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Steam boiler and indirect HW

Depending on the nozzle size , the EC 3 section can be fired to give you between 283 and 446 sq. ft. of steam . Plenty of extra capacity if you decide to add some radiators .

With the indirect heater , I agree with Steamhead - you do not want to size the boiler bigger to handle the extra load . Nothing but troubles follow with an oversized boiler and steam . What will happen with a boiler sized right with the steam load and an indirect is the indirect will give itself priority .

With the tank heating up , drawing all those btus out of the boiler , the system usually won't steam till the tank is satisfied . Which is a good thing ...... unless you have a real big use of hot water for a long period of time in the winter . Most residential homes your size are perfectly fine running this way .


  • Drew S.
    Drew S. Member Posts: 17
    Installing indirect HW with steam

    We are currently going to be installing a Peerless steam boiler in the coming weeks and have the following questions.

    The boiler has been sized based on the existing radiators and the total radiator load, without the piping load is 370 sq ft of steam or about 89000 btu's. While the 3 section boiler could do the job my installer has suggested going with the four section in light of the potential of adding an indirect hot water heater and future addition. The net SF of Steam for the 3 section boiler is 375 and for the 4 section boiler it is 471. Would it be a mistake to go with the 4 section boiler if I am considering the indirect HW tank and have the potential to add a room in the future?
  • Normally

    you don't need extra boiler capacity to run an indirect. But if you plan to add to the house, you will need more capacity so the 4-section makes sense. If it short-cycles with the existing load you can down-fire it SLIGHTLY.

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  • Scott Kneeland
    Scott Kneeland Member Posts: 158

    Beware! I have seen several Peerless EC steam boilers with indirects that become air bound due to the location of the tappings. one of which is barely below the water line. If a customet wants a indirect with steam i like the Weil McLain sgo, it has a tapping designated for a indirect. Peerless has a tapping on the side of the middle section only on 5 & 6 section boilers only go figure.

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  • Yes

    You have to be very careful how you pipe an indirect with the EC . We haven't used an indirect on an EC yet , but for baseboard heating we pump away from the 3/4 drain tapping in the back and return into that 3/4 tapping in front , just below the water line . With a flowvalve right at that point . Works like a charm .
  • Drew S.
    Drew S. Member Posts: 17
    Peerless EC

    Yes, I was referring Peerless EC boiler. It seems that the plumbing and heating contractors in this area (Middletown, CT) have a preference for the Peerless boiler. Are there any other manufacturers that you would recommend?

    One last question, what are the advantages of having a tankless coil with a steam boiler?

    Thanks for all of the sound advice.
  • Scott Kneeland
    Scott Kneeland Member Posts: 158

    It will work that way for a while but I found that after a period of time you start to draw mud and crap into the circ and the flow check either sticks open or the pump binds up.

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  • We use

    Peerless and Burnham . I've been using Peerless for 20 years , Burnham for about 5 . Both work great for steam . The Burnham V8 gives you more tappings for an indirect or a zone of heat .

    Not too many advantages of a coil over an indirect on a steam boiler . A coil does not get sludged up like an indirect tank might . But it can lime up on the domestic side . And it won't give you as steady a temp at the shower as tank of stored water . You also need to keep the boiler hot all year round for hot water . Whether this is a significant impact on fuel usage compared to using an indirect is a guessing game . The indirect will have the boiler firing a few times a day anyway .

    In the past we have used a storage tank with a coil , and kept the boiler warm ( around 120 degrees ) till hot water was needed . Then a bronze circulator turned on , the boiler water temp kicked to 180 , and water was pumped through the coil where it was stored in the tank . This also made the boiler much easier to clean because it was warm all year .
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