Tutorial Ventilation 101

[Dignan]

Thanks Hoosier. I'm only considering the couplers for each end of the cooltube. So each end of the cooltube would be glass --> coupler, male --> coupler, female --> flexible 4" ducting. The 100CFM fan would be on the exhaust side, pulling air through.

So my light socket would be mounted inside of one 1/2 of the coupler, allowing me to disconnect the halves and pull my bulb and socket out of the cooltube in a jiffy.

I may stack my axial fans just as a backup in case one of them fails. (I may do this regardless of the cooltube design I go with.)

At any rate, I got an email from the manufacturer and the ABS plastic they are made of is rated to 212 deg F, so I'm going to use them. Will take some pics and post a mini-tute.

 

[gdbud]

Do any of you know with any certainty how much heat is generated by a 400W HPS bulb?

My guess is that, with a 100 CFM fan exhausting the cooltube, temps might be in the 120F range. But I'm also concerned about fire in the event of the fan failing.

If you look at this chart if you have a 400 watt bulb with 100 cfm of air flow your tempature of the air flow would rise about 10 degrees. So if your room temp is 72 degrees the exhaust temp would be 82 degrees, so that ducting would be fine except for light leaking through it.

 

[big ballin 88]

Common figure was 20-30* above ambient exhaust temps. for Air cooling the hood. Now mind you 400w do get hot. Before i had my squirrel cage i had temps up to 100* in my closet which was terrible! Sleeping in an oven at night was not fun

 

[Dignan]

You guys are very helpful and I appreciate it. Peace.

 

[MR.Montana]

i cant afford for any smell to leak through any opening, so is it recommended that i run the exhaust 24/7? i have a room right next to the grow room, if i leave a window open in the next room, will the cracks in the door be enough for air exchange?

i dont know if its possible yet, but would it be safer if the room was sealed?

Should the exhaust be run 24/7?

 

[FreezerBoy]

Yes.

Turn off the fan and you lose negative pressure. No NP turns intakes into exhausts, allowing unfiltered air out of the cab. Smelling is telling. Hell, it's advertising. Keep your fans on.

 

[gdbud]

If you are growing in a small enclosed space like a cabinet then yes your exhaust fan should be on 24/7 It will keep your humidity down during the dark period.

 

[Ghostwolf]

This a great thread you've made here Red. I was told by BC Chronic that you could help me out with the pc case I recently made. It's 19"D x17"H x8"W. And there's three 26w/100w CFL's for light. It's not the first one Ive made but it does have me perplexed with the heat problem I have with it. The first pc case I made is 16"D x14"H x7"W and I have two 26w/100w CFL's in it with two 80mm pc fans for exhaust and a passive intake and it runs at 85F all the time, just right. But the new case uses a 120mm (78cfm)pc fan, a 90mm (don't know the cfm's) pc fan for exhaust. And a small 60mm pc fan down in the front to assist the intake. The problem comes in that the temps are any where from 88F to 98F depending on the outside temp. The case is made with three power strips on the back side panel going up, across, and down so I can move lights where I need them and to add more if I wanted. So I can't make a cool chamber for the lights. A possible answer I have was to get a 4" personal fan from Wal-Mart for $6.00 that has a bigger motor and kicks out a lot more air than the others and move the 120mm fan to the front top as a intake to blow across the lights. I think that would solve the problem but I just don't know for sure. But I need to solve it before summer if I ever hope to add any more light. Do you have any suggestions? Here's what it look like.

 

[big ballin 88]

What wattages are your CFL's?

 

[Squire5683]

Hey all... Ive been poking through forums looking for somewhere to buy Activated Carbon. Im looking for a large bag to build a filter. I have a 8'x8' veg room, and a 24'x8' flower room. Im feeding with a 10" duct and inline fan. I have the filter built, but cant find anywhere to buy a big amount of carbon. Ive looked at Home d, Lowes, pet stores, etc and can only find little 2 oz bags. Sorry for hijacking thread, but it looks like there is a lot of knowledge here. Thanks for the help!

 

[MR.Montana]

if my humidity is at only 35 % what can i do ?

