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#197043 11/06/10 11:55 AM
Joined: Nov 2007
Posts: 763
K
KJay Offline OP
Member
I was just checking out the link to these pipe chase housings on this site. I have to say these look like theyre the cats pajamas. Definitely an improvement over the witches hats with the usual 4-pounds of black roofing tar slathered all over the top of them.
Imagine how much time could be saved on post construction rooftop equipment changes by having a common chase down to a utility room capped with one of these.
I wish I had thought of this.

Pipe Chase Housings

Joined: Jun 2004
Posts: 1,273
T
Member
They are a mixed blessing.

The real headache WRT RTUs is rooftop EMT runs long enough to become trip hazards.

Beyond that, utility feeds to RTUs are often in conflict due to the layout of the RTU itself, which is where the focus ought to be.

The HVAC industry designs their equipment for ease of manufacture first -- and installation second. It's not at all uncommon to see units that have no realistic way of mounting a NEMA disconnect.

You also have an entire industry that does not worry about how power and control is supposed to get to the RTU. The result is ultra-ugly roof tops all over America.

------

A superior approach would be for the factory to wire in a control cable drop -- standardized so that trips to the roof can be minimal.

Then throw in a power cable/ factory MC drop with strain relief so that power can be brought to the RTU from below -- a trip topside by the EC being unnecessary. A suitable NEMA disconnect ( fuse layout & clearances ) would be built in to the RTU.

Then throw in an optional Fire System SMURF drop. Since the RTU is only one element in a Life Safety System a chase down through the curb is all that can be done. A suitable zone on the blower would be left vacant for the field installation of a duct detector.

These features should be made available as add-ons to the major buyers. ( The big retail chains )

In turn the big boys can begin to back out the labor savings. As it stands, ECs have to dance all over to coordinate these hook-ups. What would take minutes back at the factory takes many man-hours in the field.



Tesla
Joined: Jan 2005
Posts: 40
R
Member
Just wired a bunch of new units
thought they were sweet
open one door on the RTU and there to my surprise
discos and my 120 volt outlet already there
but the dam tin knocker left no room in his curb for the feeder pipe
so we made him pay for the roofer to put in witches hats

Joined: Dec 2000
Posts: 4,288
Member

One "witch's hat" needs to be installed for the RTU's evaporator pan drain pipe anyway. rolleyes


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