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Hot water heating Pex running through old insulated steel pipes

josieTjosieT Member Posts: 53
I've been posting frequently about my ongoing heating saga. I'm close to getting the project started. (thanks to Rich McGrath and John Commerford from the forum for all the valuable direction on helping me solve this riddle!). One of the big open questions is about insulation of the walls. There are two points: #1 reduce the heat loss to make the system more efficient #2 insulate some of the uninsulated pex lines that should have been insulated before I sealed up the walls. I have spoken to a few people about wall insulation in very old houses and have decided to hold off on wall insulation for now - both for cost and potential for damage if a proper vapor barrier is not put in place not to mention having to then repair my newly painted walls.

My central concern is #2. Most of the uninsulated pex lines (supply and return) were actually run through the old insulated steam pipes. The insulation is from the 1930's when the home was first built but nonetheless are insulated.

Can these insulated steel pipes serve to protect the pex from bursting? Any issues with having run the pex this way? Has anyone done a steam to hot water conversion this way?


  • RobGRobG Member Posts: 1,850
    What type of boiler do you have? If your home is as you described I would recommend employing outdoor air reset and constant circulation to ensure you don't get freeze ups.
  • josieTjosieT Member Posts: 53
    I have a triangle tube challenger for boiler and hot water heating. Rich who designed the system did design for constant circulation. If this is the case, should I not worry about the insulation? Not all the pipes are in outside walls. I only have 2 pairs of pipes out of 6 pairs that run in outside walls. I'm trying to to determine if I need to open up the walls and insulate these 2 exposed sets. It would not be trivial by any mean to do with my lovely plaster walls. It was quite a mess to run these up in the first place.
  • Jamie HallJamie Hall Member Posts: 14,749
    You have, as I see it, two really simple solutions. Of which the simplest in many ways -- and less hassle! -- is to do as has been suggested: run an outdoor reset on the system and modulate the circulating water temperature with that, and then run the system as constant circulation. Moving water can freeze -- but it's much much less likely to, and with your setup it shouldn't. The only problem is if the power fails and you lose circulation -- but that may not really be a problem.

    The other possibility is to use an antifreeze mix in your system, but that makes it a lot harder to work on if you ever have to do repairs. That, however, won't freeze even if the power fails.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • josieTjosieT Member Posts: 53
    I do have an outdoor reset control that is part of the boiler configuration. But one thing I completely overlooked is power outage! I'm not going to do antifreeze. The general sentiment is that it's a bad idea. that's the other thing that's bad about these kind of modern boilers is now there's both an electrical and gas dependency.
  • j a_2j a_2 Member Posts: 1,796
    Running any water pipes on an outside wall is not a good idea, at best...I opt for getting them out of the outside wall, or get a carpenter in their to discuss insulation options...
  • 4Johnpipe4Johnpipe Member Posts: 479
    Antifreeze is an option however it will de-rate the heating output of the boiler by the percentage of the antifreeze added. We always keep heating lines away from exposed areas. I know Rich came in after the system was installed to make corrections and constant circulation was his only option other than opening and relocating the lines.
    Perhaps a small back up generator with designated circuits for the hat and maybe a few more circuits would be less invasive and cost friendly...
    Considerate People, Considerate Service, Consider It Done!
    email: [email protected]
  • Bob Bona_4Bob Bona_4 Member Posts: 2,083
    My 2 cents on this entire debacle is the hesitation to open walls led to shortcuts on the initial conversion, and now the Monday morning quarterbacking.

    Converting from steam could have been a rewarding endeavour, if wall and ceiling pre and post op was anticipated, with a trim carpenter involved. It still can.
    j a_2
  • j a_2j a_2 Member Posts: 1,796
    Is it possible to aband the existing lines and run them differently.... Not there but just thinking out load... In remodels sometimes the only option is to box pipes in. Unprotected lines are a definite no no...sorry for your delimna. Best of luck
  • vaporvacvaporvac Member Posts: 1,520
    Have you seen behind these walls, at all? My steam pipes are ALL insulated, including those in the walls, but I don't know if this was standard procedure. I have plaster on lathe over brick.

    Somehow I thought the entire system had been ripped out...I didn't realize you still had the steam pipes in place.
    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
  • josieTjosieT Member Posts: 53
    @vaporvac - the steam pipes that were running through the walls are still there. These pipes are insulated (not super deep) and the new pex is now running through them. So that's why I thought maybe, I might be ok relying on the casing of the steel pipe and the surrounding insulation on the pipe. I've been debating whether to rip up the wall again but I do recall there was not a lot of maneuvering room in the wall. I'd either have to rip put the steel pipe or find another pathway. These walls are a real pain as they are not empty cavities. There was a lot of stuff in the wall.. like wood chips.

    John - thanks for the idea on the generator. Is that something special for heating systems? Or is this a standard power generator? I thought generators are pretty pricey. My electrician had recommended a backup generator to help with Long Island power outages.

    Bob - that's a really great point. I would think too that I can turn the conversion could have been positive if planned out better. I'm trying to pep myself up by thinking I'll get some efficiencies with a multi-zone system and perhaps save a little in energy. it may be worth it for me to figure out how to properly deal with the walls. I knew the walls would have to be opened. But in my ignorant state a year ago, I had no idea what to expect. The varied guidance from the local plumbers didn't help. One guy wanted to run the pex up through my kitchen cabinets. Nobody I got quotes from really thought about it in much detail.

    j a - Rich McGrath originally had an idea that I should consider just running up black steel pipes in the room. Actually, that probably is something I should consider. Given the age of the house and being a tudor, it wouldn't look so out of place. it's just two radiators upstairs that have this piping issue.

    I think when this whole ordeal is over, I'm going to have to throw a big party for the heatinghelp crew!
  • j a_2j a_2 Member Posts: 1,796
    What's nice is you keep us informed...wish more would do the same
  • vaporvacvaporvac Member Posts: 1,520
    Search around the Wall. there were a few long posts over the past two winters on generators for steam and HW systems. They outlined some of the salient safety issues as well as sizing, etc.
    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

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