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DIY Radiant heat flooring...

Post in 'The Green Room' started by got wood?, Aug 13, 2006.

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  1. got wood?

    got wood? New Member

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    OK, so with all this talk about saving money to heat your home, I'm wondering how many of you folks are radiant heat flooring fans? I've got an older home (100+ years) and I've been budgeting for radiant flooring between the joists on the 1st floor (unfinshed exposed basement) as a fun DIY project. There are suppliers that will sell you the PEX, the aluminum flashing and you supply the insulation. It seems like a no brainer to me to pump 100+ degree H2O all day instead of 160+ degree heat through baseboards. Is anyone here a fan of radiant floor heating (H2O/electric/whatever) over conventional forced air/hydronic/steam/etc? Has anyone had luck with the DIY route? It seems very straightforward to me...hot water source, pumps, PEX and a thermostat...

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  2. suematteva

    suematteva New Member

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    Got Wood,

    Not sure if this helps you.

    We have roughly a 60 x 30 ranch, the stove is in insulated basement about a third away from closest short wall. At the far end of basement, unfinished garage, above is bedroom and living room..this section has heating in floor..primary is forced air..Very happy with it, it works well with our stove setup and with the sun that this area gets in afternoon..
  3. cbrodsky

    cbrodsky Member

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    I've read that it can cause a lot of problems with wood flooring - any shrinkage you get in winter will get worse. It's not a huge problem for us, but that is the one potential downside I see. That being said, I could see trying this down the road at some point if I can convince myself it won't cause problems.

    -Colin
  4. suematteva

    suematteva New Member

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    We have maple flooring and have not noticed any different shrinkage factor...will double check but not off the top of my head..
  5. Harley

    Harley Minister of Fire

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    Well... this is not the same situation.... but maybe it will help.

    Our office and shop space had this system installed when the building was built about 5 years ago. The difference is that this system was installed in the concrete slab. It works GREAT for the shop area. when the bay doors are opened up in the winter, it take almost no time at all to maintain a good working temerature. The floor remains warm, and as we all know, warm air rises, and its a very comfortable work environment even on the coldest days.

    The office part is another story. The heat generally kicks on in the morning, so the floors and the office are nice and toasty warm when we get in. Throughout the day, the thermostat never kicks the boiler in for the office section, as the big slab is still radiating heat. On a sunny day, The solar gain heats the office up to an almost unbearable temperature. The only one who likes the system in the office is my dog, who ends up looking like a giant bear skin rug, stretched out trying to absorb as much of the heat as possible.

    I don't know if this drawback would apply in your situation, since I'm talking about a huge chunk of concrete being heated up versus in the joists of the floors in your house. It doesn't react quickly to changes in outside temps.

    I know these systems are getting very popular, so my guess is, that they would work very well in a home application.
  6. Rhone

    Rhone Minister of Fire

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    I'm going to be going that system in a couple years, my next goal is to get the 6-8 solar panels up and my 3 storage tanks, then insulate the basement, then install radiant heat. I figure, those 3 methods give me the credits & most savings doing it in that order. I asked Radiantec who I plan on purchasing my staple up radiant floor heating and solar panels about my wood floors and here's their response:

    So, that's how you protect your floors, simply set that sensor to not let your floors get over 80F and you're opting to protect your wood floors over being comfortable on some really cool days IF your house loses so much heat the floors have to maintain over 80F. Radiant staple-up heating is best for well insulated houses. They tried the staple up radiant floor retrofitting to some really old houses, and the floors had to maintain 100F+ to compensate for the heat loss and the wood floors warped. Before going to radiant floor heating, you need to up your windows & insulation to make sure your old house isn't like the test old houses they experimented on, where you lose so much heat your floors have to maintain too hot of temps. A well insulated/tight house the floors usually don't need to get above 75F even on the coldest days. The type of wood floors matter also. The wider & thicker the individual planks the worse. Solid wood floors are worse than the engineered 3 or 5 ply. Maple is worse than Oak. Things like that. Haven't exactly figured out what to do about rugs, if the sensor says stop when the floor reaches 80F and you stick it on open floor that has a rug in the middle, the rug will insulate the floor and I'd expect it to get warmer than where the sensor is.
  7. suematteva

    suematteva New Member

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    After reading Rhonemas posting, remembered that ours has a limiter for temperature..maple floor is around 3 inch std all tongue & groove..would back up what that says for most part..
  8. cbrodsky

    cbrodsky Member

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    Sounds like this would be very viable where you use radiant as a backup heat source to wood, for example. When we built in 2001, the experience w/radiant was very mixed but sounds like it is proving itself well and the sensor idea is smart. We have brazillian cherry floors throughout the entire house - very dense wood. Could mean it conducts well - not quite sure how it would play out.

