The ultimate ventilation system for a hobbyist lab? - Page 1
Forum section: electronics / projects

author: Refrigerator
author_rank: Super Contributor
timestamp: July 14, 2020, 08:15:42 pm
content: My new lab is moving along and it's about time i start thinking about ventilation.Currently there's absolutely no ventilation and the room is an enclosed space, which is very bad various reasons.There's also lots of moisture, so much so that there's some water on the floor.The only proper way to get rid of this water would be to rebuild the entire foundation of the house, which is not feasible.So i think the next best thing is to build a ventilation system to take all the moisture outside.Also i'm sick and tired of soldering fumes floating to my face.My idea is to have two air ducts, one for intake and other for exhaust. The intake duct would be along the floor blowing outside air in and the exhaust duct would suck that air in and blow it outside.As for what moves the air i'm thinking about using a heater blower from a VW Jetta that i have laying around, those happen to be reasonably quiet and powerful.I've also attached a quick sketch to illustrate my idea.What do you guys think?

author: Refrigerator
author_rank: Super Contributor
timestamp: July 14, 2020, 08:31:34 pm
content: Ps: i'm not a fan of just a hose sucking air, because they suck air from all around and there's nothing to "motivate" the air where you're soldering, for example, to go to the vent.Therefore the vent has to either be close (annoying and in the way) or you need strong suction (noisy and irritating).What i have noticed, however, is that even the most gentle of breezes can blow the fumes away, so if i could create such a "breeze" that would blow towards the intake of my fume extractor the extractor would need much less suction and could also be further away, creating a quieter and more efficient fume extraction system.

author: Ian.M
author_rank: Super Contributor
timestamp: July 14, 2020, 08:51:04 pm
content: You should have 'tanked' your basement to minimise water intrusion *before* you started your lab fitout - its too late now as you need clear access to the walls and floor. You also should have graded the floor so water doesn't pool, and if there isn't a drain, jackhammered out a sump, concreted it and put in a sump pump.However just considering the ventilation, your flag is Lithuanian, and assuming that's your approximate locale, the climate isn't good for ventilation without heat recovery - you'll be wasting money in the winter heating the cold air coming in and in the summer cooling it.If the summer humidity is high enough, your preferred basement temperature may be cool enough to cause condensation, so you'll need to mount the air-to-air heat exchanger with its plates vertical and rig a condensate drain to its input.On the exhaust duct I'd put a port for a portable air conditioner vent hose *AFTER* the heat exchanger, and a smaller port for a bench-top fume extraction system before it.

author: thm_w
author_rank: Super Contributor
timestamp: July 14, 2020, 08:54:04 pm
content: Quote from: Refrigerator on July 14, 2020, 08:31:34 pmI disagree, you want a local extraction hose (semi-rigid to allow repositioning). Yes you need strong suction, but the fan/motor can be far from where you are soldering and then the only noise you hear is the airflow.But your idea is good and is used in other applications, such as chemistry fume hoods or paint spray booths etc. The thing is you'd want a perforated table to work on, to allow air to flow up through it. Or multiple outlets on both sides and maybe one beneath your face. I don't think it would work well with just the one outlet vent below the desk.Look into duct fans and aluminum ducting. Cheap and run off 120/220V, so no need for a power supply. But if its not hard for your to adapt that heater blower that might be good too.

author: Refrigerator
author_rank: Super Contributor
timestamp: July 14, 2020, 09:39:48 pm
content: Quote from: Ian.M on July 14, 2020, 08:51:04 pmSounds expensive and i'm already short on money. Also water is not pooling but rather there's droplets hanging around. If you place anything on the ground close to the wall there will be water condensing on that thing. That's why there's nothing obstructing the walls below the desk. It's to allow the water to evaporate and the ventilation system would be there to take the humid air away.Quote from: Ian.M on July 14, 2020, 08:51:04 pmLooking at the bright side this gives me the excuse to play around with carbon filters for air recirculation and heat exchangers for heat retention.The humidity is only a problem during summer.Quote from: thm_w on July 14, 2020, 08:54:04 pmI'll be using rectangular PCV air ducting (it's cheap). Where i live duct fans are not inexpensive at all, unfortunately. Also most of them use AC asynchronous motors which are fixed speed, unless i get a VFD and that blows the budget aspect out of the water.That's why the car heater blower idea seems more attractive to me, i can power it from an ATX PSU and PWM speed controllers are super easy to make.Perhaps i can even repurpose the ESC which controlled the blower motor speed in my SAAB.Also i forgot to mention that my bench is 3.18x1.85 meter "L" shape and 0.60m deep. Both upper and lower ducting will run along the entire length of this bench.

author: Messtechniker
author_rank: Frequent Contributor
timestamp: July 14, 2020, 10:14:15 pm
content: Quote from: Refrigerator on July 14, 2020, 08:15:42 pmWas in the same position 3 years ago. 100% relative humidity all the time and water on the floor. Instead of getting an electrically operated dehumidifier, I decided to use two BME 280 sensors. One indoors and one outdoors measuring temperature and relative humidity, then calculating from these - and that's the important bit - the absolute humidity - i.e. g/m3.When the absolute humidity outside is lower than the absolute humidity in the lab, I then open the two windows. Could be automated of course. In your case this would be a good fan instead of windows. Now after quite some time relative humidity levels now range between 43% (in winter) and 63% (in summer). The recommended range for living rooms is 40-60%. No water in the corners any more. Of course the humidity increases a bit when closing the windows as more and more moisture evaporates from the non-insulated walls and the floor. As you can see, although it is raining outside (99% rel. humidity) it is still worthwhile to open the windows to get the humidity level a bit lower.Hope the pics are not messed up by the forum software. Has happend to me before.

author: H713
author_rank: Regular Contributor
timestamp: July 19, 2020, 10:09:09 am
content: I'm not an OSHA person, so take my thoughts with a grain of salt.1) Water on the floor is dangerous. Maybe fine if all you're doing is 5V logic, but if you're working with tube circuits and other high-voltage projects, this is a recipe for getting yourself killed.2) You don't need amazing fume extraction unless you're doing large amounts of soldering (like production work). Normally if I need to do more than one or two joints, I just use a reasonably powerful fan positioned within about 6" of my workpiece. If I'm doing production soldering for more than an hour, I bring the Honeywell air filter down and put it behind the fan.We'll see if I get cancer later in life as a result of not using industrial fume extraction, but hey, maybe a liberal coating of flux on the inside of one's lungs will make them too poisonous for the coronavirus to survive in

author: Refrigerator
author_rank: Super Contributor
timestamp: July 19, 2020, 05:41:44 pm
content: Quote from: H713 on July 19, 2020, 10:09:09 amGFCI/RCD's are a thing so being low impedance to ground is fine. I mean grounded wristbands are a thing as well so if anything people prefer to be grounded.It's not like i stay there barefoot, so it's fine.Also tube circuits are isolated through a transformer so i won't get zapped unless i stick my hand tight in there, it's not like i mess much with them anyways.By the way, the whole ventilation system is more for removing moisture but i'm also taking the time to make it good for fume extraction as well.

author: H713
author_rank: Regular Contributor
timestamp: July 20, 2020, 12:33:05 am
content: Quote from: Refrigerator on July 19, 2020, 05:41:44 pmEven with an isolation transformer, as soon as you clip that scope probe ground on, you are tying the DUT power ground to mains earth. Of course, grounded wrist straps are not recommended when working with HV either.The point is, a moist concrete floor is not a good idea when working with high voltage equipment.