Type: Posts; User: Islander
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no the firemarshall was not attending...i thought they were the ones responsible for fire alarm verifications?..anyhow i found several descrepiancies that needed fixing...
we have commissioned and...
I've done some of the AABC commissioning lately. I've had both the GC and mech tell me to ignore (on 2 seperate jobs)the spec's since it had so many unusual points to cover.
IE..big new specs...
external static pressure = the sum of the ahu suction/return static pressure taken approximinately 6" before the ahu and the dischrage/supply static pressure taken 6" after the ahu.
yep...most likely thats air in the system. bleed it out.
main causes i have seen are..
back of the diffuser not insulated.
building has a negative pressure and outside air is being drawn in..ac unit turns off when temp is satisfied..warm outside...
that would make for too much outside air for the ahu to conditon in the summer..down here on the gulf coast.
the full story is..
3 tons served the 1100 sq'office.
2 tons of the 5 served an adjacent
small warehouse with rolling doors open most of the time.
(2 400 cfm diffusers).
1 return air grill...
the ahu serves a small office space.(1100 sq ft).
i beleive the device was a hotgas bypass controller..
i assume it worked but need to follow up with the people that took the suggestion and used...
I have a 5 ton unit that will have some diffusers
capped off and don't want the coil to freeze up.
a couple years ago had similar problem and came here and got the suggestion to use a device that...
the only time i use static pressure to determine actual cfm is when i already know what the original cfm at the original static pressure is via traverse/balometer/etc.
sp new divided by sp old...
Thanks Sirtab i'll check that out along with the AABC one.
Incontrol.. flake off.
anybody been through the latest commissioning process whereas the test and balance contractor is required to:
*check all the controls and operations of the domestic plumbing system...hot water...
ERV=energy recovery unit.
without the dampers most of the return air will probably pull from the return grills closest to the unit...they are just a way of spreading it out by the balance...
on the question in the first post. the main duct return air damper is used to adjust the outside air to design spec's.
if it's an erv system..i can't fathom the need for a return air damper as...
the srt-10 runs a 13.2 1/4 mile...with a good driver.
Lightnings run high 13's-low 14's on average..stock.
there is already a 4 door version of the srt coming....
iaq complaint form.
IAQ...my former employer canceled adapting it
when they discovered it may lead to sitting
in a courtroom.
my experience with them on the test/balance end...
product is good...technicians good.
Lump them in there with the rest of them...in my area at least.
[QUOTE]Originally posted by deanmech
I was thinking low supply air static to be up to 2"wc; medium to 4" and high over 4". Is this correct?
****yeah. class C to 2".
class B to 4".
tons of links there you should be looking at JBF.
...i test/balance systems with bypass ducts on occasion and can tell you they do ok in general..i have'nt tested for exact accuracy/reponse of the bypass cfm though...mostly i see bypass dampers that...
build and patent it yourself.
Then attend any industrial/hvac
conventions you can find.
you could approach Trane..Carrier...TSI.. etc..
but i would'nt unless you have protected it first.
i'd still get an engineer to do the heat load calcs and test/balance to adjust the boxes.
why spend all that time ballparking it..
you can go as high as the sf# on the name plate.
often 15% higher than rated amps.
not sure how low is good...never had a problem with
low actual amps vs rated.
max cfm usually is about 1.1 x square footage of space served...min cool cfm(if applicable) is about 20% of max...min heat cfm is about 50% of max.
the 1.1 is for a typical room without tall...
single or double sensor enthalpy control along with calibrated outside air temp sensor ought to help nicely
given don't have the the leaky bldg, negative space pressure, too much min o.a., not cold...