[RE-wrenches] Solar vent for flat roof

[Joel Davidson]

The room has adequate passive ventilation. The roof vent is needed just to actively increase the air flow. The Solatube vent should do the job unless someone can suggest something better.Thank you all for your help.
Best regards,
Joel Davidson
  ----- Original Message ----- 
  From: Kent Osterberg 
  To: RE-wrenches 
  Sent: Wednesday, April 08, 2009 12:59 PM
  Subject: Re: [RE-wrenches] Solar vent for flat roof


  Allan,

  I recently studied this battery room venting issue when an inspector challenged me to show that a Zephyr vent was adequate to vent a room with a 48-volt 1700-amphour battery bank.   I ended up finding that to keep the hydrogen concentration down to 1% (1/4 the explosive limit) required 75 CFM.  The Zephyr vent at 5 CFM wasn't anywhere near sufficient; we ended up putting in a 100 CFM vent fan that is activated when the battery voltage exceeds 2.4 volts/cell.

  Using a solar vent fan is probably a good solution as long as the only charging source is solar.  If there are any other charging sources, a solar vent fan wouldn't be adequate. 

  Kent Osterberg
  Blue Mountain Solar

   

  Allan Sindelar wrote: 
We have twice used pairs of Zephyr Power Vents to successfully vent large
banks, up to around 2200A/hr @48V. A 12V unit exits roof or wall with a 2"
pvc stack; 48V is 3"; thus they flash just like standard plumbing vents.

Note that the charge rate is more important than battery capacity, as it
determines the amount of gassing that must be exhausted.

Allan at Positive Energy

-----Original Message-----

Wrenches,
Our client has 48 IBE 85N-15 batteries in a room with a flat roof. What is 
your recommendation for a solar powered vent that works well and flashes 
well so that it does not leak? Thanks in advance for your advice.
Joel Davidson 

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