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Just mortar wet return or insulate and then mortar in?

agurkas Member Posts: 238
I am cleaning up my basement floor and took our beat up mortar around wet return. What is the best practice with these wet returns?
Should I:
a. encase it again in mortar
b. put 1.25" insulation and then cover it in mortar
c. leave it uncovered and just build protective channel around it, as I am pouring new slab


  • Fred
    Fred Member Posts: 8,541
    Are you actually pouring a new 4' slab or just filling in that trough? I wouldn't use regular pipe insulation as that has too much give and will likely crack your new pour. The only reason to put a protective channel around it would be so you could pull it out later but it will likely last 30 to 50 years and i doubt that you will be able to pull it out of the protective channel anyway. (it doesn't look like new pipe. I would definitely replace it while the floor is open and put a clean-out at each end so it can be hosed out every couple years).
    If you replace it, I'd just encase it like originally done. JMHO
  • vaporvac
    vaporvac Member Posts: 1,520
    Do you have to cover it? Could you make a removable cover? It seems we're always reading about the nightmare of leaking buried returns.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • Jamie Hall
    Jamie Hall Member Posts: 21,117
    Do NOT, repeat NOT, place either black iron or copper pipe in direct contact with concrete. Most concrete is astonishingly corrosive, and that you don't want. If you must cover that wet return in concrete, encase it in a sleeve of some kind. A better bet is to leave it open and cover the trough with a cover plate.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Charlie from wmass
  • KC_Jones
    KC_Jones Member Posts: 5,410
    Not sure if this would even be feasible for you at this point, but I thought this was a great way to do it. From the very talented Gerry Gill's website.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • RobG
    RobG Member Posts: 1,850
    Since it looks like the trench stays dry, I would replace it prior to the over-pour and sleeve it in armaflex. Armaflex will deteriorate when it stays wet or is exposed to UV for extended periods of time but it will be fine for an insulator from the concrete while it sets.
  • agurkas
    agurkas Member Posts: 238
    KC_Jones, I have seen those pictures. Little too fancy and too much $$$ for something that is basically a mothballed system I am only running when it is bellow 24F outside.

    I have some left over fiberglass pipe insulation. Sound like that would work.
  • RobG
    RobG Member Posts: 1,850
    Fiberglass will absorb the moisture from the pour. Armaflex is cheap enough that it would be well worth the cost.
  • agurkas
    agurkas Member Posts: 238
    So I assume temperatures in wet return are ok then? I think I have measured that pipe at about 100F
  • RobG
    RobG Member Posts: 1,850
    No problem.