Ventilation

[edl]

Hi All - 2 issues trying to solve - heating/cooling and dust/fume extraction.

As for hvac, i think i am leaning toward a ductless or mini-split unit - this is where you have about a suitcase sized compressor outside and a long narrow blower inside - I don't think there is a return (i could be wrong about that).
- any suggestions on make model - I have a 22x28 2car garage (11'high) - best prices?

For dust, bought a HF unit - has a vacuum, filter bag up (.5 micron) and clear trash type bag on bottom half - whole thing about 70 inches high - big around as a keg - this in turn can be plumbed with 4" plastic coil tubing to various places in garage to make something like a central vac - each outlet can have a gate (so it is shut when not in use) and can have various attachments or hoses.

This leaves fumes - my first thougt is to get a ventilator fan and **** the stuff right outside - question: if i do this, do i end up undercutting the hvac - so on a hot day, the hvac runs, the sun heats up the garage, and the fume ventilator exhausts all this cold air outside (along with the fumes) - what is the best way to manage that? exhaust high/ac low? vice versa? don't exhaust but filter in some way (bearing in mind the dust extractor already filters to .5 microns - but not sure this deals with toxic fumes from say solvents, paint strippers, etc.) - THOUGHTS? Thanks!!! stephen

 

[bmwpower]

Dust collectors won't do a thing for organic vapors. You need an organic vapor filter or extract them using a exhaust fan.

 

[edl]

thanks - that's what I figured - so the question becomes does the exhaust fan undercat the climate control? what would be a good organic vapor filter?? - thanks, stephen!!!

 

[bmwpower]

thanks - that's what I figured - so the question becomes does the exhaust fan undercat the climate control? what would be a good organic vapor filter?? - thanks, stephen!!!

I never set one up, but I've researched it a bit. It depends on the CFM of your exhaust fan. If you have a high CFM fan, you will need to resupply the room with more air to counteract the air lost to the exhaust fan. With smaller fans, you might be able to get away without doing anything. You'll still have CFM loss, though. Air from the outside will be sucked into the garage from any available opening.

 

[edl]

I never set one up, but I've researched it a bit. It depends on the CFM of your exhaust fan. If you have a high CFM fan, you will need to resupply the room with more air to counteract the air lost to the exhaust fan. With smaller fans, you might be able to get away without doing anything. You'll still have CFM loss, though. Air from the outside will be sucked into the garage from any available opening.

Right - and the more cfm's out (which helps for fumes), the worse for the ac

so it sounds like an organic vapor filter might be the ticket - any thoughts where? brand? good price? etc.? -thanks! stephen

 

[JohnZ]

As for hvac, i think i am leaning toward a ductless or mini-split unit - this is where you have about a suitcase sized compressor outside and a long narrow blower inside - I don't think there is a return (i could be wrong about that).
- any suggestions on make model - I have a 22x28 2car garage (11'high) - best prices? stephen

I have a Mitsubishi 42,000-BTU ductless mini-split A/C-only system in my 44' x 58' x 12' super-insulated garage, and it works great! Intended to buy a similar Carrier unit, but they weren't being produced yet (summer of '05) when I needed it. They make them in about six smaller sizes as well. Details are at the link below.

http://www.villagephotos.com/pubbrowse.asp?folder_id=1411059

 

[kbs2244]

There is a bunch of variables here.
How big a room, what kind and how much fumes. Are the fumes made in a small place like a bench or all over the room like when welding up a car frame. If you can keep the fumes in one place, then a local fan will get most of them without wasting too much AC. Even better is a hood over the bench like the hood over the stove in your kitchen.
But if you are smelling up the whole room, I would put health before comfort and use lots of ventelation.
Showers are cheaper then hospitals.

 

[edl]

There is a bunch of variables here.
How big a room, what kind and how much fumes. Are the fumes made in a small place like a bench or all over the room like when welding up a car frame. If you can keep the fumes in one place, then a local fan will get most of them without wasting too much AC. Even better is a hood over the bench like the hood over the stove in your kitchen.
But if you are smelling up the whole room, I would put health before comfort and use lots of ventelation.
Showers are cheaper then hospitals.

Fully agree - safety first - is this to say that organic vapor filters that **** the air in, filter and eject back into the garage are not effective? Is exhausting out the only way to go with this? Thanks!!

 

[russlaferrera]

If there is room in the attic or another part of the garage you can cut down on your heat loss/gain by building a air to air exchanger.

