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Installing Indirect on my Steamer

This spring we are installing a new steam boiler Burnham MST396 and I have 388 sq. ft. of radiation without taking into account the steam piping. We already have the boiler in place and are doing as much pre-piping as possible before the change over. An after thought lead us to wanting to install a 40 gallon Phase 3 indirect domestic water heater. We a family of 3 and maybe 4 down the road.

The MegaSteam has provisions for the indirect tapping's built into the casting:

<strong>My questions are 1:</strong> Is the sizing big enough to keep up with the domestic hot water demand while heating the home? and if it is workable <strong> 2:</strong> Should we run 3/4" 1" or 1.25" supply/ return lines to the indirect?

Thanks So Much for all the help and guidance you pros have provided me~! Joe


  • Steamhead
    Steamhead Member Posts: 16,821
    edited February 2012
    We've done this and it worked great

    but not with that particular indirect. The Phase 3 indirects don't work well with steam, because their tank-in-tank design requires a bit of pressure to fill the boiler side of the tank fully. A steam boiler won't provide that pressure. They do work well with hot-water boilers though.

    Use a coil-type indirect like the SuperStor. Their SSU-45 performs about as well as the comparable Phase 3, and the design of its coil keeps it below a steam boiler's waterline. The slight pressure of the standing water keeps the coil filled.

    The pump between the boiler and SuperStor must be a three-piece, oil-lubricated  bronze unit like a B&G 100AB or Taco 110B. An iron-body one will rust up, and a wet-rotor type will seize up. The water in a steam boiler isn't kind to improper pumps.

    Here's a thread where we installed a SuperStor with a Smith G-8 boiler. The MegaSteam would be set up much the same way. If Burnham had approved the MegaSteam for use with gas burners, we would have used a MegaSteam on this job!

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    Totally agree with Steamhead

    Unless you can somehow get the whole Phase 3 lower than the water level of the MegaSteam , I'd go with a coil style indirect . We never used a tank in tank design with a steamer , but have had nothing but air troubles with the 2 existing accounts that have them . 
  • ctjomac
    ctjomac Member Posts: 52
    SteamHead...I looked up the install

    procedures for the SuperStor and have a few questions... HTP shows the supply to the indirect coming off the bottom of the boiler, not the upper half. This is opposite of what others show. Does that sound right to you?

    They also don't ask for flowchecks. Is that because the coil should theoretically be submerged?

    They also don't show a by-pass to blend the supply with the return. Won't that be too hot for the coil in the heating season?

    Thanks, Joe
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