DIY Hydronic Floor Heating

[Drake]

I am looking at getting a copy of J. S.'s "Modern Hydronic Heating" but I am finding three editions, with the newest being hundreds of dollars new. Used first edtns are much more reasonable. Would the older ones have enough basic information to still be useful/informative or way out of date(anyone who has one)?

[AC_Hacker]

Originally Posted by Drake

I am looking at getting a copy of J. S.'s "Modern Hydronic Heating" but I am finding three editions, with the newest being hundreds of dollars new. Used first edtns are much more reasonable. Would the older ones have enough basic information to still be useful/informative or way out of date(anyone who has one)?

I would say to go with the older version. The physics of radiant heating do not change much.

The newer versions are supposed to embrace the latest developments in radiant, like heat pumps, etc. I bought a copy by JS that claimed to do that, and I was dissappointed... we had better info here! But to be quite honest, if you're going to do it yourself, and want to implement the latest ideas in radiant heating, you should read through the EcoRenovator threads on radiant floors again. There is some very current knowledge here.

European practices are ahead of American practices.

If you talk to some local radiant installers, to get advice... you need to be aware that many of the rules of thumb (trade lore) is based on the assumption that you will be using fossil fuel heating of your water... and that makes a HUGE difference in how you do your floor. Unless you are a fossil fuel kind of guy.

As I said before, your very best bet would be to get a computer program. In fact, with free radiant software, go get yourself a used PC and install it.

Cheaper than a book, much deeper understanding than a book.

Motivate thyself.

-AC

[AC_Hacker]

Just a note that there will be a webinar this Thursday on installing radiant heating additions into an existing radiant system, or upgrading existing infrastructure. This should be very interesting because it must deal with most of the design and implementation issues of a new radiant installation, and it must be compatible with an old system, so a very thorough understanding is needed.

The webinar is given by an Italian company that sells hardware that is specific to radiant heating, so their motivation is to sell their hardware (which is probably good quality), but a learned DIY guy can fabricate his own hardware or substitute his way around problems.

The company maintains an archive of previous webinars on Youtube right HERE.

If anyone is interested in registering for the current webinar, HERE is that link.

There is a free technical manual archive HERE. Some awesome information.

There is also a free periodical technical publication archive HERE that has, again, some awesome information.

Best,

-AC

[michael]

Radiant Heating Technologies

I suppose everyone here has already seen these manifolds, but I just stumbled across them, and I'm impressed. It's everything I put into my own installation all in one neat package with the added benefit of being able to control a particular loop with a thermostat. That may require some careful planning, but I like the looks of these gadgets.

[Mikesolar]

I would be quite careful with them. Some of them are a cheap Chinese version of the Rehau or Watts products. I have bought a few of them over the last year and the flow meters don't work on some of them. You are better off to buy the good name brand ones. You get what you pay for. From the pictures, the flow meters look reasonable, tho.

[Mikesolar]

Originally Posted by AC_Hacker

Just a note that there will be a webinar this Thursday on installing radiant heating additions into an existing radiant system, or upgrading existing infrastructure. This should be very interesting because it must deal with most of the design and implementation issues of a new radiant installation, and it must be compatible with an old system, so a very thorough understanding is needed.

The webinar is given by an Italian company that sells hardware that is specific to radiant heating, so their motivation is to sell their hardware (which is probably good quality), but a learned DIY guy can fabricate his own hardware or substitute his way around problems.

The company maintains an archive of previous webinars on Youtube right HERE.

There is a free technical manual archive HERE. Some awesome information.

There is also a free periodical technical publication archive HERE that has, again, some awesome information.

Best,

-AC

Caleffi is definitely a good company. We use some of their solar stuff.

[Drake]

Most every thread on Eco Ren is worth a second read or even two. There are so many good topics being discussed that it is no surprise to me that there are things I did not catch or think pertained to my line of thought that now do.

[Mikesolar]

Originally Posted by Drake

Most every thread on Eco Ren is worth a second read or even two. There are so many good topics being discussed that it is no surprise to me that there are things I did not catch or think pertained to my line of thought that now do.

What other revelations have you seen?

[Mobile Master Tech]

Been away from the forum a few months-both my daughters married within 6 months of each other, 1 son graduated, the other moved, now grandbaby on the way! Oh, and there's regular life, too! And my new 23 SEER AC renovation, which I will post about!

I'm a firm believer that theory is indispensable and will get you started, but practice trumps theory every time.

I gave a detailed writeup starting at post #225 about my hydronic system, which has worked beautifully for 2 full seasons now with zero problems. Here are a few thoughts about posts in this thread since then:

Engineered wood flooring (plywood with a nice top layer) is fine with radiant heat-my 6.5" wide Tigerwood has had no issues. Solid flooring might have gap/buckling issues on extremely wide or long rooms without a break, and possibly might cup a bit, but most of the horror stories I read about involve 180F+ water temps. I have cranked my system up to 155F for several days to see how quickly I could bring the house up to temp after setback, and I can speak from experience that a system designed to work efficiently at 140F and lower temps will cause no harm to urethane gluedown engineered flooring. We even have it in the bathrooms with no problems other than the board right by the shower! (If water can frequently get under an edge, have at least 3" of something that pooling water won't hurt.)


