DIY Hydronic Floor Heating

[stefanc]

Those are impressive results for those homemade plates. I'm curious to see how well his plates would work on a staple-up installation

[AC_Hacker]

Originally Posted by stefanc

Those are impressive results for those homemade plates. I'm curious to see how well his plates would work on a staple-up installation

I think using his homemade plates for staple up would work just the same, except that the heat transfer wouldn't be as good, since the heat has to travel up through more floor, and then there are the greater radiant losses in the downward direction.

I found it interesting how much fall-off there was at the outer edge of the plates, which says to me that if the plates were wider, the heat transfer improvements would be greater.

Gary was using plates that were 0.018" thick, I'd really like to know what 0.025" would perform like.

-AC_Hacker

[Drake]

In a typoed Google search of exergy heating I came across a product called 'X-energy', a liquids claims say is more efficient than water for heat transfer - alfa-x.eu - X-ENERGY. Haven't determined yet if it is suitable for hydronic heating but in theory it should. May be better for hi-temp hydro than low. Check it out.

[stefanc]

Originally Posted by AC_Hacker

I think using his homemade plates for staple up would work just the same, except that the heat transfer wouldn't be as good, since the heat has to travel up through more floor, and then there are the greater radiant losses in the downward direction.

I found it interesting how much fall-off there was at the outer edge of the plates, which says to me that if the plates were wider, the heat transfer improvements would be greater.

Gary was using plates that were 0.018" thick, I'd really like to know what 0.025" would perform like.

-AC_Hacker

He says his press will only handle 2 ft. sections of the .018 coil stock, I'm not sure how easy it would be to press thicker plates. I'm thinking of making a similar press, but with the end of the pressing pipe curled to allow me to press a section, lift, feed more in, press again. That way I could press a continuous sheet and cut it to the length I need.

[AC_Hacker]

Originally Posted by stefanc

He says his press will only handle 2 ft. sections of the .018 coil stock, I'm not sure how easy it would be to press thicker plates. I'm thinking of making a similar press, but with the end of the pressing pipe curled to allow me to press a section, lift, feed more in, press again. That way I could press a continuous sheet and cut it to the length I need.

This sounds like a great project. Gary's spreader plate press used wooden parts and muscle power.

I don't know what kind of a tool making guy you are, but hydrolics might be the way to go for a press.

One detail on Gary's page:

"Wedges are placed under the plywood pieces to give the formed plates a slight down slope from groove to the outer edge."

... a really good idea, because with this detail, when the plates and tube are fastened to the floor, the aluminum plate squeezes tighter to the PEX. Good idea.

Good luck with this project. Take loads of pictures and post all the details of the undertaking.

Good Luck!

-AC_Hacker

[pachai]

I just thought I would share a pleasant surprise I got today -
I think it was overnight from Vermont to NJ...

I described my house to a tech at Radiantec,
and they did the math and recommended 3000' of
their tubing - which seems to be designed to be
better for radiant floors than plain Pex, and 1000'
of their plates.

At this time, I am doing just the addition, and
if I am happy with the products, I'll order
materials to do the rest of the house
(the closed parts) before we paint

If I have time when I go to do the second batch,
I may make my own plates - to compare.

I asked my builder to bring me some aluminum
like he used for the termite shield - 50' x 15" -
then I can use the DIY jig design I saw posted.


I do have a question for AC -
Am I right, you are (will be?) using your homemade HP
both for heating and cooling? If so, how do you
do the reversal ? Can it be done by just having
a few (4? 8?) valves to make the plumbing equivalent
of a crossover cable? Instead of moving heat
from the ground loop to the inside loop, move it
from the inside loop to the ground loop.
Still requires a water pump on each side.

Thanks
Seth

[AC_Hacker]

Originally Posted by pachai

I do have a question for AC - Am I right, you are (will be?) using your homemade HPvboth for heating and cooling? If so, how do you do the reversal ? Can it be done by just having a few (4? 8?) valves to make the plumbing equivalent of a crossover cable? Instead of moving heat from the ground loop to the inside loop, move it from the inside loop to the ground loop. Still requires a water pump on each side.

