Thanks to everyone for your replies, but especially to Felicia and Marc! I have preset my HVAC temperature to 70 degrees with a 4 degree drift above and below, and the relative humidity to 45% with an 8% drift above and below. I will continue to watch the tiles for further rust mark staining, as an indicator that I need to raise the temp to 75 degrees for the remainder of summer. In the meantime, I am identifying what the ducts/pipes are that sweated - my understanding is that I don't have any fire suppression system. *The manager wants to place fiberglass insulation and duct tape around them. Does anyone know of more more archivally-friendly materials to do the trick?* Thanks again, very much! On Tue, Aug 25, 2015 at 1:55 PM, Marc A Williams <[log in to unmask]> wrote: > Charlene, > > I was at the Smithsonian at the same time as Marion Mecklenburg, and his > work is exceptionally important. It established that the tight > specifications promoted by many museum texts were not only unnecessary, but > they were also unachievable for most situations. So let's get back to your > situation. > > If you have a suspended ceiling, you are lucky - you can lift up a tile > and see what is going on. That sure beats having to cut holes in your > ceiling!! 65 degrees for Syracuse is plenty cold to cause condensation. I > have been working with an internationally-significant historic house museum > in the Hartford area (who's name shall remain confidential unless they want > to self-identify) where the temperatures are not nearly that cold and they > have clear evidence of condensation on the ducts and water staining the > ceiling and even dripping. The colder the T setting, the longer the system > has to run to achieve that setting. And without doubt you will hit the dew > point for air in your space on the ducts, which easily could be as cold as > the 40-degrees range on the duct surface. Even the 50s would probably be > below the dew point during the summer in Syracuse, so anything lower than > this, depending upon the specific day, would result in condensation. > > What is of high importance is how you are controlling the RH. At the > afore-mentioned museum in Hartford, they do not have discrete RH control. > The dim-witted engineer who designed their system roughly 12 years ago (the > problem building is "new" and was built then) thought A/C alone would deal > with RH control as a by-product of temperature control. It did not, and > they have mold growing all over on their collections. HVAC engineers > generally are not trained or experienced in RH control. Or they just do > not care. I hope the former. Everything HVAC is about human comfort. It > is not about object "comfort." Humans are very sensitive to temperature, > and much less to RH, so pretty much all of HVAC control is about > temperature. Objects in general are more sensitive to RH and less so to > temperature. Of course, high temperatures can accelerate degradation > processes for many types of materials, but when looking at a mixed-media > collection, a balance of preservation, human issues, and perhaps money? are > involved. In an ideal world, we would keep all collections at perhaps 40 > degrees F and 45% RH year round. But this is not feasible technically (OK, > it is but would be really expensive), not financially feasible, or would > not be satisfactory to humans. While as a conservator, I would love for a > museum to be 40 degrees, can you imagine the complaints, not just from > visitors, but from tour guides or docents or staff, who generally are the > biggest problem. They don't care two toots if the collections are happier > if they are cold. And please understand I personally hate to be cold, even > more so than being too warm, so I am not criticizing anyone, just pointing > out the contradictions in the needs for collections and for people. > > So as a conservator with many years of experience in dealing with creating > the best possible compromise for collections that do not have a boatload of > money, I would make the following suggestions. 