# Aluminum Plate Recommendation



## virvis (Sep 20, 2009)

Researching my installation of the 1/2" pex tubing that will be heating the first floor.  Installation will be retrofit between floor joists from the basement.  I've found alot of info. about aluminum transfer plates.  From fancy (expensive) plates to flashing molded around pex (cheap), I'm looking for anyone who has installed and can give a little guidance.  My concerns are price and noise.

thanks,
Jim


----------



## Dune (Sep 20, 2009)

The cheapest ones are all you need, and may work better due to more surface area. I have installed both types and none. It is very important, whichever way you go, to insulate underneath it. This creates a pocket of warm air which is what does most of the heating.


----------



## sgschwend (Sep 21, 2009)

I used the pex ones, never saw another choice.  I have placed them 50% of the linear coverage with good results (able to heat with 120F water).  

Certainly the insulation underneath is very important.


----------



## Jackpine Savage (Sep 21, 2009)

Disclaimer, I'm not a heating professional. I am in the process of my own radiant heat and boiler install, it is possibly the longest running project in history.

First you should do the heat load calcs to see how many BTU's you need to heat the space. Then look at the heat output of the different combinations of plates, tube spacing, floor temperature, and water temperature and pick an approach. I ended up hiring a radiant heating consultant to design our system.

If you need heavy extruded aluminum plates to get enough btus, take a look at thermofin from
Radiant Engineering . I bought direct and save substantial bucks.

For lightweight plates I like the ones from Northeast Radiant Technology . The tubing actually snaps into the plate, unlike most of the lightweight plates I have seen that have a very loose fit. 

As far as noise goes you need to be concerned about installation details and your control strategy. For example, if you use a mixing valve and outdoor reset control, your floor and plates will stay at a more consistant temperature and that should lessen expansion and contraction issues. Extruded plates are supposed to grip the pex tightly enough that you can use regular pex and not get a lot of expansion and contraction noise. With the lightweight plates you might want to consider pex-al-pex. Pex-al-pex expands and contracts much less than regular pex but might be harder to work with if you have to thread it through joists.

Don't take any of this as advice, just some things to think about and research.


----------



## in hot water (Sep 21, 2009)

the extruded plates do move the energy better for two reasons.  First they grip the tube tightly.  As the most powerful means of heat transfer is conduction you want a tight tube fit.

Also the heavier gauge moves the energy to the edge of the fin better.  Thin flashing gauge plates get cool before the heat gets to the outer edge.  You really do get what you pay for with extruded plates.  Plus lower operating temperatures.

Thin flashing plates are prone to making noise.  It's called oil-canning and it sounds like those oil cans that you push the bottom.  One manufacturer suggested you fasten only one side so the plate could expand without poping.  But that defeats the purpose of a heat transfer plate if it is not touching.  They finally pulled the thin flashing plates from their offering.

There are several versions and grades of extruded plates.  I feel the "lite" version works fine, Radiant Engineering manufacturers the best they are sold under various radiant brands so shop for price.

With extruded plates you can insulate right against them, no need to leave an air space as the energy transfer is all conductive.  Spray foam is a good way to seal the joist end spaces, around the rim joist.  with fiberglass batts you want R-19 under radiant.

 hr


----------



## Gooserider (Sep 21, 2009)

in hot water said:
			
		

> the extruded plates do move the energy better for two reasons.  First they grip the tube tightly.  As the most powerful means of heat transfer is conduction you want a tight tube fit.
> 
> Also the heavier gauge moves the energy to the edge of the fin better.  Thin flashing gauge plates get cool before the heat gets to the outer edge.  You really do get what you pay for with extruded plates.  Plus lower operating temperatures.
> 
> ...



A couple of questions...  I've seen one suggestion (with a jig to make them) that one can make plates from the surplus ends of aluminum sheet generated by the seamless gutter folks (apparently they get 10-15' of waste every time they have to re-thread their machine for a different color, or change rolls) Seems like that would be better than the flashing weight plates, while still less money than the extruded plates - what do you think?  The same site (I think it was "Builditsolar.com, but I'm not certain) also suggested using a thin layer of silicone caulk between the plate and tube - claimed better heat transfer and also reduced noise because the plate was glued to the tube.

