Humidity control system

[FranklinMorphs]

Designing a humidity controller for a rack. Trying to decide between a hygrometer controlled system or just running it 15 minutes every 6 or 8 hours, will depend on season, but I'm in AZ so it's going to likely be at least every 6 hours to keep it up. Thoughts on one vs the other?

For the hygrometer controlled set-up, it would be AGPtek WH8040s for each tub, wired with diodes to a single relay for the humidifier, on the neutral side to reduce noise to the humidifier. Any tub dips below 40%, they all get a fog. I certainly don't want to have to set up an electronic valve at each tub as well, that's a bit excessive, but it's doable as well. A 1/2" valve from the garden department would get the job done for only opening the tub or tubs that are inside the trigger range. Any thoughts specific to this layout?

[jclaiborne]

I would think that if you were going to go through the trouble of setting all this up you would want to go the hygrometer route vs setting it up to fog at different time intervals. It will be quite a bit more setup time, but you truly get a hands off automated system.

[FranklinMorphs]

I would think that if you were going to go through the trouble of setting all this up you would want to go the hygrometer route vs setting it up to fog at different time intervals. It will be quite a bit more setup time, but you truly get a hands off automated system.

It occurred to me that having it hygrometer controlled would also reduce the odds of bellyrot and/or mold in the substrate as well.

Upon considering it further, I can/may have to set nozzle diameter or use a ball valve to adjust flow to each tub as they will be stacked, so I could run into issues with extreme humidity at the bottom and insufficient at the top.

I've also been stewing on how to set it up so I don't have issues with a large hole at the rear of the tub for a snake to escape through, either into the open if the tub is pulled out, or into the tube from the humidifeir. I think a metal screen could cause issues with condensation on the screen because of their density. I may try a foot screen, or just an end cap with holes drilled in it. The hole in the tub will be just large enough for the pipe to fit through, with the screen or cap secured to the inside of the tube and acting as a socket for the pipe when the tub is slid back into the rack.

[jclaiborne]

It occurred to me that having it hygrometer controlled would also reduce the odds of bellyrot and/or mold in the substrate as well.

Upon considering it further, I can/may have to set nozzle diameter or use a ball valve to adjust flow to each tub as they will be stacked, so I could run into issues with extreme humidity at the bottom and insufficient at the top.

I've also been stewing on how to set it up so I don't have issues with a large hole at the rear of the tub for a snake to escape through, either into the open if the tub is pulled out, or into the tube from the humidifeir. I think a metal screen could cause issues with condensation on the screen because of their density. I may try a foot screen, or just an end cap with holes drilled in it. The hole in the tub will be just large enough for the pipe to fit through, with the screen or cap secured to the inside of the tube and acting as a socket for the pipe when the tub is slid back into the rack.

You are talking about using a humidifier so there isn't any misting, I am not sure why you would need a ball valve per say. if you have a main line going from the humidifier to a "T" with the same length lines going to each tub then in theory the same amount would be fed to each tub. Thoughts?

[FranklinMorphs]

You are talking about using a humidifier so there isn't any misting, I am not sure why you would need a ball valve per say. if you have a main line going from the humidifier to a "T" with the same length lines going to each tub then in theory the same amount would be fed to each tub. Thoughts?

Distance from humidifier to tub will have to be different. Most likely a hardline T-ed off into each tub, fastened along the back of the rack. A manifold to ensure same length to each tub would be drastically more expensive and the increase in total system volume would require greater total output and would most likely induce more condensation in the lines. A straight vertical pipe will allow most if not all condensation to drain back to the system.

Misting wasn't exactly the issue I was worrying about, just thinking about balance in the system.

Oh, and I'm not liking my selection of hygrometers, 12v is almost impossible to actually get. The WH8040s are what I like to use, but they are 110v, so relay system is not going to work ideally. I hate dual A/C relay systems. I'm going to go with a single WH1422 per tub. It'll do temperature and humidity control in one box. Not as attractive as sytem, and even with almost identical specs, it's not quite as accurate a system, but it'll get the job done. Will require a relay on each of the heating elements, aside from the single relay to control the humidifier, but not a big deal.

[Yodawagon]

Maybe if you did a write up on how this all pans out, it could be a sticky. I've wondered about those controllers awhile now.

