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Steam Boiler Tankless Coil Repair

JoeBklyn Member Posts: 5
Hello All,

I have a Weil Mclain EG-45 steam boiler and it has a small leak at the tankless heater. I plan on replacing the gasket but I wanted to run these steps by you first just to make sure I am not missing anything. I appreciate any assistance you can give me on this.

1. Turn off boiler and shut off water supply.
2. Drain the boiler. I have a probe-type low water cut-off and the lowest drain valve is slightly below the probe. I should prepare for a decent amount of water to spill out when I finally do remove the tankless heater, right?
3. Disconnect copper piping from tankless heater and remove nuts securing the tankless heater.
4. Use a gasket scraper to remove any residual gasket from the boiler and tankless heater. Maybe hit both surfaces with some Scotch-Brite afterwards?
5. Apply a very thin layer of sealant to the front and back side of the gasket. I stress a ‘very thin layer’ because I assume that I don’t want to have excess sealant oozing into the boiler water? I purchased Hercules 25666 High Temp Red Silicone Sealant for the job (was told by the retailer that this would work for my application).
6. Install gasket and tankless heater and tighten the nuts. How tight do I need to make the nuts? I haven’t seen a torque spec. for this. Make it tight, a 1/4 turn past snug, etc.? (Boiler is running to 7 PSI which I know is another problem that I need to fix. I never hear any air coming from the main vent and the previous homeowner incorrectly set the pressuretrol... Also, I think the boiler is severely oversized. I have an 18’ x 35’ attached home on both sides in Brooklyn, NY. At one point I need to do some EDR calcs.)

Before I start filling the boiler how long should I wait for the sealant to dry? If I wait too long and leave the boiler sections exposed to air will I cause an excessive amount of rust? (I know the radiator vents always leave the boiler open to atmosphere but there are parts of the boiler that were previously surrounded by water and now they are not.)

How long should I wait to fire up the boiler?

Since I am not a professional plumber I plan on tackling this project over the summer. I am concerned that I will be filling the boiler with new water at a time where there is no heating demand. Will that oxygenated water rot out my boiler? Should I fire up the boiler a couple of times and if so, how many times?

BTW – The tankless heater is used for a couple of feet of baseboard heating in the basement. And if it helps, the boiler does have an aquastat.

Thank you all. Appreciate the help on this.


    JUGHNE Member Posts: 11,108
    If you drop the steam pressure from 7PSI to the lowest possible, perhaps 1.75 or 2, then your leak may go away.

    I would suggest posting pictures of the insert coil and it's leak.
    Some here might give you better advice. If things have leaked for some time then it could turn a 10 minute job into an entire weekend at best.
    EBEBRATT-Ed Member Posts: 15,839
    This could be an easy job or go very bad. Usually the bolts break off and you end up drilling and tapping the boiler which is not for the faint of heart. Heating the bolts with a torch, penetrating oil (krol oil) etc., It can be a real struggle

    @jughne gave you good advise. Post some pics so we can see what it looks like
    HVACNUT Member Posts: 5,888
    First, I think you should forget about the tankless for now and concentrate on why it's running at 7 psi.
    The hydro zone off the tankless, how is it wired? Is that circuit going through the aquastat and pressurtrol?
    Check the pigtail. It's probably clogged. Residential, PA404A, set pressurtrol to .5 cut in, 1 diff.

    Now for the tankless, see if you can budge ANY of the bolts. How old is the boiler? One snap and your off to get step bits and a tap and dye set.
    IMO, no sealant on a gasket. Let the gasket do what it's supposed to do. If it leaks, its probably not the gaskets fault. They always seem to get a bad rap.
  • JoeBklyn
    JoeBklyn Member Posts: 5

    Thank you all for responding. Below is the image of the coil. Looks like it is leaking from both the nuts/studs and from the bottom of the coil. I see stains all the way down the left section. The nuts don't look too bad.

    As far as the steam pressure is concerned. I know the pressuretrol is set way too high. I haven't pulled off the cover but I am guessing the Diff is set somewhere around 5.

