Thernal transfer grout or just concrete for thermal tranfer

[Mikesolar]

I'm not sure about the grout but normal cement is quite caustic and will, over time, degrade embedded copper tubing. I have replaced or patched lots of 1950 radiant heat where the copper was embedded so i think a coating of some type would be good.

AC, the purpose of a traditional radiant floor setup is not to have a "maximum heat transfer" but to have a stable and understandable heat transfer. What would happen if (extreme case), you could transfer all the heat in 10 ft of tubing? We only need X amount of heat transfer to make a space comfortable. More is useful if the heat load is very high, but then the floor temp would be uncomfortable anyway.

Eco, do you know how much heat transfer you actually need and over what area?

[ecomodded]

I will seek out a copper primmer and give it some life extending protection.

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I have made a flat face front cover for the chiller as the original was designed for taps and a cup rack which is no longer needed and only took up space as well as looked bad.



I removed the stainless bucket today so the refrigerant coil is now ready to be modified

[gtojohn]

What about other additives in your concrete like aluminum powder? Not the same application but i recall aluminized cement used as structural fill in high horsepower race motors. The al was added to make up for water cooling loss the cement displaced.

[ecomodded]

Not a bad idea aluminum has a high thermal conductivity number , its something like 200 on the thermal scale where copper is 400 and grout is around 4 , cement is about 2
When I was thinking about the speed of transfer I realized metal or thermal grout would have little effect , I will explain it below.

I checked on polyethylene's thermal number , its 0.33 for low density and 0.55 for high density.
Its the weak link in the chain and the number that will set the transfer speed to the water.

So I now believe ordinary concrete would suffice and will work fine for thermal transfer and storage.


Since the thermal cold will be leaving via the poly tube slowly the concrete or grout or metal filled cement would have the same effect on the chilling of the water. ether material will store the thermal cold and release it slowly at the poly tubing's rate.

Technically a thermal grout would speed up the time it takes for the cold to go from copper to the poly tubing but that may be as short as 5 minutes from the chillers start up but once the chiller has been on for five minutes the poly tubing will be the only material setting the transfer speed.


I am going to use common silica grout as its slightly faster then concrete and cheap so why not.

So I will gain 5 minutes in the speed of the initial cold charge. Hardly worth fussing over.

Or am I missing something ?

I checked concrete its thermal number is 1.75


Grout Fillers such as silica sand, alumina grit, steel grit, and silicon carbide increased the thermal conductivity to values ranging from 1.7 to 3.3


A file on types of aggregate

Thermal_properties__nr_10_.pdf

[AC_Hacker]

Originally Posted by Mikesolar

... the purpose of a traditional radiant floor setup is not to have a "maximum heat transfer" but to have a stable and understandable heat transfer. What would happen if (extreme case), you could transfer all the heat in 10 ft of tubing? We only need X amount of heat transfer to make a space comfortable...

Reduce the amount of heat used to heat the slab.

-AC

[ecomodded]

Not for my insulated mass but if the slab absorbs the heat faster it will also expel it faster so the whole process *could* increase slightly.
I'm thinking aloud to help get a proper grip on it.

[AC_Hacker]

Originally Posted by gtojohn

What about other additives in your concrete like aluminum powder? Not the same application but i recall aluminized cement used as structural fill in high horsepower race motors. The al was added to make up for water cooling loss the cement displaced.

I already tried that...

It makes concrete develop millions of tiny air bubbles, and rise like bread dough.

-AC

[ecomodded]

Originally Posted by AC_Hacker

I already tried that...

It makes concrete develop millions of tiny air bubbles, and rise like bread dough.

-AC

Aluminum wire or bits and pieces would avoid that issue

Or pieces of copper or even copper plumbing pipe imbedded into the concrete could speed up the transfer.

[AC_Hacker]

Originally Posted by ecomodded

Aluminum wire or bits and pieces would avoid that issue...

I was also stupid enough to think that would work too.

I used aluminum milling swarf.

Millions of tiny insulating bubbles... concrete swelling up to about 1.25 its former size.

Maybe you should start experimenting with your ideas and let us know what you discover.

-AC

[ecomodded]

Now I remember that copper reacts with concrete so that would not work either , what ever material is used for a filer it needs to be inert as well as have a high thermal number.



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