Vacuum

Jamie Hall

And I have to admit that I am slightly dubious about taking a system which was a vacuum system, but has been seriously altered, and turning it back into one. Other than the cool factor (which is undeniable!) I'm not really sure it's worth it.

In a situation where the crossover traps have been eliminated, it may make more sense to put really good main venting where they had been. One also needs venting on the dry returns, as well -- which has to be at the boiler, or near it, where they end.

I might add that some systems are dependent on having all the venting right at the boiler (Hoffman Equipped, Sarco, a number of other vapour and vapour vacuum systems) as they had devices on them which gave a shot of steam to the dry returns to close the vents under certain conditions, such as too high a pressure in the boiler, or to return condensate to the boiler. If you have one of those, that's what has to happen.

Bottom line -- to me it would depend on the specific system and what had been done to it over the years. I'm not a purist -- I just want it to work, and work well and efficiently!

samfiller

@Jamie Hall
Thank you for your thoughts, not 100% sure I understand what you mean by converting it back. It appears it was always Vacuum as the valves and traps are all for a vacuum system. I don't think anything was altered besides by the boiler.

@JUGHNE
I don't really have to much more I took so more pictures (attached).

@all Thanks!

PMJ

Remember that 2 pipe vapor/vacuum actually needs very little venting for the simple reason that after the first cycle there is very little air left in the system anyway. The steam on each new firing speeds through the mains and rads chasing the vacuum to the dry return. At any given moment the place of lowest pressure the steam will naturally choose to go is in the pipes and rads ahead of it. The more devices you put in the piping the harder it becomes to maintain vacuum. One vent point in the dry return is enough.

JUGHNE

The last picture posted shows the original air vent with 1/2 of a union hanging on it. It must have been abandoned and that Hoffman installed. It is in the upper right attached to the ceiling and seems to resemble the vent Dan describes in his book on page 261.

samfiller

@JUGHNE

Yes indeed.

Steamhead

JUGHNE said:

The last picture posted shows the original air vent with 1/2 of a union hanging on it. It must have been abandoned and that Hoffman installed. It is in the upper right attached to the ceiling and seems to resemble the vent Dan describes in his book on page 261.

Yup- that removes any doubt it's a Kriebel.

Sam, this system did go into vacuum, but not the way we think of now. The original boiler was coal-fired. The fire was banked overnight to keep it going, and in the morning you'd shovel on some more coal, open the drafts, and the steam would come up and fill the system all the way to the vent. The Kriebel was one of the few vapor/vacuum systems that allowed steam to fill the dry returns.

As the fire burned down, the air vent did not let air back into the system, so the system would go into vacuum and continue generating steam at lower temperatures. This process took several hours.

With the shorter firing cycles of oil or gas firing, we don't have that kind of time. The system would go into vacuum before all the air is out, and the resulting expansion of the air would block steam circulation. So we normally operate these systems at ounce pressures using large air vents to help distribute the steam quickly. This is what I'd suggest you do for now.

Several of our resident geniuses are experimenting with small vacuum pumps which will speed the process up considerably and make it practical to use vacuum with oil or gas firing. Stay tuned.

JUGHNE

Steamhead, thanks you just answered some questions I had floating around in my head. But there are a few more:

This system has had all the "Bafflers" replaced with Hoffman traps at the rads, so they would have to be replaced with some form of "light" check valves??

The 2 dry returns should be separated and drop down individually to the wet return with air venting for each??

The end of steam main drip (s) should also be vented??

It looks like there are 2 steam mains teed off above that old riser but we see only one end of main drip.

Also he should save the air separator and abandoned air vent, what is inside the air separator? I'm sure I'm not the only who wants to open it up and peek inside.

Steamhead

You can still do vacuum with the traps in place. The main difference is that steam won't go into the dry return. Many Vapor/Vacuum systems ran this way, and still do.

No need to separate the dry returns. In this scenario, there won't be any steam in them. The separator can stay just like it is, it's probably just a wide open casting that allows water to fall into the drip while the air rushed out the vent.

The steam mains should be vented as well, that's why I asked for their lengths and diameters. Not sure how the second main is dripped, it may be counterflow. There's not much condensate to dispose of in a Vapor steam main.

The way to run vacuum on this system now is with a small pump. At that time, the main vents can be replaced with thermostatic traps to keep steam from reaching the pump.

PMJ

Steamhead said:

JUGHNE said:

The last picture posted shows the original air vent with 1/2 of a union hanging on it. It must have been abandoned and that Hoffman installed. It is in the upper right attached to the ceiling and seems to resemble the vent Dan describes in his book on page 261.

Yup- that removes any doubt it's a Kriebel.

Sam, this system did go into vacuum, but not the way we think of now. The original boiler was coal-fired. The fire was banked overnight to keep it going, and in the morning you'd shovel on some more coal, open the drafts, and the steam would come up and fill the system all the way to the vent. The Kriebel was one of the few vapor/vacuum systems that allowed steam to fill the dry returns.

