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  1. #1
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    Default How to insulate above radiant water heating in ceiling?

    I have a 1950 daylight ranch and the radiant water heating on the ground level is in the slab, but upstairs (Where the main living area is) has radiant water copper pipes in the ceiling and there's no insulation above it. Our heating bills are ridiculous in the winter and I'd like to know how to insulate above the pipes? Do I need a radiant barrier for above the pipes or can I just lay the roll fiberglass insulation over the top of them? I've also heard that I need 3/4" air space and another person told me 6".

    This is a rare bird that has this kind of heat in the ceiling so does anyone have any experience with this?

    Thanks.

  2. #2
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    Default Re: How to insulate above radiant water heating in ceiling?

    Are you saying you have no insulation in your attic? Just how are the radiant lines installed? Can you see them in the attic?

    John

  3. #3
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    Default Re: How to insulate above radiant water heating in ceiling?

    So when you pop up in the attic you basically have copper water pipes sitting directly on the drywall of the ceiling of the second floor. They're installed through the joists (Holes drilled for the pipes) all throughout the attic.

    Honestly it's an amazing bit of work...my house is 2800 square feet so figure the attic is 1400 square feet and the whole thing is like this with pipes every 6 or so inches across the top. Amazing that this was done by hand and not with a modern lego-style piece together hydronic system. Lot of copper, lots of brazing...it's really neat, and not very insulated.

    There are parts that seem to have some kind of old ripped up insulation that I'm going to get rid of, and there's about a 300 square foot platform built up there for attic storage (no insulation below it, someone just tossed some plywood down). Mostly though it's just bare pipes visible all over the place.
    Last edited by GregoryK; 09-07-2012 at 01:31 PM.

  4. #4
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    Default Re: How to insulate above radiant water heating in ceiling?

    It didn't occur to me to ask the great questions that John did about how the radiant piping is arranged and apparently the absence of any insulation to cover the piping, so that the radiant energy & heat is directed DOWN into the living space----great post, John!

    Gregory:

    How long have you lived in the house; how long have you experienced a problem with inadequate heat; have you consulted any heating service technicians on the problem; do you hear any gurgling sounds in the ceiling when the heat is on; have you touched the copper pipes to see if they heat up when the heat is on; in what general part of the country do you live???

    This system sounds like it does originate back in the 1950s when radiant heating systems were new to the U.S., (much more common in Europe) and at that time the style or fashion was to put some of them in the ceiling---this was in keeping with many commercial applications at the time, and is still practiced in many commercial buildings today.

    The basic concept of hydronic radiant heat is that instead of running pump-driven hot water thru a cast iron radiator system, or copper fin tube baseboard system at the base of the room's walls, the strategy is to bury the copper tubing (now plastic PEX tubing used) in a 3"-4" concrete floor slab, or under floor (wood) applications, or less commonly in residential applications, in the ceiling plaster, like you have-----in each case, instead of the cast iron radiators, or baseboards radiating and convecting the hot water heat into the room via air currents, the ENTIRE PLASTER CEILING (or concrete floor slab in floor installations) BECOMES THE RADIATOR; the plaster ceiling heats up & generates infrared heat waves that give up their heat when they strike objects in the room (the floor, carpet, furniture, people, tables, etc.)---this is a notably different method from, for example, forced hot air systems that circulate fan-driven hot air in the room through steel supply/return ducts; radiant heat is similar in concept to having several large boulders in your yard (or even as part of a west or south-facing first floor wall of your house), heated by the hot sun all day long---- touching them long after sunset, they will still feel very warm, and will give off heat for many hours as you stand next to them---in all these cases, we have a LARGE MASS (boulders, concrete floor slab, plaster ceiling) absorbing heat from the sun (or the hot water pipes) & then radiating it off into a living space.


    Consider yourself fortunate; hydronic radiant heat, be it from the floor or ceiling is widely considered the best, most economical and most comfortable way of heating a home; the system you have will work wonders for you once you get it squared away with the help of an experienced hydronics contractor.


