# Installing pex radiant floor heat, questions.



## iMisspell (Jun 2, 2007)

Towards the end of dec ill be installing a radiant heat system. This coming week a representative from .radiantec.com will be calling me so i can get a quote from them. What are some things i should be looking out for or questions i should be asking. I do not know alot about radiant heat.

Heres the project.
Mater bedroom roughly 480 sqft.
3/4 t&g plywood (plywood not OSB) subfloor, quartersawn Oak Hardwood and Tile finish, joist are 11-7/8 TGI's spaced 12 on center and 16 on center with two LVL (3-1/2 thick) beams to be crossed..

Current house is 800 sqft.
Boiler (Peerless Pinnacle PI-80 (REV1)) and central air, air handler/heater coil in atic.
Hot water is held in new hot-water holding tank heated by boiler.


For the project....

_What would a good heat source be ?_
House has NG.
Currently have a Peerless Pinnacle PI-80 but that will be sitting about 40' away from the floor which will be heated.
Plan on getting a small tankless for the project to supplie hot water to a single master-bath (will have two shower heads) but thats it.

Should i get a bigger tankless, can the PI-80 handle the 40' hike ?


_Attaching the pex to the floor?_
Read about this in two different ways.
One way uses plastic 1/2 round fasteners that are nailed up
Second is staples and that allumeno heat reflector.

Would it be wise to glue and staple the reflector sheet ?


As time goes by and more questions pop into my head and more information is learned, ill post it here.


Thanks for any help.


_


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## beenthere (Oct 11, 2008)

The boiler should be piped primary/secondary, then hte 40' doesn't matter.
Next, you need to know how much heat your current set up really needs, to determine if the boiler can handle the increased load.

You need to do a load calc on the addition to see how much heat it needs, to know if you can get enough radiant heat to heat it.

Your radiant supply should be able to determine what water temp you need, and if you need a second source of heat for design conditions.

Do not try and use temp set back with a radiant system.


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## buletbob (May 9, 2008)

it sound as tho you will be installing this system under your subfloor. you will have to contend with the flooring cleats or staples that are sticking through the floor. I did this system to my house, and no mater how you fasten the heat transfer plates to the underside of the subfloor your going to be hearing the plates expanding when they start to heat up. but the comfort out ways the 4 minute noise. Good choice with the 1/4 swan oak. the heat will rise much easier and less movement with the flooring. BOB


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## beenthere (Oct 11, 2008)

Which type of plates did you use.

Single or double tube.

The thin plates, should only be fastened by 1 fastener. Weather it be nail, or staple.

More then that, and you get noise.


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## buletbob (May 9, 2008)

they where the single tube type. for 1/2" pex. and I believe they where 18" long. one fastener would not of worked. the weight of the pex pulled the plates away from the subfloor. so i used 6 3/8" long crown staples per plate 2 @ each end and 2 in the middle. this was back about 8 years ago. They did come along way with there technology. plus the fact I grounded down all the flooring nails that where in the way of the plates,which I was worried about having the floor buckle. but 8 years latter still as new. BOB


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## beenthere (Oct 11, 2008)

Yea, some of the plate designs, well, they were just worthless.


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## buletbob (May 9, 2008)

I love the warm board set up for the wood flooring, with the 3/8" pex.:thumbup:


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## iMisspell (Jun 2, 2007)

Thanks for your responses...



beenthere said:


> The boiler should be piped primary/secondary,...
> 
> Do not try and use temp set back with a radiant system.


Can you explane what you mean for both of those ? I dont understand.
I can sweat pipes, run lines, etc. but know nothing about heat sources or how they work.



buletbob said:


> it sound as tho you will be installing this system under your subfloor. you will have to contend with the flooring cleats or staples that are sticking through the floor.


Yes from under. I havnt installed the oak, was gonna do that last. The plan, snap chalk lines under the subfloor to make sure the pex is run nice and strait, then snap red-lines on the top NOT to nail and blue lines where all the joists lay to make things go alittle easier and safer (not to nail any pex), if that a wise thing ?
Did alittle reading on a radiant site and they said for new installs its best to have the radiant system runn for alittle while to dry out the subfloor of any moisture, which im sure i have been the subfloor got wet from teh rain a few times durning construction.



buletbob said:


> I love the warm board set up for the wood flooring, with the 3/8" pex.:thumbup:


If thats the subfloor with the grooves, yea...
Looked into this alittle and it looks like it could be a bit costly.


_


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## buletbob (May 9, 2008)

iMisspell said:


> Thanks for your responses...
> 
> 
> If thats the subfloor with the grooves, yea...
> ...