All it is made of is aluminum sheet in layers, separated, in a box, with an in and out. Depending on the size you can save 50-60% of your treated air. Plans should be on the net...russ

 

[edl]

thanks Russ - sounds like an alternative - but what do you experts think about the question above - do you need to exhaust fumes? can you filter them? Thanks!!

 

[PAToyota]

I'd think you'd go through filters pretty damn fast if you're filtering any volume of air - which would get expensive. Probably better to exhaust in the long run.

 

[ModSquad]

don't know if I should post here or start another post but it's related.. What if you exhausted from the room to the attic? would the fumes escape through the attic vents, or would it still have to be forced out of the building complete?

Similar situation but I'm looking more at welding and torching fumes.. if I get into painting then that as well.. not sure if I'll be able to explain properly, but here goes.

Before completing the ceiling build 4 + vent boxes that you would insert the exhaust fans into.. they would be recesses into the ceiling by say 3" for figures sake. the exhaust fan would be installed in this box. complete the ceiling insulation and drywall leaving the fan openings open.. you would set all 4 + fan on a switch to turn on. To seal it for winter as to not loose heat when not in use, you can make an insulated door to cover the holes with 3" + insulation depending on how deep you orignially made the pocket.

Can anyone picture this? would it make sense? the only thing I guess to figure would be how much heatloss would one have while the fans are running and how long would it take to recoupe that heat? probably wouldn't be bad for a forced fan heat, or similar, but in floor heat would probably take long to bring the room back to temp.. However, I don't think you'd loose enough warm air to be actully cold..

 

[kbs2244]

You would want to duct them to the outside. Normal attic venting over an insulated celing is designed for low speed convection air movment. You would overpower the vents by forcing air up there with a fan.
It used to be that people would try to use what were called "whole house fans" instead of airconditioning. The idea was the same as yours, but for cooling. They would get a big fan in the upstairs hallway celing, blowing up into the attic space. But if they didn't add venting, the system would back up and choke itself.
Remember the first thing hot rodders do is less restrictive exhaust. And not just for the sound. The biggest carb made won't put any more gas into the engine, if the exhaust can't get out.

 

[PAToyota]

"Used to be" for whole house fans? I still use mine - it's great! Pull the cool air in at night and then close up the house during the day. I agree that the air has to go somewhere, though. You can't just try to blow it into a sealed attic.

On that note, I particularly wouldn't exhaust any potentially flammable fumes into an enclosed attic. Even if they don't creep back into the house somewhere, the potential for fire/explosion is not something I'd want to deal with...

 

[ModSquad]

This is for a detatched garage, I'd never do it to an attached. hell, I'd be unsure about doing the amount of welding and cutting as I do in a attached.. but I agree with waht your saying.. I was just curious if the attic would vent well enough to do it taht way.. When I build my garage this time(my 2nd in 2 years), we used the rigevent system..

This type of vent with the eves is much more efficient then conventional vents as it usues the whole peak of the structure..

Anyway, I guess I'll just build a duct and force the air out through it. sealing it when not in use the same way will give me the same result.. just a little more work to setup the duct..

 

[kbs2244]

You know, I wasn't even thinking about it being an attached garage!!
If so, then as they say "No way in h$##." For the very reasons you give.
I said "used to be" because central air has become so common now days. When I got married 40 plus years ago I helped my father in law install some of those fans.
If he couldn't talk the homeowner into the extra venting he would go around the side of the house where the gable vent was, and tie a 6 inch pice of that pink surveyors tape to the fins. If he ever got a call back because it wasn't working like they thought it should, he would walk them around and show them the tape. It was always standing stright out from the wind. Those little 12 x 18 vents just were not up to the job.

 

[kbs2244]

You are going to have to put in a gable vent and duct over to it.
That style ridge venting works great for what they are designed for. But they just aren't designed for that much flow.
I have a 50 x 25 roof. 4/12 pitch. I just re-roofed last summer and installed ridge venting in addition the the 5 mushroom style vents already there. I have 3 inch continous soffit venting for air input. By any code, I am "over vented" and it is still hot up in the attic when the sun shines. And that is without any added air input.
Check out any commerical installation. They are all ducted with a dedicated vent.

 

[ModSquad]

cool thanks for the input. I think it'll just be easier to build some duct and use it to force the fumes out...

