When I built mine, I bought these exact dampers. I used 2 - 1 1/2" intakes 180° apart and a single 2" exhaust. I gotta keep the intakes pinched off quite a bit to keep it in the 225°-250° range.
This was my experience. Hope it will help you make a decision.
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They work fine. I built one with those type of intakes and exhaust. I found I didn't like the air control they provided on the intakes. They work great on exhaust because they are always wide open when cooking or totally closed when shutting down.
I prefer 2-1" ball valves. Either in brass(higher cost) or in PVC(very low cost). And yes the PVC valves will work fine. They don't get hot or even warm on the outside of the drum at the bottom where the intakes are to cause any problems.
I gotta agree with Jim on this one. I'd go with 2 -- 1" intakes. Either two ball valves or one intake with a cap and one ball valve.
You'll want to consider it in terms of total intake area available to the drum and the kind of temp range you want.
Here are the values for different configurations.
Number ---- Size ------ Total Area
3 ---------- 3/4" ------- .44"
2 ----------- 1" ------- .79"
2 ---------- 1-1/2" ------ 1.77"
1 ----------- 2" ------ 3.14"
(I wish this editor would recognize spaces or tabs when you try and make a table. )
I built my two UDSs with three 3/4" intakes. I have no problem keeping the temps low but struggle a bit to get and keep it above 350° when I want to do something hot like tri tip or chicken. If I built another one I'd probably go with two 1" intakes.
Based on zeroghd's experience with two 1-1/2" and bybbq's experience with one 2" intake it seems that two 1" intakes would provide a good combination of range and control.
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...I built my two UDSs with three 3/4" intakes. I have no problem keeping the temps low but struggle a bit to get and keep it above 350° when I want to do something hot like tri tip or chicken. If I built another one I'd probably go with two 1" intakes.
So I am not looking to ask a stupid question, but...
I've already popped in three 1" DIA holes for a pair of 3/4" nipples and a 3/4" ball valve, but I will want to achieve temps into the 350 - 375 degree range for certain cooking situations.
If I were to add an additional 1" or 1&1/2" hole for a larger nipple or ball valve, am I getting into overboard territory in doing so?
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Drinking is like playing golf... you'd best be prepared to play every club in your bag.
Steve the Bartender
There are no bad briskets... only poorly executed ones.
Originally posted by The Great White NorthView Post
So I am not looking to ask a stupid question, but...
I've already popped in three 1" DIA holes for a pair of 3/4" nipples and a 3/4" ball valve, but I will want to achieve temps into the 350 - 375 degree range for certain cooking situations.
If I were to add an additional 1" or 1&1/2" hole for a larger nipple or ball valve, am I getting into overboard territory in doing so?
Overboard territory...yes
Just open up the holes and use 1" ball valves and nipples.
Other problem is you have to have enough exhaust to handle the added intake. Otherwise it won't achieve the higher temps.
I have never built a drum but it seems to me that having too much intake is a good plan as long as you have a good way to close down as much/many as needed to maintain temps...
It's just my thoughts if I were building my own stick burner...More air is more better...
Overboard territory...yes
Just open up the holes and use 1" ball valves and nipples.
Other problem is you have to have enough exhaust to handle the added intake. Otherwise it won't achieve the higher temps.
I am not too worried about the exhaust volume as the lid on the drums I found came with a pair of the larger threaded access holes one smaller threaded one.
Plus if I find the need additional vents on the lid I could just add them at strategic locations around the lid and use flexible magnets to control the outflow volume.
I am not so worried about a potentially cheesy appearance as I am a flexible and efficient design.
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Drinking is like playing golf... you'd best be prepared to play every club in your bag.
Steve the Bartender
There are no bad briskets... only poorly executed ones.
How many holes are in the lid and what size are they ?
Right now there are 2 standard-sized holes which are over 2" in diameter along with a single smaller hole about 1/3" in diameter.
One of the larger holes and the smaller hole are located directly opposite of each other along the outer edge of the lid rim, the second larger hole is located directly in the center of the lid.
All of the holes have collared thread inserts with recessed caps that tightly screw into the holes.
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Drinking is like playing golf... you'd best be prepared to play every club in your bag.
Steve the Bartender
There are no bad briskets... only poorly executed ones.
Before I got rid of mine "long story" I used just one 1/2" ball valve, plenty of air flow. Now if I want to shut it down it was a positive stop. Heat creates a upward draft and will suck as much air needed through the valve. JMHO.
Does anyone know off the top 'o their head what the thread size is on the standard large bung holes that are found on drum lids?
My next idea is to find some lengths of metal pipe I can screw directly into those threaded collars to gain a better draw on my exhaust ala chimney effect, and then find those flat spring-loaded caps to attach to the tops for flow control.
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Drinking is like playing golf... you'd best be prepared to play every club in your bag.
Steve the Bartender
There are no bad briskets... only poorly executed ones.
Have you cooked on this UDS yet or is this you thinking what you need?
3 - 3/4" intakes is enough to get 350° Only 1 will be open most times
should only need 1 - 2" exhaust also
Exhaust should always be wide open. caps are only good for shutting down when done cooking and then keeping the rain out. a tin can will do the same thing.
Most are std 2"NPT pipe threads. 6"-8" threaded pipe nipples is all that is needed. anything taller may even hurt the air flow. it can cause a vortex effect and the air will swirl and not flow out right.
Have you cooked on this UDS yet or is this you thinking what you need?
3 - 3/4" intakes is enough to get 350° Only 1 will be open most times
should only need 1 - 2" exhaust also
Exhaust should always be wide open. caps are only good for shutting down when done cooking and then keeping the rain out. a tin can will do the same thing.
Most are std 2"NPT pipe threads. 6"-8" threaded pipe nipples is all that is needed. anything taller may even hurt the air flow. it can cause a vortex effect and the air will swirl and not flow out right.
I am still in the build stage at this point and researching possibilities. I have seen at least 3 dozen+ builds now all over the internet with varying opinions on using a stack to effect positive airflow. As I understand it they should work in the same way a chimney or smokestack does in that once they heat up along that length above the heat source it will encourage more updraft by creating suction.
My end goal is to be able to run up to 425° reliably when I want to bake biscuits and for certain other cooking situations such as flatbread pizzas and the like.
In any case I know that the lids that came with these barrels I picked up should have plenty of exhaust capacity as there is nearly 6 & 2/3" of area open already and 3 - 3/4" NPT nipples installed near the bottom will give me just shy of 5 & 1/3" of intake.
I am also toying with a 2" holesaw to open up the existing small hole on the outside edge of the lid... at that point I would then have over 9 & 1/3" of exhaust area.
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Drinking is like playing golf... you'd best be prepared to play every club in your bag.
Steve the Bartender
There are no bad briskets... only poorly executed ones.
"My end goal is to be able to run up to 425° reliably when I want to bake biscuits and for certain other cooking situations such as flatbread pizzas and the like."
If this is your end goal, then just install a grate higher up in the drum to hold the fire basket and another grate for a difuser just above the fire basket. Easier to achieve higher temps. You're not heating the whole drum to a high heat only the top half.
There's a pic here somewhere that I posted for this set-up with the dimensions.
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