    We bought the house a couple of years ago with the boiler in the state that it is in now, so I imagine the system has been running like this for a long while (10-15+ years). I want to reduce the settings to normal (0.5 psi; 1 psi diff.) but I don't know the history of the boiler. I don't know if there was a problem before and they solved it by upping the pressure? Was it set like this on day one? Who knows? Also, I never hear any air coming out of the main vent... The plan was to adjust the settings and change the main vent towards the end of the heating season. I know enough to get me into trouble but not enough to get me out of trouble. hahaha...

    Also, the guy who installed the boiler put the pressure gauge on the wrong side of the pigtail. I purchased a new OEM gauge and plan on installing it as shown in the manual. I will also adjust the orientation of the pressuretrol so the expansion/contraction of the pigtail doesn't throw off the level. BTW - I would like to put a 1/4" union between the pigtail and the gauge/pressuretrol. I figure the pigtail will go bad one day and having a union will make it easier to change. Does anyone know if adding a union there is against code in NYC?

    If I do end up doing this gasket it will give me the opportunity to rearrange some of the piping used for the baseboard. The installer piped everything so close to the sight glass and handle that it is very difficult to work in that area.

    For all those who read my stuff all the way to the end... thank you... thank you... thank you...

    JUGHNE Member Posts: 11,108
    Problems are not solved by raising steam pressure. Problems are simply "masked" temporarily, some think they can fix all things with pressure.

    You should set that pressure down, check and clean the pigtail, when you get that done then consider the gasket. Those first two items will be a cakewalk compared to the gasket. IMO
  • Fred
    Fred Member Posts: 8,542
    That's a micro switch in that pressuretrol so its orientation doesn't matter. If it were a mercury switch it would be affected by the expansion/contraction of the pigtail. As has been said, turn the pressure down where it should be. Also, based on the amount of condensation I see on the top half of that gauge glass, the boiler needs to be skimmed. Is there a skim port anywhere on that boiler?
    You are going to have a challenge replacing that gasket. I suspect you will have to cut the copper piping to pull that coil out and then re sweat the copper connections.
  • JoeBklyn
    JoeBklyn Member Posts: 5
    Unfortunately I don't have a skim port...
  • JoeBklyn
    JoeBklyn Member Posts: 5
    Sorry, there is a skim port but it is has a pipe plug in it.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,831
    edited March 2018
    Nice ....studs and brass nut's on the coil ...... Penertrating oil , cool down the boiler with fresh water . Let the metals contract.. If the nuts break loose , great ,Becareful , too much and you can snap the stud.. Then your drilling and tapping ... ....If in doubt , just use an nut cracker . It's an tool that will crack the nut off the stud, it's not that expensive.. Brass nuts you may not need to..

    Now once the coil is pulled it may be worse then it looks from the outside .. I would also recommend to have an new coil with in reach if the plate is far too rotted to reseat an gasket ... Me personally, I would come in and replace the coil and gaskets ... I do not like problems .

    ReInstall using never seze and new nuts , .. If the original installer had compassion for those that follow , he would have used it ...

    There was an error rendering this rich post.

  • New England SteamWorks
    New England SteamWorks Member Posts: 1,521
    I would advise waiting until heating season is over if this is something you want to try and tackle yourself. The coil is probably fine. If the coil was leaking your boiler would be over filling.
    New England SteamWorks
    Service, Installation, & Restoration of Steam Heating Systems
    JUGHNE Member Posts: 11,108
    Weekend: Pigtail.......Set pressure as low as possible.........find out about your LWCO probe and how to clean it, (carefully it is fragile). Then you could study and contemplate how to get the plug out of the skim port........don't try it now just study it.
    There may be someone here with that boiler and found an alternate plan for skimming.
  • JoeBklyn
    JoeBklyn Member Posts: 5
    Thank you all for your help. Based on your comments I am debating now if I want to do the coil myself or just hire a pro. If I do hire a pro, how long would a job like this take?

    I am not sure if this violates The Wall's No Price Discussion policy, and if it does I apologize and withdraw my question, but is a job like this typically priced at a flat rate or by the hour?
  • JohnNY
    JohnNY Member Posts: 3,244
    There's no problem with putting a union on the pigtail in NYC.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.