Radiant Floor Help

dotdotdot

We just purchased a home in which we are going to be replacing EVERY bit of flooring. The forced air furnace is working, but could use replacement as well. We've always wanted to have a radiant floor heating system and figured this might be the time to do it.



I've been looking at systems using Warmboard and Raupanel, but they seem awful expensive for a bit of convenience.



My question is, if you were trying to keep costs down and labor time/costs were not a factor, what solution would you be looking at? Could a guy just lay down 5/8" board, router his own grooves and install some kind of plate system if he had the time to put in?



Obviously, I'm completely new to this so you can't hurt my feelings. Need some honest advice here.

SWEI

What kind of floor?

Slab on grade, underlayment on joists, something else?

dotdotdot

My bad

Underlayment on joists. This is a two story home with an unfinished basement. We're not going to do anything with the basement right now, but will size boiler large enough for down the road when we do.. 4 bed, 2.5 bath at 2100 sq.ft. Current flooring is carpet, laminate wood and vinyl. We will be going to carpet, hardwood and tile.

SWEI

How much build-up can you tolerate?

It's really best to insulate underneath.  If you can insulate the 1st floor joists from the basement with wet-spray cellulose I'd go ahead and use track with plywood the way most manufacturers show in their photos.  Foil-faced polyiso paired with plates might be an option for the 2nd floor.  Roth panel works but is pricey.



Without plates or a metal-clad panel, you're looking at a lot more tubing for a given water temp.

dotdotdot

I can tolerate some

I can tolerate some buildup, but I don't think I'd want to go thicker than the Warmboard-R product, which I believe is 11/16".



We are planning on insulating the basement from the first floor, but we were planning on using batt insulation. That ok?

SWEI

Upstairs

11/16" is thin.  I've never pushed the limits on 3/8" PEX with extruded plates but it seems like it was close to that -- maybe 5/8"?

STEVEusaPA

few thoughts to the OP...

"...Warmboard and Raupanel, but they seem awful expensive for a bit of convenience."

Warmboard is easily the way to go.  When you factor in everything you are going to need, from the boiler, tubing, manifolds, circs, etc., Having an evenly heated floor makes it all worthwhile.  The warmboard will allow you to use less tubing and provide a great base to replace hardwood flooring.  Either way your insulating underneath. 

I think the idea of buying 5/8" plywood, installing it and routing grooves, is a horrible one.  You just wont get even distribution at all.  It just wont work.

And running plates underneath the subfloor, in the basement, then running the tubing, with all the pipes in the way...very labor intensive. 

The warmboard will go in just as fast as the plywood method--without days of routing.  You will still have to do some routing with the warmboard, It's the best way to go for your situation, and the added cost for the superior benefits is well worth it.

Just remember to have it professionally designed (warmboard will help with that).  You'll need higher temps under the carpet, and very controlled temps under hardwood.  Batt insulation will be fine.

dotdotdot

Thanks

Well, I guess Warmboard it is. I don't want something as expensive as this project to be done halfway and hoaky, even if it does mean saving a little bit longer for it.



Thanks for your feedback!

Rich_49

Check Out

Sunboard Panel .  More to choose from and a very fine product . More cost effective than warmboard and the SAME RESULT

STEVEusaPA

Rich....

That looks interesting. What's been your experience with it?

1. Product availability/lead time?

2. Company support

3. How many jobs have you done with it?



Thanks

Steve

Rich_49

Steve

was visiting 3 homes that were completed for a new builder I wanted to aquire .  All had radiant and all felt really good . Asked what product was there , he explained that it was a plywood product with aluminum skin that went down into the grooves also . I stated that it was Warmboard and he emphatically told me ' No , it isn't this stuff is half the cost .  Anyway , I now have the builder , have spoken to the owner of Sun Board in LI . Lead time is real reasonable , shipping also , Support seems great , he can design and I have orders in at present for 2- 7000 + homes . They have a lot of new stuff hitting shortly also , one is a plywood product that substitutes the aluminum with Graphite , even better heat transfer and a product which I have to find the right job for , it is 1" Styrofoam with a graphite covering all the way around the grooves , made well but I don't know how folks will feel about foam based .  In essence , it's Warmboard without the California Price . Hey , they might have to be concerned about a competing product now and the price will come down .  Both houses that I will be putting it in came down after all was considered by better than 14.000.00 . that's a job getter my friend .  Those houses will have the 3/4 with 1/2 tubing .  Also has a paper layer over the aluminum for flooring , tubing also stays in channel but is free moving , less noise potential .     

NRT_Rob

I have a chunk of sunboard here on my desk

and that aluminum is NOT the same level that warmboard is at. it's very thin and flimsy. This panel is better than most of the knockoffs out there, but I highly doubt it's got the same performance characteristics as warmboard.

