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Boiler Replacement Advice

Rusty18Rusty18 Member Posts: 4
The oil company came to do the annual service last week and our boiler has a hole in it. They are coming this week to put in a replacement (same model same size). The system has worked well over the past almost 40 years (this will be the third boiler, first one was installed who knows when and the one being replaced 15 years ago), but I was wondering if anyone had any thoughts/suggestions/improvements based on the pictures below.

The service tech heard the leak when they tested the LWCO - it did not work and when they filled the boiler you could hear water spilling out. A week before that it was in the 20s here in MA and everything seemed fine. I did the check I do every time the heat comes on for the first time to make sure the system is balanced, and there was steam in all the radiators and all seemed well. If the LWCO was not working (super alarming) but we still had steam despite a hole, does this mean the hole is somewhere above the LWCO and the auto feeder was just pumping new water into the system and that's what prevented the boiler from dry firing?

My other concern is the wet return. 15 years is apparently what you get out of a steam boiler nowadays, but I can't help but think about the fact that the hole in the boiler happened a few years after we poured a slab in the previously dirt-floor basement. It's probably unrelated given the age of the boiler but I can't help wonder what's going on under the concrete (the wet return is all copper under the floor). Short of digging it up for a problem that may not exist, does it make sense to install an auto feed with a meter to keep track of how much water is being added? If yes, any ballpark thoughts on how much loss is normal and what kind of numbers could be indicative of a leak?

Appreciate any and all feedback!


  • IronmanIronman Member Posts: 5,920
    The near boiler piping looks correct - which is quite often not the case with steam.

    Are there leaks on the system? Is a lot of makeup water being added?

    Get a MegaSteam, it's the best oil steam boiler. I can't remember Crown's name for it, but it's the same as the MegaSteam.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • SteamheadSteamhead Member Posts: 14,046
    Crown's version is the Freeport FSZ series, here:

    @Ironman is right. The MegaSteam or FSZ is the way to go. They're more efficient and last longer.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • The Steam WhispererThe Steam Whisperer Member Posts: 572
    Make sure they are putting in the right capacity boiler. Literally 95% of the boilers we look at are the wrong size. The normal oversizing is about 60% , though we have seen some closer to 20% and others as much as 12 times the needed capacity ( and there had been no changes to the building).
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,518
    Copper wet returns under the floor are usually not an issue. Yes, put a water meter on it. It will tell you if your losing water before is can cause harm to the system
  • Rusty18Rusty18 Member Posts: 4
    Thanks all. We are going with a KSZ125, which is an exact replacement for what is there (I was late following up on the FSZ recommendation). The installer said that because essentially no piping is being replaced, there will not be a lot of oil added to the system and the new boiler will not need to be skimmed all day. He said he would skim it, but it did not sound like a lot of skimming was going to be taking place. Should I plan on skimming it myself?

    The installers are definitely going to close the shutoff at the end of the wet return and just deal with whatever is in the boiler. Should I open the drain at the end of the return to get that as cleaned out as possible before the new boiler goes in or is that just asking for trouble? There is no drain or valve at the other leg of the wet drain where it drops vertical, so I would be relying on gravity to push as much out as possible (there is a main vent at the top of the wet return, so I could take that off and stick a hose down). If this does not sound like a terrible idea, should I keep the shutoff back into the boiler open or closed - I was wondering if there are any vacuums in the system that would prevent the return from draining. Thanks!
  • Jamie HallJamie Hall Member Posts: 13,804
    If you can get that vent off -- a rather big if sometimes -- it wouldn't be a bad idea at all to stick a hose in it and open the valve at the other end and flush that return out. Keep the job separate from the boiler, however that can be managed.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch

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