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AC_Hacker 11-02-09 01:09 PM

DIY Hydronic Floor Heating
 
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Hello all...

I have noticed that there is interest here at Ecorenovator in hydronic floor heating (AKA: radiant floor heating). Also, because of the friendly relation between Ecomodder and BuildItSolar, I should mention the great interest in hydronic heating on that site.

In my thread, Homemade Heat Pump Manifesto, there have been several posts that contain questions or information about hydronic floor heating, and I thought it would be a good idea to create a new thread as a repository for that information and for future conversation and information.

A few basics:
  • Hydronic heating uses heated water flowing into some radiating device to provide heat to an enclosed space.
  • Hydronic floor heating uses an entire floor as a radiating device to supply heat to an enclosed space.
  • Since the area of the floor can be considerably larger than the area of a typical radiator, the possibility exists that the temperature of the working fluid in the floor can be lower than the temperature of the working fluid in a typical radiator, to satisfy a given heating need. It is because of the lowered required temperature that the potential for greater efficiency can be found.
  • Typical hydronic floor heating schemes include (in order of efficiency):
    1. On-slab concrete floors with embedded water-circulating pipe. These floors are typically 3 inches (< 7 cm) thick and are insulated, at least at the perimeter, with plastic foam insulation, from the earth.
    2. Above floor installation, wherein a thin concrete (about 1.5 inch) or another thermal conducting layer carries water-circulating pipe.
    3. Under floor installation (AKA: staple-up) wherein water circulating pipe is affixed underneath the existing floor, often with aluminum spreader-plates to enhance thermal transfer. For this scheme to be effective, insulation underneath the water circulating pipes must be very good.

As I understand it, in Europe where energy costs are very high, hydronic floor heating accounts for around 80% of new construction, with the remaining 20% accounting for all other forms. In the US, where our energy policy is essentially subsidized by our military spending, hydronic floor heating accounts for less than 10% of new construction, with the remaining 90% accounting for all other forms.

The best reference book I have found so far on the subject is Modern Hydronic Heating by John Siegenthaler. It is expensive but very thorough.

However, it does not address DIY approaches and is pretty light on 'Heat Pump + Hydronic Floor Heating' which offers very high efficiency. Topics like 'Solar Assisted Heat Pumps + Radiant Floor' go un addressed.

(* NOTE: the URL for Modern Hydronic Heating does list other books, apparently by other authors that do address other interesting approaches (solar thermal, etc.) to heating. Also on this site is a download section where 15-day trial software, pertaining to hydronic design, is available. Much can be learned from trial software. *)

For approaches like DIY retrofits, where benefit per dollar can be greatly enhanced by scrounging, re-purposing and completely novel thinking, enormous potential can be found.

Yes, this time, David can really kick the Giant's butt.

Some useful links:

Best Regards,

-AC_Hacker


Daox 11-02-09 01:29 PM

Excellent idea AC Hacker. I'm working on getting my own copy of that book for reading. It seems to be the only worth while one out there. Sadly, since hydronic heating is used in such a small amount of US homes, I doubt we'll find a ton of good material on it elsewhere. If anyone has any good links, please share them.

AC_Hacker 11-04-09 09:28 PM

Thoughtful Discussion Regarding Radiant Floor Heating...
 
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I found a link to a page with a very thoughtful discussion regarding radiant floor heating. I found it particularly interesting when radiant floors are considered in the context of High Performance Buildings, and how radiant floors may never develope that 'warm feeling' in a High Performance House because so much of the radiating heat is retained by the house, that lower floor heat levels are called for.

I have been to some lectures regarding 'High Performance Buildings', and they don't use that term lightly. High Performance Buildings are very similar to the Passive House definition. To achieve those levels of performance, buildings needs to be High Performance by design. Stringent efforts to retrofit existing structures can result in achieving 35% to 50% of the Passive House standards.


So I think that 'warm feeling' would still be there.

Also, the discussion apparently assumes that no one would DIY a radiant floor. So their cost estimates are stratospheric by DIY standards.

Regards,

-AC_Hacker

AC_Hacker 11-04-09 10:56 PM

DIY Radiant Floor Heating links...
 
I talked with a local hydronic guy who told me that around here, feed water temperatures are:
  • 80 to 85 degrees for tube in slab
  • 100 to 110 for on top of floor heating
  • 120 to 130 for below floor (AKA: staple up) heating

* * *

And just to get the thought process moving, here are some radiant floor links...
  • Here's a house heated with water from a solar shed, featuring DIY radiant floor heat. It utilized the large radiant area of the floor to compensate for the lower feed temperatures of the solar system. As a bonus, the solar collectors work more efficiently, too.
  • Guy Marsden does a 3" solar heated slab in Maine (w/propane backup).
  • (...the 'NEXT' tab at the bottom will take you to the other two pages...)
  • Here's a solar shed with a hot water heat storage feature. No radiant floor, yet.
  • Here's a link to a company that supports DIY. The web site is filled with grest photos & descriptions. They also have a free downloadable design manual available here. The manual pretty much duplicates the web site, photos not as good as the web version. There's good info here, but a fossil fueled boiler is assumed, so their 'rules-of-thumb' may not hold with the lower solar or hydronic feed temperatures.
  • Here's a page from Radiantec, also supportive of DIY, with free manuals too numerous to list. Raniantec also has a list of Solar heating articles, why not combine the two?
  • HouseNeeds hosts a Hydronic Heating University.
  • InFloor has a free Deluxo Design & Installation Guide.

Christ 11-04-09 11:52 PM

Good information! I plan on using radiant floor heating with a solar/water setup that thermosiphons, and using valves and a bypass loop for excess heat energy, with ~1000 gallons of stored fluid in thermos-like insulated tanks under ground, for the times that there isn't sufficient sunlight for days on end.

