DIY Hydronic Floor Heating

[Mikesolar]

Reduce your manifold down to 3/4" and get a 3/4" pump. 1" pipe and fittings are usually double the cost of 3/4" and for your flow rate, 3/4 is needed.

[Mikesolar]

UMMM, Barry, the way you describe it, is the way is was here 20 years ago. If you read all the posts i have written, everything you have said is because good professionals were not consulted. Yes there are some people who just want the cheapest job but what can you expect from countries where there is basically no living minimum wage and insurance payments cost a small fortune. Not much left over in some bank accounts. There are some knowledgeable people doing this work (I have 1/2 million metres of the stuff installed in the last 25 years)

That said, there are also some generalizations you make that are untrue. One, Australia does not use that much radiant because it is a predominantly cooling climate and seldom gets anywhere below 0C there. The nights are cool and the days are warm....in winter. I too would be using a mini split in that situation.

Installers here who install professionally (not just plumbers who put the stuff in once and awhile) do have more training but I will agree with you, no where near as much as in Germany where the guilds and apprenticeships are well established and the theory is taught more. The tubing install is not the big issue, and neither is the materials. It is the design knowledge of DIYers.

The cost of materials here is not that much more than in Europe and the tubing and manifolds (Rehau, Viega, Uponor ) are the same main brands as in Europe. I have noted that prices are a bit higher here but remember that out of 500 million people in North America, maybe 50 million use water for heating and the rest used scorched air. There is a much smaller market than in Europe.

In-slab is not the best way of installing such a system, as the slab needs to be insulated against heat loss, hence, the pipes go onto the slab after insulation is put on the slab.

Please explain the above. I have studied European systems for years and while we don't insulate to the Swedish standard, things are getting better and any smart person insulates a slab well.

I don't see anything that you have written that conflicts with what I or a few others have written and do every day.

[Mobile Master Tech]

I've been away a while! Here are some updates and thoughts after having my system a few years and reading recent posts:

I see a great deal of back and forth over pipe diameter, insulation/radiant barrier effectiveness, Reynolds numbers, pipe routing, required supply temp, reset to compensate for outdoor temp, etc. Don't overthink it. To keep it simple, I have learned through experience (some of this is reiterated or I have previously posted):

1: 1/2" pex is used because it is relatively cheap, stupendously durable, easy to work with and a cost effective way to get hot water to a floor with no more than 12" spacing between pipes for even heating. Go smaller and flow isn't enough, go larger and cost goes way up and installation is an absolute bitch. 1/2" works.

2: Pipes in a slab may be best, but staple up with cheap stamped heat transfer plates works fine and staple-up without plates is less than worthless. My not very efficient house envelope is heated fine with 12" on center 1/2" pex and transfer plates with 125F supply (I leave it at 130F minimum for Legionella safety since my system is open loop). I cannot imagine a climate where 8" on center with staple up plates and a minimum of envelope improvements (that should be done anyway) wouldn't be sufficient.

3: I have had no failures or problems with the hydronic system. I use regular wall mounted air thermostats telling my controller to turn each zone pump on or off, and one-way bronze valves allowing water flow in only one direction. No reset, no mixing valves, no high wattage noisy pumps, no zone valves, etc. If the house needs more heat, each zone stays on longer and off less. K.I.S.S.

4: I have gotten a few more creaks/pops as the pipes expand when a zone has fully cooled and comes back on-not obtrusive, but I would like it quiet. Instead of silicone caulk as a transfer compound between the transfer plate and the pex, I would use silicone plumbers grease. It won't get runny and saturate anything nearby and would act as a lubricant for the pex in the plates to keep it from gripping/releasing-a very tiny amount does the trick.

5: I would make each loop a max of 250 feet or so for lower pumping head and route the pipes the simplest way, including pulling a single loop through to make 2 pipes in each joist bay as I described in previous posts. I wouldn't go through extra effort trying to make the outside wall areas hottest or keeping loop lengths nearly the same. Most of the outer floor area is covered with furniture and such, it's closer to the outer wall to lose heat through, plus I REALLY like feeling the warmth of the floor with my bare feet! If the loops are less than 250 feet but more than 150 feet, there isn't much difference in head. You could always crimp in a valve to partially throttle the zippiest loop in a zone if you have a large return temp difference. If that means crossing one pipe with another, just isolate the contact point with a sheath of larger pex or pipe insulation. A cleaner install is better than one with no crossover points or undue effort to evenly heat the perimeter or keep the loops the same.

