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near boiler pipe insulation

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steamer45
steamer45 Member Posts: 13
in Strictly Steam
What size wall thickness is recommended for fiberglass near boiler pipe insulation? I am awaiting a quote from a supplier to see what they spec. I would think a minimum of 1" though 1.5 would be considerably improved. The existing insulation on the mains look to be 1"

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  • ChrisJ
    ChrisJ Member Posts: 15,673
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    Hatterasguy said:

    1" is the preferred choice when cost/performance is calculated.

    1.5" is the preferred choice if cost is no object and the maximum performance is desired.

    Wouldn't 2" or thicker fall into that category?
    You can do multiple layers of 2"....

    All of my stuff is 1" but to be honest, I wish I had done 1.5 and even 2" in the coldest areas, it wouldn't have been that much.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • vaporvac
    vaporvac Member Posts: 1,520
    edited October 2015
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    When buying from my local place, I didn't really find the 11/2" much more expensive and I am using 2" in a unheated garage. Somewhere someone posted a chart showing the best thickness for various size pipes etc, so that is what I went by. The main cost differential sees to be led by the pipe's diameter. 1" insulation was much more expensive for a 3" pipe than 2", but the 1 1/ 2"only marginally more and the 2" insulation was nowhere near 2x as much. For the nb piping, I'd think it would be worth it. For an entire mains, I'd have to think about it.
    Does anyone know of chart converting the old asbestos thickness Rvalue to fiberglass thickness?
    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
  • ChrisJ
    ChrisJ Member Posts: 15,673
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    @vaporvac

    I viewed mine differently. My boiler is directly below our livingroom area stays fairly room so the insulation near the boiler is least important vs a lot of piping i have in very cold crawl spaces.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • vaporvac
    vaporvac Member Posts: 1,520
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    Yeah I know what you mean. MY mains all have the original asbestos except that in the garage. I just think there's a scientific way to judge floating around here.
    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
  • Fred
    Fred Member Posts: 8,542
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    My piping has about 80% original asbestos (about 1.5" thick with covering) and 20% 1" fiberglass. All of it in the basement. I have to say just from feeling the exterior of those insulations that the 1" fiberglass does a better job of insulating than the 1.5" of asbestos. I agree that 1" fiberglass is probably plenty where the piping is in a basement but that maybe 1.5" to 2" max would be better in crawl spaces and unheated garages. I doubt that anything more than that adds much value.
    New England SteamWorks
  • rlaggren
    rlaggren Member Posts: 160
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    Here's an insulation guide covering most types available. The one standout is the phenolic type with less than half the conductivity of most others which seem to cluster around .25-.3 conductivity - which is about R3/in if i did my math right. So the phenolic is about R6/in.

    https://www.wbdg.org/design/midg_materials.php
    disclaimer - I'm a plumber, not a heating pro.

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