey Dan,

Would you mind sharing just a bit about static pressure and hops? I am trying to figure out if these two fans I have will be enough to pull air through a design I am working on.

The blowers I have will each do 105cfm at 0.5" SP, but I'm not sure how hops affect the pressure.

My design is a box on the bottom, housing the two blowers, venting out the bottom. I plan to make 3" deep trays to stack on top. The inside volume of 6 trays would be just over 12 cu. ft.

So, my question is, what is the SP curve for hop bed depth?

Thanks for any help you can give,

MT

Looking at the rest of your design, if you go 3" deep and have a total volume of 12 cu ft, that means you have an area of around 48 sqft...roughly 6' x 8'...sound correct?

If you were blowing the air from the bottom up, the maximum air velocity you would want is about 1 ft/sec, and even that would be too fast at the end. Since it sounds like you are pulling down, you can easily do 1 ft/sec = 60 ft/min.

Doing the math: 60 ft/min * 48 sq ft = 2880 CFM

Your static pressure drop depends on not just the hops, but any other restriction you have like the mesh you are laying them on, constrictions to bringing in or blowing out the air, etc. From the design you are describing, I think 0.5" to .75" sp should be sufficient.

What I would recommend is you get an old furnace fan. Call HVAC contractors and tell them what you need and why. Their first thought is that you are trying to repair your own furnace by getting a used fan. So make sure they understand why you need the fan and mention the word "beer". They are single phase, can handle plenty of pressure drop and will move typically 1800 to 2200 CFM. This is less than 2880 but much more than 210. It will just take a bit longer to dry them. I would still put the fan in the bottom plenum blowing out like you were saying with the other units.

Just a word of warning, stray cones will find their way into the fan and are impossible to get out. So do your best to keep it clean. For our commercial growers I make them stay away from these units and use backward inclined fans that can pass the cones but if you are only drying 1 batch, you will be fine. Otherwise, either have a second fan on hand or be ready to spend time with a tweezers trying to pluck cones out from between the blades.

 

[mthompson]

You and me both...I have some data but its sketchy at best. I've built a new test rig for this year that should answer most of my questions, I hope.

Part of it is that the sp changes through the drying process. Think of it this way, as you get close to dry, those cones open up. As they open up, the sp increases, which means less airflow but that's OK. Towards the end of the drying cycle, you don't need as much airflow.

Sure would make some pretty data plots!!! :rockin:

Here's the design I threw together, based around the small blowers I have on hand.

If these won't work, I could easily adapt it to use a larger HVAC inline type blower, with the base being a plenum and adding an upper plenum on top of the stack.

I will be using this to dry other herbs as well; Nettle makes a great tea and I dry flowers to make oil infusions with as well (beekeeping hobby offshoot).

 

[mthompson]

What I would recommend is you get an old furnace fan. Call HVAC contractors and tell them what you need and why.

I have a friend that owns a Heating/AC business....he'll know what I need.

Just a word of warning, stray cones will find their way into the fan and are impossible to get out. So do your best to keep it clean.

I wonder if it would help to design the unit with sort of a p-trap bend coming out of the oast and going vertical. This would raise the blower up a bit, so that the hop bits would have to fight gravity to get to the fan blades.

Just a thought....

 

[GVH_Dan]

Sure would make some pretty data plots!!! :rockin:

Yeah, the stuff I have now looks about like a 20 gauge with modified choke. I"m trying to get it down to 410 with full choke.

 

[GVH_Dan]

Here's the design I threw together, based around the small blowers I have on hand.

Hang on, looking at your drawing, your screen area is 36" x 34.5"? That makes your area (the area seen by the air) about 8.63 sq ft.

Assuming you have 6 trays there, each at about 3" deep...that's 1.5 feet of hops and a total volume of around 13 cu ft. Does this sound right?

So for the same airflow, you now need 60 ft/min x 8.63 = 520 CFM. Even if you put a small furnace fan on there, you are talking a velocity of about 3.5 ft/min. At that velocity, you would damage the cones at the end and I'm not sure what it would do to other things you are drying.

Plus, the pressure drop is cumulative through all those beds. A furnace fan would still do the job but a simple axial (propeller) fan would never stand a chance.

Talk to your buddy and see what you can find. I'm thinking something out of a commercial kitchen ventilation hood? Or you could take the furnace fan and choke it off enough to slow down the airflow to at least 2 ft/sec.