They do make a sub floor with the grooves, but what I was referring to was the 1/2"thick plywood with the heat transfer plate attached to the bottom . this hole thing gets screwed down over the subfloor. and when you install your flooring the pex is visible so you don't have to worry about looking for it when nailing down the floor. It will be a lot more easier then doing it from under the subfloor. try this link. BOB http://www.pexsupply.com/Categories.asp?cID=819&brandid=


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## beenthere (Oct 11, 2008)

Temp set back. If you lower the temp during the day when your not using the bedroom, and try to raise it for sleeping. It could take several hours to recover 4°.


Primary/secondary piping example.


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## iMisspell (Jun 2, 2007)

buletbob said:


> They do make a sub floor with the grooves, but what I was referring to was the 1/2"thick plywood with the heat transfer plate attached to the bottom . this hole thing gets screwed down over the subfloor. and when you install your flooring the pex is visible so you don't have to worry about looking for it when nailing down the floor. It will be a lot more easier then doing it from under the subfloor. try this link. BOB http://www.pexsupply.com/Categories.asp?cID=819&brandid=


Ahh... i see.
Seen something simulare but the transfer plate was mended on the top, like a full 3/4 t&g subfloor, think it was called warmboard (which seams alittle different then the link you posted (thanks for the link)).

I like those 1/2 panels, which bring me to a couple questions.

Insulation in the joist bays below.
Heres a thread i started questioning how to insulate with the tubing stapled from below. If i was to go with the 1/2 planks could i just put R38 in the joist bays and not worrie about anything (that would be nice) ? One thing about the 1/2 that looks the most appealing is not having to work with my arms over my head :thumbup:

Installing the planks. Since hardwood will be installed on top and that and will be running perpendicular to the joists, those planks will run parallel with the joists ?

As for "mass" for absuorbing heat, how does that 1/2 compair to tubing under 3/4 ? Seams like there would be more mass to hold the heat with the pex below heating the 3/4 and the hardwood compaired to the 1/2.

One thing which will suck if i head the 1/2 rout, just got done hanging three pocket doors and left 1" to play with off the subfloor  Looks like i might be trimming off the tops of a few doors when it comes time to stain them (solid 6 panel pine) lol.






beenthere said:


> Temp set back. If you lower the temp during the day when your not using the bedroom, and try to raise it for sleeping. It could take several hours to recover 4°.
> 
> 
> Primary/secondary piping example.


Understand the temp set back now (currently do that with the hot air heat).

The primary/secondary piping is still above my head right now, thanks for the diagram, will have to do a little more research when i get some more time.


_


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## thelovehouse (Jan 8, 2009)

*SO have noise...help*



beenthere said:


> Which type of plates did you use.
> 
> Single or double tube.
> 
> ...


Just read your post about only using one fastener....my crew totaly didn't do this and I wake up every morning to the noise of a really bad troop of boyscouts tap dancing under my bed! 

I have 3 systems on my home. In cement in the basement, staple up with the noise issues on under the 130 year old fir floors in the joists and the "warm boards" in the attic. 

The heat is GREAT...the noise not so much.

The basement ceiling is still open right now and I am trying to figure out insulation. I read the other post about the plates not staying on with one fastener and think that would be the case here too. 

Any advise? I can still remove them but I paid BIG BUCKS to have them and my installers have told me that I wanted the plates and I got the plates and too dang bad it they make noise...... so much for customer service??

Oh well I have to decided what to do from here. Do I remove them before I close in the ceiling? Do I leave them enjoy the heat and get used to the start up noise? Do I take some staples out and see if just hanging there not snug to the floor is quiet? 

HELLP HELP HELP

thanks

Maria


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## beenthere (Oct 11, 2008)

Remove the staples.

Use a short drywall screw instead. It won't put out.


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## thelovehouse (Jan 8, 2009)

beenthere said:


> Remove the staples.
> 
> Use a short drywall screw instead. It won't put out.


 
But if I use just one the plates would hang down as they are long like the other person posted about. The crew who installed it did change some over to sheet metal screws but it didn't help with the noise. I think the noise comes from the tube expanding in the plates (is that right?)

thanks so much for your help with these questions!!

Maria


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## beenthere (Oct 11, 2008)

Some times its just the tube expanding.
Other times its the plate.
And some, its both.

The plates will hang down.
But, the plates will still radiate more heat, then just a stapled tube system.

If you want.
You can pull the tube out, put some talc or baby powder on the tube, and put it back in teh plate.
See if it stops the noise.


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## thelovehouse (Jan 8, 2009)

beenthere said:


> Some times its just the tube expanding.
> Other times its the plate.
> And some, its both.
> 
> ...


 
I will give that a try. I'm still so upset with the company who installed it. They "sold" me the plates then blamed me for having them LOL

Thanks for your input!

