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Mysterious infrared image caused by steam heating system

FHills Member Posts: 20
I recently rented a FLIR infrared camera to check for heating leaks around my semi-detached brick townhouse, which was built in the 1940s and has a single-pipe steam heating system.  From the outside, on the detached side of the home, the camera detected hotter areas under each of the two upstairs windows.  There is a radiator under each window.  

What is strange is that the shapes of two hotter areas are different.  Under Window A is a hot signature in the shape of a vertical line, which appears to correspond to the steam pipe inside the wall.  Under Window B is a big patch of elevated temperature like a reservoir or a lake.   The brick wall otherwise looks normal.  I have also included interior images of the radiators under Windows A and B.  They both hiss and have a little bit of leakage from the vent valves and feed pipe, but any visible leak almost immediately evaporates.  I have two questions:

1.    For Window A, is it normal for a steam heating pipe to bleed heat into a brick wall?  I scanned my neighbors’ homes and their exposed walls do not have such a signature.  Almost everyone in this neighborhood has steam heating.  

2.    For Window B, what is causing this strange patch of elevated temperature?  I suspect it could it be a steam leak inside the brick wall that’s heating up that area.  I showed the images to two plumbers and they both thought it was nothing to worry about.  Should I be concerned?

Thank  you!


  • icesailor
    icesailor Member Posts: 7,265
    Ghostly Images:

    Those are recessed steam/hot water convectors. In one photo, it shows a piece of what appears to be sheet metal behind the element. It is supposed to help reflect heat back into the room. What you see is heat absorbed by the wall and the brick. Buy a sheet of 1/2" R-Max reflective urethane foam board and put it against the wall, above the element. You won't be able to get it behind, but it will reflect heat back into the room. It will make the heater work better. Shoot the wall after. You'll probably see less image.

    If you're handy and crafty, I'd be taking the baseboard off on the side that the supply comes up in the outside wall and trying to get some poured in insulation in there. If it is a solid brick house, I doubt they left pockets for the steam pipe. More likely, that one goes up in a closet. I'd be considering taking the finish off and insulating the pipe. As far as the ones that go into the room, under the floor, that heat is lost into the envelope.

    Those brick walls are at least 8" thick because hardly anyone would use a fake running brick bond on a veneer wall. Every 5 courses, a 1/2 brick? That's a lot of cut in half bricks.
  • FHills
    FHills Member Posts: 20
    What's the "envelope" and what does it mean to use a "fake running brick bond"?

    Thank you for responding to my questions.  I suspected that the large patch heat signatures under the windows on the side wall were caused by radiators.  After all, you could see a radiator through the front wall of the house as well (in picture 1), but the heat signature there is rectangular in shape and this one is irregular,  which had me concerned about a steam leak.  With your assurance this this is not a steam leak, but just uninsulated radiator and piping, I am less worried.  I've been thinking about insulating the whole wall from the interior and will figure out a way to insulate the radiator and pipes.  Couple little questions about your response:

    1. What is the "envelope" -- is that a special space inside the wall or between the ceiling of the first floor and the floor of the second floor?

    2. What does it mean to use a "fake running brick bond"?  

    Thanks again!
  • Canucker
    Canucker Member Posts: 722
    edited April 2014
    brick work

    Icesailor is referring to the building envelope. If you insulate on the back side of the convector, the heat loss to the outside will be reduced, keeping more of it inside the living space.

    His other observation is describing the construction of your brick walls. If you look closely at your pics, you'll notice that every 5th row consists of a half sized brick. In normal residential construction, that wall would be one brick wide and not likely weight bearing, so its called a veneer. He rightly points out that to do that brick pattern(running bond) in a veneer would require you to cut bricks in half to make the short brick row. Not a cheap or fast way to do it. To do the pattern quickly, the bricks are most likely placed length wise across a base of two bricks, making your wall 8 inches thick. If they did the construction that way, he rightly points out that they didn't likely cut bricks to make a path for the vertical steam lines going to the different levels, so to properly insulate your steam risers, you should be looking in an area like a closet to find the soffits for them.
    You can have it good, fast or cheap. Pick two
  • icesailor
    icesailor Member Posts: 7,265
    edited April 2014
    Bonded Envelopes:

    The "Envelope" is usually considered that which is inside the outside shell of the structure. Its where the outside air meets the building.

    As far as a "Running Bond", it is the terminology of the pattern of the bricks when laid. When bricks are laid flat, the long way, they are called a "Stretcher Course". When a bricks are laid side by side as Stretchers, they make a 8" thick wall. To make the wall strong and to tie in the two sides, bricks may be laid crosswise. Crosswise bricks are called Headers. If a wall is high, or has many header courses, to give it strength. Every few courses of stretcher courses, a header course will be laid. Look at the outside photos. You will see some header courses that tie in the wall. If you have a wood framed building, it would only have a single 4" brick veneer. And a 2X4 wall. It takes a lot of cut/half bricks to make a fake header. Labor intensive.

    Ii only brought it up because there is probably very little space between the inside face of the brick wall and the room. There probably isn't much room for insulation. One infra red photo looks like the pipe goes under the floor away from the outside wall.

    Measure the wall thickness at the front door. If it's around 10" wide, it a 8" brick wall.

    Brick Patterns:

  • FHills
    FHills Member Posts: 20
    Wow, a lesson in masonry!

    Holy smokes!  A lesson in masonry.  Thank you both for the detailed reply.  And yes, after measuring, the thickness of my brick wall is between 8-10".