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New Weil McLain LGB-7?

4Barrel Member Posts: 125
I've acquired a building with an expired LGB-7 (unfortunate b/c it's only about 10 years old). The rest of the one-pipe system w/ wet return system is in fairly good shape, however i'm figuring the near boiler / header arrangement needs quite a bit of rework. The contractor i'm working with is recommending in-kind replacement. My calcs give me system input BTU of 735K (with 30% pickup).


1) The building is a former church with an attached residence. I'm thinking the boiler was oversized to compensate for lack of insulation in the church sanctuary. A new roof w/ insulation is potentially in the works - what adjustment in pickup is fair to account for this?

2) The current installation includes a boiler feed pump, and again the contractor is proposing in kind replacement. Is this arrangement a requirement with this boiler, or b/c it has wet returns, or is it simply a recommendation? (The WM manual seems to emphasize the importance of having one). How can I assess if gravity feed would be sufficient, or if the feed pump is a true requirement?


  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,572
    edited November 2011
    expired boiler

    that boiler can have the option of a lo-hi fire system, which when controlled with a vaporstat, could accommodate the proposed changes to the building envelope, with subsequent improved insulation.

    my system is larger than this one, with 55 rads, and no condensate-tank, feed pump, auto/over-feed--all gravity [i do have a reservoir tank], and works fine. these boilers are pretty well sized not only for edr/btu, but also for water content. if you like, you can leave provision for the later installation of one of those things. my experience is that water level problems come not from the steam production as the wet steam produced by improper piping, or height problems in the return piping, hiding the water as pressure rises.

    by all means, get the supply piping right as spec'ed by the manual, not necessarily as it is now.--nbc
  • 4Barrel
    4Barrel Member Posts: 125
    thanks nbc...

    great input.

    i'm going to snap a few pics of the near boiler arrangement and will post. perhaps, as i think you are saying, the feed pump was put in to compensate for header piping issues. stay tuned...
  • 4Barrel
    4Barrel Member Posts: 125
    edited December 2011
    Pics of expired LGB-7

    Hi All -

    Here are some pics of the expired LGB-7.

    Looking for input on header (the vendor is advocating a new single tap arrangement), and condensate pump arrangement (the vendor is advocating for a larger, 50 gal reservoir) Note the system also has two zone valves.
  • Steamhead
    Steamhead Member Posts: 15,751
    Oh boy

    that piping is a mess. Compare it to the manufacturer's specs and you'll see what I mean. Not sure if that's what killed the boiler but it couldn't have helped.

    Where are you located? You need a good steam man.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • condensate pump=band aid

    if you get it piped according to the mfg's instructions, no expensive condensate pump should be needed unless you are feeding steam to another building or two, and there it would be an unfortunate necessity.

    if it is piped right, gravity should be the only means of return.--nbc
  • 4Barrel
    4Barrel Member Posts: 125
    buffalo, ny

    hi steamhead - i'm in buffalo ny.

    what killed the boiler, primarily, is that the prior (foreclosed) owner chose to completely neglect the system, not to mention most everything else. it was not mothballed properly when the heat was shut down. it has been sitting rotting for about 5 years. too bad, because it's a mid 1990's vintage.

    the heating/plumbing contractor we're working with has brought in their supply rep, who is advocating for removing the header arrangement (such as it is), and replacing with a single 4" tap, riser and header, which is how WM specs this model. I found it interesting that it is not spec'd for dual taps, as even my little dunkirk gave that option (and that's how i set mine up). the rep stated that putting a riser on each end makes the steam "compete" with itself to enter the header, and only a much wider (larger) boiler would demand dual primary risers. i'm now wondering if i made a mistake with my set up.

    the other recommendation so far us to reorient the boiler, lowering it closer to the floor, and turning it, which would allow more A clearance for the header and secondary risers. a remaining obstacle is the placement of the zone valves, which we are keen to keep. i am saying a few prayers the one we have can be reused.

    NBC -

    in terms of the condensate return, is there a rule of thumb (time and / or distance) that i could use to figure out the need for the pump? the WM specs state somewhat ambiguously, that if "condensate return is not adequate a receiver and pump should be installed." kinda tough to know since the system isn't running. the reservoir pictured is a 9 gal, with a 1.2 gpm pump. an oddity is that an autofeeder from the public supply was added to the loop as well at some point. why would you need both the autofeeder and the condensate pump?

    regardless, the rep is reading the WM specs, and is saying that due to the size of the boiler, and the fact that is produces 76 gallons/hour of condensate, and it will take at least 30 minutes for it to return, we will need a 50 gal tank and pump, and no need for an autofeeder.

    would a test be as simple as pouring some water in to the farthest wet return, and time how long it takes to get back to the boiler?
  • Rod
    Rod Posts: 2,067
    Need to think Outside the Box

    Hi- I must first give the caveat that I’m a homeowner, not a pro and therefore my steam experience is rather limited. I also know very little about big steam systems. However, I do have quite a bit of experience with buildings, building systems and setting up production lines.

