# Self installed concrete floor?



## Extremebison (Jan 15, 2011)

Been reading all over the net and this forum but can't really find my answer, so here's my ? Is it possible to pour concrete by hand for in floor heating?  I only have about 500sq foot room to do.  I live way out of town.  I want concrete for the thermal mass and the fact it works at lower temps.

What kind of concrete? 
What is the mixture ratio?
What size of pex to run?


I'm planning to go with 1.5" of concrete as this would mean I only have to lift two doors 3/4 of a inch.


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## Willman (Jan 15, 2011)

> What size of pex to run?



You will need to generate a heat loss calculation to determine pex size and layout. Definite foam board under slab, the thicker the better as well as the perimeter. Do not skimp on the insulation as the floor heat will be an exercise in futility. Search some past threads concerning this.
Is this an over pour or starting from scratch?

Tubing doesn't like being deep in the slab so keep that in mind. There are anchors for it to attach to foam. 
PSI of concrete is determined by the loading of the floor.
Keep in mind the slab might need to be saw cut to contain cracking. If you can orient loops to aid in that endeavor you will be ahead of the game.

Will


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## SolarAndWood (Jan 15, 2011)

Are you going to try and finish the concrete or just brush it and tile over it?  Hand mixing 2 and a half yards and trying to finish it would be tough unless you had some help.  An inch and a half isn't going to leave you much room for error.

Have you considered a cast iron radiator?


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## timberbuilt (Jan 15, 2011)

The answer to your question is absolutely, although if you mean by hand mixing your own it will take a little bit of effort.

I did two infloor pours.  One in my basement with a 4" slab using 300' runs of 1/2" pex insulated with 2" foam board.  Another as a subfloor on my mainfloor of 1 1/2" of lightweight pumice mix over tji joists.  I feel like they both turned out good.  
For the main floor :  EVERYONE was telling me I had to do gypcrete, "Its the only way to go and it is how all the contractors do it."  But gypcrete is expensive and I usually try to look at the problem with all solutions in mind prior to making a decision.  I found a semi-local concrete outfit that said they could mix a lightweight mix out of pumice.  I can't remember what exactly the mix was but I think it was similar to standard slab, probably 3/4" minus pumice with a 6 sack mix.  If you are not worried about the load of the slab on joists I wouldn't even worry about the weight.  For a 1 1/2" slab of "normal" concrete your adding about 20 lb/sf to your floor load.  I put 6 mil plastic down against my plywood subfloor as protection against rot/moisture.  I then ran 2x2s as fir-ing strips 2' on center.  I then ran 1/2" pex stapled to the subfloor in between the fir-ing strips in 300' runs.  Next we wheelbarrowed the concrete around screeting off of the fir-ing strips.  I didn't put much of a finish on it because it was planned as subfloor.  I gave the floor a good month or two to cure then put recycled maple flooring nailed to the fir-ing strips. 

Good luck.


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## huffdawg (Jan 15, 2011)

Check out this site before you decide not to lay your tubing near the bottom 2" of your slab.   It is very informitive  and the guy claims to have well over 2000 pours.  I poured both of my slabs using the directions from this site.  And have had no problems.


http://www.radiantdesigninstitute.com/page40.html

http://www.radiantdesigninstitute.com/page36.html


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## sparke (Jan 15, 2011)

FYI- I believe The Radiant Design Institute is Fred Seton's work. He has been at it a long time.  Good info...


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## bigburner (Jan 15, 2011)

Ya done a few dozen myself and we always put everything in the bottom for all the reasons mentioned in the links, No problems here either. Just another FYI point - contractors and customers don't under standtension and compression loading and if they did, concrete would never be poured with out some type of reinforcement. On larger floor projects we use #4 bar tied on 24 inch centers, this eliminates any possible shearing action caused by a moving floor.


