Fears about new construction with radiant heat flooring

alexclusif

Hi all,
Sorry I'm a newbie at all this so please bear with me and my perhaps silly comments/questions.
I have read dozens of other posts just to reassure you, but I need a little more "specific" help for my own situation to remove my fears.
Brief description: We are having a new house built in Quebec, Canada (that = cold winters fyi) House is half ICFS (bottom floor) = R23.5 and half 2X6 frame with 3/4inch insulated OSB board ext = roughly R26.
2 floors (1 semi-basement? meaning 4 feet under ground, and 1 above grade floor) total sq/ft = 2000 (1000 per story).
We have put PEX in the basement slab, and will be putting suspended PEX under subfloor for above grade floor. Concentrating on the above grade floor:
Our contractor has done this before with success and we can't afford aluminium staple up plates for the whole thing, but he will be putting bubble-foil and then 4 inches of Cellulose insulation below the PEX tubing. We will have an electric water heater or boiler running the radiant flooring.
Now finding knowledgeable people on this subject in our rural area here is near impossible.
So my big big concern here and first question is:

Should we/must we install secondary complimentary electric baseboard heating for the really cold days up here or will the radiant flooring suffice?
Our electrician is about to wire up the house and we kinda have to decide this quickly.

And last but not least question: I am in love with cork flooring. I've read other posts, and researched the manufacturer to see if radiant is acceptable. It appears to be OK. However, my cork floor reseller is saying no! Help! They say I won't be able to get the room temps above 19 degrees Celsius (66 Farenheit) because of cork being an insulator.
We will have bathrooms, entrance/mudroom tiled but I wanted to put cork all over the other 800sq/ft.
This is 12mm (1/2 inch) flooring with 3mm cork top layer glued to HDF laminate and 1 or 2mm bottom cork layer. From what I've read, that's about a 1.2 R value. If I'm adding that to the OSB subfloor R value (also about 1.2) that's about 2.4 R value total that the radiant has to pass through. Is this feasable/possible/recommendable?
The maximum temp recommended for subfloor for putting this floating cork laminate over is 85 F.

I don't want to pay the high price of cork floors AND radiant heating only to realize we will be cold after all that!
Thank you so much for any input.
Muchly appreciated.

Alex

kcopp

You need to start w a heatloss... Your heating contractor should have that done. FIRST.
That will tell you if you can do the cork flooring.
The two floors will need to be run at two different temp. I m not a fan of plateless stapleup systems. They run at higher temps and typically when it gets real cold they don't perform well.
I'm actually surprised that in Quebec you don't have higher R value walls.
if your cork flooring person says no you may want to heed their advice.

Paul Pollets

A plateless staple-up will not work well in Quebec. Your comfort is at stake and your fuel costs will be higher. If a heat loss is done on radiant software, you'll see the water temps required and if supplemental heat is required. You can also do the "what-if" by putting plates in or out of the design. Many of the systems I fix are plateless, and I question the efficacy of hydronic design when they're omitted. Bad idea.

Mark Eatherton

If you can't afford to do the radiant right (with plates) maybe you should consider hot water baseboard. I may be mistaken, but I don't think that the major tubing manufacturers even show plateless staple up as an option anymore. Too much abuse and problems, like your project will have.

As others have noted, you MUST do a heat loss/heat gain calculation taking into consideration ALL floor finishes. To not do so is against the energy code here in most of the US, (IECC)

ME

KC_Jones

I am not a radiant expert by any means, but almost everything I read in your post is a red flag. First and this is blunt, if you can't afford plates which would be the proper way to do this then IMHO you can't afford radiant. Do it right or don't do it.

Second you mention a water heater. That is wrong, water heaters make DHW boilers heat the house.

If you are doing hydronic floor why consider electric as a supplement and not supplement off of the hydronic system?

You contractor is using the foil bubble garbage. It's snake oil don't waste the money.

Personally I would ditch the cork, use the money to install the radiant properly and later on I could add the cork when I have money. Changing flooring later is easy. Fixing a messed up heating system later, not so much.