    We're going with three panels for DHW so I wouldn't expect excess for dead of winter use, although I may eventually do a heat exchanger with the wood stove to help backup DHW in winter. Depending on how effective that is with a stove running 24x7, it might be a neat way to generate low grade hot water for radiant heat to essentially help distribute the woodstove heat to the perimeter of the house. What is unfortunate is that we cannot retrofit to the second floor - that is where such a technique would be ideal to help that wood heat get around to the far corners of the house.

    If only I had thought of all this and had the money/tax incentives to do all this up front before we had baseboards put in...

    -Colin
  9. suematteva

    suematteva New Member

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    Our system has been in a while a couple years before 2001, when we moved in...Rhonemas where is that company radiantec based any idea?
  10. got wood?

    got wood? New Member

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    I've read that about wood warping too...what I've typically heard in response is that for joist installations you want to run it cooler (i.e. not 120F through the PEX, closer to 100F). I too am curious about the efficiency of a subfloor and hardwood floor acting as a large heat source (radiant heat usually shines for concrete/stone installs where the thermal bounce is much more gradual).

    What do you folks use for hot water on these installs? I am going back and forth between a cheap hot water tank and tankless system. Of course tankless costs much more especially if you need to expand it later (add zones), but the systems are 90%+ efficient and very small. My cousin who is a plumber in the north west suggested tapping off of my existing hydronic baseboard system and getting a valve that can mix cold and furnace hot water (160F) to a desired temp. Not sure how crazy I am about that idea.
  11. Rhone

    Rhone Minister of Fire

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    Vintage 181, Radiantec is right in your neck of the woods in Lyndonville, VT. Here's their radiant floor systems. And here's their solar. If you go to their solar site, I'm going for the "Solar Option II" which is the retrofit solution but going for another solar panel and 2 extra water tanks. I only want to heat with wood in the dead of winter.

    Got wood the mixing is often how it's done with radiant floor heating systems. For example, in my case I expect the water from my panels to be 140-160F and they'll have to be mixed with cold water so my floors don't warp. It's also the way I'd do it with my tankless, which runs more efficient maintaining higher temps than can be sent through the tubing.
  12. got wood?

    got wood? New Member

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    Interesting...so mixing implies an `open' installation where as you add colder water to mix with the 140F+, some water must be removed elsewhere. How does the system handle the additional water, pressure release valve somewhere else in the system I assume? So are you running a tankless system as well as a boiler of some sort? Is the tankless worth it in your estimation? Is the savings there, have you seen it?
  13. suematteva

    suematteva New Member

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    Rhonemas...Thanks will check into that next week..Thought that company maybe Canadian(Quebec) because many of them love use using the word tec or tech in the name of the company.. am also going to find out how old our system is..thanks again
  14. elkimmeg

    elkimmeg Guest

    There are a couple of ways to install radiant heat the stple it to the bottom of the sub floor and the 3/4" pluwood floring above the sub fllor with routered out channells for the pex but also reflective metal to force radiant heat upward Remember under the sub floor radiant heat is in all directions that means also down and away from the heating space the srtaple under floor method can be inproved with reflective shields attached
    . As for what it will do to wood flooring Common oak flooring can shrink warp and lift. However quarter sawn oaks grains stand up best to the heat source from under it. It is less prone to the symptons of common oak Pergo flooging works real well with radiant heat plus the added advantage no nails penetrations to punch holes in the tubing
  15. suematteva

    suematteva New Member

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    Looks like Radiantec has been in business for a significant amount of time..The President has been working on this type of heating for a long time and it is there primary business...Rhonemas have you spoken with them?
  16. Rhone

    Rhone Minister of Fire

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    I've been frequent communication with them, I know three cases of people dealing with them besides myself. My in-laws have a solar house that needed their roof replaced but weren't sure how to remove the solar panels. Their system was designed & installed in 1983 by Bob Starr and running flawless since, looks to have another 15 years left on the panels, the slab probably longer than I have left. Their solar charges up a radiant floor slab. I went to find Bob Starr and found he's still in business president & owner of Radiantec. That's the first experience I've had, and how I came across them. They don't install anymore, they design and sell the componets.

