Effect of pitch on water column??

Onepipe · February 18

Im pretty good at math but im having a hard time wrapping my head around this one. I know that 1lb of pressure will like water 27.7" but what happens to the lift if the pipe was at a 45 deg angle? would it be able to lift it higher?

I have a system with water backing up higher than what I would expect but the vent is located on the top of a 45 deg pitched drip for the dry return……i did not pipe it that way.

jesmed1 · February 18

Imagine you're swimming in the ocean. The pressure varies only with the depth below the surface, measured vertically.

So now imagine the vertical distance from the vent down to the boiler water line, or wherever your reference line is. That's the only distance that matters. The water doesn't know and doesn't care what angle its pipe is at. It only cares about vertical height.

Then your conversion is 1 psi = 2.3 feet vertical height.

Or, the other way around, 1 foot vertical height = 0.43 psi.

So if your vent is, say 10 feet higher vertically than your reference line, you'd need a pressure differential of 10 x .43 = 4.3 psi higher than at your reference line to get the water up to that vent.

mattmia2 · February 18

Nope. In fact they commonly incline the column on monometers to stretch out the scale and make it more precise.

Onepipe · February 18

Got it. That’s what I was thinking but I have water some how backing up to a vent on long run times. The vent is 40” above the waterline on a gravity Return vapor system that is operating at 12oz. Now the vent in question is on its own branch with only two radiators that had traps installed years ago. All the other radiators in the system have Richardson vapor 90’s on the return side of the radiators. The wet return is clear of plugged and the system is vented really well. It runs about 1/2psi pressure furring normal operation but vapors is set to 12oz. The water only backs up on long run cycles when it’s really cold outside. Any help is appreciated

jesmed1 · February 18

So 40" water column gives you a 1.4 psi differential, or 22 oz.

I know nothing about steam, so the pros will have to help you out.

mattmia2 · February 18

Is there any hammering? is the water line stable while it is steaming? seems more likely that a slug of water is getting thrown that way. if it is working properly there should be no steam in the returns so the vent should never close.

Jamie Hall · February 18

Is this vent on the steam supply main or on the dry return? In either case, it should not have any water Is there an adequate drip to a wet return? If it's on the steam main, why? Crossover trap missing or not functioning properly?

Need to know more here.

delcrossv · February 18

Sure the wet return is really clear? Partial clog may fill the drip faster than it can drain on long runs.

Onepipe · February 18

the vent is on the dry return. The system was dirty and I have it on a skim regimen so at times the water level is moving more than it ships but nothing too crazy. As far as the wet return I have power flushed it many times and know I’m getting good return. As far as hammering it is quiet as a church mouse. That’s what has me scratching my head. I can say there there is no steam in the dry returns as you can clearly feel it’s just condensate in the pipe and the vent never closes. I can check the wet returns again possibly something broke loose but I have really good flow.

pecmsg · February 18

the angle and diameter of the pipe has no affect on the standing pressure.

delcrossv · February 18

https://forum.heatinghelp.com/discussion/comment/1843406#Comment_1843406

Maybe flush from where the vent is. Drip + wet return so you know its clear.

mattmia2 · February 18

Is there a drip that is connected to the wet return not far enough below the water line such that it can push a slug of water with air or steam behind it up the return to the vent?

Onepipe · February 18

mattmia2 no. The wet return is 8” below the water line and I have plenty of rise to both the mains and dry returns. Also the system is super quiet. I’m wondering if some how I’m getting a vacuum in the two radiators that are on that supply loop. I’m not sure how because the vent is staying open. At least when I’m around it is. I watched it run for an hour the other day and it did not do it but some time last night it did as there was a puddle of water on the floor. It was 1f last night so I’m sure it was running often.

EBEBRATT-Ed · February 18

Post some pictures.

mattmia2 · February 18

8 inches is about 4.6 oz/in^2

delcrossv · February 19

https://forum.heatinghelp.com/discussion/comment/1843451#Comment_1843451

The wet return is 8” below the water line

Maybe pushing that slug of water out of the way and letting steam enter the drip? Thinking it's acting like a too-short differential loop.

Pictures please.

Jamie Hall · February 19

https://forum.heatinghelp.com/discussion/comment/1843603#Comment_1843603

does sound like it…

techforlife · February 19

Are you SURE you only have 12 oz. pressure?

Effect of pitch on water column??

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