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  1. #1
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    Mar 2011
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    Lombard, Illinois
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    Default Radiant Heat systems

    Dear Colleagues:
    Has anyone had much experience with radiant heat system. I'm doing more high end homes with them. Besides leaks etc. what other things I should be looking at and report on. Any advise would be much appreciated

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    Fidel F. Gonzales
    RELIANT INSPECTION SERVICE
    http://www.reliantinspectionservice.com

  2. #2
    Join Date
    Jul 2008
    Location
    Utah
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    Default Re: Radiant Heat systems

    Well a couple of things:
    -I would look for proper zoning, that zone pumps or control valves are provided in sufficient number to zone areas for proper temperature control.
    -That the proper piping and fittings are used. PEX is pretty much a given requirement in my book with anything other being suspicious.
    -Look for color in the exposed piping that would indicate either corrosion or proper water treatment. I always feel better when a system is filled with a diluted glycol solution. That way if control or power has been lost for an extended period during the cold season there is a lower likely hood of frozen pipe.
    -Look for proper venting of the boiler.
    -Check for adequate means of pipe isolation. This in case of a need for service that the entire system needn't be drained.
    -Pipe INSULATION is a big one in my book too.

    Just a smidgen of many things to look for, I am sure there are better minds than mine that can add to this list5 for you.


  3. #3
    Join Date
    Feb 2008
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    Caledon, Ontario
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    Default Re: Radiant Heat systems

    Some of these systems can be complex.

    During summer months the system may be shut down, or if its a system which also produces hot water for potable use it may run all year. If its shut down or complex I would be informing the purchaser to have it inspected prior to close of title.


  4. #4
    Join Date
    Mar 2011
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    Lombard, Illinois
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    Default Re: Radiant Heat systems

    Quote Originally Posted by Raymond Wand View Post
    Some of these systems can be complex.

    During summer months the system may be shut down, or if its a system which also produces hot water for potable use it may run all year. If its shut down or complex I would be informing the purchaser to have it inspected prior to close of title.
    Raymond and Rod, Hi Guys, Thanks so much for your help. Really Appreciate your GREAT advise.

    Regards, Fidel

    Fidel F. Gonzales
    RELIANT INSPECTION SERVICE
    http://www.reliantinspectionservice.com

  5. #5
    Join Date
    Mar 2007
    Location
    Cape Cod, Massachusetts
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    574

    Default Re: Radiant Heat systems

    A few things to look for in radiant heating systems, in addition to Rod's comments above:

    1. Look for a distribution header with flow control valves. There are typically many zones piped in parallel. This is to reduce overall length of pipe and pressure drop throughout the system. The flow control valves are used to balance the system.

    2. Look for a three way mixing valve at the main header. This allows the water temp to be controlled to a required lower temp (105 approx). A low temp is required to reduce thermal expansion and temp degradation of materials in contact with the distribution piping.

    3. If the system was not "on and stabilized" at the time of inspection, I would report that the system could not be fully tested. It takes a long time for the system to reach temperature.

    4. I also tell my clients about radiant heating controls and the fly wheel effect. One of the "downfalls" of radiant heating is being able to control the temperature when you want to. You Can't. It takes so long for the material mass to heat up and so long to cool down, it is recommended that you don't try to use the thermostat for set back, or try to reduce the temp at night. It takes too long to adjust and you can't feel the effect, sometimes for hours. So in the spring, if you have the temperature on during a cold night and then the sun comes up during the day and heats up the house, you can't shut off the heat, because of the flywheel effect.

    Here are some things that I don't tell my clients but are my opinion of radiant heating and are based on my past experience as a senior HVAC design engineer.

    It doesn't save on energy - that's a lot of BUNK and here's why:

    The reason people claim it saves energy is due to the even distribution of heat and it's feel. It's claimed that it feels warmer and is more penetrating, so you are able to maintain the room temp a few degrees warmer than you would with baseboard. (And in most cases that's true).

    They don't tell you that within a closed house environment, the radiant element of energy transfer, soon get absorbed by the ceiling and walls and converts back to conductive heat. The radiant heat effect works best in large warehouses and at golf ranges.

    They also don't tell you that you have to leave the thermostat set to one temperature 24 hours a day. They don't calculate the savings of night or week end set back. They also don't calculate, the energy loss when you have to open the windows to cool off during a warm spring day when you can't turn back the setting fast enough. They also don't calulate the x-tra cost of pumping energy.

    There are some thermostats that sense outdoor temp and reset the supply temp and "sort of anticipate" the flywheel effect, but it's not perfect and many times just too complex for the homeowner to understand and manage properly.

