UDS- new build

[Mark]

I have questions before I start this. This UDS will have a 2 rack system. Sorry if they have been asked before, but I do want to get it right.

charcoal basket) It looks like 4" legs on the bottom of the fire grate (between the ash pan) is long enough to collect the ashes from the basket and not choke the fire. How tall should the expanded metal basket be to hold enough fuel for a 12-14 hr burn @ 250 degrees?

deffuser plate/water pan) What are the pros/cons of a diffuser plate/water pan? If one was to be installed, how high above the basket should it be & how much air space between the edge of the plate and the side of the barrel? If a water pan was to be installed, how high above the plate would it be mounted?

pit thermometer) Is a regular pit thermometer with a 3-4' stem be long enough, or would one with a longer stem be better? How high from the bottom (or low from the top) should it be mounted? If the pit thermometer is better I would hard mount it. If the longer stemed thermometer is the better method, I would just drill a hole and slide it in/out so I could access the basket.

grill height) I'll be using the lid the drum comes with as a top. How much space between the top grill and the lid?

Thanks for any help in advance.

[Tuck]

This ought to get you started as to most of your questions :

viewtopic.php?f=4&t=3613

Tuck said that !

[Grillatarian]

Will try and answer from my own experience and what I have read. There are good threads on this forum (and others) which are a treasure trove of info.

Top grate location? If you are wanting to do thick cuts, then you need to lower it so that the thickest cut of meat will fit under the lid. That being said, it seems that the most popular distance from the top is around 7". The lid itself will drop into the drum about 1/2" when properly seated so that would give your roughly 6.5" of clearance.

Bottom of charcoal basket clearance? If the nipples are set at 2" center of hole to the bottom of the drum, then 3 to 4" will give plenty of area for ash and good air intake.

Size of charcoal basket? Have made them from 11" to 14" in diameter and around 12 to 14" tall. Now that I know how well they conserve fuel I plan to build all of mine a bit smaller. A rolled expansion cage that is 12" in diameter with 12" sidewall height will easily hold 12 lbs of charcoal. An 11 hour cook only consumes 5-6lbs...at a constant 240F.

One thing to consider with basket size and anything you may attach to it...is weight. I have seen really heavy duty baskets, but they do be heavy. I suppose if you plan to load it up in the drum and then hit it with a blow torch or toss some parrafin cubes in it to get it going then the weight may not matter. I start mine up outside the drum and then once it is burning well I lift it and set it into the drum. Both ways are winners, just up to you.

Diffuser plates, water pans? - Now there's an ongoing debate which you can find on lots of threads. Some say "nadda needda no stinkin' plates or pans", others have had good results with such mods. If you have a lower rack then you could play around with different materials and setups and see what works best in your drum. Some people just use sand in a bowl. Others have custom cut diffuser plates, foil over all or partial sections of the lower grate, then some use water pans filled with water or other liquids.

Thermos and there location? . You can go as simple or as high tech as you want with temperature monitoring. Some of the side mount dial type are junk, but some are very accurate with 3 or 4" stems. You get what you pay for and this is one area I wouldn't try to go with the cheapest. Some of the long stem ones that are only $4 to $8 work surprisingly well. It is a good idea to always test it for accuracy with the boil test (212F). Some have adjustments which allow you to calibrate the dial reading. If you have lots of dimes you could move on up to the digital probes, even wireless ones. Some have two probes, one for the air temp the other for the meat.

I mounted an easy to read 3" gauge 2" below the cooking grate, 9" down from the top lip of the drum. Then, using a Tel-Tru surface and hang thermo I verified the temps across the grate and compared it with the reading from the side thermo. Less than 2 degrees.

One fun thing I discovered (by watching my son do it) is that if you have your exhaust stack near the center of the lid, or centered over the meat being cooked, then you can use a long stem thermo (12") to go right down the exhaust pipe and into the meat! Using the clip it comes with it stands off the metal and gives you an accurate internal temp reading without ever pulling the lid!