The case of Ray versus the A dimension

ethicalpaul

We are in agreement, Jamie, isn't that cool?

You are saying that a dry return open to atmosphere won't spew steam if the pressure is correct.

I'm saying a dry return open to atmosphere if the pressure is correct will have no need of an A dimension.

ethicalpaul

Gsmith said:

same concept on the A dimension, might not be needed in most cases, but doesn't hurt or cost much as a "standard" way of designing/installing most systems.

I am not saying don't have an A Dimension. It makes sense to have the main high and the wet return low.

I'm saying that the concern about the water level rising at the A dimension is overblown, by a long shot. (for example, like the concern about getting the main venting above the main)

Jamie Hall

Perhaps it is, as so often, a matter of using the same words to mean different things? However one wants to call it, though, the water will rise in a pipe connected to a wet return at one end and a dry return -- or open to the atmosphere -- at the other end 28 inches above the boiler water line for each psi gauge in the boiler... has to, to balance the steam pressure.

It will rise very little, if at all, in a similar pipe, but connected to the steam main at the top end...

EBEBRATT-Ed

Don't forget we are talking here about a perfectly installed system installed and working the way it should.

But:

Traps fail and are neglected. There are probably more defective traps in use than there are working traps

Pipe hangers fall off and wreck pitch

oversized boiler are a common occurrence

Radiation gets disconnected

@ethicalpaul

Think of a two-pipe system with steam traps from all the radiation and drips from the steam mains. Lets say they are dry returns and the boiler is operating at 1.5 psi.

The traps are all working and have 1.5psi- (steam main pressure drop) at the trap inlet. The dry returns run back to the boiler and drops down into the boiler. There is a main vent on the dry return to vent the air so there is basically 0 pressure in the return main because it is vented

The water in the return drop will rise up "stack" about 3' in that return drop to overcome the boiler pressure of 1.5 psi. Otherwise the water will not go into the boiler.

To prove this raise the boiler pressure to 4 or 5 psi like my example posted above and watch what happens.

The vent will close because it is waterlogged, the water will back up into the horizontal dry returns and hammer and bang when the traps cycle because traps are not perfect and pass a little steam. The radiators and traps will waterlog and gurgle and bang and they will have no heat.

We have now turned a steam system into a noisy hot water system without a circulator

EdTheHeaterMan

How did I know this would go to 2 pages when Ray said "Dimension A"

Will definitely go to 3 pages or even 4 if EthicalPaul has anything to say. And he usually does! LOL

EBEBRATT-Ed

@EdTheHeaterMan

We could start some other popular discussions such as "what pipe dope should I use", or "does my Nest need a C wire". or the one that always lights up the board "dry returns" versus "steam main extensions"

We can save those for when things slow down

ethicalpaul

Thanks @EBEBRATT-Ed I’d love to try it but I have one too few pipes! But thank you for sharing the scenario, it helps me understand 

@EdTheHeaterMan I like the joke but it takes two to tango…I don’t reply to myself 😂

EdTheHeaterMan

ethicalpaul said:

Thanks @EBEBRATT-Ed I’d love to try it but I have one too few pipes! But thank you for sharing the scenario, it helps me understand 

@EdTheHeaterMan I like the joke but it takes two to tango…I don’t reply to myself 😂

Oh hell... I always talk to myself, sometimes it is the only time I get to have an intelligent conversation.

Otherwise it is like having a battle of wits with unarmed opponents