    They also don't tell you that installed cost, maintenance and repair is greater than a conventional system.

    With that said and now off my mind, I must say that it "feels good" especially in a tiled or marble bathroom floor.

    Ken Amelin
    Cape Cod's Best Inspection Services
    www.midcapehomeinspection.com

  6. #6
    Douglas Hargrave's Avatar
    Douglas Hargrave Guest

    Default Re: Radiant Heat systems

    Re: Ken Amelin post on Radiant Heat systems
    I read with great interest Ken’s post regarding his opinions and observations concerning radiant heat and would like to follow up with some contrasting opinions and observations of my own.

    The statement “It takes a long time for the system to reach temperature” is true if by system you include the thermal mass of the home and not just the thermal mass which is part of the radiant heat system. It is important to remember that the thermal mass of the radiant heat system radiates to the thermal mass of the home which in turn stabilizes the air temperature in the home. The thermal mass of the radiant heat system does not heat the air of the home directly as is the case with convection heat systems.

    The thermal fly wheel effect of a radiant heat system is certainly very real when you consider the mass and surface areas inside the home as part of the system. The thermal fly wheel effect stabilizes the air temperature inside the home minimizing temperature fluctuation and increasing evenness of temperature between floor and ceiling. Even temperatures between floor and ceiling eliminate much of the draftiness associated with heat systems that use the movement of air for heat distribution. Air which is not in motion feels warmer than air which is in motion.

    The statement that “the downfall of radiant heating is being able to control the (air) temperature when you want to” misses the point that radiant heat systems do not heat air directly but only indirectly through the thermal mass of the home itself. Radiant heat systems are steady state systems employing thermal mass rather than on and off systems employing movement of air.

    Ken assertion that “It’s claimed that [radiant heat] feels warmer and is more penetrating, so you are able to maintain the room temp a few degrees warmer than you would with baseboard” is probably not worded correctly and should probably read “[radiant heat] feels warmer and is more penetrating, so you are able to maintain the room temp a few degrees COOLER than you would with baseboard (forced air).” The second reading of the assertion gives reason for energy savings claims attributed to radiant heat. If you can feel comfortable at cooler temperatures in a radiantly heat home then less energy is required than in a home heated by the movement of air.

    The purpose of the statement that “the radiant element of energy transfer, soon get[s] absorbed by the ceiling and walls and converts back to conductive heat” is a bit confusing to me. Radiant heat systems radiate their energy to the surrounding surfaces in the room in which they are located. The heated surfaces of the room then pass their heat to the room air via conduction. They do this through infrared radiation the same way the sun heats the earth and the earth passes its heat to the air via conduction.

    As I mentioned earlier a radiant heat system is a steady state system and not an on and off system. Attempting to apply the technology of a set back thermometer designed for a forced air system to a steady state radiant heat system does not work. Asserting that because this energy savings technology designed for forced air can not be used with radiant systems makes them less efficient is debatable and could only be proved by a comparison test. I will say that in Europe where energy costs are much higher than in the US radiant heat is the norm and forced air is not. Do the Europeans know something we don’t?

    Douglas Hargrave


  7. #7
    James Duffin's Avatar
    James Duffin Guest

    Default Re: Radiant Heat systems

    If you use the same gas fired boiler to produce hot water for a radiant system or a forced air system the gas cost will be about the same. The installation and maintenance cost of a radiant system will be higher and not worth the expense in a typical house IMO.


  8. #8
    Join Date
    Feb 2008
    Location
    Caledon, Ontario
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    Default Re: Radiant Heat systems

    James, have you had bad experience with maintenance costs with these systems?


  9. #9
    Join Date
    Mar 2011
    Location
    Lombard, Illinois
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    133

    Default Re: Radiant Heat systems

    Quote Originally Posted by Ken Amelin View Post
    A few things to look for in radiant heating systems, in addition to Rod's comments above:

    1. Look for a distribution header with flow control valves. There are typically many zones piped in parallel. This is to reduce overall length of pipe and pressure drop throughout the system. The flow control valves are used to balance the system.

    2. Look for a three way mixing valve at the main header. This allows the water temp to be controlled to a required lower temp (105 approx). A low temp is required to reduce thermal expansion and temp degradation of materials in contact with the distribution piping.

    3. If the system was not "on and stabilized" at the time of inspection, I would report that the system could not be fully tested. It takes a long time for the system to reach temperature.