As the fire burned down, the air vent did not let air back into the system, so the system would go into vacuum and continue generating steam at lower temperatures. This process took several hours.

With the shorter firing cycles of oil or gas firing, we don't have that kind of time. The system would go into vacuum before all the air is out, and the resulting expansion of the air would block steam circulation. So we normally operate these systems at ounce pressures using large air vents to help distribute the steam quickly. This is what I'd suggest you do for now.

Several of our resident geniuses are experimenting with small vacuum pumps which will speed the process up considerably and make it practical to use vacuum with oil or gas firing. Stay tuned.

I'm just a homeowner but I operate a two pipe system with very short cycles and natural vacuum. I've never been able to understand the comments about how operating this way can block steam travel anywhere in the system. Operating this way sped up steam travel to all my rads exactly the same - and it got there faster than when system was atmospheric and mains vented because now it doesn't have anywhere near as much air to push out of the system each time. The entire 2 pipe system really can be considered just one big open pipe - some air and some steam but all at the same negative pressure when the burner is off. I have put gages around to verify this - it is the same at the boiler header as at the farthest radiator. I think more folks with 2 pipes should give this a try. I've had no mysterious behavior - only improvement. All that air in and out every cycle - really? I'll never go back to that. Obviously that was never the plan when these 2 pipe systems were originally designed. I maintain that is doesn't have to be now either.

samfiller

@all

The "plumber" came back to take a look I guess the GC wants to get it done with out paying more. It looks like they will do the "work" but i need to tell them what to do.
I made this mock up for him, is it correct?

Two parts i left off not sure where to tie in the "new" water feed. Which part of the return?

Also the second return (small one on the other side of the unit) should that be tied in that main return?

He will fix the pressure relief valve he will fix. He will fix the feed to have it like the instruction. He said he will lower the PSI and switch the gauge to oz. He will replace the Hoffman 76 with a working one.

How much of an angle should the cross between the "out" and the return be?

You guys are great!

@Steamhead
I am not sure I understand

Steamhead said:

The steam mains should be vented as well, that's why I asked for their lengths and diameters. Not sure how the second main is dripped, it may be counterflow. There's not much condensate to dispose of in a Vapor steam main.

The way to run vacuum on this system now is with a small pump. At that time, the main vents can be replaced with thermostatic traps to keep steam from reaching the pump.

What am I asking them to do?

Thanks!!!!!

Steamhead

Your diagram doesn't go far enough. Here is the manual for that boiler- scroll down to see the piping diagram. The installer needs to pipe it exactly as shown, with the pipe sizes and configurations exactly matching the diagram.

http://www.peerlessboilers.com/DesktopModules/Bring2mind/DMX/Download.aspx?EntryId=83&PortalId=0&DownloadMethod=attachment

Regarding the steam mains: If you measure the length and diameter (outside diameter is fine) of each main from its beginning at the boiler to the last radiator takeoff, we will know how much air is in the main, and can recommend a vent for each main that will let the air (but not the steam) escape quickly. This will reduce the amount of time the boiler must run to heat the house.

vaporvac

also, you need to keep your current 0-30lb gauge and ADD the low pressure one. the former is required by code.

samfiller

@Steamhead

Are you saying the elbow's in the diagram are needed and have nothing to do with the elbows that I have right near the ceiling?

If I need those I guess the boiler would need to go forward a little more than a foot to make a enough room and allow the main to line up. ( I am not sure the boiler is movable)
Regarding the sizing I see they say it should go from the 3 to a 1-1/4 elbo but the return is 2" at what point does it go "back" to 2?
Regarding measuring the main, I assume you mean the 3" pipe running across the basement ceiling, correct?

@vaporvac
I dont see a spot for a second gauge.

vaporvac

45 are acceptable for the piping. I don't see where your gauge goes, but generally a second gauge can be placed of an elbow. You don't need a second hole.

samfiller

@vaporvac
So take current out put a T in and add a second gauge?

Fred

samfiller said:

@vaporvac
So take current out put a T in and add a second gauge?

The new gauge should be on a pigtail so have them take the Pressuretrol off and add a Tee onto the top of the pigtail and then a couple elbows and nipples and remount the Pressuretrol and the new gauge.

samfiller

@Fred
Thank you, I will have him do that.

samfiller

@Steamhead

Is this new mock up correct?

If yes then great I still do not know where to put the feed.
And if i should keep the second return on the other side..

The main pipe around the basement is 3" that at one point becomes a 2 inch then back to 3" with insulation its very hard to to see exactly. Its an approximately 80 ft "main". When the main hits the ceiling its a T that T goes around the house and then back in to the other side,

Steamhead

That should work fine. Keep the header the full size of the boiler steam outlet until it drops toward the Hartford Loop (this is called the "equalizer"). And the equalizer should be 1-1/2" at minimum. The return line coming into the Hartford Loop connection can be 1-1/4".

If I were doing that job, however, I'd bring both individual mains down to the header so each would come off the header separately.