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## salecker (Jan 15, 2011)

Hi Extreem
 I'v got a big mixer on wheels if you decide to mix your own.It works best with min 5 people if you want to mix a big batch.It will mix 5 big wheelbarrow loads at once,about 1/3 yrd to a mix.The more bodies you have the better
 Thomas


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## heaterman (Jan 15, 2011)

Think long and hard about your floor loading first. It will probably need to be reinforced because you are adding 10,000 pounds of weight to that 500 sq ft. once you get a handle on that you can decide to proceed or not. 

There are "recipes" out there for light weight concrete, otherwise known as lightcrete. Do some searching on the www.  You'll also want to consider the fact that unless your subfloor is rock solid you will get cracking in the cement as the house and floor move seasonally. I don't know what to recommend for reinforcement as I have never done one like that. My brother in law used a 1-1/2" lightcrete over a wood subfloor in his house and it has a few cracks in it. The carpenter handled the pour on his job rather than a regular cement contractor so I don't know if it was done right or not.  

Tube spacing, length of each loop and number of loops will depend on your heat loss for the room and the finished floor covering. There can be a significant difference in output and surface temperature depending on what you put over top of the pour. 

Lot's of preliminary work to do before deciding to pour it or not.


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## heaterman (Jan 15, 2011)

sparke said:
			
		

> FYI- I believe The Radiant Design Institute is Fred Seton's work. He has been at it a long time.  Good info...



Nothing against Fred, who has done a lot for the wood burning industry, but some of his ideas on infloor tubing and slab heating are a bit outside the realm of normally accepted practices throughout the industry. 

Good solid info here.    http://www.radiantpanelassociation.org/i4a/pages/index.cfm?pageid=438


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## Extremebison (Jan 15, 2011)

Heat loss calculations, I've been struggling with this one, as I live in a log house and burn 5 to 10 cord of wood in a winter.  I don't have a bill to show Btu consumption.

This project is going to be a renovation.  Not in a new house.

The current floor is well insulated under the plywood, all I think I need to do is rip up the old pine 3/4 slats.  Insulate the perimeter, and lay my pex on the plywood.  Lay some reinforcement steel, mix concrete and pour over the floor.  I do realize it's not quite this simple.

Base board heating is always an option, but they require high water temps vrs in floor to heat.  Plus the heat sink in the concrete will help times between firings of my boiler.

My plan is to get all my heat systems in place and work my way back to the boiler.  Then building my boiler and storage last, as this will be the major investment.

We do plan on living at this house for a very long time if not the rest of out life, so doing the floor will be worth it.

Thanks Thomas for the offer may take you up on it.  I got 20 cord delivered to the yard the boys gave me a good deal.  I won't be heading your way to cut wood as I originally planned.  I still want to get a tour of your place, just need to swing it, I often come spring bear hunting your way may stop in then.  Or if I get bored and the-40 goes away for a day I may come over for a drive and a coffee.


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## pybyr (Jan 15, 2011)

Some interesting info here (link below).  The dry clean sand option seems especially interesting- none of the mix/ mess of concrete, no worry about cracking, and plenty of thermal mass.  You'd still need to be sure that the existing floor framing is "up to" a substantial increase in dead load of the floor.

http://www.radiantcompany.com/details/suspended.shtml


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## huffdawg (Jan 15, 2011)

heaterman said:
			
		

> sparke said:
> 
> 
> 
> ...



As far as laying the tubing ,tubing spacing , depth of tubing  , insulation  and such.    Everything  that Seton has described on his web site worked great for me.

Huff


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## sdrobertson (Jan 15, 2011)

pybyr said:
			
		

> Some interesting info here (link below).  The dry clean sand option seems especially interesting- none of the mix/ mess of concrete, no worry about cracking, and plenty of thermal mass.  You'd still need to be sure that the existing floor framing is "up to" a substantial increase in dead load of the floor.
> 
> http://www.radiantcompany.com/details/suspended.shtml



I like the idea of the sand also, especially if your putting OSB over it.  I'll have to research that idea more as it would be allot easier than mixing concrete, or tearing out the basement finished ceiling to install flat plates.


