I just installed a Williamson gas fired boiler. Did the heat loss calc on Slantfin website and I am having trouble getting heat or even pressure to the third floor. I installed boiler drains in the 3rd floor to bleed but when I open them I don't get much pressure. I have an auto fill installed but thought maybe the 12-15 psi might not be enough for heating 3 floors. Please let me know if you guys have any suggestions. Thanks

 

You are probably right that 12-15 may not be high enough...

To calculate the pressure you need, measure the height in feet from the boiler to the highest point in the heating loops.

Multiply by 0.431 and add 3-4 PSI.

15 PSI would be about the minimum for 27' of elevation.

By the way, the air bleeds (vents if you will) should be installed where the piping takes a _down turn_ because the air in the system will happily move horizontally, but will strongly resist going DOWN.

 

cookman:

What size pipe or copper is being used to go to the 3rd floor??????

NJ TROOPER is ASSuming that it is a common sized pipe or copper such as 3/4 or even 1 inch. Hope it isn't 3 inch diameter vertical to the 3rd floor on a converted system.

ASSuming that it is 1 inch or under---NJ TROOPER's info is on the money. I just like to make sure that the apple orchard is growing apples before we water, weed, fertilize, plow, etc... only to find out that somebody planted onions instead!

PROPERLY BLEEDING the system is essential in YOUR case.

Are you familiar with the procedure to PROPERLY BLEED the circulating system?

A pocket of air NOT PROPERLY BLED out of a 3rd story line WILL NOT permit circulation!

NJ TROOPER or another tech can help you on this.

I have to go fly my kite before the snow comes!

NJT: didn't mean to hijack your thread but we need to get the pipe diameter out of the way!

Charlie

 

Charlie is of course correct that you need to bleed, but you did say you didn't have pressure up there, so how can you bleed with no pressure !

You ain't hijacking Charlie! EVERYONE is welcome to respond... it's a democracy here !

I think someone needs to hit the physics books though, cuz it don't matter a hoot how big the pipe is, the pressure will be the same no matter what. A 100' foot tall column of water in a 1" pipe will have the same pressure as a 10" pipe at the same height...

 

NJ TROOPER:

Are you saying that TWO 27 foot high pipes, VERTICAL, one 3/4 inch diameter and one 3 inches in diameter will get water pumped UP to the end of the pipe if we select a pump that will be able to do it on the 3/4 inch diameter one (barely)?????

Are you saying that no matter what, that pump that was able to pump water UP the vertical 3/4 diameter pipe will definitely pump water UP the 3 inch diameter one too????


I rest my case!

Keeping it simple for the not so technical!

Charlie

 

BTW:

I don't think I missed any of my BASIC physics classes, maybe some of the later ones dealing with elevator problems in dynamic environments, maybe a couple dealing with thermal expansion and harmonics, and such.

The WEIGHT (MASS) of the water column that must be overcome to PUMP on a
vertical pipe 27 feet high I calculated to be as follows:

For a 3/4 inch vessel APPROXIMATELY 5.2#
For a 3 inch vessel APPROXIMATELY 82.7#


The weight of the water, concentrating on a 1 inch opening on the pump becomes
the ACTUAL number you would be working with, NOT the psi in the pipe diameter which
should be equal in either vessel.

5.2# / 0.44 sq. in = 11.8xxx psi
82.7# / 7.065 sq. in. = 11.7xxx psi

*about the same INSIDE the vessel (as expected)

BUT:
THE FORCE ACTING AGAINST THE PUMP IS:
(assuming a 1 inch pump output)
5.2# / 0.785 sq. in. = 6.62 psi (for a 3/4 inch pipe)
82.7# / 0.785 sq. in. = 105 psi (for a 3 inch pipe)

SO, I doubt that a TACO 007 will pump 27 feet high vertically on a 3 inch diameter pipe. BUT, maybe I'm wrong. I haven't looked up the specs. on pumps yet, but did do some SIMPLE calculations to show the difference in the work load a pump has to do with larger vessels.

Maybe the specs. on a TACO is more than 105 psi output.

PS: These calculations are ONLY for a static stand alone pipe with no external forces such as boiler pressure acting and assisting.

If I am wrong, so be it. This is the way I see it and if someone can prove it to me that it is not so, I PROMISE to dig up the physics books that I haven't opened in decades. Scout's honor.

The MAIN problem here is the air in the line, not the pump pressure because you will have assist from the boiler pressure. AIR LOCK is the problem.
Charlie

 

We're not talking about the pump here... we'll get to that in a minute.

If you took a 10' tall 3" pipe with a gauge mounted 1' from the bottom of the pipe, and the same setup in 3/4" pipe and filled them both with water, BOTH gauges would read EXACTLY the same. The size of the column has absolutely nothing to do with the pressure. The only factors that are considered are : HEIGHT, DENSITY of the fluid, and GRAVITY.

Neat STATIC pressure calculator

In a CLOSED system, there is NO dynamic pressure. It's a big ferris wheel. The water coming back down due to the force of gravity completely negates the force required to push it up. So, yes, a lowly 007 would be just as capable at pumping water up a 3" pipe as it would a 3/4" pipe in a CLOSED SYSTEM. It's a PUSH ME / PULL ME situation. The only thing that would affect the amount of water the pump would pump is the FRICTION (head) of the system, and in fact, the 007 would probably pump MORE GPM in a 3" loop, all other things being equal. If this were an OPEN system, i.e. a well pump, the situation would be MUCH different.

Yes, there may be an air lock, but only because there isn't enough pressure in the system to raise the column of water to that height. There is NO pressure at the top, so it will be impossible to bleed the air.

 

Right, this is what I said... we agree.

But, you took yer gun and headed out to the field to shoot some birds !

The pump doesn't even enter into the discussion. All we care about is the static pressure. But, see my previous post anyway.

BTW, _NOW_ we are 'hijacking' ! :mask:

 

Hope you guys don't mind me jumpin in here. The pipe is 1" copper to the second floor and then reduces down to 3/4 to the third. Assuming it is about 25ft or so to the 3rd floor what should the ideal pressure be? Thanks for the help guys.

 

My gun is still in the attic! Don't even have ammo anymore.

OK, well WE agree!

Still pals!

But now the question of the air.

I would bleed the system with keeping the pressure just under the 30# relief (need an assistant to "man" the feeder to keep the pressure up) to MAYBE get the air out.

Still in agreement?

THEN, it's a push-pull situation, once the air is out, no problem to circulate the water---still in agreement?

But now the question of the air.

MAYBE the 20-30 psi WON'T be enough to 'push' through the air lock IF there is 3 inch vertical pipe with 27 feet of water. See what I mean?

Get that calculator out again.

I'm gonna see if I can find mine again!

Charlie

 

15 psi, with the air out of the system, would probably work nicely!

Right trooper?
:mask:

YES, I know! This is what YOU said originally.

BUT, will only work once the air is out.

Charlie

 

It's your thread cookman! It's us who are being bad...

If it's 25 feet, do the math:

(25 x .431) + 4 = 14.775

But, if the boiler is in the basement, on a 3 story house, it's gonna be more than 25 feet.

Bottom line is that you need enough pressure in the boiler to get the water to the third floor, and about 3-4 PSI on top of that.

If the bleeders (vents) are not where the pipe turns to go DOWN again, you will have problems removing the air.

 

I think I'm good here. I do have the boiler drains on the return to the basement so I shouldn't have a problem getting the air out just wasn't sure about the pressure. It made sense to me but I thought I would ask the experts. Thanks again guys.