Suspicious on new boiler installation

1928Steam_2 · November 2010

Hi, need some pro opinion on why my replacement boiler is not working well.

System is two-pipe steam serving two storey (+basement) house with about 30 tube radiators with thermostatic traps. One air vent (Dole 90) near end of dry return. Pressuretrol cut-in at 0.5 lbs and cut-out at 1.5 lbs. Heat and distribution with old boiler was OK, but since replacement the nearer rads seem to take longer to heat and the further rads often never heat at all because the house thermostat opens before the steam reaches them.

Two changes in the new setup make me suspicious:

1. Old boiler was in a pit. New boiler is installed on a platform to raise it up, so NWL is now 11 inches above the close nipple connection of wet return to equalizer whereas new boiler piping diagram suggests 2 inches.

2. New risers are smaller than old risers (2 inch fittings on new boiler) AND to connect to big old header they now have horizontal sections, each about two feet long and only 21 inches above NWL. (See attached photos.)

Which if either of these changes do you think could be causing my problems? Thanks for your help

BobC · November 2010

Piping

Compare the header piping very carefully with the installation manual. It almost looks like the steam takeoffs are between the two boiler outlets, if so it's not going to work well. What worked for the old boiler will not work for a modern boiler where the near boiler piping is critical. The two steam outlets should go up to a header (at least 24" above the NWL) which then turns down to form the equalizer and hook into the hartford loop. The takeoff to the steam main has to be after the second steam outlet and before the connection to the equalizer.

Also I can't see your equalizer and hartfod loop hookup. Try to get some shots from different angles so we can figure out what he did.

Bob

Mike Kusiak_2 · November 2010

Boiler size vs. installed EDR?

Does the size of the boiler match the amount of radiation you have? How does the size of the new boiler compare to the old one? Although the near boiler piping is not quite right, and might cause wet steam, I don't think that it would cause a radical change in heat distribution. The header is pretty large and does appear to have an equalizer. Rather, if the boiler is too small for the amount of radiation connected, you may get an uneven distribution of steam.

Have you tried experimenting with the venting to even out the heating?

1928Steam_2 · November 2010

Thanks, here some better photos

Thanks. There are three steam main take-offs from the header, plus another take-off just to the Hoffman Differential. This is all original piping; only the connections from the boiler to the header are new. You can see the piping better in these photos. One take-off (actually the one that serves the cold rads) connects to the header where you describe, near the equalizer. The other two take-offs do connect to the header between the two boiler connections. They would be hard to move.

The horizontal jogs in the risers from the boiler to the header certainly do not appear on the piping diagram. I wonder if they could become clogged with condensate. Should the risers have been 45 degrees instead of horizontal-- or doesn't it matter?

The Hartford loop (in copper) is visible in the photos. It is now quite small, because the boiler was raised. I wonder if having the loop nine inches below NWL defeats the purpose of the Hartford loop or presents a safety issue.

1928Steam_2 · November 2010

Size, venting

The new boiler, though physically smaller, I think has larger capacity than the old one; its an eight-section New Yorker CLS-8 329,000 BTU. Perhaps even oversized for the application.

I have not tried venting. There is currently only a single vent (Dole 90-1) at the boiler end of the dry return. Should I try a larger vent? Or an additional vent somewhere else?

crash2009 · November 2010

Hoffman Differential

Check out this recent post of a Hoffman Differential system. Ezzy just built this one. Perhaps Ezzy, Gerry, or Steamhead would know whats going on with yours. They usually dont get here till very late in the day.

http://www.heatinghelp.com/forum-thread/133125/hoffman-differential-vapor-steam-system

BobC · November 2010

Piping 2

That header looks like trouble with the bullheads between the two steam risers from the boiler. The last picture of the hartford loop shows you have too long a horizontal nipple, it is supposed to be a close nipple or a wye; on most boilers it should be 2-3" below the NWL. What model boiler is that?

45's are the preferred method of takeoffs from the mains so you don't drown the steam coming across the mains but in a true 2 pipe system the returning condensate should be pretty small as long as separate returns are handing the lions share of the returning condensate. Changing the takeoff's on that old pipe would be a bear but getting those bull T's out from between the boiler steam outlets and getting the header AT LEAST 24" above the NWL will give you better performance; that may mean moving the boiler so everything can be configured so that honking big pipe can be fed from a point between the second steam outlet and the return.

Hopefully some experienced installers will take a swipe at what should be done with this installation.

Bob

Jamie Hall · November 2010

You mention

a Hoffman Differential Loop. You also mention that your cutout pressure is 1.5 psi. That simply isn't going to work. You MUST use a vapourstat with a Hoffman Differential Loop, and although a Differential loop isn't supposed to trip until you get to about 8.5 ounces per square inch, they usually will trip a little below that. I suggest that you will get much better results with a vapourstat, fitted with a damper (after the pigtail and before the vapourstat). Set the vapourstat at 7 ounces cutout, 6.5 ounce differential (subtractive). That should help a lot.

This may be the whole reason why the system takes longer to heat, by the way.

The Dole may well be too small for the new boiler -- but fix the vapourstat issue first.

That header arrangement isn't all that good, but considering the apparent size of the thing, it should work at least after a fashion. I can see, however, how you could be getting uneven steam distribution to the various takeoffs -- and that the one nearest the equalizer would be the one which got starved.

If this is a complete Hoffman system, though, you might also check the crossover trap at the end of the main which is not getting as much heat as it should. If it is failed closed, that is a real problem.

Mike Kusiak_2 · November 2010

Pressuretrol?

Does the system ever build enough pressure to cycle the pressuretrol, or is the thermostat satisfied before you ever build any pressure? I am surprised that you don't have a vaporstat instead since if you have a vapor system it should cut out on pressure long before 1.5 PSI.

Jamie Hall · November 2010

Senior moment

the device fitted before the vapourstat is, technically, a snubber, not a damper. Sigh... get one made for steam, and the porous type.

ezzy travis · November 2010

theres a lot of things

Definitely repipe the header and the hartford loop.

Replace pressuretrol with vaporstat. The cross over trap which is probably a hoffman #6 steam trap. Replace with a barnes and jones 122 which is 1/2" or the 134 which is 3/4"

Replace the differential loop vent to a gorton #2 main hair vent works great.

Charlie from wmass · November 2010

Here is a bit about Hoffman differential loops

I also speaks of the venting requirements They used a Hoffman No. 15 which is a pretty big vent.

1928Steam_2 · November 2010

Thankseveryone for the insight and advice

I guess I have a big to-do list, but its an elegant system and I would like to get it working the way it was designed to work.

I will report results when I have undertaken these corrections.

crash2009 · November 2010

search the entire site

I just did a search of the entire Wall for you on the subject of "hoffman diferential" Every comment, question, etc. of all time is listed in the link below. Don't forget, if you need some help, you can use the Find a Contractor link at the top of this page.

As I understand it, The Hoffman Differential is very rare, and exceptional when you get it running correctly.

http://www.heatinghelp.com/forum/results/1 additional instructions required now that I have been informed search results are not linkable (thanks JPF), copy and paste "hoffman differential" including the " " then select of all time and all categories. then hit enter.

jpf321 · November 2010

valiant attempt

but search results are not linkable here

Steamhead · November 2010

That type of Differential Loop

has three connections: one to the steam header, one to the dry return and an overflow connection to the wet return. If any of this piping has been altered you're going to have trouble with it. You can see the diagram on page 234 of "The Lost Art of Steam Heating".

The main vent is located in a special tee in the dry return near the Differential Loop. This has an orifice in it, probably to keep too much steam from entering the dry return as it closes the vent. The vent should be the biggest you can get- use at least one Gorton #2.

The "colliding header" is wrong. The steam must enter the header from one end and the condensate must exit the other end into the equalizer. Otherwise you'll have wet steam. Here's a pic of one way to pipe this- I call it a "doubleheader". In this case it's a Weil-McLain SGO-9 on a Kriebel Vapor system, where we ran a 3-inch drop header into the 5-inch original header.

What make and model is your boiler? What pipe size is the header?

1928Steam_2 · November 2010

Piping for the differential loop

and location of the (single) main vent I think are OK. I am going to upgrade the vent to a Gorton #2 as you suggest. Boiler is New Yorker CLS-8. Header is 4".

The "doubleheader" is neat. I think I could do that. Are there two equalizers, one from each header? Does the fishhook shape of the risers have any purpose?

crash2009 · November 2010

Fishook shape of the risers

They call that a drop-header. A drop-header helps to dry the steam. Any water that escapes from the boiler is collected by the drop-header and directed back to the boiler. At the same time the header directs the steam up into your home. Of secondary importance the drop-header also assists in assembly. That doubleheader is fabulous. Have you tried to trace how the steam moves around inside it?

Suspicious on new boiler installation

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