Pump sizing

Dana

Can't find my pumping away book. Don't know if it would answer this question anyway. Does anyone know the formula for figuring the size of the copper primary loop piping for:
4,000,000 BTUh, 320 GPM at 40' head. Thanks

Gary Fereday

interpolate it up!

from 2"= 45 GPM = 450,000 BTUH. Tnisfron the HYeating help mouse pad! good luck!

DanHolohan

I'm missing something

Dana, who figured the pump head? You need to know the pipe size before you can get the head.

DanHolohan

big

He's got four million BTUH

Gary Fereday

nuts!

see what happens when you do not use the preview! "this from" & delete the "Y" from heating help pad! bigugh

Gary Fereday

I think

He is asking what size pipe will handle it! at that gpm and head! kinda got to work it backwards!

DanHolohan

let's see

what he says.

Gary Fereday

ratio!

set it up as a ratio to find the pipe size you want. It'll then have to be reworked back into you particular situation to see if it fits! bigugh!

DanHolohan

He may be

deep into the installation already. If he were doing it from scratch he could figure his required high temperature and then set up a temperature drop, based on the minimum return temperature, say, 140 F. From there, he'd get his required flow rate and then the pipe size and then the pump head.

It's all in Primary-Secondary Pumping Made Easy, not Pumping Away.

Gary Fereday

One hell of an engineer!

I love it, You Know where to find the answeres! Its been said that engineers just learn where to find the answeres, not that they know anything! And there you are you not only know where to find the answer but wrote the book the answere is in! Thanks for all you do for this trade! This new wall is super. How do we spell check beside just edit and re edit ?

DanHolohan

I'm not an engineer

I'm a sociologist. We're more vague.

Gary Fereday

On your WAY

to Lawyer! not bad for a heating tech! bibugh

DanHolohan

Not a tech either

I've never actualy worked. I watch the birdfeeder and dribble on my shirt.

Gary Fereday

Almost an equal

I am practcing that exact thing as we write! and am getting better at it! I know now where "The Gathering" came from Its the bird feeder!

Dana

Dan, I,m trying to work it backwords. Your mouse pad and other data usually are enough for me to get it close. This is the largest system I've ever tried to design myself. I know my heat loss for the building per floor which is 1,000,000. At 12,500 BTU,s per Gpm, thats 80 gpm per floor. I,m splitting each floor into 2 main zones off the primary so I can run one 2" secondary main per side. My baseboard is 11/4", so my heat loops will also be 11/4", which can handle 140,000 BTU,s, therefor my run outs to each section of baseboard will handle it's connected load. I'll have 4 sections at the 140,000 Btu load off each 2" main. My boilers, 10 of them, will be in the basement with aprx. 100 feet of primary supply pipe and 100 feet return pipe to each, 8, secondary mains. Is there a formula to then figure out the size of my main risers to my, 8, secondary heat zones. I know I need to flow 320 gpm in the primary main at 12,500 Btu per gpm, which is the formula I choose to use. How do I figure out what size my primary main should be for my secondary loops? Hope this makes sense to you.

DanHolohan

Be the bird

Yes, I'm providing the seed and birds are gathering. Ommmmmmmmmmmmm. Be the bird!

DanHolohan

anyway

you can post a sketch of this?

Jim N.

ASHRAE Std 90 calls for 4ft/100ft maximum head loss. Entering the friction loss chart (HOF ch 35, fig 2) for copper tubing with this value and going across to 320 gallons you are between 4 and 5 inch pipe and 8 fps. Unless your Energy Code people are very rigid I'd use 4". 320 gallons with 4E6 Btus (I am an engineer and learned exponential notation) will give you a 25 degree delta T. Any chance you could increase this.

There is an equation for pressure loss called the Darcy-Weisbach equation which nobody but computer programers uses. Get yourself a copy of the friction loss charts.

Mark Eatherton1

Why not...

increase the delta T and decrease the GPM and feet of head. This is a boiler primary, not a loaded secondary. It don't care if it sees a 40 degree delta T.

Just me rambling. Why does everyne get hung up on such tight delta t's?

She's gonna do what ever she wants to do, and most of the time, it won't make sense.

ME

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Boilerpro

I'm with you, Mark

use whatever delta tee that will fo the job, bigger delta tee usually saves you money up front in piping and the owner down the road with less electical usage and less expensive pump repairs. But be careful on too big a delta tee on the boiler loop, could end up with your boilers going off on high limit if your system is returning relatively hot water say 170 F or higher. I.E. 170 F from system, 50F delta tee through boiler, equals minimum high limit of 220F. We've seen this before here on the wall.

Boilerpro

Dana

Thanks to all for your help. Dana

RonS

HVAC SOLUTION SOFT WAIR IS VARY GOOD TO HELP YOU SIZE YOUR PIPING AND PUMPS LOOK IT UP ON THE INERNET I THINK ITS GRATE RSICKLER