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## Digger873 (Jan 15, 2011)

The weight of the concrete/gypcrete/litecrete is the biggest problem to overcome. 500 sq ft X 1 1/2" = 2.31 or approx 2 1/2 yds of concrete, at approx 75# per cubic ft or about 5000 pds for pumicrete. A regular concrete/grout mix  would weigh about double this.
If the floor can handle it the rest is easy.

Contractors use gypcrete because it was designed for this very application, lightweight, easy to pour,(can be mixed very thin without unreasonable shrinkage making it very easy to level) but it is pricey.
If you can come up with a lightweight concrete grout mix such as pumice you dont need steel (#4 rebar) all you need is fiber.
In an 1 1/2 floor #4 rebar wouldnt do much good (1/2" rebar + 5/8" OD pex would only leave 3/8" of concrete out of an 1 1/2")  and would just add weight to a floor that is already overloaded. the fiber wouldn't add any significant weight  and is a lot easier to use.
You can get it at any concrete company.
If you could determine the floor could take the weight I would not hesitate to try it.

One thing to keep in mind is if the floor is in an older house like mine it might have undersized floor joists  (2X8 when they should be 2X10) making them kinda bouncy. Without extra support there wouldn't be any reinforcing material that would prevent the concrete from cracking and breaking, but is easily fixed if you can access the bottom side of the floor joists and can add support. Of course this is assuming you are talking about pouring over a wood floor.


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## Frozen Canuck (Jan 15, 2011)

FWIW: I have to agree with the cautions above about the total load you will be adding to a wood floor of ?????? type of construction. 

If you want to provide detailed info on the floor const, for example 2x10@16" O.C. clear span distance 12' with 3/4" plywood glued & screwed at 6" O.C. Or whatever your situation is then we may be able to give you an idea of the total load (all live & dead loads combined) that your floor can safely support. 

BTW fast seat of the pants calc says the weight you intend to add (1.5" of concrete) is about 50% of the total load that a typical wood floor is designed to bear. So you would be pushing the limits to say the least (once you add all the other loads). 

FWIW I would never do this on a typical wood floor, there are just too many other low weight options out there that are going to yeild the same results in terms of "comfort" which I assume is what you want. 

Also keep in mind that if the worst were to happen & the floor failed structurally due to this excess load your ins co would walk as I doubt you will have an engineered drawing & stamp approving the additional loads. 

IMO look hard at the low weight high comfort options others have provided to you in their posts. 

Dont take a flyer on the structural integrity of your home, nothing worse than having the living quarters moved to the basement via gravity & no ins to cover the loss=bulldozer time. 

Hope this helps.


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## Extremebison (Jan 15, 2011)

The sand method looks like a real good way, eliminating the concrete = all together, and all the problems that can come with it.  There's some nice sand dunes just down the road I can make use of.  I'll research this method some more.


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## bigburner (Jan 15, 2011)

Pouring 2 inches is tuff, have done this also, and it will never be crack free. Over existing wood framed floor, we have ripped 3/4 plywood in to 12 inch strips and laid them out with just the gap of the tube 5/8. then stuck in the thin alum. heat plates and covered the whole thing with cement board, then ceramic tile. This works well and even works better if the under side can be insulated. The over pour is way over simplified, IT"S VERY VERY HARD to get a good floor, one big room is easier but a whole house with closets etc, not so much! If you do pour it make sure the you incorporate a plasticizer.


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## Extremebison (Jan 15, 2011)

As far as how the floor is built of I'll have to tear up the thing and just see.  The house was built in 2000.  But this is the Yukon you never know what one will find.  It is the ground level floor, I can't get under it to see as the logs go right to the foundation.  One would think it's built to code, but I already have problems with the septic, and I ask who approved it and I get sent in circles and told I'm on my own.  Also I replaced the outside lights with motion lights and found the connections were made with vapor barrier tape, so much for a electrical inspection.  So who knows how the floor is built.

