GPM

Paul S_3

How do you determine how many gallons per minute Is flowing through the pipe in a hot watery system....I see a formula in the new book I'm reading"classic hydronics" gpm=btuh divided by delta T times 500....or is that for determining how much you would need before installing new system and selecting a circulator pump is there a way to check to see how much gpm is flowing as is in the field?

unclejohn

Do it

Backwards or sideways. In the field you measure your ^t and the unknown is the gph.

Paul S_3

don't under stand

Can you give me an example

Zman

3 variables

There are 3 variables

GPM

Delta T

BTU/Hour



If you have any 2 you can solve for the missing 1.



If you are trying to find the GPM without the delta t or the btu/hours, you will have to either:



Calculate the size and length of the pipe and fittings and compare this system curve to the pump curve.



Measure the pressure differential on either side of the circulator and compare that to the pump curve.



Taco's flow pro university has some great webinars. John Barba is a fine teacher.



Carl

Paul48

Universal Hydronics Formula

The btuh comes from the  heat loss of a zone, or job. The GPM is the required flow to carry the btus. A zone is 40000 btus. The zone is fin tube baseboard designed for a 20* delta t.  40000 divided by ( 20x500)=4 GPM. Now you determine the head for the zone to be 9ft. You are looking for a circ that produces 4 GPM @ 9 ft of head.

Now ,suppose you went to a job and the homeowner was complaining about 1 zone always being cold. You determine the head for the zone, and find it is pumping 8 GPM. You know the heat loss is 40000. So, 40000 divided by 8=5000. Five thousand divided by 500=10. You are getting a 10* delta t from the zone. It is over-pumped.

That's what they mean about solving for any missing component of the equation.

unclejohn

here goes

lets say btuh = 100,000 ^t = 30*f  so then 100,000 btuh divided by 30 x 500 = 15,000 = 6.67 gph.

Paul S_3

thanks

thank u guys much appreciated