Question for Radiant Heat Guru’s
I’m working on a remodel where the customer is thinking of using radiant heating. Her HVAC guy told her that it would be laid on the subfloor and 1.5″ of a cement-like mixture will be poured over the tubing.
The question(s) are:
- What is this “cement-like” mixture?
- What does it weigh (lb/cubic foot)?
She’s called him with these questions, but he isn’t real good at returning her calls.
Replies
1) lite-crete or gypcrete
2) google
SamT
Go on over to the best heating and radiant gurus.... http://www.heatinghelp.com and click on "Questions". Fire away with questions.
Check back often, maybe even "save" your thread since questions rollover and disappear quickly there (2 or 3 days).
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
Here's a common one: http://www.hackerindustries.com/gypspan.htm
others are similar. no one uses lightweight concrete anymore as far as I know, so it'll be gypcrete (such as linked) typically.
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
FWIW, I have used Wirsbo's quick-trak and love it. Fast, easy and automatically gets the spacing right. Good heat transfer, too.
Mike Hennessy
Pittsburgh, PA
it works, but frankly I'd rather see someone use Joist Trak or any other extruded joist plate than quick trak. It's cheaper, similar in installation labor (in most cases, at least) and it will do a better job.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Curious why you think joist track does a better job. I woulda thought that putting the heat closer to the room and the surface that wants heating (i.e., the finished floor), at least by the thickness of the subfloor, would be better, no?
Mike HennessyPittsburgh, PA
for two reasons:one, the aluminum in quik trak is extremely thin, and only contacts the pipe though silicon, primarily. And, you still have to go through 1/2" plywood after all that, since the aluminum is at the bottom of the panel, not the top. With joist trak/thermofin extruded plates, true you have to go through 3/4" plywood subfloor, but you have solid tube contact to the plate, and the plate is full thickness aluminum which is much better at transmitting and conducting a real quantity of heat. So the conductivity boost should overcome the slight increase in upward plywood resistance. Though, your need for downward insulation is probably a bit higher for the joist mounted system. Second, the output charts in the Uponor/Wirsbo CDAM indicate that joist trak has more output at the same average water temp than quik trak ;)Quik Trak works decently, but I don't consider it a "sweet spot" of value/performance. More specifically I think it's really overpriced for the performance/labor savings you get.
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-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Ahh. Makes sense. Thanks.
Mike HennessyPittsburgh, PA
It's a lightweight cement product. Lighter than standard 'concrete'. It's historically a standard way to install it on top of the floor, but that aspect is changing. May require an increase in structure. The plywood track systems mentioned ... are easy, but very expensive (material wise). I did my own ... labor intensive, but only spent about $400 on my whole house for materials ... and about 20K in my own labor :) . The lightweight concrete provides a lot more thermal mass ... which may (or may not) be desireable. It will tend to spread out the heat a little more ... but the plywood systems usually have a way to do that w/ a metal plate. One method may be more conducive to the type of floor finish and other physical constraints in the house construction. Wood flooring would be easier, I suspect over a wood deck (nailing wise). Glue down flooring works fine on the concrete.