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WM GV90+5 with HTP SSU-45 indirect installation

andrewscj Member Posts: 2
edited September 2015 in Gas Heating
Can someone please let me what the correct schematic is for installing an indirect water heater to a GV90+ in a single zone baseboard radiator system?

I have read some discussion on this forum and other places regarding this topic, but I would like to ask this specific question. Some are saying refer to page 26 with a 3 way diverting valve ignoring extra boiler, others say page 17 and treat as its own zone from GV plus manual.


Thanks in advance for your help.


  • Ironman
    Ironman Member Posts: 6,868
    The best way is to treat it as its own zone with a separate, properly sized circ. All zones will require flow checks.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • andrewscj
    andrewscj Member Posts: 2
    edited September 2015
    Thanks Bob. I think we are going to treat it as a zone and should still be able to keep most of the existing electronics in place, not needing extra relays, controllers, or transformers from what we already have. Its already flow checked and we have the grundfos adjustable pumps, so this method is cheaper than the three way in this situation and better. The three way diverter valve sounds like it's a subpar solution from what I've read.

    I am not a plumber, this is being done by a friend who is a commercial plumber and as you may know, it takes putting in a few of these GV90+s in old houses like mine to get the hang of it.