Conditioning/cooling Replacement Air?

[tammiemabe]

Every year I have the same problem in the heat of summer. Obviously I want my exhaust to work well, but the window unit in my studio can not cool the replacement air fast enough. I thought I remembered a thread about this years ago, but I can't find it? Opposite problem in the dead of winter with heating. Any ideas/solutions?

[jplovell]

What you need is what air conditioning and heating folks call "make-up air" That is to say, you need another fan to deliver fresh air just outside the capture zone of your hood. This air needs to be deliverd in a volume slightly lower (fewer cfm) than your existing ventilation fan. As it is temperature extreme you are combatting, you need to be sure to deliver this air in a fashion such that it does not blow on you directly. The source for the make-up air needs to be far removed from the area where the current fan discharges, so as not to recirculate any of the nastiness. If you have a competent a/c service professional in your phone list, they should be able to assist you. The setup of the system is not that difficult, but getting the balance correct between the two fans can be tricky.

Joe Lovell

[tammiemabe]

thanks Joe.

[Sheila M]

I add air at the back of my bench. this assists the air going out, as well as reduces the amount of make up air I need. that way my air stays more conditioned to the temp I need. I also adjust my furnace damper to bring in air from outside and heat it/condition it.

a fan in a duct pushing air from far away, coming up, at the back of my bench, toward my exhaust.

one important note-
I always suggest making sure you are not creating negative pressure in your house. MAKE sure your furnace exhaust is not being pulled into the home. AND do not have candles lit when your exhaust fan is on.
(smoldering can happen)

and! If your fan is pulling 600 cfm.
your room is 3,200 cubic feet (like mine)
every 5.5 min. all of the air is going to leave the room.
The rest of the home is 12000 CF ...so, It will take approx. 20 min.
before my fan starts pulling onto the furnace exhaust.
hm....interesting to think about huh?

So...if you add air at the back of the bench, it gives you more time to condition your air.

Okay, who am I to know this? after auto cad drawing and working with engineeres for 10 years
on science lab systems...
many variables...
good luck!
and keep it safe and HOT!