Radiant Heating Design Help

Discussion in 'HVAC Heating & Cooling' started by mbeffa, Jun 3, 2011.

  1. mbeffa

    mbeffa New Member

    Messages:
    2
    Location:
    Cupertino, CA
    I am planning a retrofit to my heating system, which today consists of two wall-mounted
    has heaters, installed probably 60+ years ago when the house was build.

    The house is on slab on grade. Temperatures are mild, almost never bellow freezing.
    We never heat the house at night, and during the day lowest temps are in the high 30's.
    First floor has 2,200 sq.ft. and I'd like to have 4 spare circuits for possible attic expansion.

    After a few months of web reading I came up with a floor sandwich:
    http://www.beffa.com/FloorCrossSection.pdf

    and a layout:
    http://www.beffa.com/Radiant_Heat.pdf

    I still need help with the design.

    I would appreciate any critique or advice. I would not mind paying for competent advice, but so far I was not able to cut through the thick, it's just too much info out there.
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Your sandwich system adds 3"+ to the floor. Are you ok with lowering your ceiling height that much? You show hot water heat, Where are you planning to get the hot water?
    This is a job for a reliable heating contractor. He will figure out how many total btu are needed for your house, and design the zones. I am guessing your house does not have the insulation factors shown in that diagram.
  3. mbeffa

    mbeffa New Member

    Messages:
    2
    Location:
    Cupertino, CA
    I am raising the ceiling with 12", less 3" due to the floor raising. Final ceiling height will be about 105".
    I can get domestic hot water from a traditional, tank-based water heater, or from the same boiler used to heat the house.
    I have not decided yet, I am open to a suggestion.

    I have two water heaters in house now, each holds about 35 gal. Secondary was installed for convenience, when I added a bathroom.
    They've been working 24 hours/day for about 20 years without a glitch and they cost a few hundred dollars. Hard to beat.

    I am planning to insulate all the walls and the roof with R19. Slab is not insulated, maybe I can add 2" of XPS on the sides.

    If someone knows the "reliable heating contractor" who can design this system, I'd like to know. I am planning to do the installation
    myself with the help of a few friends.
  4. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,075
    Location:
    Maine
    I can design it for you. I get $ 246.00 an hour for engineering design systems and I would guess that the bill would be around 5 grand or so.
  5. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    When designing a residential radiant floor heating systems the designer (preferably Radiant Panel Association certified) will always start with a heat load analysis. A certified designer will have all the weather data for your area and can determine the type of radiant panel that best serves your heat load and your person preferences.

    A potential designer should have CAD drawings and pictures of his work and will require a drawing, which should include the house with all its rooms and windows and all insulation values, if known. From this information the radiant designer can determine if the radiant panel you have chosen will work efficiently and keep you comfortable.

    As you suggest, a combi water/space heating system appears to be in order. I just finished a radiant floor design in Oakland, CA using a sub-floor radiant system, condensing sealed combustion water heater and sub-assembly, including heat exchanger, pumps and control system with the all important outdoor reset.

    Here in Minneapolis we often use this system for basement heating which is not on grade and retrofit slab-on-grade with sandwich radiant floors and European panel radiators.

    The sandwich system you have referenced here is sub-standard for your area, increasing floor height unnecessarily without appreciable improvements in performance. "Reliable heating contractor" is good but trained and experienced radiant heating professional is even better.

    http://www.badgerboilerservice.com/hotwater.html
  6. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,075
    Location:
    Maine
    damn, there goes that commission :)
  7. crazymountain

    crazymountain New Member

    Messages:
    1
    Location:
    Montana
    It is always a good idea to talk to at least 3 different contractors before going forward. When you are ready to make a decision, get three bids from contractors that have a license, so that you are protected. This is a project for someone who has the knowledge on heating systems. www.crazymountainheaters.com
  8. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    It all looks good to me, but you could use a 1.5 x 1.5 sleeper and gain some insulation. Be sure your insulation is treated for ants.
Similar Threads: Radiant Heating
Forum Title Date
HVAC Heating & Cooling Check valve for open-direct radiant heating system May 14, 2013
HVAC Heating & Cooling Phoenix Water Heater for Radiant Floor Heating and Domestic Water Supply? Dec 28, 2012
HVAC Heating & Cooling Radiant heating/woodstove Feb 28, 2012
HVAC Heating & Cooling Reworking Radiant Heating Zones. Does this look right to you? Sep 30, 2010
HVAC Heating & Cooling will this for radiant heating Feb 6, 2010

Share This Page