lightfire
New Member
Posts:35
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| 27 Jun 2011 08:42 PM |
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I am planning a new ICF constructed home with basement. We will have wood floor for main floor and a slab in basement. About 2200 sq ft main and same with basement.
Is it advisable to not only put pex in slab but under the wood floor? Is it worth also putting it under the wood floor? |
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 28 Jun 2011 06:40 AM |
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Outdoor wood boilers tend to be sized to store heat. Indoor wood boilers "mostly European" tend to be much smaller and are to be stoked one or two times a day. Both can make domestic hot water.
Yes, radiate the basement slab and for the upper floors a sub-floor, sandwich, European panel radiator or a radiant ceilings. You will want radiant heat on the floor you spend the most time on and be disappointed if you don't have it on both.
Before you install radiant floor heating on or below a wood floor you must have an accurate heat load performed to determine the type of radiation and the design water temperature for the system you have chosen. Performance - both comfort and fuel efficiency - depends on the type of radiant floor heating you choose.
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| MA<br>www.badgerboilerservice.com |
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lightfire
New Member
Posts:35
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| 28 Jun 2011 08:56 AM |
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Posted By BadgerBoilerMN on 28 Jun 2011 06:40 AM
Outdoor wood boilers tend to be sized to store heat. Indoor wood boilers "mostly European" tend to be much smaller and are to be stoked one or two times a day. Both can make domestic hot water.
Yes, radiate the basement slab and for the upper floors a sub-floor, sandwich, European panel radiator or a radiant ceilings. You will want radiant heat on the floor you spend the most time on and be disappointed if you don't have it on both.
Before you install radiant floor heating on or below a wood floor you must have an accurate heat load performed to determine the type of radiation and the design water temperature for the system you have chosen. Performance - both comfort and fuel efficiency - depends on the type of radiant floor heating you choose.
"...and for the upper floors a sub-floor, sandwich, European panel radiator or a radiant ceilings..."
So you do not recommend using pex under a conventional main floor (at the floor joist level accessible via basement)?
Can you link an example of the type of sub-floor "sandwich". I would rather have a concrete floor or use gypcrete on top of the wood floor for this but we like walking on the wood floor better. |
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Blueridgecompany.com
Advanced Member
Posts:656
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| 28 Jun 2011 09:37 AM |
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we distribute a type of "sandwitch" system, called RHT Floor panel system,
link: http://www.blueridgecompany.com/radiant/hydronic/527/rht-floor-panel-system
There are some step by step guides to clarify install. This system is cost effective, easy to install and works well at low water temperatures.
Dan
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| Dan <br>BlueRidgeCompany.com |
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 28 Jun 2011 06:41 PM |
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Starting with a heat load analysis I look at the lowest temperature application that will satisfy the heat load. I design and install sub-floor radiant heating systems here in Minneapolis - and elsewhere - but using extruded aluminum plate still may require design water temperature too high for condensing boilers or hydro ground sources.
For low temperatures I prefer radiant ceiling, over-sized panel radiators and cement over-pours. Comfort is best in reverse order unfortunately. So the radiant floor is slightly more comfortable than panel radiators and radiant ceiling is very efficient - when designed properly - but perhaps the least comfortable. Naturally they are all better than scorched air.
Dan's product will work and is competitive but you may also consider the factory sandwich radiant floor systems such as Uponor Quik Trak, ThermalBoard, Mr. Pex RetroPanel, Raupanel or even Warmboard on new construction with a savvy general.
The key is matching heat load with heating appliance and heating panel. Look for an RPA certified designer and then compare product with application.
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| MA<br>www.badgerboilerservice.com |
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jonr
Senior Member
Posts:5341
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| 28 Jun 2011 07:19 PM |
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My understanding was that aluminum plates outperform (as in more btu at a lower temp) tubes in a gypsum or concrete over-pour. Of course there is some dependency on the aluminum thickness and % coverage and I'm assuming something over the top (like tile). Is this not true?
