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1953 in Concrete Radiant heat

I am purchasing a house built in 1953. The house is heated with a combination of Radiant floor heat and an added heat pump central HVAC system. The HVAC system was added within the last 10 years. My concern is with the floor heating. I do not know much about Radiant floor heat but do know it uses a natural gas fired burner system to heat water which is then pumped through a series of pipes which are embedded in concrete. What are the things I should look for to determine if the system is a good one? Help with any information you can.

Comments

  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,789Member
    Take a few picture of the boiler and the associated piping around the boiler. Stand back to get decent pictures. Is it the original boiler??
  • DZoroDZoro Posts: 761Member
    Not enough info to give good advise. Have a trusted HVAC contractor assess the system in person. Inspectors with good HVAC backgrounds can also be of assistance. Post a bunch of pictures and we can take a stab at it.
  • hot_rodhot_rod Posts: 11,439Member
    The biggest unknown is the life expectancy of the copper tube. It would be near impossible to know or confirm the condition or years left.

    I would continue to run it at a low pressure no more than 12 psi and cross fingers. Assuming the boiler is still in safe working condition.

    Back in those days fuel cost and energy conservation were not priorities, so insulation under or around the slab might not be ideal.

    An infrared camera and walk around the exterior of the home would show in living color how much heat energy is going outdoors.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GordyGordy Posts: 9,264Member
    Is the house on a slab, or is there a basement with radiant floor, maybe a mix?
  • soutacomptonsoutacompton Posts: 7Member
    All, I posted the only picture I had of the boiler system piping. The original boiler was fueled from a tank buried in the yard and used heating oil I think. It has been converted to a natural gas fired boiler and has what appears to be 9 separate pipes going up into the concrete floor under the lower level and into the attic where the ceiling of the upper level is heated. I have not closed on the house so I cannot easily get in to take additional pics. I will try to do that in the future for additional comments. Tell me what you see here. The house has an HVAC unit which has been added in the last few years to heat and cool both levels although the lower level has limited duct work. The unit is in the attic and is ducted mostly to the upstairs and to the limited original ductwork in 3 of the 6 rooms on the lower level.
  • soutacomptonsoutacompton Posts: 7Member
    Additionally, the house is on a slab except for the 10 x 10 basement where the gas fired boiler and piping shown in the picture is located.
  • GordyGordy Posts: 9,264Member
    edited December 2018
    I see a manifold with 9 supply pipes with temp gauges on each one.

    From your description there is ceiling radiant for heat at the upper floor.

    I really do not know how to direct you. A pressure test would be nice to confirm that there is no leaks, but could also do damage if not correctly performed.

    How long it all will last is anyone’s guess as been stated earlier.
  • GordyGordy Posts: 9,264Member
    If you love the house there are alternatives for restablishing the radiant if there is a future failure.
  • soutacomptonsoutacompton Posts: 7Member
    Gordy, What are the alternatives?
  • GordyGordy Posts: 9,264Member
    For the slab there are over the top radiant panel assemblies. You would lose a little head room, and probably have to rework base trim, and doors. Warm board R, sun board, Roth panel to name a few.
  • HVACNUTHVACNUT Posts: 2,172Member
    That's no Levitt slab radiant job. More pics.
  • Jean-David BeyerJean-David Beyer Posts: 2,622Member
    I have a house that was built in 1950. It has 1/2" copper tubing (one circuit for each room) in a concrete slab at grade. The boiler was a GE oil fired one. Upstairs was fin-tube baseboard: three feet in each of the two rooms. The whole system was a single zone, so the upstairs was always too cold.

    In about 2009, I replaced the boiler with a mod-con gas burner, replaced the three-foot baseboard sections with 14-foot sections, and ran them as two zones, with hotter water in the baseboard, and cooler water in the slab.

    I do not specifically pressure test the system, but I sometimes cut off the makeup water line and watch the pressure gauge drop. Usually, it will not drop over a period of a week.
    In the boiler is some stuff called X-100 water treatment. It comes with a test kit that I use once a year. If the concentration gets too low (due to makeup water), I have to add some. In the last 9 years, I had to add a tube of the stuff only once.

    I infer it is not leaking.

    If it should leak, I imagine I would put radiant panel on the ceilings and perhaps on walls.

    If I understand correctly, copper tubing fails either because of too much makeup water corroding the tubing from the inside, or a bad mix of concrete that corrodes the tubing from the outside.
  • GordyGordy Posts: 9,264Member
    Copper tube failures occur from to much velocity, high flyash content in concrete, or acidic soil.
  • HaroldHarold Posts: 201Member
    You might want to be sure the abandoned buried oil tank has been removed. Depending on where you are located, if a tank is down there you have to remove it or perform some sort of mitigation..
  • soutacomptonsoutacompton Posts: 7Member
    All, The house has hardwood flooring directly on the concrete slab that contains the copper tubing. I am closing on the house on Jan 3rd. I will post a number of pics at that time or shortly thereafter. Thanks for all of the information.
  • GordyGordy Posts: 9,264Member
    That’s awesome!
  • soutacomptonsoutacompton Posts: 7Member
    I have added a pick with the radiant floor heat on from the home inspection. Of the nine loops one was not circulating and warming up as much as the other 8. The temps in every zone circulated 95 degree water and the temps in the floor reached 75 degrees. I was not there so I do not know how long the system was running.

  • nibsnibs Posts: 260Member
    @Gordy
    Never heard of fly ash being a problem for copper, have you any more info?
  • GordyGordy Posts: 9,264Member

    I have added a pick with the radiant floor heat on from the home inspection. Of the nine loops one was not circulating and warming up as much as the other 8. The temps in every zone circulated 95 degree water and the temps in the floor reached 75 degrees. I was not there so I do not know how long the system was running.

    That’s beautiful, and temps are just right. Floor should feel neutral unless the load increases, and there is poor envelope insulation.

  • hot_rodhot_rod Posts: 11,439Member
    nibs said:

    @Gordy
    Never heard of fly ash being a problem for copper, have you any more info?

    There are all sorts of additives used in concrete and some, become corrosive to the tube especially when the concrete stays wet. become corrosive to concrete.
    https://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GordyGordy Posts: 9,264Member
    edited December 2018
    Yes it’s during the hydration process, and later when moisture is absorbed in concrete from other sources. There are so many mix designs with certain percentages of fly ash usually up to 30%, and a couple varieties of fly ash C, and K which come from different source materials.

    Back then the mix designs for residential were pretty straight forward. Today as @hot rod_7 notes there are all sorts of water reducers, air entrainment, plasticizers etc. in concrete. Also some residential concrete guys like the self leveling concrete add 30 gallons then look at it :) which exasperates that initial cure corrosive state.

    I had one job that was consistently getting low breaks for 7 and 14 day. 28 day just made design strength. Usually you can get strength in 3 days with a good design. It was traced down to brand x air entrainment, and brand y water reducer were not playing well together so there is all sorts of variables today.
  • GordyGordy Posts: 9,264Member
    The strongest, and least corrosive concrete is in which has the least amount of water to produce proper consolidation, and workability.

    That’s not a consistency that allows you to pour a 60x80 foundation from two opposing corners...........
  • nibsnibs Posts: 260Member
    Thanks for the tips, I always use fly ash when I can get it, thankfully did not use any when pouring my radiant floor although the only inslab copper is for my DW.
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