Thanks for all your help


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## huffdawg (Jan 15, 2011)

Heres a bunch of pics. of my install and pour for my house.  It was a 1-1/2"  over  2x12 joists   16" OC.  no spans mor than 12'   with an Engineers stamp and approval.

Huff


 sorry I cant get the link to work

http://cid-105ddae62e67650d.skydrive.live.com/redir.aspx?page=play&resid=105DDAE62E67650D!192


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## Fred61 (Jan 15, 2011)

Is it that important to have that thermal mass to store and even out the heat? I added a little mud room on my home last year and installed in-floor radiant. I laid down 3/4 inch polyiso sheets then added seven inch strips of good birch plywood spaced to accept 1/2 inch pex and layed the tubing in the slots. I then put down 1/4 inch cement board in thinset and nailed it (carefully between the tubing). My first design was to lay aluminum plates over the tubing to help distribute the heat but then decided to leave out the plates and just trowel the thinset right into the tubing. , I then laid porcelain tile on top of the cement board. Second heating season. No cracks, no squeaks yet

The rest of my house has staple up radiant and heats fine but the only time the floors are warm enough to make me giggle is when it is below zero and the house is calling for more heat. The new mudroom floor cycles more often but is very warm to the touch which makes it a pleasure to remove my shoes and boots and stand on it. I can't feel the changes in temperature when sliding my hand from one tube location to another but being a real tenderfoot, I can feel it with my bare feet.


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## bigburner (Jan 15, 2011)

my mud room is from the 40's, it was laid up in block and the floor poured to edge of the block, walls built on that. the whole thing sticks out of the ground 3 courses of block and is exposed on there sides. Water would freeze out there over night if the door to the house was left closed. 10 years ago I poured 2 inches of concrete over the concrete slab with tubes embedded and tiled over that. There is 1 run of 1/2 tube for the whole room 12x 12. This is the worst case from an insulation and exposure standpoint, for in floor. This room heats great can't be putting in more then a couple gallons a minute of warm water. It has mass!!


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## Fred61 (Jan 15, 2011)

bigburner said:
			
		

> my mud room is from the 40's, it was laid up in block and the floor poured to edge of the block, walls built on that. the whole thing sticks out of the ground 3 courses of block and is exposed on there sides. Water would freeze out there over night if the door to the house was left closed. 10 years ago I poured 2 inches of concrete over the concrete slab with tubes embedded and tiled over that. There is 1 run of 1/2 tube for the whole room 12x 12. This is the worst case from an insulation and exposure standpoint, for in floor. This room heats great can't be putting in more then a couple gallons a minute of warm water. It has mass!!



So are you saying the mass helps with the heating? I would think that if the heat that is put through the tubing is used and not wasted through loss the only difference would be cycling time and response. My floor is over a basement built of iSPs but there is no heat down there. The temperature runs about 47 degrees. I'm sure most of the heat comes from the 12 foot concrete basement wall on one side. I have 8 inch batts of fiberglass insulation in the joists. I think I'm running my water too hot, hence the frequent cycling but I need the hotter water for the staple-up since there has been so much rework done to the house the floors are 2 1/4 inches thick and I'm too cheap to install another mixing valve.


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## heaterman (Jan 15, 2011)

I'm seeing some things and suggestions here that are making me nervous..........


Here's another option that works extremely well. In fact my bare feet are resting on it right now as I sit in my chair.  No weight or structural concerns, only adds 1/2" in height to the floor, very even heat, water temp requirements are nearly as low as gyp or concrete. Response time to heat input is about as good as you can get with a radiant floor. Off the cuff I'd say it's probably 4-5 times as quick as a thin pour.

  here's a blurb   http://www.ebuild.com/articles/1211498.hwx

here's the whole 12 minute video     http://www.viega.net/productcatalog.html#model-group284639617504

We have put down literally tens of thousands of sq ft of this product. It works and works well.


