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  1. #1
    Join Date
    Aug 2011
    Location
    Charleston, SC
    Posts
    7

    Locating refridgerant lines in walls and ceilings

    I am designing a new HVAC system for a historic hotel. They currently have individual split A/C units for each room. Each AHU is a floor console, with the condensing unit on the roof. The hotel is 4 stories tall with 32 rooms. The refridgerant lines are running in the walls, floor, and ceilings in unknown locations. I wanted to locate them to save on demolition and disturbance. I had somebody out there today with a thermal camera ($10,000 unit), but in this historic building the walls are very thick with multiple wythes of brick, and we couldn't see most of the lines very clear at all. The liquid line is uninsulated, and it felt pretty warm at the unit, but it wasn't being picked up on the thermal camera. Then we tried a tone generator, and found that some of the line sets went down below to the celing space below, and we just couldn't follow the lines with much success. They tell me they have a more powerful "wand" which will be able to find the signal better through thick walls and more distance. I am hoping there will be some good insight from you all on a better solution. Right now I am thinking that we will need to cut several access doors in the ceilings and visually identify where the pipes drop down in the walls so that we can use the tone generator and wand with better success. This is a very high end and historic hotel, and I hate to do that. I really need to find these pipes because I will use some of them with a new Mitsubishi S-Series. Please advise if you have recommendations on finding refrigerant lines behind walls, ceilings, and floors.

  2. #2
    Join Date
    Nov 2001
    Location
    Seattle, WA
    Posts
    7,819
    Noise will work sometimes. If the lines are empty put a restriction at the beginning, hook up a bottle of nitrogen and let it bleed at high pressure through the line and you can sometimes hear the noise of the gas going through the lines with a hearing instrument such as made by Amprobe or the like.

    If refrigerant is still in the lines and the systems work you can something do the same with pumping down the systems individually, letting the refrigerant bleed slowly through the lines.
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  3. #3
    Join Date
    Jul 2011
    Posts
    354
    just an observation, there is nothing like the visual, then patch the walls or access doors, jmho. or run new copper lines!

  4. #4
    Join Date
    Aug 2011
    Location
    Charleston, SC
    Posts
    7
    Thanks ya'll. I wanted to mention that these are larger R22 line sets for 1 ton units (3/8, 5/8). I can re-use some of them with a 3 ton Mitsubishi S-series, but cannot re-use them for new 410A 1-ton individual units. I am thinking about connecting the 3 ton Mitsubishi condensing unit to (3) 1-ton wall units in rooms next to eachother. I would re-use one of the line sets for the main and then branch with 1/4, 1/2 line sets to each AHU. I think there will be some major demolition involved, and there is no way around it.

  5. #5
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    Don't they make radio tracers for locating underground cables that may be suitable for your application? If you could use the tubing as the antenna, or find one made specifically for that purpose.

    Quick Google search for HVAC line locator turned up www.schonstedt.com

  6. #6
    Join Date
    Aug 2011
    Location
    Charleston, SC
    Posts
    7
    Thanks, I called them and they said it is for underground only. It uses a magnetic field which doesn't do so well in walls with other wires and pipes. Thanks very much for the tip.

  7. #7
    Join Date
    Oct 2007
    Location
    Austin Texas
    Posts
    1,829
    Try a telephone line tracer. Or an electrical line tracer. It's all copper after all.
    Nemo me impune lacessit.

    How much blood do I have to bathe in to get clean?

    Don't look down on anyone unless you're helping them up.

  8. #8
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    dont give up I know they make stuff to work with wires that injects a traceable signal into the wire (like electricians use). Maybe that would work.

  9. #9
    Join Date
    Sep 2007
    Location
    Boise, ID
    Posts
    4,398
    If it's Historic you are probably looking at lap plaster and maybe some asbestos somewhere, and also lead paint. Just a thought.

    I guess I would be trying an ultrasonic detector. I'm thinking you could hear the refrigerant flowing in the liquid line, Good ones are awful pricey.
    If a nation expects to be ignorant and free, in a state of civilization, it expects what will never be. (Thomas Jefferson 1816)

  10. #10
    Join Date
    Aug 2011
    Location
    Charleston, SC
    Posts
    7
    I appreciate the comments.

  11. #11
    Join Date
    Jul 2011
    Posts
    354

    Confused

    Quote Originally Posted by toughguy1 View Post
    I appreciate the comments.
    hey tough, just curious when you bid on this job initially, did you have this all figured in, or are you figuring this out now, after you started this job. just wondering! me personally i'm big on the visual, with my own eyes

  12. #12
    Join Date
    Mar 2003
    Posts
    7,326
    call grainger and get an ultrasonic kit for less than a thousand bucks.

  13. #13
    Join Date
    Aug 2011
    Location
    Charleston, SC
    Posts
    7
    Thanks Flange. Thes, I didn't bid on the job. I am doing the engineering design. They asked me to first research the easiest, least disruptive, and least expensive way to design the renovation. The research will be by the hour and the drawings will be for a fixed price. Now, I am leaning towards cutting a number of access holes to put my eyes on it. These holes will be cut by a general contractor. There will be more demolition this way, but my drawings will be more accurate. Once I design the new drawings, including the demolition drawings, we will put them out for bid for mechanical and general contractors.

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