For fluid, I plan on either using salt/water, if I can get enough plastic tubing, or using a methyl/water solution. The fluid should never freeze, since the lines and tanks will be buried under the ground, so that they should maintain an atmosphere of at least 50*.

I may have to go against the thermal siphon idea, though, because it may not work fast enough to actually keep the home warm.

The floor is most probably going to be insulated poured concrete (which may end up being mixed with styrofoam beads) with an overlay. Some rooms may have partial brick/stone floors as well, which add thermal mass and thermal dispersion potential. (Acting like a heat retainer that also helps disperse heat across a larger surface area.)

AC_Hacker 11-05-09 12:50 AM

Quote:

Originally Posted by Christ (Post 4703)
The floor is most probably going to be insulated poured concrete (which may end up being mixed with styrofoam beads) with an overlay. Some rooms may have partial brick/stone floors as well, which add thermal mass and thermal dispersion potential. (Acting like a heat retainer that also helps disperse heat across a larger surface area.)

The styrofoam beads will reduce the thermal conductivity of the concrete...

Last summer, I was testing the thermal conductivity of various aggregates in concrete, and one of my test aggregates was aluminum chips. Made sense, beings as how aluminum is light and a wonderful conductor of heat. What I didn't count on was that the alkaline nature of concrete made the aluminum fizz, and the concrete+aluminum puffed up with a ka-jillion little bubbles and was a worse thermal conductor than plain old concrete.

The rest of your ideas sound really great.

Christ 11-05-09 12:58 AM

Quote:

Originally Posted by AC_Hacker (Post 4704)
The styrofoam beads will reduce the thermal conductivity of the concrete...

Last summer, I was testing the thermal conductivity of various aggregates in concrete, and one of my test aggregates was aluminum chips. Made sense, beings as how aluminum is light and a wonderful conductor of heat. What I didn't count on was that the alkaline nature of concrete made the aluminum fizz, and the concrete+aluminum puffed up with a ka-jillion little bubbles and was a worse thermal conductor than plain old concrete.

The rest of your ideas sound really great.

What I meant by overlay is that the water pipes sit on top of the concrete. The foam beads mixed in the concrete are a recycling method for stryrofoam, which doesn't biodegrade, and help act as insulation against thermal transfer, as I understand it.

So the actual floor layout is concrete/hybrid slab, fluid lines laid on top, flooring options laid over that.

I figure 170* is more than enough to heat the floors and the rest of the house, right? (The temp that solar thermal setups can reach, even on not-so-great days.)

AC_Hacker 11-05-09 03:28 AM

Quote:

Originally Posted by Christ (Post 4705)
The foam beads mixed in the concrete are a recycling method for stryrofoam, which doesn't biodegrade, and help act as insulation against thermal transfer, as I understand it.

Yes, the foam beads would reduce the thermal transfer of the concrete.

Quote:

Originally Posted by Christ (Post 4705)
So the actual floor layout is concrete/hybrid slab, fluid lines laid on top, flooring options laid over that.

I figure 170* is more than enough to heat the floors and the rest of the house, right? (The temp that solar thermal setups can reach, even on not-so-great days.)

Well, there are a heap of a lot of variables going on here...

So many variables that it is really difficult to keep them all in your head at once.

I would recommend getting some kind of computer simulation program and running it with different options to see how certain variations affect the outcome.

You might try this link and download some of the trial programs, might give you some ideas.

There was a really great program by a company called Slant Fin. The program was called Hydronic Explorer and you answered some questions about your house and it gave you your heat load, and you could play with the layout and get feedback on how it would affect everything.

Maybe they would make the program available to you. Worth a shot.

Regards,

-AC_Hacker

Daox 11-05-09 08:56 AM

Quote:

Originally Posted by AC_Hacker (Post 4699)
I talked with a local hydronic guy who told me that around here, feed water temperatures are:
  • 80 to 85 degrees for tube in slab
  • 100 to 110 for on top of floor heating
  • 120 to 130 for below floor (AKA: staple up) heating


Wow, that would indicate that in slab would be MUCH more efficient. Especially in a heat pump situation I'd imagine. I knew under floor had to be pretty hot, but its nice to see on top of floor in the mix too. Good info AC Hacker!

I'll hopefully contribute to this thread soon, been so stinkin busy lately.

Christ 11-05-09 12:21 PM

AC_Hacker -

Thanks for those links, I'll likely check them out and see what I can come up with.

AC_Hacker 11-05-09 01:41 PM

Various Methods of Hydronic Floor Installs...
 
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Quote:

Originally Posted by Daox (Post 4708)
Wow, that would indicate that in slab would be MUCH more efficient. Especially in a heat pump situation I'd imagine.

As I mentioned, the hydronics guy is referring to conditions around here, and the weather is much milder here than in many parts of the country and world (must remember we have an international audience here!). The feed temps would be higher in areas where the heating demands are greater, but the ratios would stay pretty close.


Heat pumps, in their present state of development, have difficulty making feed water temperatures much over 120. And the Carnot theorem indicates that efficiency is increased as Delta T is decreased. So heat pump + staple up hydronic heating is not a good match.

Here's a table of Thermal Conductivity of common materials...

The reason a slab is more efficient is that concrete is a pretty good conductor (k=0.42 to 1.7), at least compared to wood or MDF (k=0.12 to 0.17), etc. Another reason favoring concrete and gypcrete (AKA: 'the wet system') is that the slab is poured over and around the PEX, so conduction from the PEX to the concrete is assured. The aluminum (k=250) plate idea , even with a U-bend in them are not in 100% contact with the PEX... conduction needs contact.

But weight is a big factor with the slab on a suspended floor, and I have been working and testing and researching this problem for nearly a year. I think I may have come up with a way to keep cost and weight down and performance at an acceptable level.

Stay tuned...