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## heaterman (Jan 15, 2011)

Extremebison said:
			
		

> The sand method looks like a real good way, eliminating the concrete = all together, and all the problems that can come with it.  There's some nice sand dunes just down the road I can make use of.  I'll research this method some more.



Sand is a better medium for insulating than conducting. They make firebrick out of the stuff........???  just sayin.........


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## webbie (Jan 15, 2011)

heaterman said:
			
		

> Sand is a better medium for insulating than conducting. They make firebrick out of the stuff........???  just sayin.........



They make rockwool from rock and fiberglass from glass (sand).......but the original rock and glass are terrible insulators.

It's not the material, but the form it is in........which often creates the insulation. In these cases, it is often the air which does the insulating.

As to thermal mass, it always depends......if there is somewhere else for the heat to go! If a mass of floor is over wood framing within the envelope of a house, it would seem that the heat must either go into the home or back to the boiler (return water, etc).......

But when concrete is poured over earth, it might lose a lot of heat to the ground....etc.

I think part of the rule of thermodynamics is that it has to go somewhere......mass can even out the transfer (like soapstone).


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## heaterman (Jan 15, 2011)

Walk on the hot beach sand in the summer. It makes you skip all the way into the water.

Move about 2" off the top and feel the temp difference.   

Maybe Michigan sand is different


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## Frozen Canuck (Jan 15, 2011)

Heaterman gave you an excellent link to check out....please do so. If that particular product is not available in your area there are many others that all fit into the low weight high comfort category. No good reason not to use some of the best designed products on the market. The cost relative to the risk you may have been considering makes it a no brainer. 

We just left a job that was a gypcrete over pour (designed & engineered) it had TJI trusses at 6" O.C. Yup thats right you can.....just get a 4" toilet flange to fit in between & I do mean....just. Gives you an idea of how much more weight this process ads. 

In a residential setting products like Heaterman mentioned are the better way to go.


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## huffdawg (Jan 16, 2011)

Extremebison said:
			
		

> As far as how the floor is built of I'll have to tear up the thing and just see.  The house was built in 2000.  But this is the Yukon you never know what one will find.  It is the ground level floor, I can't get under it to see as the logs go right to the foundation.  One would think it's built to code, but I already have problems with the septic, and I ask who approved it and I get sent in circles and told I'm on my own.  Also I replaced the outside lights with motion lights and found the connections were made with vapor barrier tape, so much for a electrical inspection.  So who knows how the floor is built.
> 
> Thanks for all your help



If you cant get at it anywhere , it might be slab on grade.    It might say on the listings papers when your house was for sale .
When you buy a house the listing should say slab on grade , basement ,crawl space  etc.  Try to find a spot where your plumbing comes up.  like under your kitchen sinks wheree your drain goes through the floor.  Or rip some floor up in a closet.


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## Digger873 (Jan 16, 2011)

> Hereâ€™s another option that works extremely well. In fact my bare feet are resting on it right now as I sit in my chair.  No weight or structural concerns, only adds 1/2â€ in height to the floor, very even heat, water temp requirements are nearly as low as gyp or concrete.



Wow what a great product! Is it expensive?

After reading all of this thread again, I think the concrete option would not be the one I would choose. I think the  climate panel heaterman suggested is a great alternative. I didnt know this was out there. 
If you just have to have some thermal mass the plywood strips with thinset and 1/2" concrete board is another great idea, one that after doing some quick math is really affordable, would be only 1 1/4" thick and would not add anywhere near the weight to your floor.
I like this idea the most, as you could get all the material at any lumber store. Aint this a great forum.
good luck


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## Extremebison (Jan 16, 2011)

Thanks All,
I think I'll look further into heaterman product.  Keep the ideas coming!