Oh and trust me, nothing you do will prevent those cones from finding their way in. I've tried everything right up to putting window screen across the inlets of the fan. If there is an opening 1/8th the size of a cone, they find a way to squeeze through. Make your trays super tight. Turn the fan off whenever loading/unloading and make sure you clean out that bottom plenum everytime before starting the fan back up.

 

[mthompson]

Hang on, looking at your drawing, your screen area is 36" x 34.5"? That makes your area (the area seen by the air) about 8.63 sq ft.

Assuming you have 6 trays there, each at about 3" deep...that's 1.5 feet of hops and a total volume of around 13 cu ft. Does this sound right?

So for the same airflow, you now need 60 ft/min x 8.63 = 520 CFM. Even if you put a small furnace fan on there, you are talking a velocity of about 3.5 ft/min.

The trays are square, 34.5" x 34.5". Total of 12.2 cu. ft. if I remember. The 36" is OD for the unit.

I have been able to run a single variety at a time for drying every year, using larger screen boxes with a fan blowing across, but it takes up so much room! The varieties I have, all age about 2 weeks apart...... But, if I'm going to build it, I want it "worst-case" capable. Plus I am getting larger yields with better management (compost, cover crops, drip irrgation).

^^^ in large part, due to what you guys do!

Thanks,

 

[GVH_Dan]

If you get a centrifugal fan, it won't see much degradation in airflow until you are past 1./5 to 2 feet. So if you can find one that provides decent airflow across your area, you should be fine.

 

[GVH_Dan]

Plus I am getting larger yields with better management (compost, cover crops, drip irrgation).

^^^ in large part, due to what you guys do!

Thanks,

Thanks. We are trying to do our part to clear up fact from folklore and hop growing has A LOT of the latter.

While you are at it, try those nettles in a brew. I've been told they are interesting and maybe even good.

 

[mthompson]

Thanks. We are trying to do our part to clear up fact from folklore and hop growing has A LOT of the latter.

While you are at it, try those nettles in a brew. I've been told they are interesting and maybe even good.

That's what I heard. I'm thinking of doing a nettle/sumac beer sometime.... Sounds like a good candidate for using some of my wild hops cones.

All three of which I can harvest within 20 ft. of each other!

 

[mthompson]

You were not kidding about the particles GVH_Dan!!

This is after just one tray on my oast from above....

 

[TrickyDick]

Any practical advice on when to pick? There is a zymurgy (?) article by Stan H and he talks about a method that seems fairly scientific, but sounds like a lot of work, and not really sure how much of my crop would be lost each time I did the test to see if they were ready to pick...

The finger squeeze test sounds pretty silly to trust if you are a new homegrown hop producer. Reminds me of my grandmother shaking fruit and listening to it in the produce department.

TD


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[GVH_Dan]

I haven't seen the Stan H article, but I suspect it is checking the moisture content method. We have our growers do that. They pick about a 1/3 gallon of hops (100 grams), dry them down and measure moisture content. When they are getting close, you will see the moisture content begin to drop. Harvest occurs when you reach between 78 and 82% moisture content.

And you are absolutely correct. The homegrower would use their entire crop just trying to see when it is ready to pick.

We also use chemical analysis to determine down to a 3 day period when the best time to pick would be. This is easy since we have our own lab. Again, for the homegrower this would be prohibitively expensive.

Checking the feel of the hop cone can tell you if it is nearly ready but that's something that you learn with experience. The first year its pretty hard to pick that up. I tell people to use their nose and eyes. Cascade is the easiest. Don't pick them until the plant smells like your favorite IPA. The oils are one of the last things to fully develop, so don't pick until they smell good.

Also, look at the lupulin sack. It should be a little darker than school bus yellow. If it is lighter, its not ready.

Usually, when they look big and green, just like in beer commercials, they aren't ready yet. When they are ready, some of the bracts have started to turn brown and they aren't perfectly visually appealing. A lot of people complain about their homegrown hops not giving enough flavor because they haven't had a chance to develop all the oils and alpha acids.

 

[TrickyDick]

Great! Last question, until I think of another that is, do I harvest them all at once, or cone by cone as they appear to be ripe?


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[GVH_Dan]

Depends on how you harvest. If you have a lot of bines, you'll probably cut them down, drag them over to a table in the shade and pick away. If its comfortable enough, pick the ripe ones and wait on the rest. Usually the ones at the top are ready before those lower down.

 

[TrickyDick]

Thanks.

