Manual D Friction Rate Worksheet

beenthere

To have a ESP of .5", yes.

often. In order to keep duct size at a workable size for the homes constraints. You end up having to go to an ESP of .6, or .7". Or, add turning vanes to the return drop to reduce the PD of the 90 into the blower/return box.

Vanes can reduce TEL of the drop by 60 foot plus. Same with the supply trunk attachment to the plenum.

kilosos2

I had to google about the 'turning vanes' to understand what your saying. I have a open central return so, I cant use the vanes as I don't have an actually return box . ( I hope I understood your answer correctly about adding the vanes in the return) I like the idea your saying to put the vanes for the trunk lines where ever it makes turns. Turning vanes can be used in duct boards?

So you thing I should redo my calculation and use a higher esp, like .6 or .7 as you have mentioned?

beenthere

They make vanes for ductboard.

Yes. Try using .6".

kilosos2

Ok cool

That give me a FR of .23 . Finally I can now size up my trunklines. loll

Thanks again Beenthere

beenthere

Before you use .23".

How did you come up with 52 as your TEL? That sounds too short.

The supply trunk attachment can be any where from 35 to over 100' itself. The register boots will be atleast 15, a take off or start collar atleast 15'(often 35'). So there would be a min of 70' right there, with no linear length included yet.

PS: Don't use a sheet metal ductulator for duct board.

Earnie

Not sure if this will help but I used this program to do my heat loss/heat gain.

http://www.hvaccomputer.com/


Some interesting online calculators here:

http://efficientcomfort.net/Calculators.html

kilosos2

whoaaaaaa

Beenthere sorry I never saw your reply again. GOOD thing I havent done my ductwork yet.

52 TEL is the length of just my trunklines that will be attached to the main plenum. Did I just miss something???????????? Ok Your saying there will be TEL for each supply run? But I thought we don't count the TEL for the length of the flex runs? I am going to read the manual d book again. Can you tell me what will be counted in the TEL?

I happen to come back to diychatroom because I wanted to ask you if I want to add a 4" media air cleaner , what would it require coming from my current 1" 20x20 filter setup. I was thinking I would have to move up the air handler but that will require disconnecting the linesets and electrical connection which I cant do and I will have to hire a hvac company to do it for me. But I am trying to find out how will it be installed so I can instruct the AC company to do it for me. Would something like the Honeywell Model F200E1011 Media Air Cleaner which is a 20x20x4. But it says max 1200 cfm. I will need 1600 cfm . Any other air cleaner you can suggest.

I am going to read the manual d , to see what I am missing for the TEL again. I had a feeling something was wrong in the equation I did. Especially since I got a .23 FR. Which wasnt even on the ductulator's chart.

beenthere

Honeywell has larger media air filters, that are rated for 1600, and ones that are rated at 2000 CFM.

Easy way to do a manual D calc. is to only separate your devices. A/C coil, air filter, supply register, return register, dampers, etc.

Then subtract that form the air handlers ESP to get your ASP.

Then use the TEL from the manual for all of your fittings, such as take offs, register boots, etc(reducing transitions have a TEL of 5 foot on 18" and 2 foot long transitions). And figure out your longest supply run, and your longest return run. Then do the math, and get your FR. Only need your longest of the supply and of the return added together.

TEL's of high 200's and mid 300's are not unusual.


You should have many diagrams of different fittings in the manual. All with a EL.

beenthere

The media air filter, can be installed in the return drop duct work. Doesn't have to be fastened to the unit.

kilosos2

Return drop duct work. If I have a open centered return will I then be required to install it under the air handler? Check pic of air handler.

I only have supply runs as I don't have any return ductwork. I only take the length of the longest supply flex run , correct? And also take all the remanding takeoff collar's and register box's and calculate their TEL. I am having trouble finding the fittings in the manual d but I will keep looking at it. It seems like most of it is sheet metal fittings.

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beenthere

Yes, in your application, the air filter would be installed under the air handler.

And you would just use the PD of the air filter to get your ASP.

Yes, mostly metal fittings in manual D.

kilosos2

Beenthere

I started forming the TEL again. But i am a bit troubled. I have 15 drop register boxes..is the EL matters on what size the box is or what size collar is hooked up to it? Currently I used the value of 35...so 35x15=525 tel. I have sizes from 10"- 4" boxes . Another thing the take off collars that are coming off the trunklines I cant find a value for that either in the manual d....should I use 15 el also for each take off?

Let me know what u think. I am goin to try to google this information also.

beenthere

The size of the box doesn't matter. And you only use the restriction of 1 box. Since your trying to find the TEL of the single longest run.

use 35 for your take off also.

So it would be 35 for the ceiling box, and 35 for the take off, equaling 70 without any pipe yet.

kilosos2

LOLLL

Imagine I used 525 tel. LOLLL

Ok so I use the longest run including takeoff collar + flex duct+ register box.

ok ill keep u posted on my results.

beenthere

You are not the first person that added all the takeoffs and boots together, and came up with a very high TEL.