    I was talking to a friend of the family and found out he purchased the staple-up system from them to go into an addition on his house that had tile floors and they were always too cold. He told me the system is amazing, so nice to be able to walk barefoot in winter on warm floors. He called them up and they asked him to fax the blueprints, windows, and insulation facts for the room and what he got was a package that they designed the system for free and all he had to do was purchase the parts they told him he'd need, follow their blueprint of how it should be looped etc for his application, and install it. His wife told me I have to come over their place and experience how nice it is, and it was easy.

    A guy at work got curious about switching to radiant floor staple-up systems so I told him about them. He faxed them blueprints of his house along with his "plan" on how he was going to install the staple-up tubing. They got back telling him his plan would result in poor performance in one area and require more tubing, parts, and cost than necessary. They re-designed it for better performance using bigger tubing so less was required and less cost and gave him a parts list of everything he'd need and the blueprint of how it should be looped. He and his wife ended up wanting to sell the house for some reason a month later, so he didn't purchase the system. All that work they put into it was for not.

    Those are my experiences. I don't understand some things about them. The consultation, blue-prints, and parts list are all free so you don't have to try to figure it all out and screw things up or after installing it you end up with a system that doesn't do what you think it'll do. You give them the blueprint of your house/area, and they design the system for you and you get back a blue-print of how it should be installed, how the piping should be looped, a parts list, and the price list I guess they just hope you buy from them afterward because they did all that and didn't even get a dime. Their pricing is also very hard to beat.

    I've experienced different places and they are a VT company and have the VT sort of way. If you contact them, they usually get back several days later, up to a week. I love that about VT.

    Got wood, I don't understand where the "excess" water goes either from the mixing.
  17. webbie

    webbie Seasoned Moderator Staff Member

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    Mixing valves work very well and have been around for decades. What happens is this...consider a figure 8 with the valve in the center. One side is the boiler and the other the house loop. The water is circulated constantly though the house loop and each time only a little of that water is bypassed back into the boiler loop and reheated. The valve can be set to modulate in response to indoor and outdoor temps....for instance, the house water could vary from 80 to 110 in response to thermostat.

    see: http://www.acaso.se/english/termomix_dscs.htm
    these are shown without the motorized heads.

    Mixing valves allow the boiler to be run at higher and often more efficient temps, yet the heating water is tempered for the radiant or other method.
  18. norcal

    norcal New Member

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    Hello every one.

    We have been living on DIY radiant floor heat for a few years now. Love it!!

    We installed the staple up system ourselves. Since it was new construction and the hard wood was to come later (after sheetrock), I chose to staple the tubing to the joists about 1 inch below the subfloor. I used the foil, bubble, foil insulation under most of it, the section over the garage got foil faced fiberglass for sound insulation. We pulled all the tubing in about a day and a half. The boiler is a Polaris, It is advertised as 95% efficient. Our utilitie bill seems to be about 1/3 that of similar homes heated by forced air systems. When I suppliment with wood heat, it is even better!


    As for the hard wood flooring that runs through most of the house, I get a few more squeeks in the summer when heating demands are low and humidity in the house is higher. In the cooler parts of the year, especially if I fire up the wood stove, my squeeks go away and some of the joints open a bit. Both extremes are hardly noticeable and seem to have more to do with the season and in door humidity than the floor heat.


    I bought my system from radiantdirect.com. They designed th system for free and included great instructions for installing every thing.
    Also check out: radiantdesigninstitute.com Lots of good info.

    Hope this helps.
  19. got wood?

    got wood? New Member

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    Interseting...did you install the PEX on the joists because you were worried about the heat on the subfloor and eventually the floor? Don't the radiantdirect folks recommend attaching directly to the subflor centered between the joists?

    How was hooking up the manifold and mixing valves, etc? How many zones did y ou create? As it gets colder here, I'm getting more and more motivated to actually exectute this project this year! :)
  20. norcal

    norcal New Member

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    I installed the PEX on the joists because I didn't want to accidentaly get a staple in a tube while installing the hard wood! Murphy seems to follow me all the time, if you know what I mean.

    As for the placement of the tube in the joist bay, I did a lot of research and found many theories and ideas about the optimum hydronic system design. This system uses a loop of 1/2" pex (up and back) in each joist bay. This is a verry simple, well thought out system. Not to mention verry ecconomical.
    The manifolds, pumps and controlls come on a board. Screw the board to the wall and wire up the thermostats (I have 4 zones) and plug in the pex to the manifold. Just make sure to lable the tubes as you install them. Make a list and make a copy of it so you know what to hook up where.

    Good luck. Happy heating!
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