    From reading your posts we know so far that:

    1. This is a “former church with an attached residence”.  You haven’t mentioned what you now plan to use it for in the future.  The usage I would think would have an influence of heating choices.  For example: A church has different heating needs than say an office building.  As a church - the residence needs comfortable heat 24 hours a day, the church office needs comfortable heat only during working hours, and the church itself needs comfortable heat for only certain periods of the day /week.

    2. It is now planned to replace the old boiler with basically the same thing.  After looking at your pictures of the old installation it would really lead me to question anything the previous installer did, so I think it would be better to just pretend you don’t see any boiler or piping at all (like it had been completely gutted and the old piping and hardware/boiler removed.)  I would approach the new installation from the bare beginning and spec out what was needed from there. I can see there could be several approaches that might be beneficial to you.

    One thing I would check out is the feasibility of using multiple boilers. I have no idea on the economics of this but if it were me I would definitely check it out as it may offer a large saving in fuel and also has the benefit that you always have a backup boiler if one is down for maintenance etc.   With multiple boilers you would only need to use one boiler in the spring and fall and then just need to put the second one in operation during the coldest periods. I would also check out burners that had a staged firing system (low /high) as NBC mentioned as this has the potential of saving fuel.

    3. Reps.- Having been a rep several times in my past career (I’m retired now)  I’m quite familiar with how they think.  You have to always keep in mind a rep works in his company’s best interest and also for his customer’s best interests.  In the case “the customer” is the contractor rather than you as the contractor buys a lot more boilers a year than you do.  You always need to keep that in mind when the rep backs up the contractor in a discussion. I’m not saying reps. are dishonest, most of them are pretty good guys. I’m just saying keep it in mind that there is a potential conflict of interest involved.

    As for using a single boiler riser as two would “compete”. I would need a much better explanation for that one. I’m not saying using only one riser wouldn’t work. just that the “compete” has a bit of an “odor” about it.  If that were so then why don’t they “compete” on the bigger boilers which use two risers?  Everything I’ve read on steam says that the lower you get the steam exit velocity, the better, so I find it hard to believe that two risers don’t do a better job than one, especially when they double the cross sectional area.   If you note on Page 18 in the installation manual, both the tables of pipe sizes, in both Figure 17 and Figure 18, have written at the top “Minimum Recommended Pipes Sizes”. This is because the boiler manufacturer’s recommendations are the minimum rather than optimum needed for proper operation. (This is probably so they are competitive with other manufacturers in the race to be the lowest bid)

    Since  the instructions minimal it is very important to get someone who really knows steam as they will know what needs to be done to “tweek” the minimum installation instructions to the optimum.

    This is a big project when you consider both the capital outlay and probably more so the future operating costs. If it were me I think I would definitely consider getting an outside steam heating expert in as their advice could save you money big time. Two steam experts that come to mind are Frank Wilsey, “Steamhead” , who has already answered your post (Here is a link to his contact info:


    and  Gerry Gill. Here is link to his contact info: 


         Both are extremely competent steam pros and have experience doing steam systems in large buildings some of which are churches and also they have experience with multi boiler setups and stage firing. I think with the input of a steampro, the rep, and your contractor, you should be able to get the steam system you really want in both comfort and fuel consumption.

    - Rod
  • 4Barrel
    4Barrel Member Posts: 125
    Hi Rod

    as usual, i get excellent advice from this forum. thanks rod. you are right, there is a lot to take in on this project. based on my experience with my small system, i suspect a lot of things, and can ask a lot of questions, but as you point out, this requires higher level of expertise, instead of guess work. i do trust our contractor, and likewise, i believe the rep believes what he is saying. however, the details and scope of this demand greater attention. in particular, the feed system intrigues me. i think nbc is right when he says it was a band aid; the question is, what is the ultimate factor that led someone in the past to believe it was needed? i could use some help with that detective work. i'll keep you all posted on our progress.
  • band aid

    one possible reason for the feed tank could have been a plugged pigtail, causing the pressure to go higher,resulting in the water stacking higher in the returns. when the waterline gets lower, then the feed tank goes in.

    this is bad because the waterline now becomes too high, and causes wet steam, and a shorter life for the poor boiler. if the feed tank were a reservoir tank, then the waterline would be self-regulating, in that the excess water stays in the tank until needed, and cannot overfill the boiler.--nbc
  • 4Barrel
    4Barrel Member Posts: 125
    edited December 2011
    feed tank versus reservoir

    what the difference between them? how would i know if i currently have one versus the other? it looks like a tank and pump piped into the wet return system, separated off by a trap. i don't want to use these terms interchangeably if there is a difference...
  • Rod
    Rod Posts: 2,067
    Reservoir Tank

    Hi- Feed tanks have a pump to supply water from the tank to the boiler. Reservoirs expand volume of "useable water" ("useable water"-  the amount of water between the normal boiler water level and the water level where the LWCO shuts down the burner.) and are situated so they don't need a pump.  Here's a link to Gerry Gill's website which shows an installation using a reservoir tank.