Seth,

Where I live, it doesn't get hot enough to really require serious air conditioning for more than maybe 10 days a year, and usually all but maybe two of those days can be handled by ventillating the house well at night and shutting it up tight during the hottest part of the day (til about 3 pm).

I'm not sure if you're considering using a hydronic floor for cooling, but it is problematic because of humidity condensing on the floor.

Some people use an air handler for AC and radiant floor for heating.

The Europeans are using radiant cooling panels in the ceiling, which employ humidity sensors that can calculate what the dew point is and make adjustments to avoid it.

But here is a diagram of a typical reversing valve set-up in a heat pump:

I have been thinking about the cooling thing, however and although only ten days are hot enough to NEED air conditioning, it would be nice on quite a few days other than those ten days. In addition, from my extended test run I have done to heat my basement, I have dropped the ground temp a fair bit. It's not easy to tell how much because it's a moving target. But it is more than I would have guessed. I'll post some numbers pretty soon.

So, the short part of the story is that I am considering ways to put summer heat into the ground.

I'm going to do my 'reversing' on the water side of the system. Haven't got it all figured out yet...

I'm also considering just running cold loop water through a radiator for cooling, as an experiment.

Stay tuned..

-AC_Hacker

[osolemio]

"Underfloor heating" (using water, not direct electric heating) IS quite widespread in Europe, but mainly in concrete/slab/stone/tile floors, not that often in wooden floors (but it is coming also).

The system I am devising is unfortunately still is being delayed by the hybrid electric-heating solar panels not yet being available. Part of the house which has been renovated has had underfloor heating installed. The rest of the house has the original hydronic water heating as you call it (we call it radiator based central heating, or just central heating). The radiator solution has the problem that it requires a higher operating temperature, for a smaller area, than underfloor heating.

So I am considering to change the remaining ground floor and entire first floor into underfloor heating. Between ground floor and first floor is a "deck" of concrete load-bearing elements. I intend to let the first floor underfloor heating have direct contact with these, as the thermal mass is huge.

In most current solar power installations, the main unresolved issue is not to produce sufficient heat, but to store it. Not just from daytime to nighttime, but also from sunny days so overcast days, and in my system, even from summer and into winter (using the clay under the house for long term, high capacity lower temp storage).

Heat demand and supply (especially supply) are fluctuating curves, that need to be leveled, just as you turn AC electricity into DC. Because "all we want" is really to keep the temperature constant, inside our homes, no matter what the weather is outside.

I am sorry that my system is so delayed, but as soon as it is up and running, the data collected will speak for themselves. The real picture of how it works will not show until after a few years. Then I can prove that my electricity, heating and water cost will be decimated, and the seasonal heat storage will start to gain its new balance. (It takes some years to build up a reasonable temperature underground).


Just as exciting as it all is, just as frustrating is it that the hybrid solar panels keep being delayed. I really hope that they can make the 12 units I ordered, within a few months, so I can finally get "the engine for my car"

[osolemio]

Originally Posted by Drake

In a typoed Google search of exergy heating I came across a product called 'X-energy', a liquids claims say is more efficient than water for heat transfer - alfa-x.eu - X-ENERGY. Haven't determined yet if it is suitable for hydronic heating but in theory it should. May be better for hi-temp hydro than low. Check it out.

I just checked it out. Interesting video, to see the water heating up.

But in solar power applications, the only desirable effect is the anti-freeze function of this liquid. The liquid heats faster (and cools faster) because it carries LESS energy. It has a lower specific heat capacity than water. Which is highly undesirable.

In most installations with solar energy, you want the heat to stay as long time as possible. The more capacity, the more you are able to absorb the energy when it is there, and keep it when the supply is gone.

There are possibly some industrial applications where it is an advantage, but basically this is just an anti-freeze liquid, just like glycol is. Lower heat capacity and lower freezing point.

[mrd]

Random thought: It might be useful to have a liquid with a vastly lower heat capacity than water in solar installations. If you also had mechanisms to both easily mix and separate the two liquids, then you could have an intelligent controller adjust the heat capacity of the transfer fluid to optimize temperatures for given conditions.