-AC_Hacker

%%%%%%%%%%%

Daox 11-05-09 03:05 PM

One of the things I really like about the poured option is increase in thermal mass. I wouldn't try to get rid of too much weight as it'll detract from that.

Xringer 11-05-09 04:26 PM

After reading, 'When It Does—and Doesn’t—Make Sense', I've come to the conclusion
that my plan for warmer feet in the den is just a pipe dream.. ;)

I'm a little disappointed, but I need to take a winter break anyways.

Cheers,
Rich

AC_Hacker 11-05-09 05:05 PM

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Quote:

Originally Posted by Daox (Post 4722)
I wouldn't try to get rid of too much weight as it'll detract from that.

There's a lot to be said for thermal mass...
  • It's generally cheap.
  • It doesn't use any power.
  • It has no moving parts.
  • It's very quiet.
  • It's extremely reliable.

There are also some things to be said against it...
  • It is bulky.
  • It is heavy.
  • Its weight must be accounted for in structures that support it.
  • It must be correctly sized to enable it to absorb and release heat at desired rates.
  • Thermal inertia can be your friend and your foe.

So in a retrofit, things are more challenging. I did a calculation on what is to be my 'test room' (A=144 ft.sq.)and determined that a 1.5 inch slab floor would weigh 2610 pounds (Density of concrete = 145 lb/ft.sq.) 2610 pounds.

That's a lot of weight.

I also did a calc to determine how much water would be required to have the equivalent thermal storage, it came out to being close to 80 gallons. so, I could pick up a used 80 gallon water heater and put it in the basement, where it would be out of the way, and not stressing my floor supports, and pump heat into the tank and draw the heat out as required.

There are down-sides to that plan
  • If the floor 'leaks heat', it will leak into the heated space, but if the water storage tank leaks heat it will leak it into an empty basement.
  • I have to contend with pumps, controls, etc
  • I am dependant on electricity.

There's also the angle of phase change materials. I tried some tests with Glauber's Salt and was not so thrilled with the initial results, however this guy had great results. They have been tried in floor tiles, drywall, etc. Personally, I have yet to try but hold out great hope for calcium chloride hexahydrate (AKA: snow melt salt) which has a page at BuildItSolar.


Here's an awsome list of PCM papers.

But this one, Carl Vener's Dissertation, gets cited more often almost any other PCM paper.

...so the right choice is really an array of choices. It's a matter of choosing the right alternative, given all the convening elements.

So much to consider, so little time...

Regards,

-AC_Hacker

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Christ 11-05-09 07:59 PM

So what I"m getting from that little graph there is that I can store heat in thermal tanks (like I had planned) but the best thermal fluid that's easily usable is probably going to be a salt brine, right?

Unfortunately, that means I'll have to custom fabricate the tanks so that they're resistant to salt corrosion...

I'm going to have to take some time out and read those papers soon, before I even start digging my plot out. I'm planning to start digging on the nicer days of winter, because it's all shale anyway... freezing temps don't make it any harder to dig up.

AC_Hacker 11-06-09 02:35 AM

Phase Change Materials
 
Quote:

Originally Posted by Christ (Post 4728)
So what I"m getting from that little graph there is that I can store heat in thermal tanks (like I had planned) but the best thermal fluid that's easily usable is probably going to be a salt brine, right?

The graph is saying a couple of things...

When you compare concrete and water as heat storage mediums, water has a greater capacity, per mass unit to store energy. So to store a given amount of heat, you would need less water... less than 1/4 the mass of water to store energy.

The graph also looks at the energy storage potential of calcium chloride hexahydrate, a hydrated salt. The graph indicates that this salt is about 50% better than water, and over 6 time better than concrete. What the graph doesn't make clear is that it is particularly looking at the phase change characteristics of of the salt, in other words the large amount of energy that is stored and released when the salt is heated and cooled between its liquid and solid state, which occurs at around 85 degrees F, which is very convenient for heating purposes.

The links I put in the previous post go into more detail about the interesting properties of PCM materials.

[NOTE: I just came across a PDF that does a good intro to PCM.]

Regards,

-AC_Hacker

%%%%%%%

AC_Hacker 11-09-09 01:47 AM

Free Heat-Loss Programs...
 
Here is a link to download a trial copy of HVAC-Calc Residential 4.0. This is a program that runs on the PC and will calculate the heat loss (or gain) for a house.

They also have a commercial version, but the residential is more suited to homes.

This is a timed version, but the time that they allow is very generous.

It is a great way to try various "renovations" and calculate how much they will reduce heat loss.

* * *

And here is another free heat loss program, in the form of a spreadsheet, from Canada, called RetScreen.

I have seen plenty of interest in RetScreen from lots of professional people. With some going so far as expanding the usefulness of the program and making their version available also.

I have seen discussions on this site (EcoRenovator) about making spreadsheets, but if they are being posted, I have missed the posts.

At any rate, RetScreen is an impressive contribution to a world running short of energy, and it is wonderful to see what a generous nation can do.

Best regards,

-AC_Hacker

Daox 11-09-09 08:00 AM

Wow, I didn't know there was THAT big of a difference between water and concrete. :eek:

Thanks for the chart AC Hacker.

Now, I need to find an elegant way of storing water in rooms... :)

AC_Hacker 11-09-09 01:24 PM

Thermal Mass, Water Storage, PCMs...
 
2 Attachment(s)
If you can combine structural requirements with thermal mass, it's a win-win.

BuildItSolar has lots of pages illustrating work that has actually been done on thermal mass being used for heat storage.

Quote:

Originally Posted by Daox (Post 4790)
Wow, I didn't know there was THAT big of a difference between water and concrete. :eek:

Thanks for the chart AC Hacker.