With radiant ceiling, I'd be unhappy about the increased heat loss (assuming vented attic above). But radiant interior walls don't suffer from that. |
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NRT.Rob
Veteran Member
Posts:1741
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| 29 Jun 2011 08:57 AM |
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radiant interior walls also don't have as big of a comfort impact as radiant outside walls or ceilings do: it's easier to raise the MRT of the room when you are heating the cold surface directly. If the walls are insulated well, it should be a fairly moot point. but that's a big IF, admittedly.
heavy, densely installed plates rival or beat light concrete and gyp. light sandwich is in the ballpark of those products as well but probably doesn't beat them. |
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| Rockport Mechanical<br>RockportMechanical.com |
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 29 Jun 2011 09:20 AM |
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When I started in the heating business with my dad back in the 60's my first job was tearing out old gravity furnaces and installing new "forced air" models. He explained to me then, that conventional wisdom had it that the returns went on the outside (especially at the front door) to collect the cold air and the heat supplies were on the interior to lower heat loss - remember that before gravity "central heating" had only the pot belly wood or oil-fired parlor stove. My main job was to cut new perimeter heat registers under every window and a central return located in the center of the house.
Naturally this makes sense except for the fact that we are heating for comfort not for economy. One of the few systems that will not compromise either is radiant "floor" heating, followed by panel radiators and radiant ceiling in that order.
I use radiant walls on interior walls for showers and occasionally to supplement a radiant floor that comes up short of the load (a proper heat load analysis is the only way to determine if this is the case).
Radiant exterior walls would be most efficient in terms of comfort as Rob suggests but would be my last resort for the sake of efficiency. Like radiant ceilings, they are exposed to the exterior but lack the R-50 insulation found over my radiant ceilings. |
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| MA<br>www.badgerboilerservice.com |
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jonr
Senior Member
Posts:5341
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| 29 Jun 2011 11:55 AM |
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I certainly agree that for comfort, the direction of radiant heat can be important. For example, with a large view wall of windows, radiant heat on the same wall makes it feel much better.
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 29 Jun 2011 04:38 PM |
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An increase in comfort comes mainly from warming an otherwise cold floor and raising the AUST. |
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| MA<br>www.badgerboilerservice.com |
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jonr
Senior Member
Posts:5341
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| 29 Jun 2011 04:53 PM |
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Agreed, both MRT and AUST drop as you get closer to cold windows. So you feel cold even though the air temperature is the same. Put radiant on the same wall and MRT can stay constant.
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lightfire
New Member
Posts:35
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| 29 Jun 2011 05:57 PM |
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Thanks for the replies. I will probably do the radiant heat myself. We will have an open floor plan. I will tie in solar collectors and size the drainback tank with heat exchangers going to house hot water, hot tub, lower floor-in slab and possibly main floor; plans for expansion of another heat exchanger to planned future swimming pool.
What throws a wrench in my plans is that we want to install a wood burning cookstove on main floor. They do make some with a 9 gal water reservoir but dang, it would be nigh impossible to control when hooked to pex in floor. Bear in mind this is ICF construction with super-insulated ceiling and I am beginning to wonder wisdom of the radiant heat on the main floor at all; may also be a waste of funds on the basement floor. But since we bumped up sq ft to 2772 (Southern Missouri), and since I have wanted a solar system ever since before my solar company folded in the 80's when the tax credits were jerked out from under solar, danged if I am not gonna put one in even if I only have to turn on the heat portion for a few weeks of the year. I was thinking of adding the small wood burner mostly because I could and have plenty of wood on my place. WOOD come in handy when sun didn't shine. |
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jonr
Senior Member
Posts:5341
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| 29 Jun 2011 08:00 PM |
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IMO, the wood burner should heat up your 1500 gallon water tank. |
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lightfire
New Member
Posts:35
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| 29 Jun 2011 09:56 PM |
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Posted By jonr on 29 Jun 2011 08:00 PM
IMO, the wood burner should heat up your 1500 gallon water tank.
Please clarify; are you referring to the wood cookstove that I was referring to? If so, how would you propose regulating it? I haven't seen a model that actually is designed for radiant heat applications. They only come with a 9 gal reservoir. I guess it could be done with a drainback loop attached to the reservoir but still no way of knowing or changing the amount of heat going into the tank versus what is radiating/convection from the stove itself, except through water flow experimentation.
If you are referring to the small burner separate in the basement, yes it should. I was really only planning 200 gal water storage (with separate hot water tank 80 gal). |
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