Check out Safety Emporium for your N95, N99, and face shield needs.
Date: Wed, 22 Jun 2011 18:54:23 -0400
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Craig Conway <conway.csa**At_Symbol_Here**GMAIL.COM>
Subject: Re: Heat Recovery Wheel help needed
In-Reply-To: <4E01FD4F020000BA0002E375**At_Symbol_Here**gwsmtp1.smith.edu>
--20cf3001b65986ea6504a654d90e
Debbie is right that the heat pipes & coils avoid the contamination aspect
but their aluminum fins are still vulnerable to the corrosion issues (not a
s
big an issue with animal quarter exhaust). In regard to a fume hood exhaust
,
they do make corrosive resistant treatments for the aluminum (coil fins),
but I'd want to confirm how long these treatments are good for relative to
use & time. (Treatment example :
http://www.dolphinheattransfer.com/thermoguard.htm). Anything that last for
less than 20 years, I wouldn't trust my university/company to pay to
ripout/replace, in which case the system just becomes an airway obstruction
and decreases efficiency. Over 20 years might fall into the "good enough"
category.
Also note, the source below compares the different systems (pages on
enthalpy wheel, heat pipe, and coil system). It suggest the pipe and coil
systems have greater added air resistance than the enthalpy wheel, which
means you'll need to also adjust your duct-fan sizes (be sure to factor tha
t
into the cost as well).
http://cipco.apogee.net/ces/library/tdew.asp
Regards,
--
Craig M Conway
*Technical Risk Analyst*
*
*
*
*
*
*
*
*
On Wed, Jun 22, 2011 at 2:33 PM, Margaret Rakas wrote:
> The 'downside' to the LEED folks (and those paying the energy bills) for
> the 'run around' coils is that they do NOTHING for conditioned air; they
do
> recover heat (which is important during our Northeast winters) but they
> don't do anything for the humidity control we need in the summer. In say
an
> office building, a properly constructed/maintained enthalpy wheel
> essentially keeps humidity out (in summer) or in (during winter) and save
s
> you money (and energy) on that as well as 'pure' heat.
>
>
>
> >>> "Debbie M. Decker" 6/22/2011 12:01 PM >>>
>
> There are other ways to skin the heat recovery cat. We use run-around
> coils or plate-type heat exchangers 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=92s an attractive option.****
>
> ** **
>
> Good luck! Janet and Monona have given you excellent advice and referenc
es
> to wave at your LEED-besotted (love it!) engineers.****
>
> ** **
>
> Debbie****
>
> ---------------------------****
>
> ** **
>
> Debbie M. Decker, Campus Chemical 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.HeroicStories.com and
> join the conspiracy****
>
> ** **
>
> ** **
>
> ** **
>
> *From:* DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] *On Behalf
> Of *ACTSNYC**At_Symbol_Here**CS.COM
> *Sent:* Tuesday, June 21, 2011 7:49 PM
> *To:* DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
> *Subject:* Re: [DCHAS-L] Heat Recovery Wheel help needed****
>
> ** **
>
>
> Kim,
>
> Re: heat wheels: The ACGIH Manual of recommended practice specifically
> 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
> substances in the exhaust air stream since there is leakage between the
> exhaust and supply air zones. To isolate these air streams, wipers are
> employed to seal the spaces on the upstream and downstream sides of the
> wheel. During the operating life of the wheel, seals must be inspected f
or
> adjustment and replacement. The casings in the energy wheel lose their
> effectiveness and need to be replaced after several years. The drive mot
or
> and v-belt and chain also require inspection and maintenance.
>
> Care also must be exercised when the exhaust air stream has a high moistu
re
> content and the incoming air stream could be lower than 32 F. When it is
> below freezing outside, the cold incoming air could drop the wheel
> temperature 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 system.
To
> believe that thing only returns 4% of the contaminated air to the buildin
g
> 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**NOTES.CC.SUNYSB.EDU writes:
>
> ****
>
>
>
> Do any of your buildings have a heat recovery wheel in the HVAC/Fume hood
> system? Our newest building has a heat recovery wheel installed for LEED
> certification but new researchers are questioning the safety of this syst
em
> (energy research).
>
> I do not understand how these systems work. The architect has forwarded
> some white papers, but these are 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 restrictions?
> What criteria do you use for restricting chemicals because of this system
?