The other question is what about insulation if one is going over a floor?  In my house I am thinking that the first floor can be staple-up because it won't be a huge problem to pull down the sheetrock ceiling in the basement, and obviously insulation is not a problem there, but I can't pull down the ceiling in the living spaces to do staple up under the second floor, so I was thinking in terms of laying the tube above the subfloor - using Thermofin U or something along that line, but I don't see any good way to get insulation under it - since I'd be over a heated space, do I really need to worry about that?  (If I do, how would you suggest handling it?)

Gooserider


----------



## coolidge (Sep 21, 2009)

Do you have a printing company around? I use some old sheets from the presses to do my floor. Not shure if it will smell, its not ready to go yet. I got 35 two by three foot sheets for $7.  They are pretty thin but for the cash and if it works(priceless).  I still have 100( these cost me $50) if you are interested pm me.


----------



## in hot water (Sep 21, 2009)

Gooserider said:
			
		

> in hot water said:
> 
> 
> 
> ...



yes there are a number of ways to build your own, but you will not get the performance of the extruded plates. 

 In the big picture, with wood fired energy it may or may not be a big concern.  Working with silicone above your head may not be a pleasent experience, it was a "fixer" solution for loose fitting plates.  The silicone only handles one of the problems with thin transfer plates, you still need a tight contact to the floor and a way to limit the expansion when hot fluid hits them.  it was the noise that drove homeowners nuts, not the poor tube to plate transfer.

If the system was operating from a gas or Lp fired condensing boiler for example you would want to use the lowest possible water temperature. Hense the reason to go with extruded plates.

 But any plate is better than bare tube stapled against the floor.  I'd suggest running the system with homemade plates before you insulate and sheetrock hard to fix a noise problem after paint goes on 

I really like the Roth foam panels for retrofit on top systems.  Plenty of aluminum for good transfer and some foam insulation.  Makes for a nice feeling floor also.  They come in 2X4 foot panels for either 3/8 or 1/2 tube 1/2 or 5/8 total thickness.

The heat output up, compared to down below is related to the r-value you put over the tube.  Best is a hard thin product like tile .02 R value.  Thin engineered wood flooring a good choice 3/8 hardwood .5 R value.  3/8 soft wood .08.  1/2 carpet 1.4, add 2.0 for urethane type carpet pad for a total of 3.4 R.  A bad choice for radiant, takes some real hot temperatures to drive through 3.4 R value floor covering.  Plywood and carpet manufacturers squirm when you start approching 140f against their products 

Always it is best to insulate below R-11 or better yet R-19, but in some cases it just is not do-able.  Depending on floor covering how much energy goes down.

Remember the plywood subfloor 3/4 is .08 r value so that helps a bit also.


----------



## Gooserider (Sep 22, 2009)

The Roth panels do look pretty good for that application - in our case the 2nd floor is basically the master suite, so it might be a bit of a challenge for a floor covering with sufficient WAF, but I was kind of thinking some sort of engineered wood in the bedroom and linoleum or equivalent in the bath.  (I don't think the floor is stiff enough to do tile) Maybe put down some throw rugs on top of that if need be, but hopefully not.

Gooserider


----------



## Grover59 (Sep 23, 2009)

I used 1/2 pipe two for each bay, I also used alum flashing and made my own plates which worked great, I am getting ready to do the other side of the house with the same setup, I have pictures here somewhere. I do recommend the plates they make the floor more responsive. 

STeve


----------



## connerfur (Sep 23, 2009)

I'm about to under take my second and most extensive retro fit.  The first system I put in was with the "flashing" type aluminum plates that stapled up to the bottom of the subfloor.  It was a lot of work and I recommend an electric staple gun if you decide to go this route.  I bought that system from Radiantec in Vermont.  The system works well with no noticable noise.  I haven't insulated under one of the rooms but in the second smaller room, I install a reflective paper that they sell.  It also seems to work ok.  I'm sure that with a little insulation, I could dramatically improve the heat transfer to the intended areas.

This next system I'm about to use is the plate with the snap in tube channel.  Hopefully I'll be starting this one next month and should have more info on what it installs like.


----------



## 4acrefarm (Sep 29, 2009)

I have also used the plates from radiant tech they were great. On onother section i saved money by buying rolls of roof fashing. Dont do this! they are to stiff for good contact. i used them anyway they work ok, but the soft ones are better in every way.


----------