Now, I need to find an elegant way of storing water in rooms... :)


Yeah, water is a really good medium for heat storage. It has the added advantage that it can be pumped through pipes, so it may be possible to locate your heat storage tank somewhere else.

So water storage is used as a 'heat battery', and energy is stored when there is too much energy (sunny day) and withdrawn when there isn't enough energy (cold night). One of the problems in making this work is insulating the 'battery' so the heat energy isn't lost. There are water storage tanks available in the US with claimed loss rates of a few degrees per day. There are water storage tanks available in Europe with claimed loss rates of a few tenths of a degree per day.



BuildIitSolar has several pages illustrating progress that has been made along these lines, regarding water storage of heat.

In the 70s there were experiments with water filled tubes for heat storage:


Nobody ever said that they didn't work, but the idea didn't gain public acceptance.

Currently there's still work being done along this line. Here's a guy who is using water-filled windows:

YouTube - Trombe Wall? Window? best of both worlds

And you could also get a very large aquarium. Goldfish are able to survivie a wide range of temperatures.

Then there is the Phase Change Material thing... Here is a graph that I made to illustrate the sudden increase in the heat storage of water when ice is warmed from 27 degrees to 37 degrees:


What this illustrates is that it takes about a BTU to move a pound of water (ice) from 27 to 28 degrees, and from 28 to 29 degrees, but to move it from 32 degrees to 33 degrees, it takes 144 BTUs. This is huge! it's over 100 times increase, no battery, no moving parts. It happens on the molecular level and is completely reversable. The water doesn't wear out.

What's not so useful here is that it's happening at 32 degrees, and we're trying to stay warm.

But there are other materials that will do a phase change at a point nearer to our comfort level:

So there have been problems with the reversibility (AKA: incongruous melting) of glauber's salt incongruous melting, also with Calcium Chloride Hexahydrate, but for Calcium Chloride Hexahydrate the problem appears to have been solved. Paraffin doesn't seem to have the reversibiity problem, and is being micro-encapsulated and put into things from gloves to sheetrock. BASF of Germany is moving ahead in this.

Here is an interesting paper, where PCMs are combined with a flat plate solar collector to store and release heat on a daily basis.

We live in very interesting times...

Best Regards,

-AC_Hacker

Daox 11-10-09 07:45 AM

Backing up a bit, do you have the 1st or 2nd edition of Modern Hydronic Heating for Residential and Light Commercial Buildings? The first edition is a bit cheaper some places, but I'd wonder how much updating has been done for the 2nd edition.

AC_Hacker 11-10-09 12:15 PM

Quote:

Originally Posted by Daox (Post 4808)
...do you have the 1st or 2nd edition of Modern Hydronic Heating for Residential and Light Commercial Buildings? The first edition is a bit cheaper some places, but I'd wonder how much updating has been done for the 2nd edition.

I have the 2nd edition. I've not seen the first edition. I'd imagine the basics of radiant heating don't change much. If there was a third edition, with greatly expanded information on heat pumps as the prime heat source, that would be a different story.

I've also read Hydronic Radiant Heating. It is like sitting in a chair by a fire with an experienced hydronics installer and learning hydronics lore and rules of thumb from a seasoned pro. I found it to be interesting and enjoyable to read, but it is not a design manual. If a local library has it, you should read it. If they don't have it, you might request it. It does contain lore that you can use to double check any designs you come up with. For instance, who would think that there could be potential problems with hydronics in bathrooms? Seems like the best place to start... Well, hydronic installations, if not done mindfully, can cause the wax toilet sealing ring to melt, which causes obvious problems. (Now that I've written this, I realize that I would recommend this book, as an adjunct to a more thorough book, but it is not a systematic design manual)

AC_Hacker 11-17-09 02:10 PM

Thermal Transmisivity Testing...
 
3 Attachment(s)
I have been considering Maxis' method of making a hydronic floor, by building it up, using layers of Sheetrock as the thermal mass material that is between rows of PEX piping. As I understand it, Maxis grouted the channel, under, around and over the PEX to insure maximum thermal conduction.

I like the idea for more than one reason...
  • Lower weight of floor - Definitely a factor for me with my house that was built in 1892 (or earlier).
  • Ease of installation - I haven't worked with cement much and the idea of pouring wet cement onto a floor sounds very challenging.
  • Ease of un-installation - If results are not as positive as I would hope, I want to be able to return the floor to something that resembles its present state.

So, I have been considering the variables, and the physical and thermal characteristics of the mass material seems to me to be a variable worthy of attention.

I really like Maxis' idea of utilizing sheet rock that was left over from previous remodeling, it's a brilliant way to save money and material.

In my case, however I'll be buying my material new, so the choice of material is open. I tried to find values on-line of the thermal transmissivity, or K value. I found that the K values given in various product literature, varied all over the map, and it all made my brain start to ache.

So, I have been doing some initial testing of various wall-board and concrete board products. Here is a photo of my test setup...


This was all just thrown together, so I could get some idea if there was enough of a difference to even worry about.

I decided if there was a significant difference, I would refine my testing.

So the method I followed was to use a heat lamp as the heat source, placed the same distance from my test samples in all tests. The temperatures were measured each second by three thermistors placed 1 inch apart, using my DIY Datalogger. I ran each test for exactly 10 minutes using my Eco-Experimenter's Test Box. The readings for each measurement period were averaged together.


The ambient temperature was measured to be the same for all tests, my mini split does a good job of providing an even temperature. All of the test samples were stored in the same location (my living room), with 'breathing room' around each one. I kept the samples in this room for for four days, so that if there were any unusual temperature or humidity differences, they would even out.

So here I have a graph of the results so far...


This graph is useful only for ranking which material is a better thermal conductor than another, it is not useful for calculating how much better.

