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  1. #1
    Join Date
    Jun 2012
    Posts
    10

    Which way would you go and why?

    30 year old bungalow with full basement.

    Plywood sub-floor over conventional 2 x 8 joists

    Intended floor covering- recycled barn siding - everywhere.

    Choice 1... install the PEX in the joist cavities using aluminum radiator plates

    Choice 2 ....use some sort of low profile system on top of the sub-floor that will allow the flooring to be properly secured.

    Yes.... I will be using a local PRO to design the system.

    I'm just looking for opinions on whether there is a major benefit to Option 2 over Option 1.

  2. #2
    Join Date
    Feb 2010
    Location
    NE Alabama
    Posts
    301
    A lot depends on your location and the tightness of the space under you house. Pex infloor heating is usually enclosed in a concrete slab and the +55f provided by the ground under the slab provides a baseline temp to figure your heating needs from. Anchoring your pex to the underside of the floor even with aluminum backing lets the heat radiate into relatively open air.

  3. #3
    Join Date
    Jun 2012
    Posts
    10
    The bungalow sits on a full block basement. It is going to be framed and insulated to R-20 all the way around. I intend to heat the basement as well because it will be divided into rooms that will be in use all year around.

    I am in southern Ontario, Canada. Winters here are not all that tough. We are on the same parallel as northern California and Maine.

    Joist cavities can be insulated if need be.

  4. #4
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Quote Originally Posted by hydriv View Post
    I am in southern Ontario, Canada. Winters here are not all that tough. We are on the same parallel as northern California and Maine.
    As someone who has spent almost his entire life in Texas, New Mexico, and Arizona, I find "Winters here are not all that tough", and "We are on the same parallel as northern California and Maine", to be contradictory statements.
    If more government is the answer, then it's a really stupid question.

  5. #5
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    I can now see why radiant is considered CAN

    Quote Originally Posted by hydriv View Post
    The bungalow sits on a full block basement. It is going to be framed and insulated to R-20 all the way around. I intend to heat the basement as well because it will be divided into rooms that will be in use all year around.

    I am in southern Ontario, Canada. Winters here are not all that tough. We are on the same parallel as northern California and Maine.

    Joist cavities can be insulated if need be.
    Radiant with Transfer plates are going to be the most comfortable, but you knew that! Insulation is a must to control where the heat goes. seems a calculated amount of insulation ( for the plates) will allow the bstm ceiling to act as a radiant surface as well, but how to get the level of insulation right?

    Only 2x8 floor joist?
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  6. #6
    Join Date
    Jun 2012
    Posts
    10
    Mark,
    No disrespect intended but I have run across many Americans who equate living anywhere in Canada as being close to the Arctic. If you look at a map of the continent, you will see that I have to fly north west from Toronto to reach Minneapolis. In Moose Jaw, Saskatchewan....snow was still flying there a few weeks ago. That's what I call a tough winter when temps can fall to 40 below in either language. LOL

    genduct,
    If I knew for sure that the transfer plates was still the best way to go, I would not have posed the question. I am concerned about the combined thickness of the 3/4" fir plywood flooring and the 3/4" barn wood as being too much of an insulator. As you well know, you get but one chance to install these systems economically and I want to be sure that I get the very best advice possible.

    ONLY 2 x 8 joist?

    This property is new to me. Currently the entire basement area is finished but it was done poorly. Aside from shoddy workmanship, the room layout does not suit my needs. I also have no idea about the level of insulation behind the drywall. Experience has taught me that it is far, far better to totally gut areas like this completely and start with a fresh plan. I will be 68 on the 16th of this month and I have built several homes in the past but always with scorched air systems.

    This will be my final home (hopefully) and I want it done my way. No more 2 story homes for me. All the primary rooms will be on one level. My guests get to climb the stairs if they wish to stay overnight.

    I have not removed the drywall ceiling everywhere to see how the subfloor was framed and supported. There are a couple of holes in the ceiling of one room and the joists exposed there are 2 x 8's. I expect to find that dimension everywhere....unfortunately.

    In order to keep as much headroom as possible, I will probably end up using hydronic baseboard heaters on the lower level.

    Thank you both for your replies.

    Any suggestions regarding the brand of transfer plates? Any other input of any kind?

    When it comes to propane fired boilers that will look after hot water needs, I am open to suggestions.

