Old two-pipe steam with new boiler

Tom Tearpock

Ok. I've found the Trane system in the Companion. I'm confused where the end of steam should tie in. On pp 239-240 of the Lost Art ... it says the dry return (end-of steam main) should go thru the boiler return. The dwgs in the Companion imply the end-of-steam main goes directly to the boiler. Does it matter? In our system both the end-of-steam main dry return and the radiators dry return are more than 50" above the water line.

Tom Tearpock

Old two-pipe steam with new boiler

My father-in-law has a home built around 1910. It has a two-pipe gravity-return steam/vapor heating system which used to operate in a slight vaccuum. The old boiler finally gave out and the heating contractor installed a new one. As you might have expected, the volume of water available in the new system was too small and the boiler short cycled on LWCO. The contractor added "and extra 8-10 gallon tank" to the system. The tank is piped from the bottom only to the new boiler. There is a vent valve on the top of the tank that seems to let air into the system. I believe the tank should be "piped" into the "boiler return valve" piping (or somewhere) so that the system can once again operate (more efficiently) in a vaccuum. System currenlty operates at 1-2 psig. (The current complaints are 1) fuel bills are significantly higher than before and 2) water seems to be "disappearing" (although we see no leaks). The radiators (that are working) seem to be doing fine and there is no evidence of any thermostatic traps leaking by (downstream piping is cool to the touch).

Any suggestions on how to pipe the "extra tank" (the current contractor seems stumped)?

Unknown

Good timing on your question

There are two other's already up on this board right now that have illustrations that can help you understand what could be happening in that boiler.

Glenn Stanton posted a GREAT animation of a steam boiler running low on water because the system was priming. Some reasons for what I see in his picture could be that a little bit of dirt is still in the water, or the piping above the boiler is not quite right, or the boiler is TOO BIG.

If you put in a boiler that makes more steam than the radiators can use or the piping and vents can carry, the extra energy from a bigger firing rate can push out of the boiler both ways, and fast.

See Glenn's drawing, it even shows the fire stopping as the boiler runs out of water. The drawing is under the title, "Near piping on steam boiler"

I put some photos of a boiler up under "Wet steam" that acted as yours does, after the demonstrator poured 2 tablespoons of cooking oil into the boiler. This simulates the oil from doing new piping on a steam system. Even a boiler that is piped perfectly will act as yours does with dirty water, especially at the surface.

Look at some of the stories at the left under Hot Tech Topics, such as this one....

http://www.heatinghelp.com/newsletter.cfm?Id=130

Noel

Tom Tearpock

System probably not \"priming\"

The animation you refer to has a Hartford Loop. The system in question pre-dates that design. Instead of the loop it has: a check valve just before entering the boiler, a 2nd check valve in the dry return and a "direct return trap" (boiler return trap?) and the end-of-the-steam line both tee'd in between these two check valves. The check valve closest to the boiler is slightly warm to the touch (seemingly due to conduction from boiler itself). All lines feeding the check valve just before the bolier (i.e. end-of-steam line, return trap line and dry return line) are all at ambient temperature. To me this indicated the check valve is holding and no water is being forced back into return lines.

The "extra tank" added by the contractor did seem to fix the initial short cycling on LWCO. The current "disappearing water" seems to occur over a few days (i.e. must add water every few days). Unfortunately, since it has been very cold, the system has been running a lot so we haven't had a chance to see if we will get any boiler "flooding" when the system finally cools downs completely. I still have a concern with the piping for the "extra tank".

Steamhead

\"Direct Return Trap\"-

is that an old Trane unit? This unit is covered in "The Lost Art of Steam Heating Companion" and a similar (Dunham) system appears in chapter 15 of the original "Lost Art of Steam Heating".

Study the piping diagrams of this type of Vapor system, and check to be sure the returns are still piped correctly.

Also check the air vents to see if they're leaking, and if any return lines are buried they're probably leaking too, so it's best to replace them.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Tom Tearpock

Trane system

Yes, system is an old TRANE.

I have ordered the Companion and will study piping.

Only buried line was to the garage and that was isolated/capped years ago.

With respect to the "extra tank" on the new boiler, I think replacing the "vent valve" with "vent piping" to the Direct Return Trap steam line will "re-close" the system by essentially turning the "extra tank" into a large (but opaque and funny-shaped) sight-glass. I have attemped an isometric sketch.

Steamhead

Nice drawing!

You may have a circulation problem here. The new boiler probably produces steam a lot faster than the old one did. It's possible for the heating cycle to end before all the air is out of the system. The remaining air then expands with the vacuum which can block steam circulation. I wonder if this phenomenon is also holding some water up in the system somewhere?

Get some good, big main vents- I like the Gorton #2 which was originally designed for Vapor. Replace the vacuum vents on the return with the Gorton #2 units and the problem may disappear. Also make sure the thermostatic traps which vent the steam mains into the dry returns are closing properly when steam reaches them.

Vacuum operation has always been problematic with oil or gas. It really only works reliably with coal, since the coal fire is always burning.

If you can't find Gortons in your area, go to www.gorton-valves.com and ask who handles them. If no one near you does, they will sell to you direct.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Craig_2

Kick **** drawing!

Please excuse the language but that is one fine drawing. I wish I could draw half as well as people seem to do when they explain their problems. You should see my chicken scratch field drawings of my own wiring (modified knob and tube) and my Mom's hot water system. I'd be embarrassed! And to think I worked as a draftswan for 2 summers and was an architecture major for a year!!

-cf

[Deleted User]

Neat

drawing. Weil-McLain had the same problem when they went to lower mass boilers.

I believe (it's been a long time) their solution was a large pipe reservoir in the return before the Hartford Loop. In your situation, it would be in the wet return between the last check valve and the boiler.

Not sure I agree w/ your vacuum solution. Some funny things could happen. You might also want to explore using a Vaporstat. 1# to 2# seems kind of high. That might be where the water is going. Few of these older systems are tight enough to take the higher pressure without losing some.

Good luck.