6: I wouldn't buy Grand Hall's Eternal Water Heater again. I've had numerous different nuisance tripouts cured by powering off then on, the exit mixing valve go bad (under warranty but a hassle to get them to send me a new one), and a potentially catastrophic failure of the water pressure sensor. It's made of plastic and had gotten cooked from heat. I noticed a slow water leak from the heater one day, so I shut the water off and removed the covers. I barely even touched the sensor and it broke completely off, spraying residual water pressure everywhere! I didn't want the same problem again-imagine if it broke while I was on vacation for a month and the water was turned on! It's just a simple on/off pressure switch with a metric thread very close to 1/8" NPT, so I just retapped the hole and installed a metal engine oil pressure switch that fits numerous old GM cars. Done and ok now, but I wouldn't wish these problems on someone else. Great heat exchanger inside, I may repurpose someday....

7: I have learned that copper is bacteriocidic like silver is. Having copper/brass here and there in a plumbing system is a good thing, but it isn't necessary to be all copper.

8: Having an AC system with an intermittent fan function and high efficiency filters is great for air filtration and moving heat around from one area to another. Air quality isn't a problem.

9: Realtors tell me what I have already confirmed: a warm floor is one of the best features a house can have! Aaaannndd, I get to post one of the benefits I can't believe no one else has posted on ecorenovator: Kotatsus are easy! Here's a link: https://en.wikipedia.org/wiki/Kotatsu

A Kotatsu usually has a heat source under the table and a comforter style perimeter draped down that you put your lower body under. The warm floor is the heat source! I've draped a blanket over a coffee table or draped it over the edge of the couch to create a cocoon of extra heat coming from the floor. 100% of the homo sapiens, canines and felines I surveyed agree that it's awesome!



Lastly, it makes sense to design a system to work at DHW temps so you can combine systems and heat sources and not have to work so hard at making lower exergy sourcewater work. I've updated my plans to fire my energy companies and ask all of you for some Phase Change Material help at post 15 of THIS THREAD

Bumping up the temp of the heat source for a GSHP improves efficiency just as much as lowering its discharge temp. The actual temps don't matter much, what matters is the amount of lift. Taking heat from a 70F source to make 140F water is essentially the same work as taking heat from a 35F source to make 105F water.

I am also insulating and stuccoing the exposed exterior parts of my concrete basement walls so they are part of the thermal mass and not losing such an ungodly amount of heat through them. 1/2" R3.8 polyiso board is $10 at Lowes. Using dollops of adhesive and some pushpins to keep the radiant barrier side of the board 1/4" of an inch from the concrete is almost as good as the recommended 1" airgap for radiant barriers. Sealing the board at the top of the wall will prevent the barrier from getting dirty and also prevents an hidden path for termites to make it to the wood a few feet above.

Best to all! AC, I hope to see your system in this thread soon....

[buffalobillpatrick]

Mobile Master Tech, thanks for update, you are right KISS, simple is better.
But, IMHO zone pumps use too much power.

I agree with Mikesolar, he really knows what he is talking about.

My Son's new 3400ft2 house (I designed the heating system) has 6 heating zones using Taco Sentry zone valves (low power).

All flow in the 10,000'+ pex distribution system is done with 1 Grundfos Alpha ECM pump set on the lowest constant pressure mode (6' head) (very low power).

Slow flow (.5 GPM) in each loop uses only 29% of the pumping energy needed at 1 GPM (when flow is doubled head loss goes up by 3.4X)

but here is the surprise: it delivers 96% as much heat.

[Mobile Master Tech]

BBP, I agree about traditional circulators and zone valves. I read of some systems in a typical house that were too noisy to sleep and the electrical draw is 800-1200W! At what point is that considered a "hybrid" hydronic plus electric resistance heating system....

Those sentry valves look great for systems where valves make sense. The advertised wattage for conventional ones is 5-22W per valve any time it is on, plus the pump draw. The Alpha pumps are great too, especially how they self regulate for current demand. A system designed with these is another good way to do it.

I used spherical Bell & Gossett pumps designed by Laing is so makeup water can flow through them and the oneway flapper valves, allowing an open system-no corrosion issues, and all my plumbing is always flushed! The smaller ones take 9W for 0.5gpm through 250-300ft loops and the large one takes 23W to move 2gpm, 0.5gpm for each of 4 300ft loops. They have no bearings, no seals and the only moving part is the magnetic impeller which stays sealed inside the drive can. The impeller is free to pivot so they will probably never jam. They can't leak and will probably never fail. They are adjustable speed for finetuning. You are right, there isn't need for high flows and the power required to produce them.

The other reason to use individual pumps rather than one pump plus valves is eliminating points of failure. If the only pump fails, no heat. If one pump fails in a multipump system, only one zone is down. If the controls fail, both system types are down but I can just plug my pumps into an electrical outlet and I have heat. 3 items are required for a zone to function in a single pump system-controls, pump and valve. In mine, you only have 2 items-controls and pump. Fewer points of failure and fewer single points of failure.

[stevehull]

MMT,

Trying to find specifics on the Bell & Gosset pumps you talked of. Can you post a URL? I really like the 9 W low current draw for 0.5 gpm (150-250 foot loop).

How do they compare to the Taco "bumblebee" pump?

Thanks.


Steve

[buffalobillpatrick]

Moble, good reasons, your pumps are low power usage.

I will describe my thermostat -> zone valve -> pump on, as some may not be familiar with this,

3-wire heat only thermostats:

24vac transformer power to thermostat:
(1) Black wire (C) = common at transformer (grounded)
(2) Red wire (Rh) = hot thermostat power

when thermostat senses a need for heat it closes an internal contact, which connects the
hot thermostat power to the
(3)White wire brings 24vac power back to energize the zone valve.

The zone valve opens in about 5 seconds allowing flow through a ball controlled internal orifice, when it is completely open an internal End Switch contact closes.

All of my zone valve End Switches are wired in parallel, so that if (any or all) are closed a Solid State relay is energized, this relay controls 120vac to the Grundfos Alpha pump.

Note: I love SSR's they last forever & don't arc contacts, when controlling 120/240vac they turn on at the ac zero crossing time, a 4ms soft start if you will.

BTW, You won't find any 24vac (old term: coil) control SSR's so use a DC controlled SSR with DC on the end switches (wall wort), or use 24vac on end switches & build or buy a little diode / resistor / capacitor rectifier for relay control input.

My Grundfos Alpha pump is set to maintain a constant pressure of 6' head (2.56 psi) no matter how many zones are "calling for heat" so that all will receive equal flow, up to 14 gpm where it maxes out power, my system never reaches max pump power.

[buffalobillpatrick]

Steve, the Taco "bumblebee" pumps make some noise, buzz like a bee.

If you don't need all the power of a Grundfos Alpha pump, I like the Taco Viridian ECM, it's lowest setting is lower than an Alpha & is about the pumping power of a Taco 003 at much less Watts.

[Mobile Master Tech]

Steve, I'm not familiar with the bumblebee, but it seems that all the pump manufacturers are now coming out with ECM pumps which save tons of energy. It seems the Laing design still wins out to me and are most efficient. They are nearly silent. If you are 5 feet away from them you can't hear them.

I chose the Laing (Bell & Gossett bought the design) not just because of the efficiency but because they have a fluid bearing that will never wear out, there is no way they can leak, and it was easy to sweat a pipe, PEX crimp or 1/2" NPT fitting into them-no flanges, very compact manifold arrangement, and safe for potable water. Their webpage:

ecocirc e3 Whole House Potable Water Circulators – Xylem Applied Water Systems – United States

I posted detailed descriptions of my system, its components, and where I got them earlier in this thread starting here: http://ecorenovator.org/forum/renova...html#post21961

I might choose the e3-6 pumps for all zones if I did it again, since when all zones are on the total head is enough to really reduce the flow through the zones that have an e3-3 pump. The -6 has enclosed rotor fins for better pumping efficiency where the -3's are open at the top. Or, I could just use smaller loops and not worry about it.

BBP, I like your layout. SSR's are great. My Bell & Gossett controller still uses micro mechanical relays to apply 120v to the pumps, but at 25 max soft start watts with no inductive inrush current, I think they will last longer than me...

My Nordyne AC has a special thermostat, so I used it's micro relay (that would ordinarily turn on a larger relay for resistance heating coils) to complete the call for heat to the hydronic controller, so you can't call for heat and ac at the same time.

For the other zones, I used 24vac duct dampers to close the airflow for the zone to a trickle, plus heat/cool conventional thermostats. If the thermostat calls for heat, the hydronic controller runs the pump and the duct stays closed, so no AC could flow into that zone. If the thermostat calls for AC, the damper opens allowing cool air into that zone, but the heat wouldn't be on at the same time. Since the Nordyne varies its output from 1.5 to 3.5 tons, it runs slowly nearly all day during cooling season-it's already running anytime another zone would need AC. I haven't had any time where AC and heat were called for at the same time, though.

[stevehull]

MMT - just re-read your post on system design. A couple questions and I apologize if you have answered them elsewhere.

Re the open loop radiant system. Does this mean that the radiant loops are heated in the summer? I understand that by drawing off hot water (such as faucets, shower, washers, etc) removes the water from the radiant system and prevents stagnation (legionnaire's dx). But how do you do this without heating up all the loops in the summer?

I have had problems with hooking up a small point of use electric heater to "top off" the heat from a storage tank. The problem was that the small (8 kW) heaters only had a 1/2 inch connection and this restriction caused loss of hot water flow when more than one hot water need was being used. For example, showering and someone turning on the dishwasher. Or, did you put two point of use heaters in parallel?

Thanks again,

Steve