  7. #7
    Join Date
    Feb 2010
    Location
    NE Alabama
    Posts
    301
    This is from a website i found

    For many builders, the reluctance to install hardwood floors over radiant heat stemmed from problems associated with the original technology introduced more than forty years ago. Then, floors were heated excessively to compensate for poor building insulation. Those high temperatures exaggerated expansion and contraction in hardwood flooring, causing irreparable damage to both the floors and builders' reputations.
    MOISTURE CONTENT Once the sub floor, tubing and thermostats have been installed, the heating system should be run for at least 72 hours to balance the house's moisture content. Now follow the customary procedures for installing any hardwood floor. Be sure to monitor the moisture content of both the sub floor and the flooring, because this can have a profound effect on the end result of your installation.
    SLABS The slab should be dried with heat before installing a hardwood floor. Never install wood flooring over a concrete floor until you have turned on the floor heating system to remove any residual moisture from the slab. The easiest method to test a slab for moisture is to tape a 4 ft. x 4 ft. section of polyethylene plastic sheeting to the slab and turn on the heat overnight. If moisture appears under the plastic, heat the slab another day and test again. Repeat this test until no moisture appears.
    PLYWOOD SUB FLOORS Do not deliver the flooring until, you have turned on the heating system, the plywood is dry and the room has reached the proper relative humidity. radiantdesigninstitute.com

  8. #8
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    The OP is right. Much of Ontario is more moderate. pArtly because, like Western Micigan, it sits on the East side of a large body of water (lake Huron ,Erie and Ontario. IT get lake effect rain, snow and clouds which moderates teh temrpature. FOr example SE Iowa where I am is nearly as cold in terms of average temps as SE Michigna where I grew up, which is further north, But doesnt; get nearly as mcuh rain, snow or clouds in witer. I don't miss the gloom.

    That beign said, it's still a northern heating dominant climate. But not far enouhg north or as temprature as CA which has a VERY large body of water to the west of it.

    I would still price a straight split system. Trying to heat through a subfloor and hardwood flooring might not work as well as tile on a slab. It will take more loops since heat transfer is reduced. It will be easier to heat the basement (will it be finished?) with a furnace.

    IF you go radiant, you might want ot look at a combi boiler that will do domestic hot water and have a priamry loop still for hydronics.

    Finally, on other solution is a combination system with some infloor heating loops, that are suplemented with a hydronic coil on a air handler sized for cooling load (which will be smaller than heating load in your climate). Then you can add central AC later.

  9. #9
    Join Date
    Jun 2012
    Posts
    10
    Thanks for those thoughts.

    However, the very last thing I want in this house is ductwork that steals headroom from the basement level and fills up joist cavities with supply pipes and cold air returns. I would sooner stick with the electric baseboard heaters. I certainly realize that PEX in a slab with tile on the top is far more efficient but that's not going to happen.

    This is a waterfront home. Unlike some people who build subdivision style monstrosities on lakefront property, this place will look and feel like a true cottage when finished. With the barn board flooring everywhere, there will be no concerns about walking inside with bare feet that have sand on them. There will be no changes in the floor elevations and a wood floor always feels warm where as tile or stone does not.

    So... while the wood floor may not be the most ideal medium for radiant, it is what it is and I am left with trying to come up with the best components that will work.

    Air conditioning will be handled by a ductless system.

    crymtide,
    Thanks for that quote.

    Here's my dilemma. If I install the aluminum plates on the underside of the 3/4" plywood sub-floor and then turn on the system for a few days to stabilize the level of humidity, I feel that there will be problems with nailing down the barn wood because I expect nail penetration of the sub-floor.

    During the cold weather, the floor heat is going to drive moisture out of the wood, thus causing some shrinkage to take place. When the heat is turned off, warmer weather will bring humidity which will cause expansion. It is my intention to use the A/C only when absolutely needed. About all I can do is to monitor the humidity levels and supplement low humidity by way of a separate humidifier to keep things as stable as possible. I intend to make use of a moisture meter on the barn board as well as the sub-floor with a view to making the readings match.

  10. #10
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    I think having a minisplit on the wall looks a lot worse than than a couple invisoble floor registers in front of a couple window where you don't place furniture anyway. In a small home, a central floor return is fine. The main supply trucnk can be as short as 6" hgih, no more than the main support beam. The ducts can fit neatly into the joist spaces, even under the pex. I'm not sure how large the home is and how well sealed and insulated, but a 2 ton air handler will only need 6 supplies but could handle 1/2 you heating load with 30-40k BTU's and it can handle humidity control with a simple humidifer and the correct thermostat. You can even set the radiant heat as teh first stage, and hot water coil as 2nd stage. You'd also have hte option of a heat pump if you have higher gas prices and low electric rates and do dual fuel.

    If this was 2 story or without a basement I might suggest otherwise. But a full basement makes a split system easy to install without opening up walls and usually cheaper than a comparable quality and efficiency mini split.

  11. #11
    Join Date
    Jun 2012
    Posts
    10
    I truly appreciate your persistence in providing me with options. I will definitely canvas those with the local PRO. The fact that I only have 8 inch cavities to work with would seem to be a problem for me when it comes to having radiant and also duct work in the same cavity plus insulation.

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