 

[rives]

Something that I haven't seen addressed is the amount of heat loss from each type of light. Depending on their efficiency at turning wattage into light, the resultant loss to heat is different for fluorescents, HID, etc. For instance, 400 watts of LED's isn't going to generate the same level of heat that a 400 watt HPS will. I am interested in using 330 watts of PL-L lamps in a homebuilt airtight fixture, and am having difficulties figuring out the cfm rating for the cooling fan. Any input would be appreciated.

 

[FreezerBoy]

if my humidity is at only 35 % what can i do ?

Play guitar. Chase girls. Write a book... whatever you want. You're over stressing yourself. It's a weed and will be just fine.

 

[touchofgrey]

Something that I haven't seen addressed is the amount of heat loss from each type of light. Depending on their efficiency at turning wattage into light, the resultant loss to heat is different for fluorescents, HID, etc. For instance, 400 watts of LED's isn't going to generate the same level of heat that a 400 watt HPS will. I am interested in using 330 watts of PL-L lamps in a homebuilt airtight fixture, and am having difficulties figuring out the cfm rating for the cooling fan. Any input would be appreciated.

Actually I think this has been addressed, just use the chart that keeps popping up that equates temp rise with wattage. It's really designed to figure total room ventilation but the concept works just fine with a hood too. How much temp rise do you want/can you stand? 20 degrees is reasonable for a hood and the chart says about 50 cfm will handle that for 330 watts. If the ballasts are going to be in the hood you need to add that wattage too.

I run a 250 watt hood with a 60 cfm axial fan. I have a temperature probe that I set in the airstream and found that I can turn down the fan speed to reduce noise and the temp is still only about 75 or 80 degrees at 55 ambient.

 

[rives]

The chart that you are referring to is very helpful, but it appears to be for HID lamps (the wattage labels correspond closely to HID lamp sizes). Different types of lights have different levels of efficiency in converting watts to light. If you think in terms of a heat lamp vs. a halogen PAR floodlight, they may both draw 250 watts, but the heat lamp puts out far more heat and far fewer lumens than the floodlight. An even more extreme example would be a stovetop element that draws 1000 watts. It uses the same wattage as a 1000 watt HPS, but only gives off a dull glow and far more heat than the HPS. A perfectly efficient light would convert all of it's inbound wattage to light, and none to heat. LED's are as close to that as we currently get. I hope this explains a little better what I am puzzling over. I appreciate your input, and your information helps.

 

[gdbud]

Something that I haven't seen addressed is the amount of heat loss from each type of light. Depending on their efficiency at turning wattage into light, the resultant loss to heat is different for fluorescents, HID, etc. For instance, 400 watts of LED's isn't going to generate the same level of heat that a 400 watt HPS will. I am interested in using 330 watts of PL-L lamps in a homebuilt airtight fixture, and am having difficulties figuring out the cfm rating for the cooling fan. Any input would be appreciated.

One way is to look at the sticker on the ballast that should give you the total watts that the light and ballast draws and then use that number for the cooling rate.
My ASHRAE book shows the fallowing values
Compact Fluorescent
Lamp wattage 13watts, lamp and ballast 17watts
Lamp wattage 18watts, lamp and ballast 22.5watts
Lamp wattage 22watts, lamp and ballast 24watts
Lamp wattage 26watts, lamp and ballast 33watts
You should use the Lamp and ballast figure

HPS
Lamp wattage 150watts, lamp and ballast 188watts
Lamp wattage 200watts, lamp and ballast 250watts
Lamp wattage 250watts, lamp and ballast 295watts
Lamp wattage 400watts, lamp and ballast 465watts
Lamp wattage 1000watts, lamp and ballast 1100watts
These HPS values are for magnetic type ballasts

 

[InducedSerenity]

Hey guys.. long time listener, first time caller

I'm trying to solidify a ventilation plan so I can get up and running here, here are the details / air calcs from this thread:

4x8x7 box - 224 sq ft
2x 1k HPS with 6" ducts + dedicated fan
Carbon Filter w/ own fan

2 1k hps = [(3.16) * (2000)] / 20 = 316 CFM
Plus scrubber, 1 min per air change = 224 CFM


Assuming that's right… which fans? Like most other people, I want something decently quiet that can't be heard from the next room if possible.

