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Insulation on return lines.

J.A.J.A. Member Posts: 18
My building is having new insulation put on our steam mains in the basement. While preparing for the work to begin (clearing out storage bins etc.), I found that a number of sections of the return lines were insulated. This is not the case everywhere, such as the high traffic areas, which lead me to believe that at one point they were but somewhere along the line people removed some insulation. My question is should we have all of the exposed return lines re-insulated? I have looked around the site and found a discussion or two that questions such a tactic, but I could not find much in the way of a definitive answer. Here is some info that may help:

The building is from the 1920s, the system is one pipe. My first thought was that none of the return lines were insulated, mostly because the returns I was able to see were in the main corridor and laundry room. Now that I see differently, should we re-insulate all of the lines, just replace the insulation only where it is, or remove the insulation from all return lines? Also, there are just some places that we will not be able to insulate, such as in the super's apartment the return is tucked away inside a wall (although that provides a small amount of insulation I suppose). Any thoughts on the subject would be helpful. Please let me know if you need more info. Thanks.


  • gerry gillgerry gill Member Posts: 2,994
    its more of an economical thing than anything else.

    if you can afford the extra cash layout to insulate the returns it will make the system a tad bit more efficient..since the condensate will be a bit warmer when it gets back to the boiler, thereby using less btu's to again make it much more efficient? well a 'tad bit' is probably the best answer anyone could realistically give.

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

  • J.A.J.A. Member Posts: 18
    All right

    Thanks Gerry. While no concrete measurements can be taken, I'm going to trust the Dead Men who originally installed this system and at the very least replace all of the insulation that is removed from the returns so we don't see any decrease in system performance. I'm also thinking that as long as we're putting insulation on places that currently have it, we might as well put it back on places where it has (probably) been removed. Since it is 2-inch pipe I believe the scale someone had previously posted said 1-1/2" insulation for anything over 2-inch pipe and 1" insulation for pipes under 2 inches. I know there is a money component to that, so maybe 1-1/2" insulation on the steam mains and 1" on the returns?
  • gerry gillgerry gill Member Posts: 2,994
    that would be fine,

    we use 1' for everything, but that has more to do with mating up to old asbestos than trying to satisfy the energy code.

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

  • nicholas bonham-carternicholas bonham-carter Member Posts: 8,193
    "While you are at it"

    don't forget the other tuning-up items which will follow the dead men's original plans:

    1. keep your pressure low, with a vaporstat [0-16 OZ.], and install a good low pressure gauge, [, 0-15 OZ.].

    2. make sure that your main line venting is up to the job. my 6 returns [on 1,050,000 btu]  have 4-5 gorton #2's each, and all the air is out by the time my gauge shows 2 OZ!

    3. let nothing pass the lips of your boiler, except for pure water [have it checked]. keep all cleaning products, water-softener salt, paint thinner, etc. away from the combustion air intake! anything containing chlorides can be a boiler-killer!--nbc
  • J.A.J.A. Member Posts: 18
    Removal continued

    The removal of the old insulation is now complete, and the measurement of the pipes for new insulation will begin on Thursday. I'll keep updating as it goes along.

    As for my current setup, over the past few years I've taken over running the heating system, found the wall, purchased and read the books, took Dan's course etc. I started with lowering the pressure, then adding vents onto the main ( I have 2 Gorton #2s at the ends of 3 mains (more on that in a bit), then going throughout the building and neighbor's apartments and properly pitching radiators and most recently I added a few gauges (0-3psi and 0-20oz). There is plenty more to do, and hopefully within the next week I'll put up some pictures of the set up and perhaps a drawing or two of the piping, since I have a number of questions about it. Thanks for your continued help.
  • RodRod Posts: 2,067
    Sizing Chart

    Hi- This chart might be of help to you as it gives the circumferences of the different size pipes which makes it easier to determine the sizes when the pipes are in place.

    - Rod
  • J.A.J.A. Member Posts: 18
    The work begins...

    We have over 700 feet of pipe to insulate, about a third of it for the steam pipes. Measuring all of it was pretty simple, thanks Rod, for the chart. The contractor asked if I wanted him to insulate/cover the pipes off of the boiler (near boiler piping) with CP-11. Most pictures I've seen of people's systems only have the mains insulated once they start running horizontally. I feel like if they covered all the near boiler piping with CP-11 and smooth coat cement (like they do for Ts and elbows) it would make any future work on the boiler, including replacement, a much more difficult job. Thoughts?
  • SteamheadSteamhead Member Posts: 13,998
    I'd insulate those pipes too

    it'll save a lot of energy before boiler replacement is needed.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • RodRod Posts: 2,067
    Covers for Insulating Fittings

    They make covers for fittings - Elbows ,Tee etc.  They are PVC on the outside and insulation on the inside.   Any large insulation supplier should have them. Check around for pricing as it varies a lot and with a large amount you should be able to get a fairly good price break.  

    Insulate all steam pipes especially those near the boiler. I left my near boiler piping bare for a couple of years (had a really warm basement! :) and when I did insulate those pipes, it was a noticeable difference. Here's a link to an article of Dan's on insulating steam pipes.

    - Rod

    Here's a couple of links to PVC fitting covers:
  • RDSTEAMRDSTEAM Member Posts: 134

    If the money is there than do it but you might not get your money back. it will avoid future headaches such as leaks due to more carbonic corrosion by keeping your reaturn temp higher but as far as saving fuel money....who knows how much that would be...... 1" insulation is all you need and going any larger will just do more harm to your wallet and not give you anymore benefits. and as far as fitting insulating. just use standard fiberglass piping and loose fiberglass with ZESTON fittings. looks great, less mess, less future headaches and its reusable as long as the condition is ok.
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