Counterflow header

Onepipe

Alright so i know headers have been talked to death at this point but i am on a personal mission to save the world from wet steam….all of the boiler literature and Dans book talk about the supply main take offs from the header should be off the top of the header pipe not the side. I get that. So here is my question: with a Counterflow system or partial counter flow system wouldn't it be beneficial to pipe the supply main into the header with a 45? My thinking is that with a Counterflow you will have a lot of condensate raining back on your steam supply as it’s returning to the boiler. If it was on a 45 (same as when you pull off the main for riser take offs and radiators) it would allow the condensate to drain back to the boiler on the bottom of the pipe. Thoughts? Or am I over thinking it

EBEBRATT-Ed

Picture the counter flow pipe pitching down towards the boiler. When it gets near the boiler you put a tee in it and drip the branch of the tee down into the boiler return or hartford loop. Thats where all the condensate goes. Then you feed steam in the other run of the tee.

Onepipe

Got it. That make a lot of sense. 

KC_Jones

Some of the boiler manufacturers actually recommend piping the supply into the top of the counterflow main with the drip out the end, basically just like a drop header design.

Onepipe

Interesting. As long as you have head room I guess. In my case I do not. So I’m going to pipe in a condensate drop off the main. It has three mains but only one is counter flow. I think they piped it that way to provide more moon in a living area of the basement. Easier for the plaster guys I guess. 

EBEBRATT-Ed

@KC_Jones

I really love some of the boiler mfgs drawings. You come up out of the boiler straight and come across level cause there is no swing joint and then drop down into a tee on a pipe that is pitched. I would like them to tell me how that is supposed to be done especially with bigger pipe that doesn't bend

clammy

On a counter flow system I basically pipe the boiler as I would any steam boiler . For a counter flow main I usually feed my supply in the top side off my boiler header into the counter flow and let the drip drop as in diagram above . I prefer this method over dripping down the supply and back into the header I feel that it’s counter productive . I always let the end of the counter flow drip into the wet return . I ve used this variation for close to 20 years and usually unless it’s an extremely hard tight spot to pipe it has always been a vast improvement over what was not working before . Please remember that on a counter flow your not moving the same amount of Btu as you would w a Pararell flow main . So there usually a size bigger then usually for trouble free operation and a vapor stat is usually more then often required for proper operation and please do not over size . As always note be kind to your self and over size the near boiler piping you will be glad you did . Counter flow system perform best as w all steam system when supplied w dry steam this only happen w proper near boiler piping and for better performance it would be wise to go 1 size large then what the boiler manafacture suggest if they say 21/2 go 3 . Low exiting velocities and dry steam is you what ever steam system needs to perform as they should small undersize header work but w high exiting velocities carrying over moisture . Anyone who says it bunk well keep doing what your doing then cause you don’t know the difference except there fill of excuses and it don’t matter answers .
If you look about enough you will find loads of different ways to pipe a counter flow the most import is to be sure that the end is dripped and that your pitched enough for your condensate to drip into a wet return even if it’s a tee facing down for a drip that’s fine and another note is even though you don’t usually need a huge drip I prefer to always use a full size tee and nipple and then reduce to a size which will handle the edr of condensate w a fudge factor .
Counter flow proper operation swings upon dry steam low pressure and proper drips for condensate.
Peace and good luck clammy

ethicalpaul

Hey clammy! What did you mean that counterflow isn’t the same BTU? Is it more, or less?

and where does it come from, or go? The burner doesn’t know it’s counterflow, right?

Jamie Hall

ethicalpaul said:

Hey clammy! What did you mean that counterflow isn’t the same BTU? Is it more, or less?

and where does it come from, or go? The burner doesn’t know it’s counterflow, right?

I think that what @clammy is referring to -- correctly -- is that for the same pressure drop in the same size pipe, a parallel flow arrangement will move more steam (or, conversely, the pressure drop for a given flow in a parallel flow main will be less than in a counterflow main). Either way, a parallel flow main has a greater steam flow and therefore BTU flow than a counterflow.

EBEBRATT-Ed

It is strictly because for a given size pipe more steam can flow in Parallel pipe system than in a counterflow. Counter flow requires double the pitch and a bigger pipe to handle the same load as parallel flow

ethicalpaul

Ahh yes gotcha. It is weird though, they both have the same condensate in them.

EBEBRATT-Ed

@ethicalpaul

Counterflow the condensate opposes the steam so they want the pipe upsized and more pitch to drain the condensate.

ethicalpaul

Yes, but does it matter I wonder.

In my parallel flow it goes from 2” at the start to 1-1/2 for the second half. And the second half is where the condensation is deepest.

i get the theory but I wonder if it’s just something that someone thought made sense and never tested. I’ve grown skeptical can you tell? 😅

Waher

EBEBRATT-Ed said:

@KC_Jones

I really love some of the boiler mfgs drawings. You come up out of the boiler straight and come across level cause there is no swing joint and then drop down into a tee on a pipe that is pitched. I would like them to tell me how that is supposed to be done especially with bigger pipe that doesn't bend

Two added short nipples and elbows later to make it look more like a standard header with two swing joints to allow for proper expansion/pitch:

It's awful how even some of the boiler companies can't get their near boiler piping correct in their technical literature.

trivetman

@ethicalpaul -

could you please repipe your mains in counterflow and glass to run the experiment?  I look forward to the video!