Maria


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## Joe F (Jan 27, 2008)

What about using one drywall screw on the plate and supporting the other end of the plate with an angle bracket.


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## buletbob (May 9, 2008)

I have tried some different approaches to securing the plates to the underside of the floor, I even Ripped and installed 1/4 Luann plywood to the underside of the sub floor, using one edge of the ply to support the pan and stapling the other to the subfloor. And I'm Still getting the noise, As Beenthere suggested it appears that the noise is coming from the pex and the pan expanding.
Next time I come across this type of install what I plan on doing is rip 1/4" x 6" strips of ply and staple them to the underside of the pans and the subfloor, Sandwiching the pan between the ply and the subfloor.
My reasoning is that with the warm boards you do not get the noise being the pan is compressed to the plywood. BOB


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## thelovehouse (Jan 8, 2009)

Thanks everyone for your ideas. My warmboards too are nice and quiet. I didn't have that option for this floor though as it is the old exisiting 130 year old wood and I didn't want to cover it. I wonder if I used screws but didn't snug the plate to the floor or maybe screws with a rubber washer so there is a gap? Of course we are talking about 700 plates here......but we are also talking about a house I hope my great great grandkids will be living in someday... My kids are the 5th generation to live in it 

Maria


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## beenthere (Oct 11, 2008)

buletbob said:


> I have tried some different approaches to securing the plates to the underside of the floor, I even Ripped and installed 1/4 Luann plywood to the underside of the sub floor, using one edge of the ply to support the pan and stapling the other to the subfloor. And I'm Still getting the noise, As Beenthere suggested it appears that the noise is coming from the pex and the pan expanding.
> Next time I come across this type of install what I plan on doing is rip 1/4" x 6" strips of ply and staple them to the underside of the pans and the subfloor, Sandwiching the pan between the ply and the subfloor.
> My reasoning is that with the warm boards you do not get the noise being the pan is compressed to the plywood. BOB


Then you may get a pop noise as the plates expand and push a way from the floor.


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## buletbob (May 9, 2008)

beenthere said:


> Then you may get a pop noise as the plates expand and push a way from the floor.


That could happen, But what i am thinking is, when u install the warm boards with the alum. plates fastened to the bottom of the plywood why does that not pop???. that's sandwiched between the ply of the warm boards and the subfloor its self correct?.


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## beenthere (Oct 11, 2008)

Your water temp is lower.

Or it should be.


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## buletbob (May 9, 2008)

understood.


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## iMisspell (Jun 2, 2007)

beenthere said:


> Your water temp is lower.
> 
> Or it should be.


Im gonna make my own "warm boards" (not really warm boards, but you will see from the thread there) soon, should the same apply, cooler temp water ? If so, how can one figure/calculate this out ?

_


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## thelovehouse (Jan 8, 2009)

buletbob said:


> That could happen, But what i am thinking is, when u install the warm boards with the alum. plates fastened to the bottom of the plywood why does that not pop???. that's sandwiched between the ply of the warm boards and the subfloor its self correct?.


My warmboards do not have plates at all. They are plywood/particle board that has a trench cut into it for the tubes. The whole thing is covered in a thin metal/foil but there are not seperate plates to rattle.

Maria


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## thelovehouse (Jan 8, 2009)

*Insulation question-radiant heating*

Ok another question!

I have the staple up system below the floor on the middle floor of my home. I also have it in the cement for the floor below.

My question is do I NEED to insulate with special insulation? I really don't care if the heat goes up or down as they are all living space.......I want to use some R30 for noise reduction but is that OK? It is a large house so there will be substantial cost to use the foil/bubble insualtion. 

So is it worth the cost? Is it a must do? Is it a should do? Is it a.....well up to you if you do or don't 

THANKS everyone

Maria


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## buletbob (May 9, 2008)

thelovehouse said:


> My warmboards do not have plates at all. They are plywood/particle board that has a trench cut into it for the tubes. The whole thing is covered in a thin metal/foil but there are not seperate plates to rattle.
> 
> Maria


Hi Maria I'm not formilular with the type you are describing. The ones I have installed are the Wirsbo Quick track .The plates are pressed onto the back of the panel and holds two panels together to form the track. yours , (The warm boards) are 3/4" thick plywood that is secured to the tops of the floor joists acting as a sub floor and radiant panel all in one. 
different, but the end result is the same. you will not get any sound from these products from expansion and contraction. just the staple up plates that are secured to the bottom of the existing sub floor, as mentioned in the above posts.
BOB


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## DIYgeorge (Jan 16, 2009)

Radiantec sold me these really cheap (but not inexpensive enough) aluminum plates . . which they have since discontinued.
They're really thin.
Can these put up with only one staple?
Should they?
Thanks.


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