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Any effects on NOT insulating dry returns?

I've got a one-pipe steam system that functions quite well thanks to a lot of information on The Wall. However I'm trying to find a general consensus on the question of whether or not to insulate dry returns. I am trying to think of anything that could be a reason for insulating them (water hammer, cooling effect on water, etc) but nothing really makes sense. Does anyone have any negative experiences with leaving the dry return run "naked", or are there any proven facts to support either side of the argument? Thanks!


  • Scot BScot B Member Posts: 26
    Page 85 of The Lost Art Of Steam Heating

    Checking the size of the main against the connected load paragraph. " The heat loss through uninsulated pipe is more than five times that through uninsulated pipe". While you are talking about returns and this about mains you will still be losing heat you paid for out of the uninsulated pipe.  Once again thats heat you paid for! In the long run the conservation of the heat will probably pay off.  Just saying.
    wood fired one pipe steam, free from the oil man!
  • Scot BScot B Member Posts: 26

    Remember it takes 1 BTU to raise one pound of water 1 degree fahrenheight.
    wood fired one pipe steam, free from the oil man!
  • Jamie HallJamie Hall Member Posts: 6,653
    Yes, you will lose some heat

    in the dry returns.  But very darn little.  Otherwise, there is no functional reason to insulate them.  Won't hurt anything, but, in my (not so) humble opinion there is no need to do it.

    I might add that in my system, none of the returns are insulated...

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Charlie from wmassCharlie from wmass Member Posts: 3,911
    One reason I have been taught to insulate returns

    Carbonic corrosion. the more the water cools the more carbon dioxide it can absorb and therefore the more corrosion that can occur. There is also the heat loss to the basement and the need to raise the water from a lower temperature to boiling during a heating cycle. That said few returns get insulated. If you can afford to insulate them I say do it. It can only help.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Charlie from wmassCharlie from wmass Member Posts: 3,911
    My comments apply to one pipe systems

    Jamie has a vapor system and his dry returns see much less heat than you have in a one pipe system.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Dave in QCADave in QCA Member Posts: 1,660
    edited January 2012
    Is this a Dry return, or a Dry Return?

    The term Dry Return can mean 2 distinct things... as has been made clear in both Charlie's and Jamie's posts.  Since this is not a 2-pipe system, we are talking 1-pipe.  And, isn't it true that when we say "dry return" in a one pipe system, we are actually referring to the end of the steam main, when that main continues forward after the last radiator or riser, usually in a reduced size, has no steam load, but becomes filled with steam during the heating cycle? 

    Anyway, the point I'm trying to make and taking forever to do so, is that if the dry return being referred to in this thread actually becomes filled with steam, of course it should be insulated.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • gerry gillgerry gill Member Posts: 2,663

    Thats an excellent point..well stated..

    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • Hap_HazzardHap_Hazzard Member Posts: 1,349
    It shouldn't fill with steam.

    If the main vents are in the right place the steam should not fill the dry return. I'm sure the vapor pressure is pretty high given that they have hot water running through them, but they shouldn't be filling with live steam when they're already full of air that has no way to escape (unless you're a bonehead noob like me who runs his dry returns together above the water line, allowing the steam from one main to push the air into the other main).
    1983(?) Peerless G-561-W-S
    3" drop header, CG400-1090, VXT-24
  • Hap_HazzardHap_Hazzard Member Posts: 1,349
    The real question is...

    Are these returns in living space, i.e. space that needs to be heated anyway? If so, is the heat already more than adequate in this area?

    If you have a finished basement and spend a lot of time there, and the temperature is just about right, then you'd need to find some other way to heat the space if you insulate, and most of them will cost more. But if the heat is excessive or you never go down there--except to blow down the boiler and check the water level--that heat would be better used upstairs.

    Using the heat from returns is not as bad as from mains because the steam has already condensed. It takes a lot more energy to turn 212° water into steam than to raise the temperature from room temperature back to the boiling point. When you boil water on the stove, it comes to a boil in a few minutes, but it can take over an hour to boil away completely.
    1983(?) Peerless G-561-W-S
    3" drop header, CG400-1090, VXT-24
  • Thanks all

    Thanks to everyone that replied so far! My run is in the unfinished side of the basement so I don't need to worry about using it as indirect heating. I will probably insulate the return line this weekend - like everyone has said, it can't hurt!
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