I live in FL. Lots of humidity. A/C indoors though, but as you mentioned, SWMBO will probably not tolerate hop drying smell (does it really smell?) indoors.

I have a basement area, which has AC but no air return, so little air changes in the room. Some leaks out when you open the doors, and through the crack.

Have an old box fan and some scrap wood, could probably pick up some screen from home despot, and fashion a drying box. Do you think would be better to use outside in the high humidity, or inside in basement with low humidity but little airflow aside from incoming AC?

If outdoors, I could run some lizard heating cord (25watt) not supposed to get above 90" and I could throw a temp controller on it, and incorporate into the box design to warm the air? Doubtful that would do much outdoors to alter the RH much to make a difference, and just add complexity to the design.

Do you think I'd need a speed controller aside from the high-medium-low setting to adjust the fan speed?

Last year I dried in the oven with the oven light as heat source and the convection fan on. Got super hot because I didn't realize its a halogen light..... Haven't used those hops yet. Got a little over 1 oz last year. I only have four plants.

TD


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[day_trippr]

Depends on how you harvest. If you have a lot of bines, you'll probably cut them down, drag them over to a table in the shade and pick away.[...]

That's what I do - with a beer or three, of course!
Last season's Cascade haul. That was preceded by the Centennial and followed by the Chinook.
Three days of stripping bines. I don't even want to think about stringing that out over multiple harvests...

Cheers!

 

[GVH_Dan]

Thanks.

I live in FL. Lots of humidity. A/C indoors though, but as you mentioned, SWMBO will probably not tolerate hop drying smell (does it really smell?) indoors.

I have a basement area, which has AC but no air return, so little air changes in the room. Some leaks out when you open the doors, and through the crack.

Have an old box fan and some scrap wood, could probably pick up some screen from home despot, and fashion a drying box. Do you think would be better to use outside in the high humidity, or inside in basement with low humidity but little airflow aside from incoming AC?

If outdoors, I could run some lizard heating cord (25watt) not supposed to get above 90" and I could throw a temp controller on it, and incorporate into the box design to warm the air? Doubtful that would do much outdoors to alter the RH much to make a difference, and just add complexity to the design.

Do you think I'd need a speed controller aside from the high-medium-low setting to adjust the fan speed?

Last year I dried in the oven with the oven light as heat source and the convection fan on. Got super hot because I didn't realize its a halogen light..... Haven't used those hops yet. Got a little over 1 oz last year. I only have four plants.

TD


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I would go with garage or in a shaded area outside. No sunlight. If you did it in the basement, the moisture from the hops would quickly overwhelm just a little A/C. Plus there's a good chance the smell will find its way up. Don't give her a reason to ban your hobby.

Even outside, you will be able to get down to 20% moisture content or less even in sticky Florida. After that, if it doesn't seem to want to finish drying add a little heat. Only do that at the end.

Keep the air flowing as much as you can. The more air flowing through the hops, the more moisture it removes.

 

[TrickyDick]

Hey thanks!

Gonna pick up some screening material today on the way home and get started.
You think it's OK to have regular 20" box fan and then some 3-4" pine boards nailed up to form a frame with screening material right on top of the fan, or should there be some distance between the screen (that hops sit on) and fan? I'm thinking to pull air through the screen rather than to push. Garage can get into 90's during the day. When I get home from work, temp spikes because my car is a hot rod and even normal driving it gets really hot and stays that way for many hours after driving. Haven't checked garage temp changes this would cause, but I can monitor temp and RH easily enough. I have a porch that is cooler and out of direct sunlight most of the day except for an hour in the evening. It's basically at the ambient temp and cooler than the garage


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[GVH_Dan]

If you don't go much more than a couple inches deep, the box fan should be able to pull the air through.

It will be better to "suck" the air through the bed. It gives better uniformity. Mount the fan on the bottom of the screen pulling down. If you push the air up, you'll end up blowing cones all over the place when they get close to dry. Make sure the screen is much smaller than the cones.

The porch sounds fine. If they need help drying, you could just move it into the garage to finish.

When I get home from work, temp spikes because my car is a hot rod and even normal driving it gets really hot and stays that way for many hours after driving.

Now you're just bragging. Even my mini-van heats up the garage...a bit.