EBEBRATT-Ed

Not any of this is rocket science. Just think "inside the pipe" as Dan recommends and you can easily solve most problems

jumper

Anyone seen a counterflow two pipe? Return risers connected to bottom of main?

I bet there's some counterflow without even a header or a drip. Pure counterflow.

ethicalpaul

jumper said:

Anyone seen a counterflow two pipe? Return risers connected to bottom of main? I bet there's some counterflow without even a header or a drip. Pure counterflow.

Yes we have seen often them directly piped to the header. It can work but it’s unforgiving!

EBEBRATT-Ed

A lot of the old boiler they just let it drip back into the boiler supply. Most counterflows are short mains because of the pitch required and not many radiators so not much condensate so it didn't bother the older boilers. Not a good method though.

jumper

EBEBRATT-Ed said:

A lot of the old boiler they just let it drip back into the boiler supply. Most counterflows are short mains because of the pitch required and not many radiators so not much condensate so it didn't bother the older boilers. Not a good method though.

Depends on how low boiler can be located. In bad old days boiler shack was downhill from house. Gleaned fuel was sort of free if time doesn't count.

Onepipe

One of the boilers I’m working on right now is half counterflow and the main just drains into the header. The system runs quiet but lots of wet steam and high heat bills. I’m going to add in a drip and a drop header and can’t wait to see how the performance changes. There was a number of issues on this unit. Undersized main venting, failed radiator vents, pitch issues. All that has been addressed and boiler is going in next week. Look forward to seeing the effects. Because of height restrictions I’m going pipe the main as Ebebratt-ed recommended. I’m going to screw a tee onto the end of the main with the spur pointing down. I’ll bring the steam into the end and hook a drip to the wet return from the spur. There is a chance I can get up into a joist pocket and come in from the top but it’s going to be tight. 

EBEBRATT-Ed

@Onepipe I don't know what size drip your planning on I would say 3/4" is minimum. But in any event I would make the tee full size of the main with the branch of the tee the same size, drop down with a nipple and then use a reducing coupling.

Onepipe

Ebebratt-Ed so my counterflow portion of my main is 2” and the wet return is 1-1/2” so I was planning on using a 2” diameter nipple 6” long and then reducing down to 1-1/4” for the rest of the drop. I’m assuming 1-1/4” is oversized but I have the fittings and pipe already for portions of the wet return. 

ethicalpaul

The performance may not change. BTUs are going somewhere and that somewhere is in the house

EBEBRATT-Ed

@Onepipe

sounds fine.

jumper

ethicalpaul said:

The performance may not change. BTUs are going somewhere and that somewhere is in the house

Now that is an interesting subject. Wet steam condenses at same temperature as dry so.....????

Onepipe

jumper, here is my understanding of the physics of it all. Although wet steam condenses at the same temp as dry steam, wet steam is not carrying the same BTU’s as dry because it has less latent heat. The benefit of the 980ish BTU’s of latent heat per lb of water is only available from changing state. So figuratively speaking if you had a given volume of dry steam you would get (for my example) 980 BTU’s per pound of steam. BUT if it was 50% wet steam then you would only be moving roughly half the BTU’s roughly 490 for the same volume. This is because water only moves 1btu of sensible heat for one deg change. (no change of state, no latent). You can only move so much volume of steam through a pipe at a time so if half is water droplets you just are loosing out on efficiency. 

Just my understanding 

EBEBRATT-Ed

@Onepipe

excellent description. It's all about steam quality

jumper

So subject is about boiler "working" to transport heat? But ethicalpaul asks where does wasted work end up if not heat in building?

EBEBRATT-Ed

It all stays in the house either from boiler jacket loss or the heat goes into the boiler water except for what goes up the flue.

Onepipe

Ya I don’t think there are any BTU loss, just far less efficient re location of the BTU’s is all.

ethicalpaul

I will say that when my old boiler was shooting water around the main, it still heated the house.

I can't see how, even with that significant wet steam, that the BTUs would go in the boiler jacket...

I propose the BTUs go into making steam just as before.

Now I'm not saying that there won't be problems! There will be balance issues, and possible water shooting out of the main vent or other vents, but the heat is going into the steam pipes.

sorry for being pedantic on this, but combustion and steam-making efficiency is going to be the same regardless of wet steam.

EBEBRATT-Ed

@ethicalpaul

What I meant was wet steam, dry steam whatever after combustion takes place the heat goes into the water to make steam, up the flue or through the boiler jacket and into the basement.

If you read about commercial boilers they talk about "fuel to steam efficiency" that all there is. Whatever boiler converts the most fuel btus to lbs of steam (BTUs) the best is the most efficient boiler.