The horizontal axis is the "time' axis, the vertical axis is the temperature axis, no scale is implied, however, beginning temperatures were about 70 F and ending temperatures were as high as 145 F. The time duration of the test was about ten minutes. The time shown in the graphic is about eight minutes.

It is clear that in this test, Durock is the best conductor of heat then Wonderboard, and that Sheetrock (both white face and green face, anti mold) has the lowest thermal conductance of the materials tested.

I'll be repeating the tests, and adding other materials that seem appropriate.

Stay tuned...

-AC_Hacker

Xringer 11-17-09 02:28 PM

I Googled "Durock thermal conductivity" and got some interesting hits.
It seems this is some good stuff for shielding your wood or pellet stove from walls
and floors containing wood.. Good to know. I may re-install my wood stove someday.

I was looking at a thin sheet of Durock a few weeks ago.. It was HEAVY stuff!
It felt like I was handling a sheet of solid concrete. It's some impressive material,
and I was wondering what it would do to my saw blades.. ;)

Daox 11-17-09 03:07 PM

Quote:

Originally Posted by AC_Hacker (Post 4818)
I have the 2nd edition. I've not seen the first edition. I'd imagine the basics of radiant heating don't change much. If there was a third edition, with greatly expanded information on heat pumps as the prime heat source, that would be a different story.

Speaking of the 3rd edition. My wife was out shopping the other day and she knew I wanted this book, so she visited the local book store. Apparently, the 3rd edition is going to be coming out ~August of 2010. I'm currently planning on holding off on doing any floor work until some time after that.

dremd 11-22-09 05:23 PM

Subscribed:
The In Floor PDF you linked to was SUPER informative!

One thing I'm still trying to figure out is pump sizing. I see the head through x feet of y pipe, but what I don't understand is what is a good flow rate.

AC_Hacker 11-22-09 08:39 PM

Quote:

Originally Posted by dremd (Post 5013)
Subscribed:
The In Floor PDF you linked to was SUPER informative!

One thing I'm still trying to figure out is pump sizing. I see the head through x feet of y pipe, but what I don't understand is what is a good flow rate.

dremd,

I'm assuming that you're referring to this link?

http://www.radiantcompany.com/manual...l_web-2009.pdf

I'm still trying to work out the pump thing myself...

I know that it's in my hydronic book, but I haven't dug that deep yet.

So far, I know that if you pump fluid through a pipe, that there is a pumping rate where 'turbulent flow' begins. An it is desirable to pump fast enough to reach turbulent flow, because heat transfer is enhanced, and hard as it is to believe, power required is reduced.

The factors affecting the threshold of turbulent flow are:
  • smoothness of pipe
  • diameterr of pipe
  • viscosity of fluid
  • etc.


If you're gonna do some research, there is a mathematical construct called Reynolds number that is pivotal in calculating pump size.

There's probably a free program that will do this for you, or a Java Script page calculator that will do the trick.

Please share with us what you learn.


Best Regards,

-AC_Hacker

dremd 11-22-09 08:56 PM

Quote:

Originally Posted by AC_Hacker (Post 5016)
dremd,

I'm assuming that you're referring to this link?

http://www.radiantcompany.com/manual...l_web-2009.pdf

Actually I was thinking about http://www.infloor.com/downloads/res...stallation.pdf
The radiant company one is good also, but the InFloor one was more at my level.


I've been reading everything *** Backwards, I thought that turbuant flow was to be avoided. Makes much more sense now.

AC_Hacker 11-22-09 10:19 PM

dremd,

I added the 'Residential Design and Installation' to the first post of this thread.

Thanks,

-AC_Hacker

AC_Hacker 11-22-09 11:46 PM

Post from Maxis (in US units)
 
This post, originally by Maxis, is full of useful details of a radiant floor install he is doing in Latvia (if I remember correctly). He is retrofitting a house and interestingly is using three different approaches (different approach for each floor) in his retrofit. I have relocated this post here, since it is more relevant to radiant floors than to Homemade Heat Pumps.

To make his information more accessable, I have added units that should be more familiar to American readers. I may have been a bit heavy-handed in my conversions, so they should be viewed as 'ballpark' attempts, and not as engineering data.

-AC_Hacker

* * *

Quote:

Originally Posted by Maxis (Post 4664)
The first I should say that this will be the first winter with HP and radiant floors in my house. I could say something about results only after some time -when it will get colder.

Answers to your questions:
Quote:Originally Posted by AC_Hacker
A) Did the minimum bending radius of the PEX determine the pipe spacing? Did you use bending forms, or did you just allow the pipe to bend as it would and put concrete on top?

I have read that one meter of 20mm (3/4 in) pipe could give about 18W (61 BTU/hr) heat with standard temperatures. That means, if you put 5m/m2 (3/4 in. PEX, spaced 7 3/4 on center) than you will get about 90W (300 BTU/hr). In our area the heat loss range is from 60W to 150W per m2. I have used 16mm pipe and I put about 5 to 6m/m2 (5/8 PEX, spaced 6 1/2 in. to 7 3/4 in.) - I have not less than 15cm (6 in.) between pipes and then bending is not an issue - I didn't use any bending forms. Actually pipes should be put as spiral (not snake) and then you have only 90 degree bends. With spiral you also will get equal temperature in all room.

Quote:Originally Posted by AC_Hacker
C-1) How thick was your polystyrol (polystyrene? EPS?)? What kind of mesh did you put on top?

It was 75mm (3 in.) thick. The recommended thickness is 100mm (4 in.), but I had limitations and couldn't put more. The polyethylene film should be put on top to not allow concrate to flow between plates. Then I put 5mm (7/32 in.) (to be able to walk on it ) steel reinforcement mesh with 150 x 150 mm (6 x 6 in.) cells (than you don't have to measure the distance between pipes - just follow the mesh).