Byron


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## goosegunner (Jan 16, 2011)

heaterman said:
			
		

> I'm seeing some things and suggestions here that are making me nervous..........
> 
> 
> Here's another option that works extremely well. In fact my bare feet are resting on it right now as I sit in my chair.  No weight or structural concerns, only adds 1/2" in height to the floor, very even heat, water temp requirements are nearly as low as gyp or concrete. Response time to heat input is about as good as you can get with a radiant floor. Off the cuff I'd say it's probably 4-5 times as quick as a thin pour.
> ...




When this stuff is used do you put down anything else for insulation under the floor?

What about on a basement slab, would it work on a basement floor that does not have foam under concrete?

What have you found to be the lowest useful water temp?

gg


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## pybyr (Jan 16, 2011)

Is there a reason that it needs to be an in-floor system?  From what I've gradually osmosed over time here in the Boiler Room- if I were working from a clean slate, I'd probably go with euro-type panel radiators-- they'll respond much more quickly than a floor, and are much less material and labor intensive, especially if fitting into existing construction.


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## huffdawg (Jan 16, 2011)

I wouldnt pour on anything if I didnt know what was under it.     Lots of suggestions and nobody even knows whats holding the floor up.


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## benjamin (Jan 16, 2011)

I don't have anywhere near the experience some of you guys have, but I'll tell you what I've gotten away with so far. 

I converted a barn with 2x8 floor joists, added additional beams to reduce the span and poured 1 1/2"- 2" of concrete/limecrete mix over pex, then tiled it.  I also poured an 1 1/2" concrete slab over a 13x22 floor and tiled it with granite. The granite developed a hairline crack that is only visible if you know where to look, this was over a cold joint in the pour.  

It was a lot of work but I'm very happy with the result. Just came home after three days with no sun and temps 5-25 and it's 64 inside.  

The weight is not that big of an issue to deal with, especially over a crawl space.  You have to add some beams and posts, but there is a way to do that if you want to.  

"is the mass that important"  ask anyone who has burned wood with storage (mass)  and without it how important it is.  Sure you could build a shed and buy some propane tanks to store the heat, but the floor will do the same thing without the complexity.  Of course the complexity also gives you control that you don't have with storing the heat in the floor.  

If you're feeling adventurous look up "screed floor" on google or youtube and see how the europeans do things.  

I'm not saying any of this is worth the effort, especially with a newer house, but if that's what you want then go for it.


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## in hot water (Jan 16, 2011)

Thermal mass be it a tank of water or a concrete slab cannot create energy or heat, It's just a flywheel. 

 In some, many, cases it is an asset to a radiant system as it can help dampen wide temperature swings.  But you still need to put energy into it and keep putting energy into in proportion to what it loses to the room and any loss down or out the edge.

In some cases where you have wide and sudden outdoor temperature swings, or maybe a lot of passive gain, a high mass system can cause some overheating.  It takes a while for that flywheel to wind down when you have it filled with thermal energy.  The more mass you have the slower the response.

Using a control to keep the slab at the exact temperature to meet the load helps with high mass.  An outdoor reset control helps adjust that input temperature to the slab and prevents overshooting.  Of course it adds more cost and complexity.

It always comes down to the individual application and your expectations.  Read some of the homeowner reviews on those high mass sandbed system.  In the shoulder season, the fall for example when the slab is charged up, but the outdoor temperatures are still mild, opening and closing windows is the only "temperature control" they have.  Using open windows to control an overloaded warm floor is not for everyone.

hr


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## Extremebison (Jan 17, 2011)

I'm not worried about ever being to hot in this country.  It has been -40C  or -40F here for the last week.  I'm not lazy and will open a window if this is a problem.  We deal with -30C very often, so comfort is a priority.  Having stored heat, whether in the floor, or tank, or both helps cuts down in wood consumption and reduce the need for a full bore fire to be stocked all night, to keep warm.  AS this is the final goal of the system I want to build, the floor being one unit of that system.  

