Steam boiler two risers and two mains

Scott216

A year ago I had my steam boiler replaced with Peerless 63-04 (177,000 BTU/hr). My original boiler had one riser on the side. The new boiler has two risers on the top (2" dia). I have two mains in the house (2" pipe) - I'm not sure of piping terminology, I'm calling the pipes that run along the ceiling that connect to all the radiators "mains". The installer tapped one main between the two risers - a no no; the other is off to the side of the risers. After the new boiler was installed I had hammering which I didn't have before. The installer also used copper pipe, which shouldn't contribute to hammering, but I understand is bad for the boiler because of thermal expansion. I just ripped out all the near boiler copper pipe and my plan is to use black iron pipe. I'll have the two 2" risers go into a 3" drop header, then connect the two mains off to the side of the drop header. Similar to this picture, but with a drop header.


I have a couple questions. Since 3" black iron pipe is really expensive these days, could I just pipe each 2" riser directly into each 2" main? If so, what is important to remember doing it this way? If I shouldn't do that and I go with my original plan, is it beneficial to have the drop header close to the risers? I see most pictures where there's two 90 elbows joined by a short nipple. Is there an advantage to this, or can the drop header be farther from the risers?

Jamie Hall

No, you have to have the header in there -- your diagram above is correct. The length of the horizontal pipe between the two 90s in a drop header arrangement isn't critical.

pecmsg

177K BTU's?

Thats a lot of steam?

109A_5

The manual gives the sizes, building it into a drop header does not change the sizes. You can go bigger, slower steam velocity, more time for the water to drop out.

Scott216

pecmsg said:

177K BTU's?

Thats a lot of steam?

177K is the input, gross output is 147k BTU

Scott216

109A_5 said:

The manual gives the sizes, building it into a drop header does not change the sizes. You can go bigger, slower steam velocity, more time for the water to drop out.

Thanks for the info I already got a bunch of 3" fittings, so I'll just to with 3". That stuff is really expensive.

Scott216

Jamie Hall said:

No, you have to have the header in there -- your diagram above is correct. The length of the horizontal pipe between the two 90s in a drop header arrangement isn't critical.

Thanks. I figured I needed the header, but wanted to double check.

EBEBRATT-Ed

You need a header it doesn't have to be a drop but can be. Make sure you have 24" from the center of the gauge glass to the bottom of the header

Steamhead

Scott216 said:

That stuff is really expensive.

Yeah, but you'll love how well it works!

pedmec

Each pipe in that diagram serves a purpose. To deliver dry steam.

Two risers out of boiler lower exit velocity helping separate steam and boiler water. Depending on size of the boiler and boiler piping recommendation from the manufacturer you can have one riser but two works twice as nice when it comes to lowering the exit velocity. ALWAYS FOLLOW MANUFACTURERS PIPING PLANS AND SIZES.

Elbows facing toward rear of boiler act as swing joints. reduces the chance of expansion cracking boiler.

Header again acts as separator and a manifold. Allows condensate to separate from steam before it heads to the supply. Pitched toward equalizer to drain header.

Equalizer help balances boiler water line by adding pressure to the boiler return. Helps stabilize water line in boiler. Also prevents boiler water from backing out.

Skip these steps and you have a good chance of water hammer.

And i disagree on copper piping not causing water hammer. Copper has no thermal mass so you are losing heat rapidly thereby increasing condensation. This condensation happening at the near boiler piping will throw water out into the system creating havoc. Insulation will help but that's not the proper approach. cast iron fittings with schedule 40 steel is the proper piping method. I believe that most pipe fitters and plumbers, tradesman who take there craft seriously will agree. there is no place for copper in a steam system except maybe on the return (but i personally frown from that too).

Dan didn't call it the "lost art of steam heating" for nothing.

ChrisJ

@pedmec
Insulated copper should behave no different than steel in this application.

But I still probably wouldn't use it 

Scott216

pedmec said:

...Copper has no thermal mass so you are losing heat rapidly thereby increasing condensation. This condensation happening at the near boiler piping will throw water out into the system creating havoc. Insulation will help but that's not the proper approach. cast iron fittings with schedule 40 steel is the proper piping method. I believe that most pipe fitters and plumbers, tradesman who take there craft seriously will agree. there is no place for copper in a steam system except maybe on the return (but i personally frown from that too).

I'll be replacing the copper with black iron pipe. Should I insulate the iron pipes, or is that overkill?

ChrisJ

Scott216 said:

...Copper has no thermal mass so you are losing heat rapidly thereby increasing condensation. This condensation happening at the near boiler piping will throw water out into the system creating havoc. Insulation will help but that's not the proper approach. cast iron fittings with schedule 40 steel is the proper piping method. I believe that most pipe fitters and plumbers, tradesman who take there craft seriously will agree. there is no place for copper in a steam system except maybe on the return (but i personally frown from that too).

I'll be replacing the copper with black iron pipe. Should I insulate the iron pipes, or is that overkill?

Absolutely you should insulate the piping.  I would recommend 1" from buyinsulationproducts.com.   

pedmec

not true. no thermal mass in copper. increases heat loss thru the pipe faster than steel and cast iron. that increases condensate in the steam. that's why you can touch baseboard piping 5 minutes after the loop stops circulating and its cold.

EBEBRATT-Ed

I don't like copper for steam just because I like to do threaded pipe, at least I did when I was working.

But copper can be used for steam successfully. Iron Fireman had thousands of jobs piped in copper for the mini tube systems like @gerry gill installed. They used copper for all the mains and ran their systems at 5psi.

If you plan the piping correctly solder everything good proper hangers AND allow for expansion it would be fine.

There was a job posted here on the Wall within the past year of a 1930s house with steam all piped in copper. Many posters (including me) thought it was hot water, but it was not.

The problem with copper if used on near boiler piping is no room for expansion and the joints let go If the piping was changed to allow for that copper would be fine.

You could also braze the joints like refrigeration which would anneal the pipe and fittings and have no issue

ChrisJ

pedmec said:

not true. no thermal mass in copper. increases heat loss thru the pipe faster than steel and cast iron. that increases condensate in the steam. that's why you can touch baseboard piping 5 minutes after the loop stops circulating and its cold.

Mass in this situation is irrelevant if you insulate the piping.
Copper also conducts heat far better than steel but again insulation.

Expansion would be the greatest concern.

Jamie Hall

The key to using copper is, as @EBEBRATT-Ed said, allowing for expansion. And the key to that is to make sure that expansion stresses the pipe and fittings in such a way that the pipe bends to take it up, and is free to bend, rather than putting a twist on a fitting solder joint. "Swing" joints, such as are created in making a drop header, aren't great, but work well enough if all the pipes are long enough. The twisting will mostly take place at the threaded joint into the boiler. Straight up to a header will stress the boiler sections -- again unless the pipes are long enough (you don't usually have enough head room!). And you need to make sure particularly on longer mains that the pipe is anchored at just one point, and just supported but free to move lengthwise (and, depending on the layout, sometimes laterally).

j a_2

Looking for a steam heating contractor in Boston , I went to find a contractor on this site but not interested in them

ChrisJ

j a_2 said:

Looking for a steam heating contractor in Boston , I went to find a contractor on this site but not interested in them

I'm not positive he does Boston but as far as I'm concerned Charles Garrity is the best in the business