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# Any one see Contractor News cover ?

Member Posts: 5,884
Please tell me I missing something here.

30" on center, 180 degree watere temp, and aluminum fins that you rivot to the tubing ????

This is efficient ? This is what Floor warming ??

??????

Chowdaman

• Member Posts: 64

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

Maybe the goal is lowest first cost.
They've achieved 40 btu/sqft/hr in this configuration.
• Member Posts: 5,884
40 ????

What insulation underneath ?

What floor covering ?

I assume thats 180 water temp. ??

• Member Posts: 580

I assume my article is in this new issue?
• Member Posts: 568
Cheap?

The fins ain't so cheap but less tubing is needed. Heats by convection in the joist space. High temp so not so energy saving at the heating plant. Less responsive to OD reset it seems. Air space between the floor, fins, and insulation below is crucial to convection within the cavity.

But it DOES work.
• Member Posts: 299

Now how about bringing us up to date on your revolutionary method to determine water volume in a system?

All the best,

Robert

ME
• Member Posts: 580
It is on its way as soon as I write it up

I will post it right away.
• Member Posts: 61

RFH Professionals please bear with me:

Just a comment for those that read The Wall and are still learning about radiant floor heating as I have been reading many posts here of late referencing 40 Btu/ft2:

With regard to the 40 Btu/ft2 heat output. First go to the acceptable (allowable) floor surface temperature rule of 85oF for occupied space and then to the formula for calculating floor heat output. If we keep the math simple and use a heat transfer coefficient of 2 (in lieu of 1.96) and the formula for heat output where 2 times the surface temperature minus the room temperature gives the output per square foot  then 40 Btu /ft2 with a 70oF room temperature gives a floor surface temperature of 90oF. This 90oF floor temperature is over the limit for acceptable floor surface temperature in an occupied area. Just want to avoid going back to the sweaty sock days that stumped the growth of floor heating and made for uncomfortable customers. (Ref: RPA Standards and Guidelines: http://www.radiantpanelassociation.org/files/public/GdlnQuick.htm )

40 Btu/ft2 = 2 Btu/ft2oF (90oF  70oF)

So with a good floor heating design  the most heat that a floor should provide with the acceptable surface temperature rule of 85oF and a room temperature of 70oF is 30 Btu/ft2. So if your heatloss for the space requires more than 30 Btu/ft2 then you need supplemental heat from a short piece of baseboard convector, radiator or kickspace heater. Simple as that. But remember if you review your heatloss at higher outdoor temperature, then the need for supplemental heat will go away. So supplemental heat should be allowed to shutoff as outside temperatures increase while the floor heating system maintains comfort. Also remember that you can add more insulation into the design of the space if construction will allow possibly eliminating the need for supplemental heat. With large glass/fenestration areas, sometimes you have no choice. Your heating professional can take you through the what ifs with a good software analysis in a matter of seconds.

As I know many DIY read this site as this is a great place to learn as I do everyday, I provide this thread as (a reminder for some) that this is a simple explanation for an important design parameter in radiant floor heating (written by engineer) that is really important. It is a very simple concept, but will make for a miserable customer if it is not addressed during the design of the project. Not to mention the potential damage to floor coverings due to high exposure temperatures. And this is the best example of why it cost less to hire a professional.

Also note that the Radiant Panel Association has a certification program for contractors that cover both installation and design. Not all contractors have taken this certification, but are still very capable. But if you are trying to decide between several contractors and you have not seen there work (or they do not have a track record), then ask what radiant schools they have attended or if they have an RPA certification. You could ask them what Siggys first name is. If they do not say John, you may want to go to the next question  what does PEX stand for?J

• Member Posts: 61

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

>

> Maybe the goal is

> lowest first cost. They've achieved 40

> btu/sqft/hr in this configuration.

RFH Professionals please bear with me:

Just a comment for those that read The Wall and are still learning about radiant floor heating as I have been reading many posts here of late referencing 40 Btu/ft2:

With regard to the 40 Btu/ft2 heat output. First go to the acceptable (allowable) floor surface temperature rule of 85oF for occupied space and then to the formula for calculating floor heat output. If we keep the math simple and use a heat transfer coefficient of 2 (in lieu of 1.96) and the formula for heat output where 2 times the surface temperature minus the room temperature gives the output per square foot  then 40 Btu /ft2 with a 70oF room temperature gives a floor surface temperature of 90oF. This 90oF floor temperature is over the limit for acceptable floor surface temperature in an occupied area. Just want to avoid going back to the sweaty sock days that stumped the growth of floor heating and made for uncomfortable customers. (Ref: RPA Standards and Guidelines: http://www.radiantpanelassociation.org/files/public/GdlnQuick.htm )

40 Btu/ft2 = 2 Btu/ft2oF (90oF  70oF)

So with a good floor heating design  the most heat that a floor should provide with the acceptable surface temperature rule of 85oF and a room temperature of 70oF is 30 Btu/ft2. So if your heatloss for the space requires more than 30 Btu/ft2 then you need supplemental heat from a short piece of baseboard convector, radiator or kickspace heater. Simple as that. But remember if you review your heatloss at higher outdoor temperature, then the need for supplemental heat will go away. So supplemental heat should be allowed to shutoff as outside temperatures increase while the floor heating system maintains comfort. Also remember that you can add more insulation into the design of the space if construction will allow possibly eliminating the need for supplemental heat. With large glass/fenestration areas, sometimes you have no choice. Your heating professional can take you through the what ifs with a good software analysis in a matter of seconds.

As I know many DIY read this site as this is a great place to learn as I do everyday, I provide this thread as (a reminder for some) that this is a simple explanation for an important design parameter in radiant floor heating (written by engineer) that is really important. It is a very simple concept, but will make for a miserable customer if it is not addressed during the design of the project. Not to mention the potential damage to floor coverings due to high exposure temperatures. And this is the best example of why it cost less to hire a professional.

Also note that the Radiant Panel Association has a certification program for contractors that cover both installation and design. Not all contractors have taken this certification, but are still very capable. But if you are trying to decide between several contractors and you have not seen there work (or they do not have a track record), then ask what radiant schools they have attended or if they have an RPA certification. You could ask them what Siggys first name is? If they do not say John, you may want to go to the next question  what does PEX stand for?:)
• Member Posts: 5
ultra-fin

I have used this system in a retrofit for small spaces such as bathrooms, breezeways, etc. where a full mixing down strategy is cost prohibitive. It works fine but again you have to do the math and keep the floor surface temp in the low 80's. The product has it's place but I would be wary in using in in a whole house situation.
• Member Posts: 5,884
SO Steve

with out a " full mixing down strategy " how do you keep the floor in the low 80's ?

Scott

• Member Posts: 64
Ultra -fin

You could limit the flowrate in that loop. The air under the floor will buffer and even out the heat flow.
• Member Posts: 6,928

Those Ultra-Fin output numbers are a bit misleading. They seem to be the output from the fin itself (NOT the floor) but expressed on a square foot basis as it it were the panel output.
• Member Posts: 411
Contractor News

I was so hot on the ultra fin artical I almost missed HR's artical,Nice job Man!
• Member Posts: 781
Ultra-Fin

I would question Ultra-fin as to the associated SWT vs Cavity Air Temp Required to produce Target Surface Temp. That may or may not require a mixing device. In any event, it's Bang/Bang set point system not conducive to reset. Response time would do it in. Higher ^T's means lower system efficiency, and probable overshooting during shoulder months or Indian Summers. It does, based on what I've read, provide very even surface temps. Might be good for perimeter boost on a reset system. Just my .02.

Jed
This discussion has been closed.