It is metal sheet used as roof or wall material. Look in pictures for details
http://www.companies.lv/img_small/ko...1205404086.jpg
The reinforcement mesh pieces was fixed to each other with special steel wire http://www.bbgroup.lv/upload/9f0add6...65e060c2d7.jpg


As I said I could comment results after some time. But I have read thet there in Latvia it works fine.


Average temperatures C in my area in each month:
Jan -4.7 C (23.54 F)
Feb -4.3 C (24.26 F)
Mar -0.6 C (30.92 F)
Apr 5.1 C (41.18 F)
May 11.4 C (52.52 F)
Jun 15.4 C (59.72 F)
Jul 16.9 C (62.42 F)
Aug 16.2 C (61.16 F)
Sep 11.9 C (53.42 F)
Oct 7.2 C (44.96 F)
Nov 2.1 C (35.78 F)
Dec -2.3 C (27.86 F)

Possible minimum C in each month:
Jan -33.7 C (-28.66 F)
Feb -34.9 C (-30.82 F)
Mar -30.3 C (-22.54 F)
Apr -13.1 C (8.42 F)
May -5.5 C (22.1 F)
Jun -2.3 C (27.86 F)
Jul 4 C (39.2 F)
Aug 0 C (32 F)
Sep -4.1 C (24.62 F)
Oct -8.7 C (16.34 F)
Nov -18.9 C (-2.02 F)
Dec -31.9 C (-25.42 F)


Heating season = 203 days, average temperature 0,0 C (32 F)

Insulations:
Basement: 120mm polystyrol (4.75 in. EPS)
1st floor: walls are 210mm (8.25 in) logs - cutted from both sides + 50mm (2 in.)wood/concrete plates from outside
2nd floor - 200mm (7 7/8 in) rockwool


I didn't use this method, but there is different reflection materials, some are insulation + reflection sheet in one, some are just reflection material. There is the link to one page where you can find how to make it by yourself:
Solar Shed -- House Heating

Best regards
Maxis


AC_Hacker 12-26-09 12:44 PM

Maxis, how are your warm floors working?
 
Quote:

Originally Posted by Maxis (Post 4664)
The first I should say that this will be the first winter with HP and radiant floors in my house. I could say something about results only after some time -when it will get colder.

(...see full post above...)

Best regards
Maxis

So Maxis,

How is your hydronic floor heating project working for you?

Are you staying warm?

I'm very interested to know how it is performing for you.

I'll be starting my floor pretty soon.

Warm Regards,

-AC_Hacker

Captron 07-15-10 12:04 AM

Hi Everyone, I read this thread with interest as we have just developed exactly what you were looking for Hacker. Check out www dot dshh dot info

I like to think of it as:

FREE HEAT FOR LIFE ;-)

We did the development in NZ, and now have interest from all over since we received Patent Pending status.

Our Digital Self-Heating Home system (DSHH) uses sun when available, stores excess summer solar under the slab, integrates log wetback (fireplace Boiler) AND hot water heat pump. In addition we integrated hot water into the package so the HW Heat pump heats the hot water first then the house.

We don't have a presence in the US yet, will be looking for regional key distributors sometime next year, but for now can get the specialized stuff. Realize the Thermal heat core storage is normally put in at time of foundation. It can be put in beside an existing home if the home is thermally efficient and the pipes are in the floor slab.

Any interest should be funneled through info at dshh dot info. We are gearing up for the 110V scenario at present due to interest from Canada.

Cheers for now,

Captron

AC_Hacker 07-15-10 12:16 PM

Hello Captron...
 
Hello Captron welcome to Ecorenovator,

Quote:

Originally Posted by Captron (Post 7387)
Our Digital Self-Heating Home system (DSHH) uses sun when available, stores excess summer solar under the slab, integrates log wetback (fireplace Boiler) AND hot water heat pump. In addition we integrated hot water into the package so the HW Heat pump heats the hot water first then the house.

AC_Hacker here...

First off, I'm not the administrator of this blog, nor do I have privileged status of any kind here. Furthermore I can only claim to speak for myself and not for the other posters on this blog.

So, having said all that... it is my understanding that this blog is not a target for sales information (with the exception of the irritating insert adverts that diminish the usefulness of this blog for everyone). Rather it is a space where people with the skills and gumption and not unusually, very little money, share information about systems and structures that they have conceptualized or constructed or re-purposed, with the ultimate goal of reducing their energy consumption.

In short we are an innovative, resourceful, and relentlessly determined lot.

So, if you actually read a bit on this blog before you posted, you may well have already realized the kind of 'room' you were walking into before you spoke.

Having gotten all those bits of my own opinion out of the way, I looked at your web site and it looks like your company has learned many of the lessons of Passivhaus, regarding insulation, sealing, etc. I am interested in the details of your underfloor heat sink concept. I couldn't find enough info on your site to be of any use to me.

So for the sake of illustration, if you were building a home that was 2000 square feet in area, and the climate was such a severity that it required one Ton of conventional heating & cooling (1 Ton = 12,000 BTU/hr = 3.5 KW-h)...
  • How much mass would you allow for the floor heat sink?
  • Does your design system account for the large range of ground temperatures you might encounter in Finland, Alaska, Southern Spain, Caracas, etc.?
  • Would you use regular cement or does your system also feature change of state additives (Phase Change Material)?
  • If it does use PCM, what is the formulation?
  • Are you running PEX through the slab for heat storage and heat reclamation?
  • What kind of PEX spacing do you usually use?
  • Are you running straight water or do you use antifreeze?
  • How much insulation would you place under the floor to reduce loss?
  • What percentage of heat do you estimate is nin-recoverable (lost) from your slab?
  • How do you deal with interior summer heat while you are heating the thermal mass?
  • Are you using radiant floor heating or have you placed an insulating layer over the heat sink structure and under the floor?
  • Are you using inverter type mini-split heat pumps or are you going with inverter type central heat pumps and zoning the various areas of the house?
  • Does your scheme use continuously variable brushless fans for ventilation?
  • Are you employing HRV or ERV in the ventilating system?
  • Are you using cross-flow, counter-flow or enthalpy wheel exchangers?
  • How many airc hanges per hour do you design to?
  • Do your wall structures use a separate, inside utility-wall to prevent insulation wall intrusion?

