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Help!! Crazy boiler expansion tank setup.

JOutterbridge
JOutterbridge Member Posts: 20
edited November 24 in Radiant Heating

Alright peoples, here is one I've never saw before. I'll attach the pic below for reference since I'm typing from my laptop. A new Laars mini therm boiler, very simple install.

The pump is 6 inches above the supply outlet which is standard. The domestic water feed is on the supply side directly under the flow check. The expansion tank is teed into the boiler bottom drain valve though. Is there any way this actually works? It's in between the supply and return side if you look at the technical drawing.

My dilemma: I don't want the expansion tank teed into the water supply under the flow check valve because it would be after the pump that is directly off the supply side boiler feed. Space is limited on the return side where i want the expansion tank. Is it alright to leave it as is temporarily? I would like to repipe the return side completely to make it right in the future with an air eliminator added. In the meantime will the loop be alright with the point of no pressure change at the bottom of the boiler? The home inspector also said the water heater can't be piped into the boiler flue since is has an automatic damper. Never heard of that before but I'll listen to any advice you guys have. Natural gas natural draft for both. 6 inch flue 200k BTU combined.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,722

    Not the best, perhaps, but it will work.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JOutterbridge
  • hot_rod
    hot_rod Member Posts: 23,257

    The tank connected to the boiler like that should work for "pumping away, it does on low pressure drop boilers like cast iron. Copper tube boiler2s have a bit of pressure drop, but for a temporary fix, give it a try.

    However the fill valve would want to be connected at that same PONPC point of no pressure change.

    Does your boiler have that low loss header assembly as shown in the example you posted?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JOutterbridge
  • JOutterbridge
    JOutterbridge Member Posts: 20

    The header is not in place. It is piped in standard return 1 1/4 and supply side the same except for the pump being immediately off the supply vertical.

    The 1/2 inch domestic feed will be an easy change because there are 3 shutoffs. I'll probably be back at the house tomorrow to get more pictures. Shouldn't be too hard to figure out a total solution for pumping away with an air separator added.