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Does NEC forbid using a disconnect switch for both protection and unit operation? Typically we would have a separate disconnect and ON/OFF switch but it has been suggested to combine these two. It doesn't sound right but I couldn't find in the NEC where it was explicitly forbidden. Any help on...

chicopee, When you say a duct that can withstand a fire rating equivalent to the wall, are you saying that if the wall is 2 hr rated, the duct needs to be 2 hr rated also? With either some fire rated insulation or a fire rated enclosure? We already have an approved fire damper in the wall, so...

Ah, thats what I was looking for, thanks!. I hadn't thought to look in NFPA 820. NFPA 820 9.2.9 says "Ventilation systems shall not transfer air between unclassified interior spaces and classified interior spaces." So it looks like I've provided a transfer path between the classified and...

Do you mind explaining a bit more on why this would be a maybe? I'd like to be as knowledgeable as possible when I approach others for help. As for the engineer who classified the area to begin with, because hes electrical he knows what to do with his own equipment but he was unsure as to how...

I have a small wastewater facility which consists of two rooms, a main area which houses the pumps and wet well and a bathroom. The bathroom is partitioned off from the rest of the facility with the entrance on the exterior of the building. Any personnel wishing to use the bathroom has to leave...

IRstuff: During my search on the board I've seen you use the figure 1120W/m^2 in other replies, and you mention you took it from some MIL spec, is there an ASHRAE equivalent? I understand this is the peak solar radiation for something like 1% of the year? MintJulep: Yes, that would just be...

I just reread my first post and realized that it was causing the confusion, it is not an 'outdoor' space as I stated. It is just a building located outdoors, which now that I've typed it out sounds extremely redundant. I hope this clears up any confusion I've caused. If it helps the building...

Yes, indoor space only with exterior exposures.

IRstuff: You're correct that I did not perform any sort of search, I will definitely do one in addition to this thread. However, I would also appreciate any help you would have to offer on this subject. MintJulep: It is a single story building with only one room and no windows. A standard...

I am determining the amount of air required to cool a outdoor space with only fans, so the indoor and ambient temperatures will be very similar. For my purposes the roof load from the sun will be the only heat conducted to the space. The only method I have found to determine solar load is the...

I too practice in the Northeast and that has also been my experience, with locating heat sources for exterior walls at the floors. However, as the Architect or Client will inevitably ask, can I definitely demonstrate that floor heat is more appropriate than overhead heat? This is when I would...

willard3: Which is the primary reason I was looking for research data or the like in ASHRAE, ARI or AMCA. At least with these publications I can find supporting evidence to defend my design decisions, although hopefully not in court! With that being said, do you have any experience or...

imok2: I'm not sure what your reference to the Lewis Research Center is for, I did a quick google search on all those terms and came up with nothing produced on July 6, 1965. Is that supposed to point me to a research article? Also, can you rephrase your accompanying sentence? I'm not sure...

I have a copy of "HVAC Equations Data and Rules of Thumb" and one of the sections has the following: A. If heat loss exceeds 450 Btu/hr. per lineal feet of wall, heat should be provided from under the window or from the base of the wall to prevent downdrafts. B. If heat loss is between 250 and...

You're all right, I was just reading the table wrong. I knew Cameron wouldn't be that far off. Thank you for all the help, that's one mistake that I won't ever make again.

I'm located in Central Jersey. I have tried the Crane 410 method, and it gives similar results to ASHRAE. My question is why is Cameron giving head loss estimates that are seemingly so out of line with the rest of the industry?

Has anyone had any experience using Cameron Hydraulic Data for their head loss calculations? I was recently checking some head loss calculations when I discovered that the head loss I had calculated was almost double of what was previously done. Doing some backchecking we found some...

davefitz, that is exactly what i need to do, i need to show that the surface temperature of the flue will not cause any harm to workers or tenants. however as indicated by my first post and my subsequent attachment, i dont think the client has given me enough information to make this...

any information that can shed any light on this whatsoever would be greatly appreciated

anyone?