Ultra-Fin-what's the deal?

ALH_4

When talking about output, never leave time out of the equation. While steady state output is important, I feel that response time is equally important. Also, identical calibration of the camera is very important for a side by side comparison of this type.

I agree with Tim, that conductive methods will always beat under-floor convective methods.

-Andrew

Jed_2

Ultra-Fin Intallation DVD

There have been some previous threads touching on the Ultra-Fin method of suspended joist heating. Most seem to be negative with caveat's, i.e. low unit load requirements would, or could, meet the heating requirements. They're sizing software does not calculate BTUH/FT². There is no design SWT given(assumed boiler water temp of 180°F).
They do suggest rather high BTUH/ft² for 180° and 160° boiler temps. Tube spacing anywhere from 12-30", depending on the room's H/L.

I keep hearing reports of content and comfortable HO's who have this system installed. Don't know the details of these installations, but I'm in Maine, with a fairly low ODT. The claim is Ultra-Fin works great with hardwood flooring. I can understand the claim of uniform, even, surface temps, but question joist temps and unit load claims.

I have been challenged to support a contra-defense as to why we should not recommend this method.

I don't support it as "one size fits all" method, and wonder about high joist temps, and the marketing claims of output. Obviously, there would be supplemental scenarios, but I haven't heard of any in my area.

Is there any test data as to the actual heat transfer co-efficient for Ultra-Fin suspended joist heating? They claim rapid resonse times in they're video.

Jed

hr

A place for UF

I completed my first UF job this fall for a customer. As of yet the boiler has not been installed.

I will be doing some comparing, as part of the home has Thermofin transfer plates.

My plan is to take the infared video camera along and watch the performance and output differences. Sometimes actual color pictures tell me a better story than long formulas.

This type of system has been around for many years. I have seen and heard of baseboard fin tube being used this way back in the 50's. The director of the RPA grew up in a home in the coldest part of Montana that was heated with fin tube below the floors

I have built some copper bends for a contractor to install a fin tube system last year some time. Where are you eleft?

I'm sure the systems work within their limitations. Experts tell me it is fairly hard to actually model, with FEA, a convective system like that.

UF does advertise Warnock Hersey testing of that product. That's a lot more than most radiant products out there

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Tim Doran

Transfer Coefficients

The transfer coefficient in a radiant system is between the panel surface and the space. It is driven by the Average Uncontrolled Surface Temperature, View factors, the emmissivity of the surfaces, and convective currents. Typically a radiant floor has a transfer coefficient of about 2btu/sqft-f. The manner in which the heat is deliverd into the floor assembly has no effect on the transfer coefficient. ASHRAE systems & equipment chapter 6 & Applications chapter 53 give most of the required calculations.

The floor assembly and the transfer coefficient are the bottle neck in many cases and drive/limit the response time. An underfloor fin system may respond more quickly than a staple up or suspended tube application but could not possibly keep up with plates. Suspended applications including the fin applications rely on convection and radiation vs the conduction of the plates. No contest. Hope this helps.

Tim D.

J.C.A._3

Hot Rod,

I anxiously await the infa-red images of such a system.

I was going to suggest last night that the poster go and seek your previous pictures that showed the difference in "tranferability" of heat between the staple up VS. heat transfer plates.
I would like to see the 3 methods compared side by side, by side. I'm placing my dough on the tranfer plates as the best emitter of the bunch! Chris

hr

Well put, Tim & Andrew

That explaination is a keeper, Tim. Boiled down, the floor surface doesn't know, or really care, how it gets warmed Although the occupants might as Andrew mentioned when time and comfort are factored in. The BTU output will be the BTU output, all things heated equally.

The wrench in the works of course will be the fluid temperatures. Surely I will need to drive the UF much harded than a healthy extruded plate to get any where near an output comparison.

But for my fairly mild climate maybe I'll still be in the condensing boiler sweet spot? If I need to drive UF at 140 while plates at 120, I can live with that. 180° plus would make me squirm a bit, especially when I buck nup for a condensing boiler

The niche I see for UF is adding some radiant onto an exisiting HWBB system. How often do we see the question here? Maybe weekly.

Dangle some PAP, rivet some fins, and heat on homeboy.

No need for p/s, mixing devices, return protection illusions, etc.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

jeff_51

have used this many times in crawl spaces

but never in whole house. As has been stated, it is the differance between conductivity and convection. You cannot insulate the joist track with the ultrafin and get good convection, whereas obviously that is what you want with radiant to prevent convection and keep the heat in the floor. It certainly works very well in crawlspaces where you essntialy have no heat, and want to put some heat under that floor, but of course you also can overheat the crawl pretty easily. If you have large access into the crawl at several areas, not a problem, but we have certainly put in small window fans to move air around under them (or just leave them overheated). I have seen a couple in houses where the naked fin is run around the perimeter in the basement and none on the main floor. No ugly painted and banged up baseboard cover that way. They seem to have worked well, but the basement ceiling is always pretty warm. They seemed to have been done in the late fifties, but if you want to finish the basement, it sure causes problems. No convection if you cover the ceiling. I think it died out when people started finishing their basements in the early 60's,. I will admit to not being up on the "new version", so am as interested as you are. Don't you love this sight.