I'm sure there are many more questions...

Best Regards,

-AC_Hacker

Captron 07-18-10 04:58 AM

Digital Self-Heating Home
 
Hi A.C., Yes, I hear ya, but think: How would you have introduced this to someone who has already expressed the need/interest when you had that ability sitting in your lap? It certainly wasn’t a "blatant" plug. You are being introduced to a product not yet in the states; we will be looking for a master distributor next year and you will hear much more about it then. Think you have been given an inside hint about what’s coming in an area you obviously love.

There are great questions:thumbup:, have a closer look at the site and our methodology will begin to make itself felt. It's not a "see all do all" solution for all locations, but for many places it is.


So for the sake of illustration, if you were building a home that was 2000 square feet in area, and the climate was such a severity that it required one Ton of conventional heating & cooling (1 Ton = 12,000 BTU/hr = 3.5 KW-h)...
• How much mass would you allow for the floor heat sink?

DSHH: We don’t tell everything on line or we cut our own throat, however: The design is a balanced system designed roughly for lowest cost in a give area with a give heat requirements. Sometimes this will only allow us to offset the heating load, which is why we added the Hot Water Heat pump and log wetback options.

We have an energy efficiency requirement to meet design parameters. It is engineered around certain fixed (Winter vs summer, temp expectations, thermal leak factor) & Variable parameters (Solar insolation factors, roof or adjacent real estate, water table level, earth type etc).

Based on the moderately high rate of loss given, this would be a moderate to cold climate in winter depending upon thermal efficiencies of the home. Missing from the equation is the heating window, for how long, or at what point do you no longer need to heat the home. These are just a few of the things we factor in.
In general we would ballpark this as 1.6CuM of Earthen thermal mass per SqM of warmed floor area. Thus for every SqM of floor space, we would design in roughly 1.5 SqM of thermal mass. This does not translate well into 1SqFt to 1 CuM.

To put this in perspective, for this guestimated design: One SqM = 1.5CuM of thermal mass. (3.29Sq Ft = 53Cu Ft) Thus we heat from the op an area about 1.6SqM deep for every SqM of Heated floor space. (5.25 deep per 1 Sq Ft)


• Does your design system account for the large range of ground temperatures you might encounter in Finland, Alaska, Southern Spain, Caracas, etc.?

Qualified Yes, however the law of diminishing returns forces us to assume a stance of offsetting the heat demand at a certain point, vs supplying all of it.

We are beginning tests in Canada next year in a location where winter temps get down to -45/-60c (-49f/-76f) in N Alberta. We have to figure out where to stop. In this area frost levels are 1.2M (4’) deep or more.

So far in NZ we have not had to add supplementary heat to any of our homes beyond solar and occasional use integrated log wetback use. We now have systems well into winter conditions of -15c (05f). As this is the only heat we have insisted they install a moderate How water heat pump which we also integrate into the hot water providing lower cost hot water on non solar days. We now are putting homes into one of the coldest towns in NZ, in the alpine region of the country.


• Would you use regular cement or does your system also feature change of state additives (Phase Change Material)?

No we use only require std 20MPa concrete and only in our ICF sub walls, we don’t specify the cement portion to the concrete at all.
We do have users who included insulation particles and air-entrainment, but with decent ICF thickness and the use of 90mm (3”) drain-flo EPS on the outside or inside of this thermal insulation levels are significant enough to contain most of the heat injected during the summer.

Remember, the bane of solar heating is not that it doesn’t work, but rather you need help over the dark days and bad weather. When you engineer the solar system to provide enough winter heat, you have huge summer overloads of energy, and rather than shut part of the system down in summer we inject the huge quantity of heat into a poor thermal mass which becomes saturated over time, doming down beyond 2.5M (8ft) below the insulation under the slab.

Visualize this as an 8 ft deep containment system the whole size of the house and you begin to get the feel of the huge area/qty of heat we are storing, usually just in time for winter if we have our calculation right, the thermal mass at the op sits in the 60-80c (140-175f) range after min 5 years of dumping vast amount of Kw of energy over every summer day and most of the should seasons, and much of the winter as well, as most of the solar array is quite large.

FYI I would guesstimate the solar array to be capable of min 13Kw, or over 280 Evacuated solar “U” tubes. These tubes still work well although at diminished capacity even down past 18c (0f)


• If it does use PCM, what is the formulation?

No, as it mentions on the website and above we use low cost in-situ earth, contained in ICF. It HAD to be low cost to work and be attractive, and not decrease carbon credits.

• Are you running PEX through the slab for heat storage and heat reclamation?

We run triple layered JH O2 proof pipe in both the slab and core, but at differing thicknesses and spacings.

• What kind of PEX spacing do you usually use?

We have to keep some things under our belt now don’t we ;-) Also we don’t normally use PEX

• Are you running straight water or do you use antifreeze?

Cold areas: System limited to 100c @ Min 35PSI use 50/50 Glycol

• How much insulation would you place under the floor to reduce loss?

Not much needed as it only serves to isolate the hot heat core from heating the slab in summer. Normally we use 90mm of HPDI special under floor high pressure steam popped EPS

• What percentage of heat do you estimate is nin-recoverable (lost) from your slab?

Very little is ‘lost’ from the slab, into the house excepted, if our specs are followed during construction. We loose about 50% from our heat containment in the early years improving by 50% more as years progress and the system reached stasis with the surround grounds outside the ICF containment area.