1) As soon as possible > begin monitoring your environment with data loggers. Do not rely on info > from the HVAC system - it may not be accurate for the specific location of > objects in your room. 2) Understand the basics of T and RH. Near the > floor will ALWAYS have higher RH than near the ceiling - Ts are higher at > the ceiling and since the absolute amount of moisture in the air is the > same in the room, warmer Ts at the ceiling mean the RH is lower; cooler Ts > at the floor mean the RH is higher. This is straight, plain physics. If > the air circulation is high and temperature stratification does not exist > (I don't believe I have ever seen this in a museum), then the RH at the > floor may be the same as at the ceiling, but only if the T is the same. 3) > If you have true RH control, which I really hope you do, but seriously > doubt you do, I would set the T in the general 75 degree level in the > summer while keeping the RH at about 45%. If you can do this, wonderful! > 4) I would gradually let the T creep down with the seasonal change, > certainly as low as 45 degrees in the dead of winter. And I would try to > keep the RH up at 45%, although I doubt you will be able to do so. The > colder you keep it, the easier it will be to keep the RH up. If this truly > is a storage room only, you may be able to do this. But if people will be > in there, expect complaints and you may have to make alterations due to > human issues. These suggestions will save you money both in the summer and > the winter. And if you do not have to pay your own utilities, it will save > energy, reduce pollution, and reduce global warming. All are wins. > > This is much more complicated than I have presented, but I am trying to > simplify it as much as possible. Yes, I understand that I may have > overlooked a few things, but for the potential "haters" out there, please > understand that saying "you must contact a conservator or informed HVAC > engineer" simply is not possible for a lot of institutions. I wish it were > not so, but it is. So, we try our best. Thank you. > > By the way, there is a GREAT preservation architect in Syracuse who may be > able to help you, and I would be happy to provide his name if you contact > me privately. > > Marc > > American Conservation Consortium, Ltd. > 4 Rockville Road > Broad Brook, CT 06016 > www.conservator.com > 860-386-6058 > > Marc A. Williams, President > MS in Art Conservation, Winterthur Museum Program > Former Chief Wooden Objects Conservator, Smithsonian Institution > Fellow, American Institute for Conservation (AIC) > > > > *From:* charlene martin > *Sent:* Tuesday, August 25, 2015 12:10 PM > *To:* [log in to unmask] > *Subject:* Re: [MUSEUM-L] HVAC settings for mixed collection storage rooms > > Thank you for the reply - I have definitely added more info, so please > reply with further advice! > > My archive storage rm is located in Syracuse NY, within a mixed use office > floor. *Is **65 degrees is too cold for the summer? What is the ideal > seasonal drift rate for summer in Syracuse NY, for both temp and RH?* > > We just moved in 2 wks ago. I designed the archival storage room as a > preservation space, but have found some specifications were compromised. As > a result, I have a suspended (drop) ceiling made of tiles of some > corrugated-type material, set on a grid. > > The moisture is showing up in the form of rust-colored spots on the tile > (please see pic).I do not have a schematic of the ductwork in the ceiling > (am working on getting that from the facilities manager), but I suspect > that pipes are indeed "sweating". > > > > > On Tue, Aug 25, 2015 at 11:25 AM, Marc A Williams <[log in to unmask] > > wrote: > >> Where is your facility/museum located (town, state)? That may make a >> difference in the recommendation. 65 degrees is really cold for the >> summer. Depending upon your specific situation and lay-out of HVAC >> equipment & duct work, I would guess that you are getting condensation on >> the ductwork, which is causing the ceiling to be wet from dripping above >> it. This is relatively common, but is not always noticed. Do the ducts >> run near the spots? What type of ceiling do you have - plaster, drywall, >> suspended, something else? How does the moisture show up - damp spots, >> water dripping, mold growing, something else? The more info you can >> present, the better the answer. Of course, nothing beats in-person >> observation. >> >> Marc >> > > American Conservation Consortium, Ltd. > 4 Rockville Road > Broad Brook, CT 06016 > www.conservator.com > 860-386-6058 > > Marc A. Williams, President > MS in Art Conservation, Winterthur Museum Program > Former Chief Wooden Objects Conservator, Smithsonian Institution > Fellow, American Institute for Conservation (AIC) > > > > > ------------------------------ > > To unsubscribe from the MUSEUM-L list, click the following link: > http://home.ease.lsoft.com/scripts/wa-HOME.exe?SUBED1=MUSEUM-L&A=1 > ========================================================= Important Subscriber Information: The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes). If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).