    4. I also tell my clients about radiant heating controls and the fly wheel effect. One of the "downfalls" of radiant heating is being able to control the temperature when you want to. You Can't. It takes so long for the material mass to heat up and so long to cool down, it is recommended that you don't try to use the thermostat for set back, or try to reduce the temp at night. It takes too long to adjust and you can't feel the effect, sometimes for hours. So in the spring, if you have the temperature on during a cold night and then the sun comes up during the day and heats up the house, you can't shut off the heat, because of the flywheel effect.

    Here are some things that I don't tell my clients but are my opinion of radiant heating and are based on my past experience as a senior HVAC design engineer.

    It doesn't save on energy - that's a lot of BUNK and here's why:

    The reason people claim it saves energy is due to the even distribution of heat and it's feel. It's claimed that it feels warmer and is more penetrating, so you are able to maintain the room temp a few degrees warmer than you would with baseboard. (And in most cases that's true).

    They don't tell you that within a closed house environment, the radiant element of energy transfer, soon get absorbed by the ceiling and walls and converts back to conductive heat. The radiant heat effect works best in large warehouses and at golf ranges.

    They also don't tell you that you have to leave the thermostat set to one temperature 24 hours a day. They don't calculate the savings of night or week end set back. They also don't calculate, the energy loss when you have to open the windows to cool off during a warm spring day when you can't turn back the setting fast enough. They also don't calulate the x-tra cost of pumping energy.

    There are some thermostats that sense outdoor temp and reset the supply temp and "sort of anticipate" the flywheel effect, but it's not perfect and many times just too complex for the homeowner to understand and manage properly.

    They also don't tell you that installed cost, maintenance and repair is greater than a conventional system.

    With that said and now off my mind, I must say that it "feels good" especially in a tiled or marble bathroom floor.
    Thank you for all your work to help. I really appreciated...
    Best regards.

    Fidel F. Gonzales
    RELIANT INSPECTION SERVICE
    http://www.reliantinspectionservice.com

  10. #10
    James Duffin's Avatar
    James Duffin Guest

    Default Re: Radiant Heat systems

    Quote Originally Posted by Raymond Wand View Post
    James, have you had bad experience with maintenance costs with these systems?
    In my previous life I was involved with the maintenance of several hundred boilers, chillers, radiators (steam and hot water), fan coil units, and air handlers. The maintenance cost and the amount of maintenance required was always higher on systems that pumped water all around a building (like radiators) than systems that used air handlers to move air around a building.


  11. #11
    mathew stouffer's Avatar
    mathew stouffer Guest

    Default Re: Radiant Heat systems

    Check the pressure guage, always a must. No pressure.. big problems If you have a therm cam that is always helpful, you would be surprised how may zones are inopertive. Know your boilers, certain boilers are problems in my experience. Look for entran tubing, knowing that will save you a big head ache. And an easy was to cover your butt is to tell the client to have it serviced annually. Listen to the zone pumps as well, the bearing burn out in the pumps and they squeal like a girl


  12. #12
    Join Date
    Mar 2007
    Location
    New Mexico
    Posts
    1,258

    Default Re: Radiant Heat systems

    Quote Originally Posted by James Duffin View Post
    If you use the same gas fired boiler to produce hot water for a radiant system or a forced air system the gas cost will be about the same. The installation and maintenance cost of a radiant system will be higher and not worth the expense in a typical house IMO.
    Not many hot water forced air systems around here, although my brother uses a very old one in PA. You'd need to compare hot water baseboard to in floor radiant to get a better use and maintenance cost. Now, if you are going to need central air anyhow, that also adds a factor into the equation.

    Personally, my next house will definitely have in floor radiant. Less cold areas, more comfortable heat, less dust and real easy to implement solar storage for heat source. We don't use central air very often here, although it is showing up in a lot of the newer houses.

    Jim Robinson
    New Mexico, USA

  13. #13
    Join Date
    Jul 2008
    Location
    Utah
    Posts
    389

    Default Re: Radiant Heat systems

    Quote Originally Posted by Jim Robinson View Post
    Not many hot water forced air systems around here, although my brother uses a very old one in PA. You'd need to compare hot water baseboard to in floor radiant to get a better use and maintenance cost. Now, if you are going to need central air anyhow, that also adds a factor into the equation.

    Personally, my next house will definitely have in floor radiant. Less cold areas, more comfortable heat, less dust and real easy to implement solar storage for heat source. We don't use central air very often here, although it is showing up in a lot of the newer houses.
    Jim I think you hit it on the head and while off topic just a bit I have to agree with you that people that live/have lived in cold climates and have lived with radiant heat will almost universally agree it is the cat's meow of comfort during cold seasons. I too will never have a home in a cold climate again without radiant heat.


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