The biggest challenge of any non-slab system is getting the heat out of the pipe into the rest of the floor, if you have any hope of applying the exergy concept of using the lowest grade energy source that can do a given job, instead of wasting high grade sources like fossil fuels or electricity to generate high deltaT's. PEX and wood are not very thermally conductive, so staple up systems without transfer plates are useless. Thermafin style clamp on radiators that only heat the air in a joist space are much less effective and much more costly than transfer plates. The best transfer plates are extruded, "omega" shape stamped plates next, and "u-groove" stamped plates after that(but plenty good). Some kind of thermal transfer compound (I used 100% silicone caulk) is essential. If in doubt, study the heat transfer capabilities of heat sinks with and without something besides insulating air to fill the valleys between even the smoothest surfaces.

While a slab works best and is easier in new construction than retrofit, the cost/effort/new flooring/door & trim modifying to retrofit it ruled it out for me. You can get nearly as good a result with standard thermostats having a 1degF differential, no reset valve and a properly done staple up for a fraction of the cost. Transfer plates get the heat out of the pipe, then the joist bay is warmed in addition to direct contact conduction. My 12" spacing system has capacity to spare using 130F water, so I'm sure those in the frigid north can do so with 6" or 8" spacing. My degree days at 65F are 3061 heating, 2010 cooling. You can even retrofit from above if you remove the flooring-see how in my posts. All flooring materials insulate the heat source from the room and carpet is the worst, but as long as the floor is sufficiently insulated from anywhere you don't want the heat to go and the system is sized so the final output is sufficient, cover it with what you want. Radiant barriers help a lot-hold a piece up between you and something hot and you will see what I mean. They are only effective if one side stays clean AND has an air gap of at least 1", though. Tighter pipe spacing to allow for carpeting loss or staple-up can use the same low water temps as wider spacing in a slab. There is a practical construction limit, but the only efficiency difference is anything you lose to the outdoors.

There is a great difference in the heat output needed on a 0F night vs 40F with full sun a few hours later-a slab can't react as quickly as staple up can. Sometimes that is advantageous(like banking solar heat), sometimes not.

Like AC said in the first post of his juggernaut, the "Heat Pump Manifesto", cost puts many systems out of reach for most people. The point is to find cost effective ways to get a durable, quality, safe result so more people can have comfortable, efficient lifestyles that help us pass a better world on to future generations. One way is properly designed, non-stagnant open loop hydronic systems that are simpler and cheaper, plus allow more resources to be put towards a more efficient heat source. Purging is a cinch by opening a faucet-no extra manifolds needed!
Any arguments concerning the risks and required safety maintenance of an open system should apply equally to regular DHW systems, but you don't see code sections or recommendations requiring weekly flushing of those! My old builder grade water heater and my new Eternal hybrid each say they are approved for DHW and space heating. In an open system, making sure all water always sees at least 130F and doesn't stagnate is sufficient. You can use a stratified storage tank to get 130F out of a heat pump while the compressor only sees 105F or so-my solar assisted GSHP is the next project!

Get Sioux Chief manifolds ($10-60 each on fleabay depending on sizing) and cut the 3/4 pex end off and solder a larger copper fitting on it to reduce head loss.

Randen, don't worry about the durability of PEX-see my posts about torture testing it. Well made collectors are better than homemade and copper is by far the best piping for them, but because of conductivity. PEX won't burst if frozen, and you have to get it hot enough to go transparent (270F) before it is soft enough to cause problems at the low pressures in a collector. 85% of something is better than nothing, if cost is an issue.

Cbearden, I have found that 1/2" pex is great, but anything larger is way too much of a hassle to deal with because it is so stiff. The actual sizes for 3/4" and 1" are smaller than the same nominal size copper or PVC which causes greater head loss so you need more pump or the next larger size PEX to prevent this. I only use copper, corrugated stainless(for heat exchangers), PVC or CPVC for anything larger than 1/2".

Lastly, I think people should plan for more shorter loops instead of fewer longer loops. Two 150ft loops will put out more heat than one 300ft loop because the water is warmer at the end of the loop, enabling lower source temps. The pumping energy is cut in half-my Laing/Bell & Gossett circulators take 11 watts for my smaller zones that have 1 or 2 loops, and 23 watts for the main zone with 4 loops. Use tees to split off for 2 loops or Sioux Chief manifolds if you need 3 or more for a zone.

I also want to give many thanks to all contributors for their info, especially AC Hacker! This forum by far has the most usefulness and the least posturing/BS of any I've ever seen!

Craig
The MMT

[AC_Hacker]

Originally Posted by Mobile Master Tech

...I'm a firm believer that theory is indispensable and will get you started, but practice trumps theory every time...

MMT (AKA: Craig),

Awesome post! Loads of good information here.

Good to hear of your success.

Do you have other energy projects on the drafting board?

Best,

-AC