Piping in second steam boiler

Jim Walls_2

Sorry , this is more of a question for Dan , than a helpful response. I know there can be venting & piping problems associated with converting from coal to another fuel on old systems . Does the same hold true in reverse , with a modern coal burning boiler ?

greg_7

adding second steam boiler

We will be adding a second steam boiler to our club's system. We have a newer Dunkirk gas boiler. We will be adding an Axeman-Anderson Anthratube anthracite coal boiler to cut our energy costs so we can stay open.

The controls are the same. I assume the water levels should also be the same. The Axeman unit has only one outlet, whilst the Dunkirk has two. Any ideas?

The coal boiler will be controlled by a separate thermostat. I have a hot water coal Axeman in my house and I can assure you that it is a modern automatic boiler and operates very similarly to the gas units.

Unknown

a couple thoughts

The water lines MUST be equal, like you said. The water in the boilers will be equal, so plan for it.

I'm a fan of oversized headers. I like one or two pipe sizes bigger than the supply main, if only one main. If more than one main. I'd use the size pipe that would carry all of the mains horizontally, and go one or two sizes bigger than that. I like the water and steam to slow down in the header.

I like the equalizer to be full header size until it hits the hartford loop on jobs that aren't exactly in the book. Because the boilers are different, I'd do that here. Cheap insurance.

It needs a dropped header to keep the condensate in the header until the condensate reaches the equalizer. Use ALL of the risers. Keep the equalizer and the piping below it to a minimum of fittings. That equalizer is handling thirty MPH water and steam. Keep the path straight and direct.

Noel

M. John Kontny

Steam Boilers

Steam boiler replacement can be tricky regarding the balance if the condensate returns through the piping and does not have a condensate receiver and feed pump.Best to upgrade with a new receiver and feed pump if you change the boiler to a smaller more efficient profile.

Unknown

I don't agree

in every case. It causes a lot more maintenance, a lot more expense, and a lot more repairs down the road.

It can be an indication of not studying what's there and what was intended by the original designers.

Although I agree that if you put all of that gear in every time, you won't need to learn what's there.

And you can run any pressure you like and still get some heat.

I've removed boiler feed tanks before to get vapor systems to work and vent quietly and quickly. They were piped right beside the boiler. The air was originally intended to vent at the OTHER end of the building.

Hey, it's supposed to hammer like that when it starts. It's steam!

I don't think I'd use a boiler feed pump and tank on every one pipe steam system, either, with more than one boiler. That's just how I feel.

Noel

greg_7

Further notes:

1) This is a gravity one-pipe system.

2) We will be installing a second Hartford Loop for the new unit.

Noel's advice seems basically on point for our needs. I was just reviewing my copy of the "The Lost Art..." and I am wondering how we should pipe the header given this situation:

The risers are split and run from each side of the currently installed boiler that I'll call Unit 1. One riser heads up and jogs back a few feet and then up from the boiler and the other heads away from Unit 2 before heading up.

The additional unit, Unit 2, must be installed about 8-10 feet away across the condensate return from Unit 1. Unit 2 has a single 3" riser. Unit 1 has two 2" risers.

Utilizing a drop header for both units can be done.

How can both units steam into both risers with-out bullheading or staggering the risers and the boiler leads?

I was thinking that the header could be piped in a long "J" from the new Unit 2 across the front of Unit 1 and then back in a loop to the equalizers. the supply mains would then tee off and be down stream of all of the boiler risers.

Any ideas?

Unknown

Does this drawing...

Fit your circumstances?

Jim Walls_2

gas to coal ? Dan ?

Sorry , this is more of a question for Dan , than a helpful response. I know there can be venting & piping problems associated with converting from coal to another fuel on old systems . Does the same hold true in reverse , with a modern coal burning boiler ?

Unknown

Jim, it does.

Thought provoking question. If the house holds it's heat, a coal cycle that delivers steam to each radiator at the same time will heat the room in.....how many minutes? Then how do you slow the heating? If you slow the fire, some radiators will stop heating, some will keep heating. The end ones will draw air back in through the radiator vents.

If you valve it off to cool all the radiators together, the pressure in the boiler will get away. Bad plan there.