    I've also attached a drawing of reservoir tank for a small boiler as it best illustrates the position/ connection to the boiler and how a reservoir tank supplements the boiler's water volume.

    - Rod
  • gerry gill
    gerry gill Member Posts: 3,047
    Rod, you sell yourself short,

    as you know more about steam than you give yourself credit for..Steamheads right..that piping is less than desirable..the condensate tank is just dumb.. if water can make it back to a condensate tank, it sure can make it back five more feet to the boiler...now a feed tank which was proposed is a different animal..i don't have any objections to a feed tank..its one of those 'you cant go wrong if you use a feed tank' things..you also cant go wrong using two risers out of the boiler..i'm wondering like Rod was if multiple boilers perhaps fed by a common feed tank, wouldn't be better, along with potentially a small boiler feeding whatever the zone valves feed..it might be more economical in the big picture.
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • Dave in QCA
    Dave in QCA Member Posts: 1,776
    a few additional comments

    First, I'd like to say that I agree with all previous posts.  The advice is all excellent, and Gerry's praise of Rod's comments, knowledge, and ongoing efforts on this site are well deserved

    A few additional comments:

    I would go beyond describing the existing close boiler piping is less than adequate, it is horrible!

    The sales reps comments as to two risers fighting with each other was totally bogus!  The correct answer would be "because 2 are not necessary."    The LGB series does not call for 2 risers for less than a LGB-13.   But, they are very clear on the requirements for a proper header and the piping sizes required.  LGB-7 needs a 4" riser and header.   Of course, this is the minimum, and a larger size would be fine.  They are tapped for 6".  Two risers would be fine too, but since the spec for this boiler isn't at the edge of a sizing break, the advantage of doing so may be small.  Note also that the internal passages between the sections are a full 9 inches, and I have been told by at least one of the pros on here that the LGB has a large steam chest area and makes very dry steam when piped properly. 

    Your pictures are a little hard to see because they don't enlarge much when clicked.  But, I am pretty sure I am seeing 2 zone valves off of that mini header.  I assume that one is for the church and one for the residence, so that all steam goes through one or the other zone valves.

    This type of set up creates some special considerations, i.e., when a zone valve is closed, the end of main and wet return become a dimension B.  There may, or may not be enough height between the water line and the piping to accommodate this.  Also, if a zone has been steaming and the zone valve closes, it will produce a vacuum pretty quickly.  Special considerations involving check valves and some good vacuum relief can take care of it, but without provision, it can suck the water out of the boiler down to the Hartford Loop level, causing the boiler fill valve to activate and resulting in a flooded boiler when the vacuum subsides and the water returns.   A good feeder tank resolves all of these issues because it separates the boiler from the return piping.  A feed-water tank will also provide a very steady water level in the boiler.

    Firing rate of a large boiler feeding two zones also becomes an issue, as the boiler must be rated to heat the entire system at the same time.  When only one zone is calling for heat, the boiler's ability to produce steam will far exceed the demand or capacity of that zone and pressure will quickly rise.  (Also, it looks like the largest zone valve is either 1.5 or 2" feeding to a 4" main.  The flow capacity of this valve should be evaluated and it should be determined what the pressure drop across the valve must be to deliver the required steam.  I suspect that with these zone valves the system will not operate on the typical 8 oz vapor parameters.)  Thus, it is a good idea to utilize 2 stage firing.  The LGB-7 comes standard with hi-lo valves.  To activate 2 hi lo firing, a pressure control (vapor stat) would be necessary.

    When you add the cost, (new equipment and ongoing maintenance) of one large boiler, 2 zone valves, a feed-water tank and pump, hi-lo firing, it would be good to compare to the cost of 2 separate and properly sized boilers running at low vapor system pressures, It is very likely that such a system would have no zone valves, no feed-water tanks and since this is a one pipe system, there will be no dimension B to deal with.

    It would be a fun scenario to put the comparisons together. 

    My apologies for my usual verbose writing.  I don't know if I have added anything, or simply restated what has already be said, adding what is probably already obvious to all.

    It's snowing lightly in the Quad Cities ---  Cheers!
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • Rod
    Rod Posts: 2,067

    Gerry & Dave - Thanks a for the compliments!  Coming from you guys that means a lot!

    - Rod
  • 4Barrel
    4Barrel Member Posts: 125
    Thanks to all

    rod - i've taken your advice. will provide updates as the picture becomes clearer. thanks everyone for the interest.
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