Rich_49

Rob

Sunboard Panel has 2 thicknesses of aluminum , .002 & .007 . Which are you looking at ?  My thought on this is as follows . Either product (wb or sb ) will heat up rapidly and transfer heat to the space .  As far as the same level , where do we draw a line , I think there is a diminishing return . I always see everyone using payback so here it is . Is an extra couple thousandths of thickness worth an extra 14,000.00 on my project , that is the price difference taking all involved into account . Will that couple thousandths of an inch ever be worth the investment or higher first cost . Warmboard has never had any real competitor , now let's see what their economic stance becomes because until now it has been pretty rigid . I also believe that the Graphite covered product is gonna beat the hell out of both the aluminum products .

NRT_Rob

hardly matters

.007 is still significantly thinner than the lightest gauge aluminum we'd ever use in a plate. .002 is basically useless other than to help prevent heat striping.



I don't know if it would be worth it or not. I don't know your heat loss or the impact of whatever the water temperature differential would be on your efficiency, need for supplemental heat, number of mixed water temps, or zoning. I would be skeptical that the "all in, apples to apples" price difference is so high on any but the absolute largest projects.



You can "transfer heat into the space" with anything. the question is, at what water temperature and how fast, and where does that fall along the lines of your particular project's needs? certainly there are times that the performance differential won't be as import... i.e. less resistant floor coverings and lower heat loads. that's a completely valid analysis.



but don't pretend they are the same. they are not.

Rich_49

Rob

You will have to excuse me in my following comment , a rebuttal to your superior attitude . Some on this site may look at you as other than what you are , a man , just like the rest of us . I , my friend am not one of them . I will address your last post one point at a time .



Rob says : don't know if it would be worth it or not. I don't know your heat loss or the impact of whatever the water temperature differential would be on your efficiency, need for supplemental heat, number of mixed water temps, or zoning. I would be skeptical that the "all in, apples to apples" price difference is so high on any but the absolute largest projects.

My heat loss does not matter , for the sake of this discussion we will say my heat loss is the same as yours . A home that is well insulated , has 15% glazing area , R21 walls , R35 ceilings , R19 below our panels . You know , just a well built house . We agree we are not discussing paper thin faux aluminum such as in the garbage many use on a regular basis . I do not know what your zoning strategy is but mine is as follows : Extensive , taking into account orientation , use patterns , finish floor R values , BTU per sq ft requirements .  I also don't know what your water temp strategies are but mine are as follows :  I rarely use more than 1 temp because of the way I zone , it works like this surface temp determines air temp , air temp satisfies t stat , zone shuts off , no more flow , no more heat . Pretty simple .   Price difference is really very high as I mentioned , The house that is referenced is only 5,800 ft ( small in my little niche market) and the difference is 14,000.00 .  I will probably do 10 such size projects this year , I will keep my 140K and not send it to California . Now let's discuss Resistance , I believe , correct me if I am wrong , that 2 different  products which in the final stage has 7/8" of plywood below the tubing and R 19 insulation as opposed to a product that has 5/8" of plywood and R 19 that one of these would suffer just a bit less downward loss . Now take into account that 8" spacing always requires lower SWTs . What about the thickness of the aluminum ? I say the .007 will heat and begin transfer a bit more rapidly , this is negligible , and in my humble opinion has not much bearing on our similar systems .

 I think the speed at which we transfer energy into the room is miniscule , the water temps will certainly be lower .  Rob , it takes quite a bit longer to feel 180* water through L copper than through M copper , that difference is only .003" , so I can safely say Sunboard will begin upward momentum a bit faster .

I never pretend my friend , I just make logical conclusions taking all factors into account .  14,000.00 , lower SWTs , similar response time , better downward losses , locally produced .  No skimping on quality in my opinion and I am very discerning and refuse to put out a substandard product .

  But Rob if you want to pay for more aluminum , a West Coast lifestyle and a hefty Freight bill , be my guest .  

  

  

NRT_Rob

I have no idea

where your complex comes from, but I'm just talking math here. If disagreeing with you means I have a superior attitude, so be it. Your comments indicate that your understanding of these issues isn't as solid as you seem to think it is though, so maybe you should consider upgrading your walls from glass before you start throwing those stones.





1- of course heat loss matters. the higher the heat loss, the higher the water temps you need. with weaker panels the water temp you need goes up faster than with more conductive panels. If your heat loss is low, the difference between panels is lower. Saying heat loss doesn't matter is factually wrong. And it's not housewide heat loss we're concerned with here, really, it's the worst heat loss in the house you're heating with the radiant in a room by room calculation. No one can answer that question without doing the math. I work on supergreen projects that still have individual rooms with lots of glass and high heat loads, and you still have to meet those loads, so that means turn up the water temp or add supplemental.... moreso with weak panels than with strong ones.



