Stainless air/water heat exchanger in parallel Oil/Wood system?

aczlan Posted By aczlan, Mar 7, 2013 at 12:37 PM

  1. aczlan

    New Member 2.

    Mar 7, 2013
    North of the Fingerlakes in NY
    I am currently running a parallel wood/oil system (Vallient oil boiler with a Riello gun and a locally built wood boiler) in a closed loop system.
    My "wood boiler" is essentially a firebox with a L shaped water tank (~5" thick and ~32"x32" on each leg) on it which sits on the top and left sides of the firebox. It does well pre-heating the water and keeping the oil boiler hot, but the recovery time when there is a large demand (such as the indirect hot water heater calling for heat) is not good.
    I have available to me (for free) the stainless secondary heat exchanger out of a HE gas furnace. I am told that it should be able to hold up to the pressure in my system as they are rated for ~90PSI and my system runs at 25PSI.
    The idea is to mount it to the right side of the boiler (the side not currently covered by a tank) as that side is well over 300F when there is a good fire going.. It would be plumbed in before the L shaped tank so that that it acts as a pre-heater for the L tank which should (hopefully) get it warm enough to keep the oil boiler from firing and to eventually add heat storage.
    Attached is a diagram of the physical tank layout and the logical piping layout. Currently, water comes in via port 2 and out port 1.
    Wood Boiler.png
    I would change so that it came into the heat exchanger on port 4 then out 3 and into 2 and back into the system via port 1 (as seen in the picture).

    What would be the downsides to doing this? It was suggested by my heating guy who seems to know his stuff and is offering the heat exchanger to me to experiment with (he wants to do something similar for his pool heater) .


    Aaron Z

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