I will reiterate what was already said, if a heatloss wasn't done then your entire system is essentially throwing darts at a dart board. You might get lucky, you might not.

alexclusif

Thank you all so very much for your comments. Very thought-provoking stuff.
I'll have to look into a heat load calc as I don't even know who does that kind of thing around here and the costs involved.
You all seem very clear that if I'm to do the radiant route, to do it with the plates so I'll reconsider that.
KC-Jones, I didn't quite understand your comment about water heaters. I know in USA, you use a lot of gas powered etc boilers, but here everything is electric. Water heaters with tanks, tankless water heaters, and boilers. Not sure if that's what you were referring to or not. Anyways if I understand correctly, I can use a instant water heater/boiler just for the radiant, and another for domestic hot water, OR I could maybe use a combo unit that does both.

alexclusif

Ok I'm back after more research. The bad news is my contractor did the install without the plates (budget related) had no choice. The good news is he HAS installed half a dozen of them in the past and the clients all seem satisfied except for a select few who use a single radiator on the realllly cold days.

So I went and purchased my own program and did my own heat loss/gain calc since my contractor isn't technically inclined...Anyways I did several different tests and whatifs with the help of the software developer so should be KINDOF accurate.

My results are 28000btuh total heatloss for entire home, and 20000btuh for first floor. Which = 20btuh/sqft. So now what? Still at a loss with lack of knowledge. If we use a 50000btu electric water boiler to manage both floors (2000sq/ft, basement = inslab pex), how do I calculate how many btuh/sqft will be radiating out of my floor/subfloor? If it's any help I even calculated the R-value of my entire floor system - R2 which seems scary high. Anything you geniuses need for info, I'll give but I'm really in need of some pro advice.

Simpler break-down:
50,000btu boiler
2000sq ft
1000sq ft top floor with heat loss of 20btuh/sqft
max allowed temp above subfloor (below cork): 82 degrees F

Q: Can I get up to 20btuh/sqft or no with this underpar setup?
Many thanks in advance.

Zman

Your experience with this project is one of the truly odd things about the construction process.

I am fairly certain that the builder did not just throw up some roof rafters and say "this didn't fall down last time so let's do it again..".
The plumber did not install 2" waste and vent for the toilets and figure the turds are not that big so they should fit.
The electrician did not just start running wire figuring it will be close enough and the last house did not burn to the ground...
All these guys had a methodology, most likely required by code, they used to determine that the work they do will function safely and correctly.

So why is it when it comes to heating, it is OK to just take wild **** guesses and assume it will work just because the last guy didn't complain much?

The answer to your question is probably...

I have seen lot's of old staple up jobs that function just fine at ~20 deg/sq ft. Some don't work that well, usually because the same sloppy methodology was used in other components like insulation and air sealing.

I would not use electric if you have other choices as it is the most expensive option from a fuel cost point of view.

I would also be aware that the in slab portion will need much lower temps than the rest of the house. If your builder runs them both at the same temp like "he did on the last job", those spaces will often be uncomfortably hot as the slab temp overshoots it's target. Those slabs will also have a tendency to suck up all your boilers BTU's when both zones are calling. This will cause the upper floor to under perform.

I still remember the the words the contractor said on my very first construction job over 30 years ago. The siding crew working on one side of a roof was not paying attention to the siding crew on the other side. When they got to the top, they realized that the boards where misaligned by 1/2 course.
The contractor looked up, took off his hat and yelled "What the **** am I paying you guys for...."

This would not be an inappropriate question to ask a heating contractor that is incapable of doing a heat loss calculation.

kcopp

"Ok I'm back after more research. The bad news is my contractor did the install without the plates (budget related) had no choice. "

He had a choice... he chose poorly.

SWEI

Zman said:

I would not use electric if you have other choices as it is the most expensive option from a fuel cost point of view.

That may or may not be true in Quebec, especially as regards off-peak use. FWIW, Thermolec and Dettson are both located in Quebec and manufacture electric boilers.

Gordy

Hydronics is a science. His (satisfied) customers probably have no clue a system could be much better than the design he used.

jumper

Unless there's a ceiling height issue,I don't understand why electric ceiling radiant isn't the standard when energy source is electric. Unless you want to keep the option of heat pump or solar for future.

Electric ceiling radiant enables customizing for each room. Bedrooms can be cool except for the bed area for example.

vibert_c


Alex is getting his first experience in dealing with contractors
that have hooked a newbie on their fish line. They are quite
capable of building your home by their design and standards,
in spite of what is written in the building plans. [It is
questionable if they can read English] Negotiations go down
hill quickly when it involves a custom built dwelling.

