There are other ways to ski n the heat recovery cat.  We use run-around coils or plate-type heat e xchangers where the exhaust air and supply air never meet.  We had a terrible problem with a heat wheel arrangement that spilled exhaust from animal quarters into supply air in our veterinary teaching hospital.  Finally, at great expense, the system was ripped out and replaced with run-around coils.  The run-around coils also take up less space in the HVAC system overall so that’s an attr active option.

Good luck!  Janet and Monona have given you excellent advice and references to wave at your LEED- besotted (love it!) engineers.

Debbie

---------------------------

Debbie M. Decker, Campus Ch emical Safety Officer
Environmental Health and Safety
University of California, Davis
1 Shields Ave.
Davis, CA  95616
(530)754-7964/(530)681-1799 (cell)

(530)752-4527 (FAX)
dmdecker**At_Symbol_Here**ucdavis.edu
Co-Conspirator to Make the World A
Better Place -- Visit www.HeroicS tories.com and join the conspiracy

Kim,

Re: heat wheels:  The ACGIH Manual of recommended practice specificall y says these should not be used.   The following is a quote from page 10-11 of the 27th edition of the book:

"The use of a heat wheel should be avoided where there are hazardous s ubstances in the exhaust air stream since there is leakage between the exha ust and supply air zones.  To isolate these air streams, wipers are em ployed to seal the spaces on the upstream and downstream sides of the wheel.  During the operating life of the wheel, seals must be inspected for adjustment and replacement.  The ca sings in the energy wheel lose their effectiveness and need to be replaced after several years.  The drive motor and v-belt and chain also require inspection and maintenance.

Care also must be exercised when the exhaust air stream has a high moisture content and the incoming air stream could be lower than 32 F.  When i t is below freezing outside, the cold incoming air could drop the wheel tem perature below the dew point of the exhaust air causing water drops to form.  These water drops could then freeze on the wheel causing deterioration of the wheel materials."

But it's the first line of the quote from the manual that is most important :   "...there is leakage between the exhaust and supply air zones."  Look hard at the mechanical drawings of the heat wheel s ystem.  To believe that thing only returns 4% of the contaminated air to the building as the manufacturers claim you'd have to believe that you can assign a section of a Jacuzzi for peeing.

Monona

In a message dated 6/21/2011 4:21:44 PM Eastern Daylight Time, kauletta**At_Symbol_Here**NOT ES.CC.SUNYSB.EDU writes:

Do any of your buildings have a heat recovery wheel in the HVAC/Fume hood s ystem? Our newest building has a heat recovery wheel installed for LEED cer tification but new researchers are questioning the safety of this system (e nergy research).

I do not understand how thes e systems work. The architect has forwarded some white papers, but these ar e vague, at best, on chemical safety data &testing.

If you have a heat recovery wheel in a chemistry building -

How did you determine it was safe to use?
Do you have chemical restric tions?
What criteria do you use for restricting chemicals because of this system?

Any help or insight you coul d provide is greatly appreciated!

Kim Auletta
Lab Safety Specialist
EH&S    Z=6200
Stony Brook University
kauletta**At_Symbol_Here**notes.cc.sunysb.edu
631-632-3032
FAX: 631-632-9683
EH&S Web site: http://ww w.stonybrook.edu/ehs/lab/

Remember to wash your hands!