 

[TrickyDick]

Thanks,
I don't like to brag but if you want to check it out (not that my driving is so impressive) I've posted some vids to you tube - search on DrTrickyDick

Got the screen, too hot to attempt to construct anything right now, and the hops aren't ready yet. They're getting close, but not ready. I've got a few days at least I think to get the dryer ready.

that's an impressive haul Day_Trippr ! How many plants??

TD

 

[TrickyDick]

harvested second year columbus today. net weight wet is 8.4 oz. not too bad. I expect a second harvest being in FL, like I had last year. My setup uses eyebolts as pulleys, and I can lower the whole bine for harvesting, and just pick cones, and then hoist back up. Have a steel wire connected to a steel ring and the coir twine is tied off the the ring, which in turn is bolted to the planters. Is working pretty well except for one plant near an AC air handler - blow hot air on it and "burns" the sterling hops.

Anyway, Built a drying rig today to suck the moisture out of the hops. Outdoor kitchen is in the high 80's today R.H. just short of 60%.

I'm hoping to hit about 2oz final dry weight in 2 days, then harvest the chinook dry those before my trip. They are nearly ready for harvest, most cones seem not quite ready or I'd have done those first. Much better aroma from the columbus, which seemed to have matured more rapidly as flowers, but less vigorous than the chinook vegetative growth. Seem the chinook flowers take longer to develop

TD

turns out my box fan keeps crapping out in the heat. I removed the smoke filters from my BBQ hood, and threw it up into the hood - 1600 cfm. should dry them out good, plus keep them off the floor level where my dog could potentially get into them.

 

[day_trippr]

[...]
that's an impressive haul Day_Trippr ! How many plants??TD

Four...

Cheers!

 

[TrickyDick]

Ok,

so my harvest on Sunday was 8.40 oz net weight. After a day in the BBQ hood they are down to 3.45 oz. A little math tells me that there is 41% of the original weight. Is this percentage the same as the % moisture? If so looks like I have a winner with the BBQ hood - just need another day.

TD

 

[day_trippr]

It can't be percent moisture, because in theory if you dessicated the living crap out of the hops they'd weigh zero

Cheers!

 

[GVH_Dan]

I don't quite have the time but the formula is MC = (Ww - Wd)/Ww x 100%

Ww = wet weight
Wd = dry weight...weight of the hops if all water is removed.

If you pick them at 80% MC, the dry weight would be somewhere around 20% of that weight. So if you are shooting for 10% moisture content, the final hops must be between 1/4 and 1/5th the original weight.

So for you, the dry weight of those hops was probably around 1.7 oz...therefore they are:

(3.45 - 1.7)/3.45 x 100% = 50.7%

You still have a long way to go. figure at least 3 days, maybe more if it is raining or really humid.

 

[TrickyDick]

Oh crud. Thanks. Was hoping it'd be 2 days. Have another bine to pick and dry before my trip.


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[TrickyDick]

48 hours and down to 2.45 oz from initial 8.40oz. 29% of original weight. Seems to take longer to get below a certain % maybe logarithmic or parabolic. One more day. If I'm below 2 oz I think I may declare finished since 1.9 oz would be between 1/4 and 1/5 of original weight.

Thanks.


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[Oxbow]

I'm working to dry my first year harvest in a simple oast on the cheap. Trying to use some principles from this thread I built a 3x5x4 box with three screen-bottom trays. The bottom of the box is elevated and there are three box fans suspended at the bottom of the box blowing down to pull the air through the trays.

Question is: do I leave the top of the box completely open to let as much air in at one time as possibles or do I cover a portion of the top to increase the velocity of the air being sucked down into the box?

 

[day_trippr]

I'd leave it open to keep the velocity low and as even across the oast area as possible...

Cheers!

 

[Oxbow]

I'd leave it open to keep the velocity low and as even across the oast area as possible...

Cheers!

Makes sense, thanks!

 

[day_trippr]

The down-draft system likely helps, but you still want to be careful that the cones aren't fluttering around in the wind as they dry and the petals start to open because that will shake a lot of lupulin nuggets out of the cones (as I discovered on my first year's harvest).

There's no need for speed

Cheers!

 

[GVH_Dan]

Exactly. Its VOLUME not VELOCITY that matters. You want the most air possible to touch the cones so they can dry as quickly as possible, More air means a higher velocity but you don't want to artificially increase that velocity.

One of the reasons is because box fans can't handle a lot of resistance to air flow. When you restrict it to increase air flow, that will actually decrease the amount of air touching the hops. As day tripper noted, it will also give your girls a good shake and that means loss lupulin.