BUT - here's the rub: Since this is all going to be in a room with a locked door, I want to intake from a large central heating duct in the attic (heater off, obviously), coming from downstairs ceiling, and exhaust into a nearby vent until summer, then just push exhaust into the attic.

I've been looking at S&P fans, should I run a 8-to-6-reducer to TD-200's (538/476 CFM max) for both uses, and just experiment with different speeds to accommodate the different static pressures of the filter and the long intake / exhaust ducting? Or do I need something louder and more serious?

I'm not stuck on these fans by any means, I just want something reliable and quiet that can handle intake through 20 feet of ducting. I'll also have to figure out how to rig up a weak fan to vent a small 4x4 veg cab but I'm sure I can piggyback that somewhere here with a couple of Y ducts.

Sorry for the long posts, and TIA for help.

 

[touchofgrey]

The chart that you are referring to is very helpful, but it appears to be for HID lamps (the wattage labels correspond closely to HID lamp sizes). Different types of lights have different levels of efficiency in converting watts to light. If you think in terms of a heat lamp vs. a halogen PAR floodlight, they may both draw 250 watts, but the heat lamp puts out far more heat and far fewer lumens than the floodlight. An even more extreme example would be a stovetop element that draws 1000 watts. It uses the same wattage as a 1000 watt HPS, but only gives off a dull glow and far more heat than the HPS. A perfectly efficient light would convert all of it's inbound wattage to light, and none to heat. LED's are as close to that as we currently get. I hope this explains a little better what I am puzzling over. I appreciate your input, and your information helps.

I'm not an engineer but I'm pretty sure the heat generated by the use of electricity is uniform. Heat is measured in BTU's and 1000 watts is 3415 BTU's if my memory serves me correctly. You feel more heat from an infra red bulb because of the infra red, not the burning of electricity.

 

[touchofgrey]

Hey guys.. long time listener, first time caller

I'm trying to solidify a ventilation plan so I can get up and running here, here are the details / air calcs from this thread:

4x8x7 box - 224 sq ft
2x 1k HPS with 6" ducts + dedicated fan
Carbon Filter w/ own fan

2 1k hps = [(3.16) * (2000)] / 20 = 316 CFM
Plus scrubber, 1 min per air change = 224 CFM quote]

I'm more of a micro guy but looking at the spec sheets of the TD-200's I see that depending on the system static pressure, you might not get the flow through the scrubber you're looking for. Total static pressure seen by the fan is the total system on each side of the fan. You can calculate/estimate the static pressure for the system by adding up all the components, there are resources on the web to give you SP loss in ducts and elbows. Also, I'd recommend using rigid duct since you've got long runs and the friction loss is much less than flexible duct with bumpy inside surface.

You could probably add a Y to the hood fan and do the veg box since it doesn't have the static pressure from a scrubber to deal with. Just use volume dampers in the Y and you can adjust the settings to balance the airflows and get the draw you want. Again though, you need to watch the static pressures in the 2 runs and try to balance them - you may end up with a 6" duct from the AC hood and a 3" or 4" from the veg cabinet. The closer the static pressures in 2 runs coming together the less "damper down" is needed and dampering down adds static pressure and reduces airflow.

 

[rives]

I'm not an engineer but I'm pretty sure the heat generated by the use of electricity is uniform. Heat is measured in BTU's and 1000 watts is 3415 BTU's if my memory serves me correctly. You feel more heat from an infra red bulb because of the infra red, not the burning of electricity.

Energy (electricity, in this case) is converted into work. The level of efficiency at this conversion determines how much energy is lost to heat (see http://www.uwsp.edu/cnr/wcee/keep/mod1/rules/enconversion.htm ). A HPS lamp uses a ceramic arc tube because internal temperatures can range up to 1300 degrees C, well beyond the capabilities of glass or quartz. Some of this heat makes it out to the glass envelope, and beyond. You can hold a fluorescent lamp in your hand - better not try that with even a low wattage HID lamp.