[FranklinMorphs]

Absolutely will do. Going to be a bit of a protracted process, but will be getting their.

[FranklinMorphs]

Update for anyone intersted. I got ahold of a company that is importing from the company that makes AGPtek, WillHi and many other of these chinese manufacture controllers and have a temperature controller and humidity controller on the way from China. Got one of each on the way now to set up and test out and I'll let you guys know. I have to admit, I got an amazing deal, possibly because I told the guy that if it worked well, I would need about a dozen more of each.

He was able to get me an ITC-1000 set up for 110V AC. The interesting thing I found out is that they use the same relay for the 110V adn 220V models, which is rated at 10A at 250V, so at 110V, it should easily handle north of 15A, or well over 1500W. Absolute overkill, but that will mean that the solid state relay should not have any overheating issues in our applications.

He was also able to set me up with my preffered Hygrometer. A WH8040 model MH13001, and in 12V DC. This will allow me to use a less expensive and more reliable purely DC system on the humidifier circuit, as the fan and the ultrasonic mist generators are both DC themselves, and building my own humidifier will allow me to install a float valve in the water circuit so I don't have to constantly fill it and try to retain the water level at closer to optimum levels to keep the mist generator working efficiently. I will have to do some work on the air flow direction to try and keep as much water suspended as possible and get the lift I need. It would seem, off hand, that a cyclical motion in the air would assist with particulate suspension at higher flow rates, so long as I am not forcing the mist to change direction too sharply.

Lastly, I went by my local hardware stores to look into how to piece this whole mess together, and spent some time with my current household humidifier playing with condensation and lift to see what I need to do there. Lift is going to be an issue with anything off the shelf I've decided. In a piece of 2" ABS I wasn't able to get anything more than 4 feet of pipe in before I got MAJOR lack of flow from the system. So, in poking around at Lowes today I've decided to use a 2" main stack, inverted sanitary T's(to help allow the mist to drop down into the Ts instead of having to make a hard angle, or curve upward) then immediately drop to a 3/4" tube to restrict flow, with an inline ball valve to help me even flow out between all the tubs, then back into a 1-1/2" adapter, that slips quite nicely into a 2" drain cap. That will allow me to install the drain cap into the tub, so the snake can not escape, and will slip together and apart easily to allow the bins to slide in and out, exactly what I had wanted, if a bit over-complicated.

The reason for the 3/4" reduction in the middle there, combined with the ball valve is two fold. Firstly, 3/4" will still be more than enough flow, second it will make regulation with a ball valve easier as I won't be having to make absurdly tiny changes as I would with a 2" ball valve, and finally, the 3/4" ball valve is only 25% the cost of the 2".

I do have one question after further mulling on the design and layout, due to the sheer number of hatchling tubs in may rack designs, it seems excessive to do a controller and sensor for each tub, especially given the tub sizes. I would tend to think that the hatchlings will enjoy/prefer higher humidity to begin with, so would it not be reasonable to just have them get some mist when the rest of the rack gets mist and not set up triggers in their tubs, especially if a row of hatchling tubs(3 or 4 per row) will all be run on a single temperature controller anyway?

[FranklinMorphs]

Got everything together and holy crap does it churn out the mist and move some serious air. I have just a 6' stack pipe on it currently, and with just a 90° on top, it spits mist about 4' out and will overload my hygrometer anywhere inside about 2.5'. The 3/4" reduction does enough to cut down flow that I think it'll be just right, however it will definitely require being set up at all levels to keep humidity reasonable.

Also, it does a hell of a job cooling the air in the system. With it wide open and temperature sensors near the intake and inside the stack pipe, there is about a 10° temperature drop. I may try an aquarium heater to bring the water temperature up and hopefully prevent the temp drop, but I'm not sure if it'll be anywhere near enough. I'll definitely be piping the mist in on the cool side so as not to drag the hot side down.

Hygrometer itself works great, exactly as it should. Now I just have to get the rack itself built so I can set it all up on that. Will be tough to really give the system a shakedown run till I get the temperature controller in as well, and it seems to be taking forever to get here unfortunately.

I'll get some pics of the individual parts used later on and see if I can capture the mist on camera.