SWEI

Steamhead said:

The original boiler was coal-fired.
...
As the fire burned down, the air vent did not let air back into the system, so the system would go into vacuum and continue generating steam at lower temperatures. This process took several hours.

With the shorter firing cycles of oil or gas firing, we don't have that kind of time.

Every time I read this, I immediately think of modulating the burner. Have you guys ever retrofitted a modulating burner to a vapor/vacuum system to see if you can get the system "breathing right" again?

Steamhead

That would be great, if we had commercially available full-mod burners or at least low-high-low burners in the usual residential sizes, and the proper controls to operate them. Hey Carlin, Midco, Beckett etc- you listening?

samfiller

@Steamhead

So you are saying to get rid of the T on top have each side come down independently via an elbow (one for each).
As well to have the equalizer 2" even though manual says 1-1/4.

I made a new mock up based on that is this correct?

What about the feed and "second" return?

Thanks!!!

Fred

That is not right. There should not be two horizontal pipes above your boiler, just one. The Riser out of the boiler should have a 90 degree elbow on it, your right and left risers to the mains should then tie into a horizontal header and at the end of that horizontal header should be another elbow that becomes your equalizer. Your Hartford loop shold have a close nipple on it to tie it into the equalizer. Sorry for butting in but I don't want to see a misunderstanding cause you to have this plumbed wrong again.

SWEI

Steamhead said:

That would be great, if we had commercially available full-mod burners or at least low-high-low burners in the usual residential sizes

I'll say it again {dons flamesuit}: Most of the magic of a mod/con boiler comes from the MODulation.

Corollary: One of these days we will get a steam system deep enough into vacuum to get CONdensation.

Steamhead

samfiller said:

@Steamhead

So you are saying to get rid of the T on top have each side come down independently via an elbow (one for each).
As well to have the equalizer 2" even though manual says 1-1/4.

I made a new mock up based on that is this correct?

What about the feed and "second" return?

Thanks!!!

Fred is right. If you're going to bring the two mains down that far, just put two tees in the new header and connect each to one of the mains.

But that's just my preference. The existing tee where the two mains connect is not "bullheaded", so it should work OK.

samfiller

@Steamhead @Fred

Thanks for input- I dont think he is going to want to bring down everything I am just trying to figure what is correct and have him do it-
This mock keeps the everything the same except angles the steam supply from the Header to the current T.

I am going based of the manual, I have he elbow right away going into a right elbow a angled T to the steam supply the reducing elbow going into the equalizer and the Hartford loop.

Will this work?

thanks again!!

Steamhead

It will, with one change as mentioned earlier: the length of the horizontal pipe at the Hartford Loop connection must be as short as possible, to prevent water hammer there.

samfiller

@Steamhead
Great, and yes a close nipple for the Hartford loop. THANKS!

Now....
@all
What about the feed and "second" return where should they go?

Steamhead

All the returns and the water feed should tie together on the system side of the Hartford Loop, before it rises and connects to the equalizer.

And you can do away with the check valve on the dry return drip.

The last thing I'd do is replace the Pressuretrol with a Vaporstat that cannot be set higher than 1 PSI. This system will run on ounce pressures, anything higher is wasteful.

samfiller

@Steamhead
I will work on getting him to put in a vaporstat worse case ill get it installed once he finishes.

I guess this is the final mock up?

Steamhead

That'll work! Now go and enjoy Thanksgiving.

samfiller

@Steamhead
Thank you!!

Also do I need that vent on the main? if yes can i put it here?

Steamhead

Yes. That capped riser should be a good place.

samfiller

@Steamhead

OK gr8! Is that the same one as on my return (Hoffman 76)?

Fred

Yes. Also remember the Header should be a minimum of 24" above the water line. Higher is better. It looks like you could go 30" maybe even 36" and the Tee for your Riser to the Main can be on the first section of Horizontal header, before it turns to go to the equalizer. As Steamhead said, what you have will work but if moving the Tee to the riser makes it more convenient to attach to the main, that will work equally well.

samfiller

@Fred @Steamhead

Great! thanks!!

Steamhead

samfiller said:

@Steamhead



OK gr8! Is that the same one as on my return (Hoffman 76)?

I'd go bigger on the dry return- Gorton #2. It doesn't hold vacuum but will let the air vent very quickly so you won't need more than a few ounces pressure.

Did you get around to measuring the steam mains yet?

samfiller

@Steamhead

Thanks for your help- If I understand you correctly I wrote it above.

"The main pipe around the basement is 3" that at one point becomes a 2 inch then back to 3" with insulation its very hard to to see exactly. Its an approximately 80 ft "main". When the main hits the ceiling its a T that T goes around the house and then back in to the other side,"

Thanks!

Steamhead

So you're saying that the pipe comes out of the boiler, tees off into two mains at ceiling level which form a loop around the basement? Is there a pipe that drains the far end of this loop? How about a picture?

samfiller

@Steamhead

Exactly- That is the picture I sent before if its a good place for a vent.
It then goes down then goes around the Basement close to the floor, into the other side of the boiler.

In the mock up you should see it on the back right.

Thanks!!!!