Again thanks for all this advice, keep it coming
Byron


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## Fred61 (Jan 17, 2011)

benjamin said:
			
		

> I don't have anywhere near the experience some of you guys have, but I'll tell you what I've gotten away with so far.
> 
> I converted a barn with 2x8 floor joists, added additional beams to reduce the span and poured 1 1/2"- 2" of concrete/limecrete mix over pex, then tiled it.  I also poured an 1 1/2" concrete slab over a 13x22 floor and tiled it with granite. The granite developed a hairline crack that is only visible if you know where to look, this was over a cold joint in the pour.
> 
> ...



Not only is thermal mass important but where it is is and how much is also important. I would rather have my thermal mass in the storage tank than in the floor. Even with my relatively low mass 2 1/4 thick floors with staple-up I frequently overshoot my temperature setting on the wall thermostat because the floor is emitting so much heat after the thermostat has been satisfied. On the other hand it often lag when the thermostat calls for heat (response!!). My mudroom floor is very responsive with the cement board/tile sandwich.


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## in hot water (Jan 17, 2011)

I've tried both high and low mass.  In my shop it make sense to have the radiant in the slab, exact temperature control is not that important.  In the house I went with plates under the wood floor and some radiant ceiling.  In that application I would rather the thermal "battery" be in the buffer tank.  With low mass, especially a dry system with plates you can accelerate and decelerate quickly.  So it allows for quick setback as we leave the house at 7AM and return about 6-7 every evening.  i can set back to 65 and within 15- 20 minutes feel warm when the floor and ceiling start warming up.

On my next remodel a blend of floor radiant in the tile bed and panel radiators will be my choice.

The current issue of Solar Today magazine has an article on sand bed radiant storage., "Storing Summer Heat for Winter"  I like the method they used by insulating completely around the sand bed.  Then a second installation of radiant tube on top.  Now they have the ability to pull the heat when it is needed.

www.solartoday-digital.org/solartoday/20110102/#pg28

hr


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## benjamin (Jan 17, 2011)

I agree with everything Fred and HR have said, but it comes down to what you're trying to achieve.  An automatic system is nice, but most of us are still going to be throwing the wood on the fire. 

As HR warned, I got caught with a roaring fire and the sun coming out unexpectedly on Sunday, if 84 degrees in January is considered a failure, then I can live with that.  I can get away with a range of 60-80 degrees, even 58 or 90 once in a while, so the mass in the floors and walls adds a small buffer that smooths the wood heat and solar gain over a day or two.

The sand bed system is an interesting idea.  The "summer heat" title was somewhat misleading, they didn't mention what percentage of the heat was stored from summer and what percentage was stored a few days or weeks.  If you really want to store summer heat look at Annualized Geo Solar or Passive Annual Heat Storage, they have ideas in use for storing much larger amounts of solar heat from season to season. I haven't seen a sand bed hooked up to a wood boiler but it makes a whole lot of sense to me.  

Back to the original post, I can't see the project being worthwhile in such a new house, but it definitely can be done and can make wood burning much easier to manage.  Another similar option is a masonry heater.  I've heard they are even harder to get the time lag just right, they take a long time to heat up and can then overshoot the temperature. You could build your own version to match your requirements.  If you're considering pouring your own concrete floors over wood then I'll assume you're the type who's not afraid to experiment a little with a super sized Russian oven.


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## Extremebison (Jan 17, 2011)

The current issue of Solar Today magazine has an article on sand bed radiant storage., "Storing Summer Heat for Winter"  I like the method they used by insulating completely around the sand bed.  Then a second installation of radiant tube on top.  Now they have the ability to pull the heat when it is needed.

www.solartoday-digital.org/solartoday/20110102/#pg28

hr[/quote]


I like the idea of having both, pex through the sand and on top of the sand, combination of both stored and instant heat.


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