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side-vented cast iron boilier

hydro_newbiehydro_newbie Posts: 37Member
I’m having my boiler replaced, and I’m looking for something simple and reliable. The current boiler is a mod/con which is side-vented with Z-vent AL29-4C pipe. We have a chimney, but I’m relatively certain it is unlined (will confirm this wkd). So I’m looking for a cast-iron boiler that is capable of side venting. This seems to narrow the selection quite a bit. I’ve found the following models online:

Burnham ESC, Smith GVX, Weil-Mclain CGi, Utica SVB series 2, Peerless PSCII

Any thoughts on whether any of these stand out (good or bad), or if there is one I missed?



  • IronmanIronman Posts: 5,309Member
    What make and model is your current boiler?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • newagedawnnewagedawn Posts: 549Member
    peerless psc
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"
  • hydro_newbiehydro_newbie Posts: 37Member
    @Ironman The existing boiler is a Burnham CHG150. From slant/fin and fuel usage over the winter, I probably need 80MBTUH output (and that still has padding so could probably go smaller).

    @newagedawn Any reason to love the Peerless over any of the others?
  • IronmanIronman Posts: 5,309Member
    What type of heat emitters do you have?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • hydro_newbiehydro_newbie Posts: 37Member
    Sorry to leave this hanging. I PM’d Ironman directly because I was worried I might annoy folks by generating another mod/con vs CI thread...but now realise I might have appeared rude...:blush:

    If anyone was interested, here’s info on the system/setup:

    2-story house, ~2k sqft, 2 zones (upstairs/downstairs), each fed by an oversized fan coil (one in basement, one in attic) that also do A/C in the summer.
    Slant/fin heat loss was 78MBTUH for 70deg/0deg. Fuel usage over the winter shows that’s not terribly unreasonable (could probably go smaller).
    Boiler is in an unfinished basement, vented with Z-vent (AL29-4C).
    Hot water is from indirect.
    The fan coils will emit 82MBTUH (basement) and 63MBTUH (attic) with 180deg at 4GPM.

    I'm avoiding a mod/con due to potential longevity issues (in fairness this isn't really clear-cut at this point) and likely extra electricity consumption due to longer cycle times (fan coils running longer).
  • bob eckbob eck Posts: 893Member
    Where are you located at?
    F W Webb has a Advantage (US Boiler - Burnham) cast iron boiler that is sidewall vented with 3" SS pipe and fittings. 85% AFUE
    Weil McLain GV90+ cast iron boiler that vents sidewall with PVC pipe and you can check to see if you can use SS vent pipe and fittings for venting.
    Cast iron boilers can last 30 plus years with proper maintenance.
    High efficiency gas boiler work best with heating system designed for using low water temps through the heat emitters.
  • hydro_newbiehydro_newbie Posts: 37Member
    Thanks Bob. I'm in MA, just north of Boston. I'll take a look at the Advantage, but was looking at the ESC3, not sure what the differences are. The GV90+ is interesting; I hadn't looked at it too closely.

    The 2 hydro air units are oversized enough to run lower water temps even on design day, but they use inefficient PSC motors. The extra run times of the units would eat into fuel savings from a condensing boiler. Ironman brought up possibly replacing them with ECMs, which I will look into.
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