Exhaust and possibly MUA for a small room?

[amickracing]

At the local votech they are doing some changing. They are moving 3-4 blueprint plotters into this room. They also have one of them plastic prototype machines (not 100% sure how it works, but it looks cool!).

Anyway, this room is 20'x20', about 8.5' tall. Obviously the stink will be great in there, and they are worried about that. They don't know what they want, they just want something, and cheap. My 1st thing to say was talk to an engineer about this, as they can figure everything up "properly (hopefully)", and sign off on it to eliminate any problems down the road. They don't want to... that's our job I guess.

I'm not real sure what to do here.... I would guess that 300-500 CFM might be enough, but likely on the small side. Not to mention there's no real good place for make up air. The 2 walls into the hallway are fire rated, so a fire damper would be required (or a fire rated grill?). The other 2 walls are into other rooms, and we can't transfer there because they aren't near big enough either.

Could bring it in from the roof (where the exhaust is going out), but then we'd have to heat it too, well to do it right anyway.

I kinda thought of a HRV, but there's no possible place to put the cond drain into for at least 50' or more (plus numerous fire walls).

Every good option I can think of to do this right will involve at least a couple grand, but likely much more than that... and I have a good feeling they'll throw our bid out (not always a bad thing).

So, what would you guys do?

[slimwoodie]

they're prolly lookin' at 6k$

rooftop, w/ power exh,
duct
gas line
roofing
curb
electric
etc

that ..

or open a window

[amickracing]

Can't seem them going with a RTU (aside from cost). The whole school is full of VAV's and boilers (and chillers I assume). The building is controlled downtown, so a RTU would be something else for them to control... only they wouldn't know when to control it, and I'm sure wouldn't leave that up to the teachers lol.

Seems like a no win situation really.

[Carnak]

There is no way of doing this cheap. I wouls says slims estimate is a little slim :)

[atmosphere]

I think the hrv with a cond pump with copper tube disch. thru the firewalls and the seperate mua/exh ducting is the right direction if the RTU is out of the question.
The control could be locally with a CO2 sensor in the space with a lockbox.
A demand ventilation system.

[ralphtheplumber]

The whole school is full of VAV's and boilers (and chillers I assume).
If you have hot and chilled water available, it shouldn't be that big a deal to rig up a little 2T fan coil as a makeup air unit. Interlock it with the exhaust fan and stick a 2-position damper on the OA louver.

You might also want to look at how the return/relief air works in there. You might be able to divert a little relief air through that room for pretty cheap.

[slimwoodie]

There is no way of doing this cheap. I wouls says slims estimate is a little slim :)


Maaaaybe ....:)

i was figgerin' a 3 ton electric heat ....

[slimwoodie]

Maaaaybe ....:)

i was figgerin' a 3 ton electric heat ....

Whoop's ... I did say .... Gas Line .....

didn't I ....;)

[TABTech2007]

You mention the school has a (or a few) variable volume systems running through it. That may be your only option. The plotters don't produce much heat load, however the prototype machine may, so heat load calcs should probably be done to satisfy that equipment. I think 600 to 800 CFM should be plenty sufficient for the space. You should consider tapping into the existing variable volume system and running a CONSTANT VOLUME box to the space. You need to grab exhaust from somewhere though and you don't mention that situation. If there is a system that can be increased to handle upwards of 800 CFM then you may be in luck. However, it may be more beneficial to install a dedicated exhaust system for the space. Also, have the box calibrated to maintain the supply total but have it control to the space pressure. I would think you may want that room to be slightly negative (-0.01 to -0.05"wg) to the adjacent space(s) or better yet a corridor. This allows the room to be properly ventilated through the BMS system.