Here are two items to be aware of when Canadians are
involved.

For a heating device to be called a boiler it must be able to
boil water; otherwise it is known as a water heater. [don’t
ask me how I learned this]

Hydro Quebec has a corner on the heating market in Quebec
with their dual rate scheme. For a very low rate they will
provide you BTUs till the outdoor ambient falls below -10̊C
degrees. At that point you must resort to a backup strategy
History shows that this might happen three times during the
heating season for only part of a day.
There is no Time of Use scheme in Quebec.

Alex you have started out seeking help a least one year too
late. I hope your grey hairs don’t show too vividly when it is
all over and you move in.

alexclusif

Thanks guys, appreciate the feedback and yes the grey hairs are coming faster than anticipated! I agree with you all about the contractor being...subpar. Building is one thing, science is another. And he is a fine builder, but not so much in the sciences of engineering etc. We're far behind here everything is still old-school. The fact I had to attempt my own heat calcs says a lot. Vibert you are right - I'm a year or 2 too late. Anyways, the basement will be zoned different than 1/st floor so no problem with management there. I did try to get inslab PEX on the first floor too but lost that battle as well. What can I say - budget is king in custom builds.
For your info though, you guys have to stop with the electric vs gas boiler/heater issues for us Quebecers...I am certain electric isn't the best option out there for anyone, however up here it is THE option. Electricity is cheap and electric heaters/boilers are MUCH cheaper than others. Super efficient as well.

kcopp

Hydro-electric is a beautiful thing....

SWEI

...as long as you live near a dam.

alexclusif

It's renewable energy and "free" until HydroQuebec passes it through their greedy hands. Once electric cars go mainstream, who knows how high they'll skyrocket their prices. For now it's still "manageable". Ironically they sell it to you USAers cheaper than to us who have the dams...

Solid_Fuel_Man

Yes, first and only "Electric furnace" I've seen was in Quebec, looked like a conventional scorched air furnace, only it had a 1/0 aluminum SER cable going to it. Had a 100amp 240v rating if I remember correctly. Enough power consumption in one appliance alone to run at least 2 entire houses in my area. But if Electric is cheap, then go Electric. Least amount of maintenance for sure.

jumper

Consumers don't know until it's too late. Those all electric subdivisions have electric furnaces. Cheapest option especially when home is built with A/C. Cost is acceptable with modern insulation. But if I had electric heat I'd want radiant with individual room control.

Alan (California Radiant) Forbes

It's not too late to install Ultra-Fin. We gave up using plates years ago since it's much easier to install; one run per bay instead of two. You've just got to be careful about installing the insulation properly to allow convection.

You can get up to 46 BTU output per square foot at 180° water temperature, so you won't have a problem at 20 BTU's. You will be able to run much lower water temperatures.

http://www.ultra-fin.com/

alexclusif

Thank you, looks like a great product! Will check out prices in my area. On another note, can anyone please illuminate me on the effects of the R-value of the floor in respect to radiant efficiency? Some "experts" are telling me it will only slow down reaction times but won't affect output at all (explanation being that the heat "has to go somewhere" and if it's insulated underneath,can only go up", others are saying the complete opposite, that the output will be rendered practically useless. Neither seems logical to me, because if you put R60 of insulation somewhere, I doubt the heat "has to go somewhere" and will make it through. However, R2 in my small brain isn't THAT much as to make output almost obsolete, is it???

gennady

ultra fin

hot_rod

gennady said:

ultra fin

Nice installation of the UF, there is a place for that application.

Some beefy floor joists there! Hope you didn't have to drill them too much?

Gordy

alexclusif said:

Thank you, looks like a great product! Will check out prices in my area. On another note, can anyone please illuminate me on the effects of the R-value of the floor in respect to radiant efficiency? Some "experts" are telling me it will only slow down reaction times but won't affect output at all (explanation being that the heat "has to go somewhere" and if it's insulated underneath,can only go up", others are saying the complete opposite, that the output will be rendered practically useless. Neither seems logical to me, because if you put R60 of insulation somewhere, I doubt the heat "has to go somewhere" and will make it through. However, R2 in my small brain isn't THAT much as to make output almost obsolete, is it???