One pipe TRV's won't work at all.

Double hung zone valves are how they used to do it. Open a window.

Good question. I hope others post thoughts on this one.

Noel

Boilerpro

Noel, my undersized boiler ideas may work here

If you keep the main vents real big, and keep the rad vents very small and sized according to the load each radiator supplies (not the radiator capacity), that coal fire should get steam out to the end of the main real quick and then all the rads will come up to temp together...Basically just a variation on master venting from what I can see. When the coal fire burns down, all the rad vents will let in some air in proportion to thier size. On most systems the rads will be only partially heated and not be under pressure, since the steam will be condensing as fast as it comes into the rads. Still working through this in my mind. Dan H. wants to discuss this general concept more tomorrow when he gets back, hope to have your input and, if yor're around, Steamhead (and everyone for that matter).

Unknown

I don't see how you intend to prevent overheating....

unless you let the fire die down......

Thinking WAYYYyyyyy outside the box, what about a two-way diverter valve, along with two equal zones of one pipe steam, and drips to handle the condensate, and a timer to alternate the valve every half hour, which would allow the vent to let air back in as it closed half of the system. The fire could be half the size that it would be if it saw the whole load at once.

That way, TRVs would work and........


Nah, to unconventional....

Noel

greg_7

coal overheating and cycles

I guess that most folks aren't familiar with modern automatic stoker-fed coal boilers. The fire is not hand stoked. The massive heat surge that one of those big cast behemoths create doesn't happen.

For instance, the Axeman Anderson Anthratube 130 (130,000 BTU) has a firebox about the size of a 3 gallon bucket. The whole unit, exclusive of the bin will fit in a 3'x5' area.

The fire is small and banked when the t-stat is not calling for heat. I'm sure that the fire will radiate a fair amount of latent heat for a period of time after shut down, but this is no different than cast gas boilers. The manufacture recommends the anticipator on triple aquatat be set at 10.

A large fan pulls air through the fire, both aiding combustion and forcing the hot gases through a convoluted path of water passages.

It burns very hot when running and the cools off just like a gas or oil unit. The concept of the boiler is to replicate the ease of operation and efficiency of the modern gas or oil unit.

Most of these units (sold since 1944) were competing with oil. Anthracite was and is much cheaper to use, but had big disadvantages: dirt, dust, ashes overheating, etc.

A-A figured out most of the problem, except for the ashes.

So the double pane vent doesn't apply here. But it is an interesting discussion.

Assume that the boiler will function much like a gas unit.

greg_7

drawing

I wish I could post drawings...

The drawing is almost right. Switch units so that the single supply unit is on the left and the supply mains are just about where the two pipe unit is. The dry return will drop between the units.

We are also planning two hartford loops.

Unknown

Paint

I use "paint" to draw my pictures.

I don't understand the two hartford loops, and I don't reccomend any piping that causes the steam in the header to go in the reverse direction. The boilers feed into it first, then the steam take offs are next, and the equalizer is last. This relationship is important to keeping the water inside of the boiler and the header drained and the steam dry. I wouldnt put an equalizer between the boilers.

Noel

greg_7

Loops

Actually, the idea of piping a hartford loop for each unit came from Dan's book, "The Lost Art of Steam Heating." I wasn't planning on it, especially because the return comes between the units. When I sat back and thought about it, it made sense to pipe each unit that way.

The reason why I was pondering a j shaped header is the lay put of the supply pipes. I'm sure we could pipe the steam take offs after the second boiler, but then we'd be swinging one of the pipes about 4' over to get past the boiler. The equalize could be moved to the end.

Steamhead

Master Venting for Anthratube

from the way you describe its operation, I'd treat it just like an oil or gas boiler.

When the draft fan shuts off and the fire slackens, you will still be circulating some steam thru the system. As long as there is steam in the mains, the main vents will remain closed. The steam should keep circulating all the way out to the end of the system.

For this to happen, the steam pipes must be insulated and the main vents properly sized. You can get sizing charts- and also experience Dan H. doing what he does best- by ordering Dan's "Dead Men's Steam School" video and workbook.

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