2- you need more zoning with wider water temperature requirements from room to room. weaker panels have wider water temp variations than stronger panels across different heat loads (flatter curve). whether this changes anything on your project cannot be known by some guy standing at a computer in maine without a floorplan. Just noting it's a consideration. If you zone really heavy in all cases whether it's needed or not, then this probably won't change anything for you. Of course, you're not the only one who will ever read this thread.



3-I prefer single temp systems too. it's a lot easier to keep them single temp with a narrower water temp variation, which is affected by loss, floor covering and panel choice. again, weak panels vary more widely and more often require multiple temps. again, no idea if it applies to any of the 10 houses you will do this year without doing the math. but it's a concern. and of course, you don't know if it applies either, right now. sounds like you aren't even doing the math to tell if you need this or not, so hey, good luck.



4-I was talking about finish floor resistance, not plywood under the aluminum. the plywood under the aluminum isn't worth thinking about because of course we are all insulating properly under our radiant panels, right? even 1" of plywood won't change your insulation strategy or your downward heat loss by any significant amount.



5- 8" spacing does NOT always require lower water temperatures. this is your biggest misunderstanding of all. the HIGHEST AVERAGE CONDUCTIVITY from pipe to floor surface has the lowest water temperature requirement. You can help a weaker panel in this regard by tightening tubing on center so each point of floor surface is closer to a pipe (less resistance between the two). but warmboard's aluminum is quite sufficient to do the same thing at a wider on center. the weaker panels do not. does your $2.25/sq ft between the two include the +50% pex/manifold cost differential?



6-the Rate of heat transfer is measured in BTU/sqft/hr. that's the potential output of the floor. the rate is different for more conductive panels rather than weaker panels because they can conduct more heat to the floor surface faster. that's why these methods are better than suspended tube, for example: the rate suspended tube is capable of is much lower. the rate warmboard is capable of is higher than less conductive panels.



Sunboard, for example, publishes some really half hearted output chart on some Loopcad template on their website. they don't label it very clearly but it appears that their panels put out 15-18 BTUs/sq ft/hr at 110 degree supply water. I presume that's for wood floor finish but they don't say. I can beat 25 BTUs/sq ft at the same temp with warmboard. that's the difference good aluminum makes.







sunboard may be very adequate for your projects: I don't know because that requires job by job analysis for me to say. Certainly you have some projects that are better suited for it than others. I'm not saying you shouldn't use it or that you are causing any problems on your systems.



but I CAN say your reasoning, at least, is mostly wrong. If that makes me "superior", I can live with that.

SWEI

Single temp designs

Frequently require variable tube spacing.  I'm currently working on a job with tube spacings of 6", 8", 12", and 18" in different rooms of a ~1500 ft2 house.  Doing so put the water temps within half a degree across the whole system.

Rich_49

Swei

Is this an overpour house ?

Gordy

Single temp systems

Sometimes you can keep a set spacing, and just go with a well placed panel in a room.



I would much rather have a smaller 9" on center panel covering the foot traffic of the space verses an18" on center layout covering the entire room.



But then the details in the design dictate this, and the necessity to change it up.

SWEI

little house

is slab on grade.  We pushed for plates in the ceiling, but they didn't want to spend the money.  It's a tight little house -- design day loss is 18,020 BTU/hr and requires 85F fluid.



(and it's Kurt.)

Gordy

I Recall

Now Kurt.

A box of hot rocks in every room ;-)



To bad The Ceiling radiant is a missed opportunity. What was the reason? cost, or the want of warm floors, or a heated ceiling could not possibly be efficient.

SWEI

Cost

was the issue.  When the owner/builder does the grunt work, tube in slab is quite affordable.



Original plan was ceiling plates and a Daikin Altherma for both heating and cooling.  Sizing was wonderful (minimum modulation rate is 5,000 BTU/hr on those) but the combination of cost and complexity will almost certainly lose out to a Thermolec B-6TMB. 



DHW will be solar, boosted by an electric tankless.  First combo I've done like that but it's looking like it will pencil out nicely.  Possible active solar space heat -- still working on the details.

NRT_Rob

variable tube spacing

matters more the less conductive your radiant media. with slab, it matters. concrete is not as conductive as aluminum. with continuous full thickness aluminum across the top of a panel, with excellent tubing contact in the groove, it doesn't. the apparent conductivity from pipe to any floor point is not very different in that case.



Are you doing 18" o.c. in a garage? that's wide for foot comfort in a residential space is all.