Plumdog_2

Did just such a job

Dangled the PAP, riveted the UF on there, and blocked insul board underneath w/foil. Can't vouch for any Co-efficient of Transfer, because it's always tough to drive heat out thru 1.5 inches of wood, but that UF pulls the heat out of that PAP in fine fashion. Like sticking your hand in the oven. It would be easy to overdo it with 180 degree water.

Dave McGavin

UnderFloor versus InFloor systems


or HIGH temperature versus LOW temperature space heating systems. As fossil fuels costs rise and energy shortages loom, can we afford to continue burning oil and gas to produce heat in stationary objects (buildings)? Should we be conserving fossil fuels for transportation systems?

LOW temperature heating systems (less than 120*F) can provide comfort and operating economy by moving heat from the ground under or around a building with a HeatPump (GeoExchange). A heating distribution system that requires high water temperatures or even medium water temps will not be able to utilize the heat under our feet when fossil fuel becomes a precious commodity. I wonder when our leaders will encourage the installation of LOW temp heating systems in all new buildings so that there will be a possibility of some contented voters when fuel restrictions are implemented to conserve dwindling energy reserves.

GeoExchange may not be so cost effective as a heat source in every home at today's energy cost but it is probably the only option left when shortages cause rationing and increasing energy costs. Most warm water radiant heating systems that are installed in a concrete slab or above the subfloor will be just as comfortable with the appropriate, GeoExchange heat pump as they are with a gas, oil or electric boiler. If we consider the energy savings possible with some ground source heat pump systems (3 to 4 times energy output for each unit of input) and the reduction of greenhouse gas emissions, I wonder why there are generally no incentives to encourage GeoExchange installations or to, at least, encourage the installation of LOW temp radiant heating systems in new buildings so that GeoExchange will be an opton in the future? Is this an option now where you live? Why are we installing any high temperature space heating systems now when “we can see the enemy and it is us” as Pogo said? (Walt Kelly “Pogo comic strip”).

Jed_2

Tim & Hot Rod

Thanks for the reply's. Yes, Tim, that does help. But, I too, anxiously await HR's thermal imaging snapshot. I have seen the image comparisons with the various methods, and look forward to where UF fits. But, I just can't see the claimed outputs of UF, as they are so far askew, it seems.

Hot Rod, what is FEA?

Jed

Tim Doran

Finite Element Analysis

FEA programs mathematically model assemblies for all sorts of things like stress and thermal transfer. They can very acurately predict the performance of a particular assembly. The catch is that the numerical grid that has to be assembled can be very time consuming and at times difficult to get just right. Something like UF can be a real pain in the back side to model.

I have the UF literature somewhere around here but can't locate it right now. I seem to remember a previous discussion and I think at that time I suspected that the output of the UF most likely included back losses. Or put another way. I think that the figures represent total output of the fin system and do not differentiate between what is driven into the space and what is lost downward and/or outward. All systems can provide high output when you measure more than one exposure.

Tim D.

hr

Some FEA

example, showing EPDM rubber vs pex in a slab.

Dale at Radiant Engineering has done a lot of work with FEA and got Siggy hooked on the program. The nice way, for me, is to see the numbers crunched, then the FEA prediction, then the infared camera views. The magic happens when all come within a few degrees on one another. These FEAs came that close to Dr Kilkis calcs.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

ALH_4

Predictions

The mathematical theoretical world is better in some cases than others. FEA does not take into account installation methods. The number of screws, staples, nails etc that are used to secure transfer plates are not included.

Wood is assumed to be perfectly flat, with no voids, with no inconsistencies. The aluminum is also considered perfectly flat with no bends or twists. The contact between the two materials is assumed perfect. None of this is ever true.

Resolution is important. It's the same as when you take a photo of an aircraft carrier. If you take the photo of the entire ship, the bolts or rivets are not distinguishable. The big picture loses the smaller details. If the photo is taken with a high resolution camera (better FEA software), less data is indistinguishable.

Boundary conditions are known or assumed as input and the "interior" values are interpolated based on these boundary conditions. Lines of constant temperature are then plotted based on the interpolated values. I am certainly not an expert on FEA, though I have had the pleasure of performing some simple fluid flow analysis by hand, and developing some simple Visual Basic programs to do the same.

I prefer to see side by side testing, just as Hot Rod is doing. Theoretical data is a great predictor, but nothing tells the truth like the real thing.

-Andrew