Solenoid or servo valves with UDS ATC

I have been using my UDS for about a year. I am not able to find a sweet spot where it will "just sit" at a certain temperature. Many online forums have posts where people say their UDS will sit at a temperature for hours and hours.

Therefore, I am interested in a temperature controller. I would like to be able to start a cook late at night and sleeeeeep.

I find that I can adequately control my temps using my ball valve. Has anyone used a solenoid valve (or similar device) instead of a fan with their ATC? I know a fan might be needed later in a long cook when fuel diminishes. But until then, opening and closing a valve would supply air using natural convection?
When using a fan, does air continue to feed into the UDS through the fan blades, and then the fan comes on when that small air supply is not enough?

I have read where people have talked about inlet leaks. I fully understand that. I can say that I was very careful when I made my UDS. I have 3 inlets. I drilled the holes with a step bit. The fittings threaded in the holes. I put a nut on the inside, but they were not necessary. Perhaps wind is the culprit. My UDS is on my deck. My control valve is horizontal, on a 90 deg elbow attached to the inlet.

I try to run it around 225 or 230. The temps change slowly. I adjust when the temp is climbing and it goes above 235. Then I adjust again if it is falling, and goes below 220. On a good day it will go an hour or 2 between adjustments. But, it always seems to be drifting up or down.

I usually fill the basket with new Kingsford and wood chunks, and I put a handful of lit briquettes on top in the middle.

When it climbs and gets to within 30 deg of 225, I start adjusting down to avoid overshoot.

What would you suggest? Re-arrange the valve? Create a wind block?

Thanks very much for the reply. My basket is pretty standard - compared to others I have read about. The bottom is a Weber coal grate (15" dia I think) with expanded metal sides. I think I used 2 1/2" bolts upside down as legs underneath. I definitely could raise it up 1/2" or so to test a theory.

Wow. Thanks guys for the quick, and very helpful feedback.

> First, I think the basket height is the factor I can adjust the easiest and quickest. I tried to balance the height of the legs with keeping the coals as far below the meat as possible. I do use a pizza pan and a water pan above the coals, so maybe I can raise the basket an inch or so. I don't run my UDS every weekend, so I don't know when I will give that a try.

> Second, about the exhaust: I am an engineer, so I had a little fun calculating cross-sectional area of pipes in different quantities. (I attached the Excel file in case someone is interested). I used 4 1" 90s because mathematically, they are the same area as 1 2" pipe - 3.14 sq-in. However, I am also practical, so I know that other factors affect this - like fittings, bends, etc.. I used 90s to keep rain out during bad weather cooks. Perhaps I can just enlarge the holes and use larger 90s.

Someone suggested that the 90s can aloow wind to create back pressure. I can see how that would happen. How do you keep rain out of straight-pipe exhaust?? Seems like that would be a hassle.

Thanks again!

Wahoo95 said:

Howdy neighbor....nice drum!!!! My question is have you ever let you drum temp rise and not make adjustments to see where and if it settles? Sometimes some drums simply prefer to settle at a certain temp and it sounds like you may have been making adjustments to yours prematurely which causes it to never settle and you to constantly fight the temps. Just a thought!

As for the ATC, I typically cook without one, however I will hook one up to mine on occasion when I do overnight cooks or need to cook while away from home. Works great on mine and my ATC holds temps within 5 degrees.

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Thanks. I am not sure I have ever left it alone to see if the temp would settle in. I should put that on my list of things to do. It would be fairly easy - just hook up my iGrill, get it near 230, and then let it go.

What ATC do you have? Would you buy it again, or which one would you recommend?