 

[ron in sc]

I

have a 22x28 2car garage (11'high)

I'm building a garage of similar size, 24x26 with 14' ceiling. I want some sort of fume extraction too. I was think maybe some sort of ventilation fan could be installed somewhere in the building to pull out fumes. The type of fumes I will have are from welding and painting. I'm not talking about the small bathroom type vent fans. I'm think of something much bigger and maybe even with an explosion proof motor.

 

[kbs2244]

In Charleston you are not going to have a lot of climate problems needing closed up, heated buildings. For the welding you might be able to get buy with just the constant air movement from those wind powered, ball shaped, turbines. I am a big fan of them in warm climates. Easy to install, no power required, nothing to be maintained, and the move a lot of air.

If painting is going to be a lot of what you do, then a designed paint booth with explosion proof fans is a must. But if you are talking shooting primer onto something you just fabbed, wait for a breezy day.

 

[edl]

In Charleston you are not going to have a lot of climate problems needing closed up, heated buildings. For the welding you might be able to get buy with just the constant air movement from those wind powered, ball shaped, turbines. I am a big fan of them in warm climates. Easy to install, no power required, nothing to be maintained, and the move a lot of air.

If painting is going to be a lot of what you do, then a designed paint booth with explosion proof fans is a must. But if you are talking shooting primer onto something you just fabbed, wait for a breezy day.

And so we come full circle - how do you balance climate control with fume exhaust in a 22x28x11 space? - it seems that the 2 are diametrically opposed - ?

 

[trovato]

And so we come full circle - how do you balance climate control with fume exhaust in a 22x28x11 space? - it seems that the 2 are diametrically opposed - ?

I don't think there's any magic here. You exhaust as much as necessary and you heat as far as possible from the exhaust point with as many BTUs as necessary. If the heater isn't big enough, it just gets colder.

 

[Lu47Dan]

PPE = Personal protective equipment , get yourself a good respirator rated for what you are doing , staining ,painting , etc. Than use it . If you were able to lay your hands on a filter unit rated for VOC's (volatile organic compounds) you could vent the filtered air back into your shop , but how much would the filters cost compared to an air to air heat exchanger over time ? If you would install and a/a heat exchanger you would recover a percentage of your chilled air , thus saving some money , the percentage of loss on the heat exchager is what you want to look at . You should wear your PPE at all times when working with chemicals . As for the added cost of running an exhaust fan , how much is your health worth ? By far I would rather wear the PPE and run the exhaust fan than get sick and pay the hospital bill . JMTC Dan

 

[kbs2244]

Lu47DAN has it right.
So called "wasted" heat (or cooling) is cheaper than hospitals.

 

[edl]

NO QUESTION - Health and safety first - this is an attempt to something in addition to (and not in lieu of) PPE - sounds like there is no magic bullet - it is a zero sum game - OK, so one just needs to add some additional electricity as part of the "cost" of an organically volatile restoration project (in Souther/Northern climes, no inconsequential - but there you have it) - thanks to all for the input - stephen

 

[trovato]

It would probably help if your ventilation is variable speed. You don't need a wind tunnel in there every minute. That way you could tune your ventilation and heat loss to the task at hand.

 

[edl]

good point Mr. T - thanks, stephen

 

[flexysteve]

I dont mean to drag up an old thread, but I'm having a house built with a 20 x32 (9 foot ceiling) attached garage and just want ventilation. I don't care so much about the heat and A/C (the house is in NC). But I wanted good ventilation for when I do painting, fiberglassing and carbon fiber. The resin is 10x worse than paint. I use a respirator but wanted to see what was the best for ventilation. The sidewall, back and front (garage door) all lead to the outside. The room above the garage is finished so I can't go through the roof.

Should I just make a vent for the garage door and have them put in a service door in the back of the garage and put a giant fan in front of the door. I'd prefer not to leave the garage door open to avoid nosy neighbors.

I also might want to set up some "paint booth" on the cheap. Probably using roll down tarps to section off an area and keep dust out. What would be a good way to set that up to pull the fumes out.

I know its a ton of questions and thanks for your help
Steve

 

[kbs2244]

If you want to be inconspicuous, I would just leave the garage door open about 3 inch at the bottom, and have a 24 x 24 inch exhaust fan blowing out the back. Or maybe s dutch door leading to the back.
But what about smell? If that stuff is that bad, I don’t think you are going to fool the neighbors.