    I would recommend that you first get a heating contractor/technician over there to take a look at the system; first to check the heating pipes in the attic to make sure they are filled with an adequate amount of water (any air in the piping is bad; it is a very common cause of no heat in hot water systems, because air always rises to the highest point (the attic) in hot water pipes) & will always rise in the pipes to the attic/ceiling piping, peventing them from giving off heat) ; there is almost always little AIR VENTS along different points on the copper piping that can be opened with a small screwdriver or key-way tool (hold a small cup underneath to catch any water coming out) to get the air out of the pipes; close the little vent screw when all the air is expelled, & only water comes out; if you can't find any air vents on the attic/ceiling piping, & there is no heat in the pipes when the heating is turned on, there are usually purge fittings near the boiler piping to get the air out.

    Check that the pipes get HOT when the thermostat is turned up and the heat is on; you'll have to verify that the pipes are heating up the plaster ceiling---you and the contractor can then think about covering the attic tubing with insulation so that the radiant pipes don't have to fight the attic winter cold to heat the living space below.

    Check the Yellow Pages under "Heating Contractors" and check their display ads for those specializing in "hot water" or "hydronic" heating; also Google the same info along with your town/city on your computer to also find the right service person.
    Last edited by brewster; 09-07-2012 at 03:19 PM.

  5. #5
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    Default Re: How to insulate above radiant water heating in ceiling?

    Quote Originally Posted by brewster View Post
    It didn't occur to me to ask the great questions that John did about how the radiant piping is arranged and apparently the absence of any insulation to cover the piping, so that the radiant energy & heat is directed DOWN into the living space.
    This is what I want to do is put a blanket of r30 or more on top to force the heat down instead of just warming the attic which seems to be what it does best. I don't know how to go about this because I can't find anyone who has done an install above pipes like this before. Do I need a radiant barrier? Does it create condensation? One guy who worked on my boiler told me that I needed a 6" air space and another guy told me 3/4" and the third guy told me to put the insulation right down over the top.

    I'm a little confused but I'm also tired of $200 heating bills. All I want to do is put a cap on the top to keep the heat in the house.

  6. #6
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    Default Re: How to insulate above radiant water heating in ceiling?

    I would do just what you are thinking of. What I would do first is talk to a insulation company and see what they suggest. Not sure if you should use a vapor barrier or not. But you do need to get insulation over the pipe. I am very much surprised you haven't had any problems with the lines freezing. (or have you) Just curious as to what type ceiling you have is it drywall or plaster?
    I have installed many system like that but never in a ceiling. Mostly in floors and some times in walls but never in a ceiling.

    John
    Last edited by johnjh2o; 09-07-2012 at 02:56 PM.

  7. #7
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    Default Re: How to insulate above radiant water heating in ceiling?

    Yeah, I've talked to insulation companies as well and they all have different opinions. I'm just trying to find someone who has actually seen/installed something over the top of the pipes.

    I live in Oregon, not much freezing goes on around here. Light snow some years is as close as we get.

  8. #8
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    Default Re: How to insulate above radiant water heating in ceiling?

    It's a very simple matter to check the heat output of the system first, before thinking about any insulation.

    The insulation will do absolutely nothing if the pipes aren't getting hot.

  9. #9
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    Default Re: How to insulate above radiant water heating in ceiling?

    I know that they are getting hot, I've felt them (Also you can touch the ceiling...I'm tall enough to do comfortably). The water temperature is set to 125 usually and it works fine, just there's nothing holding in heat.

  10. #10
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    Default Re: How to insulate above radiant water heating in ceiling?

    If you can't get a insulation company to advise you I would just use insulation with out a vapor barrier. You can't just do nothing unless you like paying to heat your attic. When they were using electric radiant heating in the ceiling that was how they insulated it.

    John

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