Make sure when insulating the floor you pay extra attention to detail in the rim joist area. Air sealing especially.

Also think of it this way R 2 is 200% better than R 0. So the insulation below has to be of a much higher value to direct the transfer where you want it to go.

Mass of the above floor assembly plays a huge roll. You certainly would not want to do set backs. So delayed response is certainly a part of a high r value floor assembly.

Alan (California Radiant) Forbes

I don't think you will have a problem with cork floors. It's a very stable material with a low R-value; R-1 I seem to remember.

However, you may want to treat it like hardwood, letting it acclimate for a couple of weeks in the house with the heating on before installing it.

alexclusif

Thanks guys, you're all so very helpful. Nothing like knowlege! I'm getting more valuable info from you few than any stores/"experts" I'm talking to. Really really appreciate it. Will keep you informed of any interesting developments as we go.

Solid_Fuel_Man

There are so many variables with heating that someone can't say "xx works and you are no different". People's expectations are different even if the homes are cookie cutter identical.

Some like to "set it and forget it" while others are obsessed with micro-managing heat output. I've been in many many houses with staple up radiant without plates and people are generally happy. "The floors are warm all the time!" What they don't know is that 180 degree water is killing the efficiency of the system and there are much better options, if time and money were expended at construction time.

Many of those homes have auxiliary baseboard for "we use that when it gets really cold" with a seperate thermistat no less...knowing in my mind that this hack of a system is costing thousands more to operate than if it were done right to begin with. But those people have nothing else to compare it to and are still generally happy. In the end, at least they don't have scorched air!

Taylor

Rich_49

Plomberie Chauffage Normand inc . Ask for Morgan Tallman

j a_2

@ K C ,,,Water heaters are used to heat homes up here in the Boston area....Mostly with hydro air and some with copper fin baseboard....It's generally a city thing...Worked on many of them in my days....just an FYI

Gordy

On New Year's Eve none the less. Thanks @Rich .

j a_2

Heat loss for radiant is not quite the correct wording...The good book says Radiant heating involves the regulation of heat loss per square foot from the human body...Mr Retired Dan speaks about that COLD 70 thing in what I have to say was one if not the best books I have ever read...Hydronic Radiant Heating....loved the Lost Art book as well....But this book should be read by just about everyone involved in this industry.....

alexclusif

Ok back again with more concerns (and grey hairs). Math issue:
Here goes: my flooring suppliers suck at giving answers, but I still have done enough research to know that cork floating floors "shouldn't" be exposed to heat above 85F (that is above subfloor temp I'm thinking).
Now math problem: if the subfloor is maxed out at 85F, and the room temp is say 72F, will I attain that 85 degrees ABOVE the cork? Remember, cork floating = R1.1, same as OSB subfloor for a total of R2.2. That is only 13 degrees difference in subfloor and room temp, and if I'm learning what you've been teaching, the less difference, the slower/less heat transfer is being done. Won't the R1.1 basically cancel out those few degrees difference...Water temperature becomes irrelevant because it can't allow the subfloor to go beyond 85F. Ultrafins, aluminum transfer plates etc all rendered almost useless (not quite because still allow for lower water temp but still) because of flooring limit. I hear the same is true about hardwood floors - can't go above 85F subfloor temp. And for the even more mathematically inclined out there, is there any way I can calculate btuh/sqft output I'll manage based on these room temp/floor temp/R values?
Thanks guys you rock as always. And for what it's worth (yeah I don't mind typing it out so all can understand), the info you're putting out here is not only helping me but many others also. You're being generous with your know-how and you deserve all credit.

Gordy

Healthy heating.com is an excellent web site. Compliments of Robert Bean.

hot_rod

The heat transfer from a radiant panel is driven by the ∆T or temperature difference. You can increase the output by increasing the floor surface temperature, or reducing the ambient temperature in the space.

Most of the radiant manufacturers have graphs showing that relationship. This from a recent RPA newsletter, an Uponor graph I believe.




The insulation value of the floor coverings are also shown for quick reference.




The maximum surface temperature is also about comfort, some suggest 82- 83 is about as warm as the surface should be for barefoot use. Above that it becomes too warm and some may experience sweaty feet

Keep in mind, even with the best radiant installation it is almost impossible to get the entire surface a consistent temperature, striping over the tube will be the warmest spot.

