Ventilation of Automotive Service Area

[Hillbottom]

Can anyone suggest a good source of information on code requirements and methods of meeting them in regard to automotive service area ventilation? The only info. I have been able to come up with is in the BOCA code which says I need 1.5 cfm of exhaust per sq. ft of space. I have recently had several car dealerships ask me to air condition their service bay areas. With the ventilation rate as called for by BOCA, my system capacity calculations are coming up with some extemely large sytems. Does anyone know if the BOCA ventilation rate applies if there is a direct connect vehicle exhaust system intalled? Any info. would be appreciated.

 

[ChasBean1]

Your last question, NO, I don't know, but don't have BOCA handy at the moment. I would imagine the 1.5 cfm/ft2 is a good value to exhaust the garage even with tailpipe hoses attached, due to adhesives, petroleum, solvents, etc.

If they want air conditioning for this type of space that has large and varying openings to the outside, let them know this will be an inexact science and will be largely inefficient. If you have a 10,000 square foot service area and exhaust 15,000 cfm from it, you will want to supply at least 15,000 cfm of conditioned outside air (no return air) to the space. This will cost them big time during design seasons.

My advice: Tell them to continue with standard draw-through exhaust ventilation per BOCA, use their existing unit heaters in the winter, and if they want, use DX split system spot coolers or fan coil units (recirc only) blowing air directly on most-frequented work areas during summer design days.

 

[buildingconsultants]

Hello All!

It sure is a nice idea to have a workshop air conditioned, but it may not be as practical as desired. You may want to consider to calculate an overall a/c load for am 8 to 10 foot height, even though your ceilings are much higher. Typically the cold air will fall to the floor and provide some comfort. However in an automotive shop, our main concern is to get rid of the fumes. Typically the floors are concrete in auto shop, but you may be designing for an upper scale shop.

Hope this helps.

 

[Hillbottom]

Spot coolers and individual air handlers won't be practical in the areas that I am dealing with and they definitely want A/C and not just ventilation. These are high end, upscale type, dealerships (Mercedes, BMW, etc.) and they want to keep their mechanics comfortable and productive. Each service bay has its own vehicle lift and there are 16-20 service bays per dealership. I assume there is a lot of money to be made in automotive repair because I have pointed out that operating costs will be high. It doesn't seem to matter to them. What does matter is that the system is installed properly and meets applicable code. I am just having trouble convincing myself that the capacities I am coming up with are correct. If anyone knows of any other codes that may apply, please let me know.

 

[stevenw]

We have done several upscale dealerships this year and have run into the problems. They were all willing to pay for the tonnage and the ventilation. We ran DX splits down the service bays, exhaust fans at the ends, carmon hoses ever other bay.
They also wanted circulator fans at each bay, 10' high pointed down at the hood. The fans cool down the engine when they pull a car in to a bay. They said the fans pay for them selves in less than one year. ($75/hr mechanic standing around wainting for an engine to cool).

Also watch your restroom/locker room numbers. More women are working in upscale shops these days.

 

[ChasBean1]

If operating cost isn't a concern, I would supply a 100% outside air volume (DX with a gas heater) equal to, or just higher than the exhaust volume.

Arrange the air pattern to try to make it one-pass with minimal recirc. Piston flow - with main concentration of supply in the back of the bay and exhausting from the front where the garage door(s) are. Or downflow - supply air through several diffusers with low throw high, exhaust low. (Some ideas, anyway). -CB

 

[Drazen]

Chas goes right to the point: air exchange is number one priority in this kind of working area. As you have to have large quantities of air flowing in and out, radiation heaters are the choice as they don't interfere with ventilation adversely. For incoming air, I would propose "neutral temperature" heater-cooler, i. e. heater that will warm the air up to 22 deg. C in winter and cooler that will cool it at 25 deg. C in summer.

This is only cooling you practicaly need even if you don't care about investment costs! (Maybe it is not the case in the middle of Arabian desert - hope you're not there!)
Large air exchenge and lot of natural draught inherent to such shops should do the job. Anyway, too cold air linked to uncontolled local draughts can make a lot of problems to workers. I saw couple of shops designed with this "neutral temperature" feature that have very confortable micro-clima all the time.

This is matter of real life, respecting all handbook recommendations! One additional practical thing: if your custemer feels that they need more cooling in the summer (which I strongly disbeleive) you can rather easily upgrade your incoming air cooler without disturbing the whole concept. (your cooling generators must have some reserve!)

Points not to forget: do you have CO sensor installation mandated by law as we have it here? We also have obligation to design 50% of exhaust grills near the floor.

Good luck!