>
> Any help or insight you could 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://www.stonybrook.edu/ehs/lab/
>
> Remember to wash your hands!****
>
> ** **
>
--20cf3001b65986ea6504a654d90e
Debbie is right that the heat pipes & coils avoid the contaminatio
n aspect but their aluminum fins are still vulnerable to the corrosion issu
es (not as big an issue with animal quarter exhaust). In regard to a fume h
ood exhaust, they do make corrosive resistant treatments for the aluminum (
coil fins), but I'd want to confirm how long these treatments are good
for relative to use & time. (Treatment example :=A0
http://www.dolphinheattransfer.c
om/thermoguard.htm). Anything that last for less than 20 years, I would
n't trust my university/company to pay to ripout/replace, in which case
the system just becomes an airway obstruction and decreases efficiency. Ov
er 20 years might fall into the "good enough" category.=A0
Also note, the source below compares the different syst
ems (pages on enthalpy wheel, heat pipe, and coil system). It suggest the p
ipe and coil systems have greater added air resistance than the enthalpy wh
eel, which means you'll need to also adjust your duct-fan sizes (be sur
e to factor that into the cost as well).=A0
Rega
rds,
--=A0
Craig M Conway<
font color="#3333ff">Technical Risk Analyst
<
/i>
On Wed, Jun 22, 2011 at 2:33 PM, Margaret Rakas
<mrakas**At_Symbol_Here**smith.edu> wrote:
The 'downside' to the
LEED folks (and those paying the energy bills) for the 'run around'
; coils is that they do NOTHING for conditioned air; they do recover heat (
which is important during our Northeast winters) but they don't do anyt
hing for the humidity control we need in the summer. =A0In say an office bu
ilding, a properly constructed/maintained enthalpy wheel essentially keeps
humidity out (in summer) or in (during winter) and saves you money (and ene
rgy) on that as well as 'pure' heat.
>>> "Debbie M. Decker" <dmdecker**At_Symbol_Here**UCDAVIS.EDU> 6/22/2011 1
2:01 PM >>>
There are other ways to skin the heat recovery cat.=A0 We us
e run-around coils or plate-type heat exchangers where the exhaust air and
supply air never meet.=A0 We had a terrible problem with a heat wheel arran
gement that spilled exhaust from animal quarters into supply air in our vet
erinary teaching hospital.=A0 Finally, at great expense, the system was rip
ped out and replaced with run-around coils.=A0 The run-around coils also ta
ke up less space in the HVAC system overall so that=92s an attractive optio
n.
=A0
Good luck!=A0 Janet and Monona have given you excellent advi
ce and references to wave at your LEED-besotted (love it!) engineers.
=A0
Debbie
---------------------------
=A0
Debbie M. Decker, Campus Chemical Safety Officer
Environmental
Health and Safety
University of California, Davis
1 Shields Ave.
Davis, CA=A0 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.HeroicStories.com=A0and join the conspiracy
=A0
=A0
=A0
=A0
Kim,
Re: heat wheels:
=A0 The ACGIH Manual of recommended practice specifically says these should
not be used.=A0=A0 The following is a quote from page 10-11 of the 27th ed
ition of the book:
"The use o
f a heat wheel should be avoided where there are hazardous substances in th
e exhaust air stream since there is leakage between the exhaust and supply
air zones.=A0 To isolate these air streams, wipers are employed to seal the
spaces on the upstream and downstream sides of the wheel.=A0 During the op
erating life of the wheel, seals must be inspected for adjustment and repla
cement.=A0 The casings in the energy wheel lose their effectiveness and nee
d to be replaced after several years.=A0 The drive motor and v-belt and cha
in also require inspection and maintenance.
Care also must
be exercised when the exhaust air stream has a high moisture content and th
e incoming air stream could be lower than 32 F.=A0 When it is below freezin
g outside, the cold incoming air could drop the wheel temperature below the
dew point of the exhaust air causing water drops to form.=A0 These water d
rops could then freeze on the wheel causing deterioration of the wheel mate
rials."
But it's th
e first line of the quote from the manual that is most important:=A0=A0 &qu
ot;...there is leakage between the exhaust and supply air zones."=A0 L
ook hard at the mechanical drawings of the heat wheel system.=A0 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**NOTES.CC.SUNYSB.EDU writes:
<
/span>
Do any of your buildings have a heat recovery wheel in the HVAC/Fum
e hood system? Our newest building has a heat recovery wheel installed for
LEED certification but new researchers are questioning the safety of this s
ystem (energy research).
I do not understand h
ow these systems work. The architect has forwarded some white papers, but t
hese are vague, at best, on chemical safety data &testing.
If you have a heat re
covery wheel in a chemistry building -
How did you determine
it was safe to use?
Do you have chemical restrictions?<
span style="font-family:Arial,sans-serif;background-repeat:repeat;color:b
lack;background-color:white">
What criteria do you use for restricting chemical
s because of this system?
Any help or insight y
ou could provide is greatly appreciated!
Kim Auletta
Lab Safety Speciali
st
EH&S=A0=A0=A0 Z=6200
Ston
y Brook University
kauletta**At_Symbol_Here**
notes.cc.sunysb.edu
631-632-3032
FAX:
631-632-9683
EH&S Web s
ite: http:
//www.stonybrook.edu/ehs/lab/
Remember to wash your hands!
=A0
--20cf3001b65986ea6504a654d90e--
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