Talked to the Canadian warmboard people - they wanted $278 a panel (in Canadian Dollars).  Compared to the already high prices for warmboard in the USA discussed here, this really adds up.

I think that a better product for them would be a simple formed aluminum sheet bonded to a moulded foam panel.

This would be lighter, cheaper to produce and ship and could be laid on top of a normal plywood subfloor later in construction, making everything easier and eliminating worries about damaging grooves, tubing or problems with dirt accumulation.

The heavy, expensive routed out plywood part of warmboard really is no improvement on subflooring.

Or perhaps more along the DIY line, preformed Al grooved channels with 6" flat flanges on either side of upset grooves could be sold by the foot.  These could be laid alongside 1 foot planks ripped out of flooring sheets to make the raceways and semi circle sawn sections of flooring could form the return grooves.

The aluminum plates would thus be something like staple up channels, but instead laid on top of the subfloor, over the planks. PEX (PAP)would then be laid in the channel groove.

I think there was an article in one of the home building magazines a while ago about laying radiant floors with a system something like this.

Graham

you're talking about Roth panel, with the foam panel

it's harder to install by a fairly wide margin, but it's great for slab retrofits. laying it down later doesn't help that much in terms of protection though. the biggest risk is flooring installation.

while warmboard may not be better than a regular subfloor, installing the radiant and the subfloor at once is typically quite a labor saver.

your second idea is called the sandwich method, but it's not typically 100% coverage or the thickness of warmboard, so its performance suffers as a result. with lighter guage aluminum, thinner plates are recommended and we generally use a 9" o.c. with 8" strips of plywood. it's adequate for a lot of people, but it's a LOT more work than warmboard, and again performance is much lesser. You can use heavier gauge aluminum and get closer to warmboard in performance... and cost.

there is no free lunch, it's just a question of what trade offs are worth it and what aren't. that's a different equation for each project.

Have you looked into this product?

http://www.rehau-na.com/construction/heating...plumbing/radiant.heating/raupanel.shtml

it loks like it may be more inline with what you are thinking about.

regards

JW

that's a great product... and it's more expensive than warmboard ;)

Thanks for the link to the raupanel - I see there is a distributor near here. Had a look at what the aluminum thickness of warmboard represents (0.025 inch) which is about twice the thickness of plain old aluminum flashing (0.011 inch). It would likely not be too hard to press or roll a groove in channel of aluminum that thick.

Seems the ideal system for us would be to use thick enough (>=0.025 inch) staple up style Al channel of a type that could be laid over plywood strips, all over an existing conventional subfloor. So my next step is to find a range of suppliers of staple up channel or get some fabricated locally.

As we have an off grid heat source planned (evacuated tube solar) and only solar PV panel power, pumping power losses are a factor so a 1/2" or larger channel would be best to reduce losses from circulating fluid

I was wondering if 1/2" ripped and placed to form channels with the channels lined with a thin formable layer of aluminum ( a thick version of foil) would be efficient.radiating the heat as well as Wrapped around and in direct contact with the PEX and overlapped onto the top surface of the subfloor directly in contact with the bottom of the finish floor. The warmboard uses aluminum on the bottom UNDER the plywood and loses in passing the heat thru the ply. If you found effectively a thicker version of aluminum foil applied this way I would think it would work effectively and be cost efficient. The end result would be a foil coverd sub floor transfering the heat to the finish floor as well as reflecting the heat upwards.

Any opinions are VERY welcome.
Thanks

I think that you have an  incorrect concept of how warmboard works. Look at the attached picture. The aluminum is direcly under the  finished floor. The heat transfer does not have to go through the plywood.

Everything that I've seen shows the aluminum on the top of the panel. Other than cost, the biggest downside that I see is if it gets wet, it would be very slick.

HaHaHa, I guess that I wasn't quick enough!

my apologies I named the wrong product the product I saw was 1/23" thick with a plate on the underside almost like a roll out type thing.

Another product found at www.radiantec.com = Uponor Quik Trak plywood Panels that use 5/16" tubing - too small for my purposes (low temp solar collector heat source with solar PV panel driven pumping power at a premium). The panels are essentially aluminum between two planks with the gap in the planks forming a groove - poor contact with the tube and the plate is under the plywood strips.

Did find some info on 7/8" tubing - now I need to find a good aluminum strip. Uponor had 7" by 16" long 7/8" grooved plates at $1.02 each but no info on how thick they were - looked pretty thin in the illustration - anybody know how thick their strips are?

Be careful. Large diameter pipe does not help you at all, it's a waste of money for nearly no benefit, makes the installation ridiculously hard. You are far ahead of the game to use pipe at a tighter on center, smaller diameter, more loops.

Uponor's Quik Trak panels are not anywhere near the same league as the panels previously mentioned and you would be far, far better off during a regular sandwich method install with plates on top of the infill than you would quik trak. It would be half the material cost, similar labor, and a good 10 to 20 degrees lower in water temperature requirements.

Design for a 20 degree drop across your loops and 1/2" tubing runs can easily be designed with ridiculously low pressure drops.

If you are trying to do this with a solar collector for a heat source, you are very unlikely to get away with using aluminum flashing of any kind though unless you have one super, super tight envelope. In good envelopes with a mixture of light and heavy plates (heavyweights being Radiant engineering's Thermofin "U" plate) in sandwiches we typically see a max temp of 120 degrees (compare that with a typical 130+ for quik trak and 100 for Warmboard) and even that occasionally requires some supplemental radiators. You're pretty unlikely to have 120 in the middle of winter from solar, depending on where you are and your panel array of course.

The plates you are talking about are their lightweights. Uponor does not make a 7/8" grooved plate though so I assume you are talking about Radiantec's plates which, IMHO, have extremely poor tubing contact. disclaimer: in many ways I am competitor to radiantec, so take that for what it is worth.

Did you read this thread I started several months ago? Several good responses concerning make your own plates.
http://www.greenbuildingtalk.com/Forums/tabid/53/forumid/12/postid/27452/view/topic/Default.aspx

ok the bottom line is here for me.. If i rip 7/16 plywood or 9/16 if neccessary and put the pex in the slots formed on 8" centers on top of the sub floor is it worth it to put in the plates and if so what is the most cost effective way to do it without the stock holders perspective or someone looking to sell something. The do it yourselfers dont mind the work but would like a working alternative to multiple $ per foot.

thanks

The plates are necessary if you want a lower operating temperature and you don't want striping.

Generally, that's what you want.

If you don't want "multiple' dollars a square foot, I would respectfully submit you don't want radiant floor unless it's in concrete you're going to pour anyway, or you have extremely low heat loads. You can get close to the comfort and most of the efficiency with radiant ceiling, panel radiators, even baseboard in some cases and all are cheaper than radiant floor.

A good ceiling or radiator system is better than a bad floor system by any criteria you choose to measure it (comfort, efficiency). That's just fact. People who claim otherwise are looking to sell something on false pretenses, that just because "it's radiant" or "it's radiant floor" that it is necessarily better.