steam problem - need solution - DVW

David Van Wickler_3

Engineer called - contractor called. Somehow it's my prblem because it's my boiler!

Take a look at my drawing and see what you think would be the solution.

The boilers are flooding -me thinks it's gravity siphon syndrome. They installed 4psi spring checks and they are making a racket. I also happened to provide the receiver tank and Duplex pump set.

Thanks in advance.

David Van Wickler

Mad Dog

Good possibilty Dave. but are you

sure a makeup valve is not passing water or its being bypassed somehow? You might need to break that vacuum that could be siphoning water in to the boilers. maybe that high loop should be vented to the atmosphere to break vacuum? Just some thoughts. Mad Dog

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David Van Wickler_3

Heres my solution

Is this acceptable?

DanHolohan

One feed pump

for three boilers? Are there zone valves on each boiler, with separate pump controllers to open and close them?

Are all boilers firing at the same time?

Mad Dog

That might work , but

why not at the highest point? Vacuum breakers can be problematic and have nuisance leaks. Can you open that up to the atmosphere at the top with a tee and a high standpipe? As long as your pump doesn't overpower the loop and shoot water out of your standpipe, I think this would work. Mad Dog

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Mad Dog

Was that high loop existing or was it added recently?

what I'm getting at is....is it neccesary? Have to go meet Dan for Iron & Beer night at the shop with Noel, but steamhead and some of the other sharp steam wallies will be by very soon I'm sure. Mad Dog

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David Van Wickler_3

actually its

FIVE BOILERS

I have equal water lines because I used circuit setters - see drawing. I did'nt think about a siphon issue. No zone valves Dan (engineer was against them, even when I showed him a Triad boiler design - approved by the great danster! no less. I represent Triad).

So all boilers get a little water, I know the inherent problem with boiler pressures and water flow and suppressed water lines.

Is zone valves the simplest answer?

DanHolohan

Zone valves

and spill traps on each boiler. I helped Triad come up with that sketch a long time ago. It works.

Steamhead

I think MD is right

the vacuum breaker should go at the highest point.

Look on page 177 of Lost Art. It has a diagram showing a vacuum breaker and double elbow which should solve your problem.

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Mad Dog

I may be right on the vacuum issue, but that might only be a

small part of the problem. Look in to what Dan is talking about...Noel is also very good with commercial steam and water level problems...ohhh Noel???? Mad Dog

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flange

when you say the boilers are flooding can you be more specific. is it one, all two? under what conditions?

David Van Wickler_3

flooding

all boilers at once when the heat demand has been satisfied or the outdoor air temperature is above cut off.

What happens is the high loop creates a sphon effect and was drawing through the original 2psi spring checks.

The engineer said put 4psi spring checks.

This solved the problem but created another one with noise and the check valve fighting to close because the column of water is pulling it open.

YES,

zone valves and spills would be the ideal solution, but expensive and it does add another mechanical/electrical component.

Why not this?

Unknown

That would work

What check valve are you thinking of using? It would need to open fairly easily, be VERY steam-tight, and operate quietly when the pump starts and stops.

Noel

David Van Wickler_3

What is a good steam

check valve? that is quiet and steam tight over thousand of cycles?

Unknown

That's the key question.

I know of a few noisey ones....

The plastic seated ones come to mind, but will they open easily under the slight vacuum like they would need to?

I have doubts about the plain-Jane swing checks.

Noel

David Van Wickler_3

ahh yes

there will always be a column of water against the check valve, but only if I break the vacuum at the top - this would drain the leg towards the boiler and leave the water at the top of the pipe to act against the check valve.

NOW,

What about the slug of air in the pipe between the boiler water line and the water line in the pipe? Will that make noise in the boilers or be a nusiance in the system?

Bob_19

Why not

use a motorized fill valve before the boilers if this is a commomn feed pipe for all the boilers? Any boilers calling for water can operate valve. Only issue i see with this is a lag time issue between open/close and multiple boilers calling too close to each other. Seperate valves would be better but maybe not absoulutly neccesary.

If I see this correctly( it looks like one pipe for all boilers) a single valve would secure the line and give positive shutoff against gravity flow.

I see your concern for using a breaker, my thoughts also.
Why add any more air than neccesary to the feed water.

We used those spring checks before and had nothing but problems with flooding issues with the off boiler.

Unknown

Only on the first pump run cycle

after that, pressure will keep the check closed.

On the first pump cycle, the mains will be consuming steam fast, and the air won't all be out of the mains. It will still be venting. I think the "new" air will find it's way out of the boilers. It'll be noisey.

Noel

David Van Wickler_3

Then the solution is this

zone valves on each boiler. Each boiler is equipped with individual pump contacts for maintaining water level. The boiler will call for water, the zone valve will open and the end switch will close the boiler feed pump contacts

What U think all

-David

Steamhead

That should work nicely

let us know!

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