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Use heat exchangers in an open trough reservoir?

cgregory Member Posts: 6
I can't fit a typical pressure tank into the available space, but can put in a 600-gallon insulated and covered trough for a thermal reservoir. The question is transferring the heat from the boiler to the trough. I'm wondering if I could use a properly-sized heat exchanger with the pressurized boiler loop delivering the heat to a separately-pumped unpressurized loop in the trough. Rather than the 15 psi of the boiler loop, the pump would have the same flow rate, but 2-3 psi or so. Has anybody any experience with this sort of system?


  • Jamie Hall
    Jamie Hall Member Posts: 18,929
    Since this seems to be a do-it-yourself type setup (though I can't quite figure out how you have room for a 600 gallon trough, but not a more typical buffer tank...) -- might it not be easier to create your own multipass tube bundle, circulating water inside the tubes from the boiler, and heating the water in the trough?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,450
    edited December 2018
    Wood guys do this quite often, get a bunch of soft copper, either two or three parallel runs of 1/2L or a couple of 3/4L. Keep in mind that vertical height is key in your storage. If it's a long trough then not nearly as much capacity to efficiently store heat.

    We use 500-1000 gallon propane tanks for this purpose. Usually around a dollar a gallon used. Propane (on any other large pressure vessel) is for pressurized storage and require no HX, think of it like a very large buffer tank.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • hot_rod
    hot_rod Member Posts: 16,296
    Check with Tom at this site, he builds custom tanks and heat exchangers, copper to pex.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream