Ah, it seems I misunderstood the point you were making.

No, not at all. 150 watts per person is a common figure in heat load calculations. Nearly all of it comes from respiration and the exposed head though.

My experience with IR guns makes me distrust them on reflective surfaces, possibly for the reasons you suggest.

BTW, I grew up near Powell Butte in Portland. In the 60's the slogan was "Keep Oregon Green." Last year I saw bumper stickers that said "Keep Oregon Weird." I miss home.

Oregon is still here, and it is still green and wierd.

I live in the St John's area. You don't see many of the "Wierd" bumper stickers in this part of town... it would be redundant.

-AC

@ Mikesolar
I guess my problem with this whole tangential discussion is the idea that there is someone in this discussion that supports reflective bubble wrap. No one here does who is at all informed, least of all me. It just seems like a straw man to get people riled up that signifies nothing.

The thing that irritated me so much was the migration of the bubble wrap issue (or vice versa) to Michael's post that the mylar flat reflective material was inherently defective. No evidence except his own heresay is given as evidence. But his description was not challenged because there is so much prejudicial evidence from the reflective bubble wrap issue. As a person who has covered his entire rafters with the non-bubble wrapped version of the stuff I find that objectionable. But for some reason my issue about that is conflated by you and others as a reflective bubble wrap issue. It isn't.

Part of my irritation is no doubt my own fault. I should have been more direct at the very beginning in challenging Michael's assumptions about the flat reflective barriers and asking for more evidence from him. My bad.

In the southern US, usually square footage is more expensive, typically homes don't have basements(which is where we normally put ducts and furnaces in the North), and people down there building houses don't think the public wants an air handler or furnace in a closet near the kitchen(noisy near the bedrooms or living rooms). There's more to it than that but if I had to move to the South for some reason and bought a house with ductwork in the attic, I'd seal up the attic, insulate the attic, and seal all the ductwork(so the air inside the ducts can't touch the air in the house). I'd likely remove it rather than just close it off though because insulating and sealing the attic would be easier. In the southern US I'd want the most cooling efficiency I can get and the winter isn't that cold so both of these coins add up to a mini-split setup. ..just don't forget to deal with solar gains through windows. I'd still do R60 in the attic, even down there, that way I don't have to care how hot the attic is.

Hi Exeric...is this you being more direct and asking? I'm sorry to seem dense, but what were my assumptions about the flat reflective barriers? mm

Well Michael, you said that in your experience the reflective material tends to just flake off. That certainly isn't my experience. Maybe what you are looking at is based on a different substrate from what I'm using. I don't know. What I'm using is a plastic poly type substrate and the silvery material is stuck on very securely. I don't see much of an issue there with it flaking off.

Also, you said that you didn't think that it would reflect radiation because one side of it is in contact with a surface of some kind, be it the substrate itself or something else. That isn't the way it works. Only one side needs to have an airgap. The other side can be in direct conductive proximity to any material. That is the physics of a reflective material - it does not conduct light or heat from one side to the other, but instead reflects it back.

Sorry to be so late with this.

Exeric,
Please read my posts on this again. I am NOT dissing radiant barriers although I think the insulation aspect of the bubble part has been misrepresented by the industry.

I am, however, stating where, in MY climate, they will work best. Mylar coatings are great and like I said somewhere earlier, I have used them as a radiant barrier first in 1993, and still do. That house did not use bubble wrap just mylar coated building paper (which is still in good shape, BTW.

For most of my history I hated cooling because it was never needed where I grew up. No one had it. Things are different now and cooling is being demanded and I have to work with that.

Your reflective barrier in the attic is a good choice and I have nothing against it.

I think it was me that he referring to.:D

That makes me feel a lot better. No hard feelings on my part. Continue as you were, all of you.:D

Something new in radiant heating & cooling...
 

I just stumbled across this item:


It's called a capillary tube mat and it's embedded in walls, floors, and ceilings for radiant heating and cooling.

Looks pretty much like the solar swimming pool heaters I see on Craigslist.

Very close tube spacing... very low profile.

Hmmmm........

-AC

I've never understood this either. Our house had two heat pumps, 2 ton each. The main floor system had the air handler and all ducts in the attic. It blew 120F air for a minute at the beginning of each cycle. The condensate pan was primordial soup. Virtually all of them I've looked at eventually plugged up and overflowed condensate into the ceiling.

I replaced both units with window shakers during the remodel. The summer electric bill dropped by half so I never got around to installing a new heat pump.

Another odd thing is the regional preference for black asphalt shingles. I put a light colored metal roof over mine with a convective air gap. Also cut a 4 inch wide opening along the ridge, screened it, and covered with a ventilating cap. My summer attic temperatures dropped 30 to 40 degrees. A sealed attic is definitely a bad idea here. 150F is normal in a Georgia attic.

The new (single) air handler is going in the basement. All but two ducts are out of the attic. Those are heavily insulated and I may still block them off if the system performs as expected.

I am installing hydronic for primary heat to take advantage of the lower delta T. The air handler will be primarily for air purification in the winter.

I now have 38 windows in my house (about 15 before the remodel). The summer heat gain with premium windows isn't that bad.

I am trying to buy XPS foam to place under the slab. Dow recommends Foamular 250 for residential applications. I'm having trouble locating a supplier. Home Depot is supposed to be an authorized supplier but my local store doesn't know it exists.

We don't have Menards down here and I couldn't find it on the Lowes website. Any suggestions as to where I can get it?

Lowes sells the pactiv brand XPS board. I believe the 25PSI stuff is the Greenguard. The 25PSI strength is the ASTM type IV product class. Insulfoam has the R-tech IV product line. These are comparable to the Foamular 250 insulation.

Edit: Confirmed. Here's the comparison sheet.

Lowes part # 304089 (1 inch), 304090 (2 inch)

Thanks Jeff. Lowes is a longer drive but they are a better store than my local HD. I'll make the trip after the holidays.

Just a quick follow up after years of using my floors....
 

Here is an original post:
http://ecorenovator.org/forum/renova...eating-21.html

After a few years of using my floors I can say only one thing AMAZING.....

Failures 0. Everything works just like clock. No noises. Temperature is stable and I don't need to touch anything.

My heating bill for 4200sqft home is about $70 on coldest months.

Vlad

Those are some impressive results. I looked back quickly through your thread and I couldn't conclude the heat source that your utilizing for that $70.00/month heating bill.

The home you have is a rather large at 4200 sq ft. and heating that for $70.00/m is unbelievable. If you could maybe list the items that make this feasible would be great.

Did you get your DIY Geothermal heat pump system installed?? Do you still have some input from the gas fired DHWT.

Thanks Randen

Here are more details:

1. Heat source is DHWT regular power vented 65% efficient 24000BTU net

2. Floor coverings 20-25% tiles rest hardwood no carpet

3. Max water temperature at manifold entry this heating season 90F (Max Min values stored in control unit)

4. $70 is a difference in my gas bill summer/winter. We use gas for heating hot water we have gas range/stove and gas cloth dried.

5. The crawl space walls are just 8" concrete non insulated yet. The concrete slab is also uninsulated. The first floor is uninsulated from this cool crawl space.

6. I didn't hook up heat pump for heating system it only used for AC and preheating cold air for fresh air supply. I use it just once in a while max ones a week in winter and as needed for AC in summer.

The design I used is very simple and cheap and you can buy most components right at your closest lumber yard.

I see people are trying too hard to make tube part more efficient by using some expensive materials and insulators like HD foam etc. The water temperature in loop is very low the heat loss is minimal in this area.

I think the biggest efficiency contributor is my control system multizone manifold using outdoor temperature sensor and variable speed pump control. All components are listed in thread before.

Also this system is low thermal mass system it follows heat demand just almost like air furnace. Concrete filled floors are very high thermal mass systems and will work efficiently only if heat demand is stable. We have one day 15F the next day 45F. Concrete floors will be comfy one day and will fry you the other day.

If I were to build this system again I would use high efficiency HWT or boiler as a heat source or WW heat pump. Also I would build arduino control system using flow control sensors and adjustable flow control valves for each loop and speed control for main water pump. This would make system even more flexible and controllable and definitely more efficient :)

Vlad's House...
 

I'd have to add to what Vlad has said, by noting that his whole house is new-built with 6" studs, 24" spaced walls, insulated with mineral wool, double glazed windows.

And also Vlad is a total fiend when it comes to sealing air leaks. I've never seen anyone so thorough with a can of foam.

Please note that his HDD is a fairly moderate yearly average of 6399 Fahrenheit (based on 68F) or 3555 Centigrade (based on 20C).


Hey Vlad, how many Therms of gas did you burn during the months of December also for February? Please include the billing dates for Dec & Feb. Also your zip code or equivalent.

I've come up with a very interesting way to do a heating analysis for your house.

Best,

-AC

Just for a little comparison our home is about 3600 sq ft. and 2 x 6 construction wrapped in a layer of 2" foam with stucco finish and well sealed. The home is heated in floor with a 6" concrete slab and all covered with tile.

Geo thermal and solar hot water. $280.00 per month (4 month winter) for electricity to operate the Geo thermal heat pumps.

The cons: lots of glass, Expansive glass block wall (R3/4) Open space lots of wind.

The pro: Oil heat would have been $6100.00

Awesome work Vlad

Randen

My walls are R22 Roxul insulation and roof is R40. As I said before my crawl space has no insulation and first floor is exposed to this cool place.

Here are some gas info coldest Feb 2013 11 GJ low summer Jul 2013 4.5 GJ a month.

It is hard to estimate because we use a lot of gas for cooking cloth drying water heating etc. 4 adults and 2 toddlers.....

On average during heating season it adds about $70 max to gas bill

I have designed & installed 2 working radiant floor systems. Both at 8,500' altitude zone 5, high winds often in Winter.

1st in in my current house, The upper 2 levels (2,000ft2) is heated via suspended 1/2" pex 8" OC under sub-floors. 2 runs between 16" OC TJI floor joyce. At bottom of 4" air gap below pex I have Reflectex, then sheetrock for ceiling below.

Roof is about R50 on average, walls R35, windows are tripple pane argon filled + outside 1/4" tempered storm windows (due to wind gusts >125mph)

The 3rd level is 1,020ft2 basement which is 5' below grade, 3' above. Walls are sheetrocked R18 ICF. Slab floor is insulated underneath with 4" XPS. Enough heat comes down through ceiling in Winter to keep basement @ 64*+-2*F

This system works well @ design temp. of 0*F & wind of 50mph. Using about 20MBH (20Kbtus) My 40MBH boiler runs at about 50% duty cycle at design conditions.
All floors are tile & surface temps. never go above 75*F.

This requires 145*F hydronic water temps at design, my LP boiler does not condense so it works just about as Eff. @ 180*F as it does at 130*F.

BUT, I wouldn't do suspended pex subfloor heat again.


2nd house is my neighbors 3,500ft2 log home, did this one with pex in concrete slab with 2" XPS under, he is penny-wise pound-foolish & this is all he would pop for.

His house is pooly insulated & has major air infiltration in wind, I don't realy know if he payed off building inspector?

His condensing (marginally) 150MBH boiller keeps up but he has to overheat his hickory flooring. He use about 4-5X LP vs my house.

BBP

A/C, I don't recall if you have implimented your radiant floor yet?
Your last post regarding build-up seems like it was months ago.
The build-up & close spacing looked "GREAT" to me for your situation & requirements.
You will have slightly less heat transfer than if imbedded in concrete, but will have an advantage of quicker responce to changing weather.
Any updates?

I am preparing the room for the floor. I've put in he electrics, now I'm insulating with some kind of board to go up on the walls. Right now I'm on a tight budget, and it's my policy to not borrow money, so I make progress when I can... which means it's going slowly.

This week's victory was putting in a pretty high performance window with triple glass and double low E. I have also reduced the glass area of the room, possibly more than I anticipated.

My decision to do built up is based on the fact that my house is very old (120 years), and the foundation is not the best (basalt rock & river sand mortar). I did a calculation that 1.5" on my 12' x12' room would weigh 2700 pounds, which I'm not comfortable with... gypcrete wouldn't save much weight at all.

So, built-up will be the way for me. I sure have thought about it, and a wet system would be cheaper and quicker, and maybe even more efficient.

So, I have been watching Daox's office project (which is similar to Vlad's). I really like how he's going about it, and mine is going to be along the same lines.

My strategy is to increase the R-value under the floor and decrease the R-value on top of the floor.

Best,

-AC

AC, gypcrete is 40% less weight than concrete and 2700lbs is diddly if your joists are not at their limits. Unless you really know that the stones are in a precarious state, I wouldn't worry too much.

I'm looking at buying a 175 year old house built on stone with what they call a "flow through" foundation. A river seems to run through it at some times of the year but nothing has moved upstairs. The walls and door frames are all straight.

It is not recommended to use regular concrete under less than 2" BTW (if that is what you were thinking).

Mikesolar, is that rec on regular concrete in regard to radiant efficiencies or structural( like cracking) do you know?

I have read about DIY light weight mud: As I recall, you substitute pearlite for the gravel.
Lowe's sells pearlite in bags fairly cheep.


http://www.perlite.org/library-perli...e-Concrete.pdf

More perlite % = lower weight/strength/thermal conduction

Correct me if I'm wrong here...

Density of gypcrete is 110 lb/cu ft

Density of concrete is 150 lb/cu ft

Density difference = 150 - 110 = 40 lb/cu ft

percent difference = (40/150) * 100 = 27%

Where did I make a mistake?

Gypcrete would have to have a density of 90 lb/cu ft. to be 40% lighter.

-AC

Yes. I think that the idea is to get better conduction, ant the more perlite that is added, the worse the conduction.

I'm seeing perlite touted as a thermal insulator.

Shouldn't I be going the other way with a radiant surface?

-AC

Yes, more thermal conduction is goal.

I found THIS paper about additives to concrete to improve thermal conductivity.

-AC

As I have been searching for a control panel system to match a simple 2 or 3 loop one zone radiant layout I have been asked by suppliers "what is the hot water source?" Are control systems that specific to method of hot water? I want to stay as generic as possible to be able to switch "sources" as availability, knowledge of DIY and economics change. The manifold and loops are constant if designed properly what are the components that are specific to water source? Is their a design that gives you the most options? Are the requirements based on on-demand or storage sources? Or high temp vs low temp supply?

Drake, Will your loops be in a slab that is properly insulated with FOAM R10 or more underneath, or in heat transfer plates, or suspended under subfloor?

The water temp. required for each method is quite different, say aprox. 25*F Delta up with each.

Gain in efficiency is pretty large with minimizing water temp.

No boiler is made small enough for a small heat load, thus a buffer tank would be required.

The PEX loops & manifold could stay the same regardless of heat source, mine have.

Yes, two loops will be in a high mass(4") slab with 1 1'2' thermax below. And a third loop in a thin slab(1 1/2") in a lofted bedroom. 600 sq ' new space will be built to "passive house" standards. Am favoring off peak heating a 120 gallon DHWH tank as storage and incorporating a mixing valve to lower loop temps as slab are said to work best supplied with lower temp fluid. Tank and loops a dedicated system, another DHWH sperate for potable use. But in the future I would like to go Geo or something when I have the time after completing the build(4-5 yrs) as a heat source with as little retrofit as possible.

If you think you will want to 'go geo', be sure you design your floors for geo now... it'll make your conventional heating cheaper too, in the meantime..

-AC

Drake, I would make it 2 zones with seperate thermostats, 2 zone valves & 1 pump.
With different slab thickness & bedrooms are usually set at lower temp.
I like the Grundfos Alpha, low electricity use & automatically sets its own speed to match backpressure.
Use O2 barrier 1/2" PEX spaced at 8" OC, limit each loop to 250'
Get a Taco Outdoor Reset Thermal mixing valve (ODR TMV). It will minimize water temp. to zones based on outdoor temp.

AC, to the best of my research high mass(concrete) floors are the best design for low temp hydronic radiant heating I have come across. It also is the best for solar passive gain storage. I have gotten a consensus that this floor design will function equally well with any source of hot fluid run thru it. From your comment am I missing an alternative design?

BBP, all your recommendation are now in my folder on hydronics for when I get to that part of my new construction. Am I correct that all these components would be part of what is considered the "control panel" portion of a hydronics system?

Why limit to only 250' ?
I have 2 zones of 800-850' (240-260m) each as well as 6 other zones all fed from a a single grundfos alpha 2.
This is through 17mm PEX, the pump usually draws 21w so is not struggling at all.

Steve

Drake, yes control components. What does your " 1 1'2' " mean? 1.5" not nearly enough.

THERMAX? Sheathing

Thermax is polyisocyanurate foam, this type should NEVER be used under a slab, it will waterlog & loose most all of its R-value.

In Mn. I would use 4" minimum or MORE of XPS (blueboard) or EPS type2 or 3

To push 1gpm through 800' takes 3.2X energy vs. 1gpm through 250'
Read: Modern Hydronic Heating by John Siegenthaler, P.E.