K Factor for Trane VAV

[sysint]

Anyone have a K factor chart for VCW boxes?

[powerhead]

I have a list of Flow Coefficients from a Siemens manual that lists a Trane box as 0.66.
It does not list model numbers and I don't know how old the list is.
Hope that helped.

[joey791]

Sys is this the older boxes or the newer ones?

I have a IOM manual on these model boxes in Pdf form and at the beginning it says for air balancing instructions see
EA10_IOM2-E, the manual I have doesnt have the K factor but the one I just listed should.

[chrisc]

If you know the inlet size of the box, regardless of manufacturer, the number will be the same. A 10" box is a 10" box, ask any balancer.

[sysint]

...you know you say that and they all end up being a little different. What's the reason is what I want to really know.

[chrisc]

Even if they are the slightest bit different, your balancer should give you the proper multiplier to compensate for that, but I know what your talkin about!! I'll check my online info for the Trane VCW box and get you the correct info, hey man, don't you ever sleep? Bacnet rules!!

[sysint]

... too busy fighting the ASHRAE BACnetter propaganda...

if somebody would send over a cape I'd be set.

[joey791]

Sys, see my post above, that should be the manual you need

[klrogers]

Originally posted by sysint
... too busy fighting the ASHRAE BACnetter propaganda...

if somebody would send over a cape I'd be set.

Keep up the good fight, we need you!

[tab-tech]

....the amount of CFM a box will deliver at 1 inch of differentialpressure.

[digo]

reviving this thread... I was looking for the same thing, found this IOM dated June 2006. See page 32 for an updated pressure differential vs cfm flow chart with actual box sizes.
http://www.trane.com/Commercial/Uploads/Pdf/1100/vav_unitiom.pdf

[simux]

Duct Size Area K Factor
5 .14 3.27
6 .20 2.65
8 .35 2.44
10 .55 2.30
12 .79 2.30
14 1.07 2.30
16 1.40 2.27

This is the chart I have for Trane, hope it helps!!!!

[digo]

HW spudders ask for the k-factors as box CFM @ 1 in w.c.

What's the conversion from your method?

[tab-tech]

For TRANE VAV's, the K-Factors is actually the volume in CFM that the box should deliver at 1.00 inch of pressure drop.
How-ever, these are based on ideal installed conditions which are not always available at actual installed conditions. The procedure I usually use is as follows:
1. Command all VAV's in a given system to their maximum (usually cooling) setpoints. This is usually accomplished by commanding the variable damper to its maximum design cfm. This also locks all box variable dampers in their maximum demand setpoints through the control system since they will try to maintain that commanded volume. This temporarily prevents dampers from changing and through the testing and calibration process.
2. Once the VAV's have settled in, measure the total air flow at all supply outlets of the VAV box. Compare your "Actual Measured Volume" (CFM) to what the control system is sensing (Sensed Volume). This will tell you how far off the actual is from the sensed.
3. If you want to change the K factor to recalibrate the sensed flow closer to the actual measured flow, do the following
Divide the "measured total VAV volume" by the "sensed volume". This will give you an amount of difference between the two.
Multiply that amount of difference by the existing (DDC shown) K Factor for that size box to derive at a new K Factor.
Enter that new K Factor into the appropriate cell block. You should now see the "Sensed Volume" for that VAV the same as what you measured (or at least within a few cfm)
4. Proceed through all remaining VAV's in that system using the same procedure as above.
5. Once all VAV's have been verified as correct, dont forget to release the damper command points for all VAV's back to normal operation.

Hope this helps. I have included what I have for TRANE K-Factors for various size boxes.
Also, I assume these VAV's are NOT fan powered? Although the K-Factors would be the same for any inlet size VAV regardless of fan powered or not, the procedure for balancing would change somewhat if fan powered depending on whether the fan powered VAV is parrallel or not in its relationship to the air flow through the VAV.

TRANE VAV K FACTORS

BOX SIZE K FACTOR

24 RT 8000

16 “ 4000

14 “ 3000

12 “ 2000

10 “ 1400

8 “ 900

6 “ 500

5 “ 350

4 “ 225

* Based on rated CFM for each box size at 1 “ static pressure

[digo]

tab-tech, I'm looking at a the newer VariTrane Single-Duct VAV boxes (VCCF series), and the numbers you are giving above match the max CFM value for each box size, but they don't exactly match up with the curve on page 32 of the vav_unitiom.pdf as for the CFM @ 1.00"
Doe anyone know where to find this?