 

[Oxbow]

The down-draft system likely helps, but you still want to be careful that the cones aren't fluttering around in the wind as they dry and the petals start to open because that will shake a lot of lupulin nuggets out of the cones (as I discovered on my first year's harvest).

There's no need for speed

Cheers!

Regarding the lupulin, I dried my test batch down to what I calculate to be 10% moisture. At that level, is it normal to see some lupulin dust at the bottom of the pails used for transporting the dried hops and the bowls that go on the scale? It's a fine dust at the bottom. The hops still smell good so I don't think I've lost everything but I thought it was worth asking.

Exactly. Its VOLUME not VELOCITY that matters. You want the most air possible to touch the cones so they can dry as quickly as possible, More air means a higher velocity but you don't want to artificially increase that velocity.

One of the reasons is because box fans can't handle a lot of resistance to air flow. When you restrict it to increase air flow, that will actually decrease the amount of air touching the hops. As day tripper noted, it will also give your girls a good shake and that means loss lupulin.

Noted! Thank you!

 

[day_trippr]

If you're just seeing a dusting that's pretty much unavoidable even if everything is perfect. My shop floor starts looking dusty when the oast is running, and the vacuum freezer bags will have little deposits of dust in the corners when I use the hops. There's so little actual mass in all of that that I don't think twice about it.

Otoh, the first year I ran my blowers flat out and jiggled the crap out of a batch of Centennial for two days. I swept up about a cup of gold much to my chagrin

Cheers!

 

[Oxbow]

If you're just seeing a dusting that's pretty much unavoidable even if everything is perfect. My shop floor starts looking dusty when the oast is running, and the vacuum freezer bags will have little deposits of dust in the corners when I use the hops. There's so little actual mass in all of that that I don't think twice about it.



Otoh, the first year I ran my blowers flat out and jiggled the crap out of a batch of Centennial for two days. I swept up about a cup of gold much to my chagrin



Cheers!

Ok that's great to hear. I was getting a little dust in the corner of my vacuum bags as well but that sounds normal.

 

[mthompson]

Ok that's great to hear. I was getting a little dust in the corner of my vacuum bags as well but that sounds normal.

Can't save it all....just be reasonably gentle when handling the dried cones.

If I have a lot of yellow on the inside of my vacuum bags, I'll dip them in the boil to sorta rinse them a bit. I know the foodaver ones are rated for boiling temp.

 

[day_trippr]

fwiw, this doesn't rate it's own thread, and it fits the scheme of things in this one so I figured I'd drop it here.

My first quasi-oast build consisted of three frames with dados that capture 43" x 31" screens liberated from some basement windows. For three years I just stacked the frames on saw horses with a pair of 20" box fans perched on milk crates and blowing up into the stack. Effective, but not particularly efficient.

I decided an upgrade to a down-draft system was in order. I'm almost certainly going to need to harvest the Centennial this weekend, so today I built a matching base unit with the same two 20" box fans and some leftover plywood and 1x8s. I removed the fan guards, screwed the fan shells to the inside, then reattached the guards as shown. Et voila! 28 square feet of drying surface ready to go again!

I'll still use the saw horses but one can imagine with everything essentially sealed together it should work much better even as I likely use the slowest speed settings to keep the cones from bouncing around...

Cheers!

 

[cernst151]

There are a handful of production wet hop beers available, so a wholesale rejection of using wet hops is not true. I'm not convinced that the tradition of drying is little more than a tradition out of necessity for preservation, from times predating refrigerated and frozen transportation.

I don't get the impression of a "wholesale rejection" of wet hops from anybody here. I have had a few very good commercial wet hop beers but I can say that the last 2 years I used wet hops from my bines in my beer and each time they came out tasting too grassy so this year I've decided to dry my hops. It helps that my bines are finally producing more hops than I can use wet before they're not fresh anymore.

This will be the first year I've dried my hops though so I'll have to post again with my first batch made from homegrown dried hops. If I get the same results maybe it's something with my soil or my specific bines. I can certainly say that I got very different results from using my homegrown wet Cascades and Centennials than I did from store bought hops of the same variety.

I've got my first small harvest of hops drying right now on a 2 layer drying rack I built that was inspired by this thread. I'd be hesitant to freeze wet hops but if you do it please let me know how it works.

 

[cernst151]

My first quasi-oast build

Holy crap! I posted my picture before I saw yours. I was pretty proud of it too until I saw your setup. That's nice!