There are a range of opinions on flooring temperatures maximums, the best advice is to go with the guidelines from the manufacturer of the products and the adhesives used.

The RPA publishes a Flooring Guide, it has the most up to date info from the radiant friendly floor covering manufacturers.




www.radiantprofessionalalliance.org

Radiant ceilings and wall can have a higher output, higher surface temperature possible. Figure 0.71 BTU/hr/ sq. ft. for every degree difference, in an assembly of 1/2 sheetrock over transfer plates.

So a 110 supply at the ceiling with 70° room temperature would get you about 28.4 BTU/ sq.ft. output

Gordy

Remember insulation delays response of heat transfer. It does not stop it. The higher the r value the longer the delay. This is why I posted earlier as to why you would not want to use setbacks. How you control the system is crucial. Outdoor reset, and the use of Floor sensors are a big part of this. A tstat alone will only compound the delay in response.

Alan (California Radiant) Forbes

Indoor reset works hand-in-hand with outdoor reset. Think Vitotrol or Tekmar thermostats.

jumper

If you're not confident why go ahead? Do you anticipate switching to heat pump? If not, electric resistance heating in ceiling will give you superior radiant heating. And your contractor can sell the boiler,tubing,&pumps to somebody else.

Gordy

I'm all for ceiling radiant with some floor in barefoot areas. I had both in some rooms.

alexclusif

Gordy thanks, and Hot Rod, awsome info on those images/websites. I read the entire brochure. Lots of valuable info.
Your first image right off the bat gives super simple calculation right at the top : Floor surface temperature = BTUH/SQFT/2) + Room Setpoint. So in my case, to "guess" what temp I can get away with as per manufacturer recommendations, I used the following numbers: BTUH required in whole house heat loss calc = 20BTUH (some rooms needed more, some less, but hey I believe air moves), and Room Setpoint = 72F.
So to see if it all works ok here is the math = 20BTUH / 2 = 10 +72F setpoint = 82F Floor surface temp.

Now flooring manufacturer says that apparently supposed max temp on top of cork will always be 5 degrees less than temp at subfloor because of insulating properties...doesn't make sense according to what you've been telling me (that R value only DELAYS heat transfer) but if that is true, 5 degrees less means to get to 82F surface, I'd be heating subfloor to 87F.
Max recommended subfloor temp by flooring manufacturer is(85F)...
So I'm going to have to cheat and increase the floor temp slightly and hope my floors don't implode.
Interesting in that article though about the 85F limit set by manufacturers on hardwood floors being kind of missunderstood - that 85F limit should in reality be the max bearable bare foot temp and not that of floors. Because in direct sunlight, floors endure way more than that. Very true. Now I don't know if that is the case for laminates or just hardwood.

Jumper, great ideas, just too late. Wouldve/couldve/shouldve maybe added or gone for in ceiling, but house is built. Radiant tubing is already in joists, and well that's that. Maybe next time around

Gordy

When I say delay, it is to say that the response will be less than say an over the top assembly with ceramic tile verses joist bay. The more rvalue between the tubing plates the slower the response.

However once everything reaches a setpoint equilibrium, and you are just bumping the setpoint to maintain it. This becomes less of an issue. When it becomes an issue is if you use a setback schedule especially a deep one. Also a tight envelope could create an overshoot potential coming out of set back.

With proper controls which Alan has pointed out in his posts this becomes a mute point. Just want you to understand why you need controls instead of just telling you to use them. This helps you understand the system dynamics better.

hot_rod

If you enjoy reading and researching, the amount of research and data on the science of heating, comfort and radiant surfaces at Healthyheating will keep you busy for months. It is an excellent site for myth busting

I think the numbers that some of the flooring manufacturers present is more hearsay than actual testing. As you mentioned any floor covering exposed to sunlight in a south facing room has the potential to exceed 82 degree surface temperature. Probably the bark on the cork oak tree also.

The key is to keep the floor temperature at the lowest temperature to over come the heat load in the space. We have all sorts of controls and variable output components to accomplish that now a days.

http://www.healthyheating.com/Thermal_Comfort_Working_Copy/Definitions/floor_temps.htm#.WHDs9bHMy7Y