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Air exchange with radiant

Lurker_2 Member Posts: 123
So the radiant system is in the works, have a couple of guys getting quotes together. Now it starts me thinking about ventilation. Do I really need some fancy air exchange system or can I just open the dman window once in a while.
Well, I better get it figured out before the walls are finished. I was thinking of ducting it for air anyway....

Any direction to point me on that subject?


  • Robert O'Connor_7
    Robert O'Connor_7 Member Posts: 688
    Ducting it anyway??

    If you are going to install AC, why not install a good media filter and a good humidifier. The added humidity will maximize your overall comfort in the winter, and help with the air quality as well..Robert O'Connor/NJ
  • Mark Hunt
    Mark Hunt Member Posts: 4,909
    Air changes

    Air changes in any structure are directly tied to how well the structure is sealed and not by the type of heating system in the structure.

    If the home is loose, it won't matter whether you have radiant or forced air, the house will be dry in the winter. If it's tight, you will need mechanical ventilation.

    Ask the builder what he is shooting for in the way of air changes per hour.

    Mark H

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  • don_37
    don_37 Member Posts: 2

    would radiant heat have anything to do with air changes?

    I think it depends on how tight the house is and more so
    of a issue of moisture control.Sure we all need some fresh air,but if your envelope has lots of leak,you will get plenty of fresh air.Thru fireplace,furnace, or anything that needs air to burn.

    Plus the humidifider to replace the moisture that all that entering air will need after its heated up.

    How tight is the envelope?

  • Lurker_2
    Lurker_2 Member Posts: 123

    I didn't think dry in the winter was the problem, thought it was the moisture.

    I dunno, but most of the builders I know wouldn't know the difference between air changes per hour and diaper changes per hour. Leave it to the heatin' guys.

    funny, I'm looking at paying more money to let the heat out of my house.....maybe I should just unlatch all the andersons.....

    Seriusly, it just seems I'm going to end up with the whole duct monster I didn't want anyway

  • Lurker_2
    Lurker_2 Member Posts: 123

    It is new construction, although I didn't like the way he did the housewrap, like in 4 foot strips instead of one big roll. All andersons, or some high quality low e vinyls. The rest is still open frame. I suppose if we are careful with the vapor barrier it will be pretty tight
  • Mark Hunt
    Mark Hunt Member Posts: 4,909

    Every hole that is drilled in your new home will act like a chimney. Those holes are what allows "stack effect" to take place.

    Warm, moist air rises and leaves a structure at the top. Cooler, drier, denser air enters at the bottom and begins to pick up heat and moisture and the process repeats itself over and over.

    Fiberglass insulation does NOT stop air movement, it only slows it down. If the builder is using fiberglass and he is not going to seal all of the holes that get drilled, you will probably not need mechanical ventilation.

    I know that many builders have no idea what "air changes per hour" are, much less how to calculate what the correct ACH should be. I have yet to see a new home that is being built to "code" require mechanical ventilation. Most of the ones we test are so loose they need serious air sealing.

    If you were using dense packed cellolouse or Icynene, then I would say that mechanical ventilation would be a must. More than likely your home will not be so tight.

    Mark H

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  • don_37
    don_37 Member Posts: 2
    I hear

    its anything under .3ach,is when one would need to add fresh air.I like Mark have yet to see it in my area.

    One way to tell where the cold air is entering,take a meter that read rh and where ever it the highest is where you have a leak.

    Other then that a blower door test will tell you where you need to make improvement.
  • Weezbo
    Weezbo Member Posts: 6,232
    Depends what state your in:)

    now that might sound like a loaded statement so i will clarify.if you build your own home and have no intention of selling it,and you dont live in a state demanding outside air changes you are in one state now if you live in a state where the building requirements are wraped around the house belongs to the bank and the bank isnt a real estate agentcy,the building codes are all about high effecientcy and health concerns then you are in another...you may read about air handeling units known as HRV's two popular ones are Vanee and life breath. there is so much info it is easier to read the whys and wherefores than to write bits and pieces to describe in detail.,
    you will recover some heat sure however they are also energy drains and are honestly hard to determine the exact amount of good they are actually doing for your health. having said that there is a descided difference in a home with one than without.
  • jerry scharf
    jerry scharf Member Posts: 159
    HRVs, ERVs and leaky houses


    Like others said, it's all about how tight is your house. Your builder may not have a clue, but a blower door test will answer that.

    If you have a leaky house, then you'll pay a bit more for heat and have lower RH in the winter, but nothing is needed.

    If you're tight, then you do need to change air. There are two main reasons for this. One is moisture contributed by cooking, washing, breathing and the like. The second is the build up of VOCs and other pollutants in the house air.

    If you have an A/C system going in, it's standard to use that air handler and ducts to attach the air exchange system to.

    HRVs move the inside air past the outside air to transfer some of the BTUs in/out of the stream. HRVs have to have a condersate drain. ERVs are the high end, and transfer moisture as well as heat. Some boast very high numbers, but also require maintenance.

    If you're not sure, you can always put the roof or wall penetrations in for an HRV/ERV, then see what a blower door test says when the house is all insulated. Also, make sure whatever you might buy will fit into where it needs to go.

    good luck,
  • hr
    hr Member Posts: 6,106
    A blower door test

    when the home is completed is about the only way to get an accurate infiltration number. Too many factors, product quality and workmanship being the biggest, that will determine what you end up with.

    Opening windows is probably not the most efficient way to get air changes. Think I would look at HVR units for HX and fresh air requirements.

    hot rod

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  • Lurker_2
    Lurker_2 Member Posts: 123

    I will continue rattling around how I want to duct for potential A/C and wait to see how tight the place ends up. I think it will be average, since I will be taking some care to seal it up, but frankly it sounds more trouble than it is worth to make it refrigerator tight
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