• How do you deal with interior summer heat while you are heating the thermal mass?

See above. It’s a balanced system. We will be getting an engineering firm or university to contract to ascertain many of the variables to be able to plug into a computer program. Right now we do it by and base educated guesstimates on experiences to date.

• Are you using radiant floor heating or have you placed an insulating layer over the heat sink structure and under the floor?

See above.

• Are you using inverter type mini-split heat pumps or are you going with inverter type central heat pumps and zoning the various areas of the house?

We don’t have access to inverter Hot Water heat pumps as yet. We would prefer them though. Right now we use 6-10kW HW units, a good deal as it heats the hot water as well at less cost than other fuels as a rule. We h\are installing one now in a very cold area where we put in 2 6kW units simply staged for cold weather. We estimate the 2nd one will only been needed occasionally when ambient insolation is obscured for long periods, even in winter.

• Does your scheme use continuously variable brushless fans for ventilation?

No supplemetary ventilation included we simply heat the slab fro warmth. It is not yet a full on package – later maybe. It use continuously variable brushless fans and low cost air-to-air heat exchangers.

• Are you employing HRV or ERV in the ventilating system?

No, customers choice. We don’t even recommend these with our full energy efficient designs as they typically blow cold air during winter nights. They do have their place.

• Are you using cross-flow, counter-flow or enthalpy wheel exchangers?

Nope, See Above.

• How many airc hanges per hour do you design to?

Non, we focus on the warmth aspect.

• Do your wall structures use a separate, inside utility-wall to prevent insulation wall intrusion?

Our current maximum spec for the EE home (not to be confused with the DSHH system) involves 200mm (8x2) with 95mm (2x4) offset studs, 12mm (1/2”) plywood sheathing with building wrap. In locations where external temps dip below freezing for more than 2 weeks at a time we add in a std vapour barrier. They glue gypsum boards here, and this drives them crazy.
To avoid this entirely we are now doing more homes & commercial completely out of ICF:
1. Built in concrete thermal mass
2. Double insulation excellent R values, improved thermal efficiency
3. 90mm of Drainflo EPS almost doubles the thermal value
4. No risk of rotting timbers
5. No risk of wind ingress
6. Fantastic noise containment or rejection
7. All owners rave about their homes being warm and solid
8. Fast erection
time



Hope this helps, it won't work in every situation to eliminate alternate heating, we can calculate how much solar heat we can generate which will offset other forms of heating.

Cheers,

Ron @ DSHH.info

lt190b 12-07-10 09:16 PM

proper technique for radiant heating | BreaktimeA C Hacker check out this blog post from PhillK hope this works lt190b

AC_Hacker 12-08-10 02:07 AM

Quote:

Originally Posted by lt190b (Post 10102)
A C Hacker check out this blog post from PhillK http://forums.finehomebuilding.com/c...comment-732109 hope this works lt190b

lt190b,

I clicked the link and got a "Page Not Found" message.

Could you try again?

-AC_Hacker

lt190b 12-08-10 07:02 PM

AC Hacker i think the edited link will work now. lt190b

AC_Hacker 12-09-10 12:30 PM

Quote:

Originally Posted by lt190b (Post 10132)
AC Hacker i think the edited link will work now. lt190b

Yes, it's working now. Good info.

However, many people are commenting on the wonderful photographs...

Are you able to see the photographs?

-AC_Hacker

lt190b 12-16-10 06:59 PM

Quote:

Originally Posted by AC_Hacker (Post 10154)
Yes, it's working now. Good info.

However, many people are commenting on the wonderful photographs...

Are you able to see the photographs?

-AC_Hacker

No! seems there are some problems with changes made to forum lt190b

AC_Hacker 01-19-11 11:03 AM

Hydronics design Spreadsheet...
 
I found a hydronics design Spreadsheet that was created by SlantFin.

It could be useful in estimating heat loads and designing hydronic systems.

AVAILABLE HERE

...it could also be useful in developing your own special-purpose spreadsheet.

-AC_Hacker

Piwoslaw 01-19-11 01:42 PM

AC_Hacker asked me to post what I know about how hydronic floor heating allows a heat pump system to be more efficient, compared to normal wall radiators.

A heat pump system gets more efficient when the water temperature is lower, which can be had by increasing the area of heat exchangers (radiators). This means either increasing their size, or their number, or going with a totally different approach and using the whole floor area for heating. This brings the water temperature down from a max of 85°C to a max of 55°C. Normal temperatures in a floor heating system are usually closer to 40°C. This is also good for increasing the efficiency of a system with a condensing furnace, since it only condenses (efficiency above 100%) when the temperature of the returning water is below the dew point.

A side effect of using hydronic floor heating is that heat is distributated much better than with wall mounted radiators, allowing the room temperature to be 1-2°C lower, which leads to further savings.

As for how to plan and build such a system, the only "real" info I found was: when laying the water tubes, there should be at least 8 meters of tubes in each square meter of floor area, you may want slightly more in "cold" areas, ie close to doors and windows. I could not find anything about what type of tubing to use or what diameter (I assume there is only one standard diameter?). Of course, the tubes should be in loops, plumbed in parallel, not series, to distribute the heat more evenly and to reduce pumping losses. There should be a reflective layer underneath, and foam insulation under that. Tiles are good for covering it, wood is not.

Another thing that increases the efficiency of almost any heating system with radiant floors is a heat buffer. The buffer allows the heat pump (or whatever other heat source) to work at its most efficient speed/setting, while heat is taken from the buffer only when it is needed. Low temperature (floor) heating allows the buffer to give up more heat before needing to be charged again. Great for when you have a cheap source of heat (solar, electric with night tariff, etc.). It also allows zoning of the heated part of the house, which allows you to save by reducing heat use in unoccupied rooms.


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