Ultra-fin a good system?

shavano

I’m new to the world of radiant heating. New house in upstate NY, builder is suggesting we use Ultra-fin. I’m a bit skeptical since the tubing and plates are not physically attached to the floor, wouldn’t that be a better system?

Ironman

It depends on the type of boiler that’s used. Ultra Fin is designed for high supply water temps. If you were putting in an oil fired boiler that ran at 160-180*, then it might be a viable option. If you’re installing a mod/con gas boiler, then it’s a terrible choice since mod/cons run more efficient at the lowest supply water temps.

Let me caution you here: proper design is essential to getting a radiant floor that performs correctly; it’s not just a matter of hanging tubing and connecting it to a boiler.

The average plumber, HVAC guy or builder is clueless about properly designing and installing a radiant floor - but they THINK that they know how to do it.

There some men on here that offer radiant design services and you’d be well served by using one. It would be much less expensive than having it done wrong then having to pay to correct it.

Of course, several on here are glad to offer free advice, but that’s not the same as design service.

@Steve Minnich is one.
@Rich_49 is another.

hot_rod

There was a method promoted by the radiant tube manufacturers called”joist bay” heating. The bare tube basically warmed the air in the space which in turned warmed the floor. UF took that method a step further by adding the fins to increase convection currents in the space 

I would do a room by room heat load calculation, determine the available floor space. 

Fastening the aluminum plate directly to the subfloor gets you conduction heat transfer which is a more powerful method to transfer from the water to the floor. If you were to boil a pan of water on an electric stove, would the pan in contact or the pan held 4” above be your method?😚

Their output charts show output at various supply temperatures.

My opinion is you cannot get much above 25 btu/ sq ft output from a floor with an 82f surface temperature in a 70f space, regardless of the installation method. The math works out to about 2 btu/ sq ft for every degree difference
82-70X2 = 24 btu/ sq ft from a floor

Radiant floor output is based on floor surface temperature regardless of how you get there?

If you have a lot of nails protruding, the heat transfer type plates can be an expensive install, UF can be an option

Properly applied the UF can and does work.

EdTheHeaterMan

The system you and @hot_rod Bob are referring to requires that each joist bay be sealed by the insulation below the tubing. Consider if you will a plenum box that is sealed on all sides and each seam. the top of the plenum is the subfloor, the sides of the plenum box are made of of the top half of the floor joists and rim joist. the bottom of the plenum box is made of the top of the insulation. As long as the plenum is sealed properly and there are no air currents inside the plenum box, then that section of floor will be heated properly according to the design.

Now consider a light fixture or electrical box is installed in that joist bay. The fixture may be lighting the room below the floor. at the other end of the joust bay, someone took out a section of the plate to run a plumbing pipe for the tub. Now that hole for the light below the plenum and the pipe opening at the other end at the top of the plenum will allow a convection current to move the air thru the plenum at an accelerated gravity flow rate whenever the heat in the tubing is present. This convection current will render that entire joist bay irrelevant when it comes to heating the room above. The convection currents will remove any heat from the joist space before it has a chance to do any floor heating

hot_rod

Use incadescent bulbs in the cans to make up any heat loss

Many of the can lights now are LED and you can insulate right against them if they have the IC rating. Or get rated "tents" for other style cans.

shavano

Thank you all for your kindness and useful information. My builder is offering an alternative product called Radiant Side Trak by Hydronic Alternatives. The main difference seems to be that the plates are larger and physically attached to the bottom of the floor, relying more on conduction than convection. Would this be a more efficient solution?

GGross

shavano said:

Thank you all for your kindness and useful information. My builder is offering an alternative product called Radiant Side Trak by Hydronic Alternatives. The main difference seems to be that the plates are larger and physically attached to the bottom of the floor, relying more on conduction than convection. Would this be a more efficient solution?

Yes this would be a much better solution than joist bay heating.

Alan (California Radiant) Forbes

We used to use plates, then switched to Ultra-Fin. Instead of two runs per bay with plates, only one run is required for UF. Also with plates, you are usually limited with water temperature - 120F max. Any higher and your hardwood floor will react. UF allows higher water temperatures without affecting the floor. 

And mod-con boilers will work fine with UF and in most cases, water temperatures will be low enough for the boiler to condense. That’s all I use. 

Above all, like everyone says, follow the manufacturer’s guidelines. 

UF has never really caught on here on HeatingHelp and I don’t know why??

GGross

@Alan (California Radiant) Forbes
For me personally it is that I can generally accomplish the same results with a lower water temperature. It is good to hear positive results while running condensing temperatures though so I will definitely revisit these. I sell the cross manifolds from Ultra-Fin so it would be nice to stock and sell the UF as well. It does surprise me that these are not used more often in retrofit applications though, they seem to be less expensive and slightly less labor than plates. I am still not sold on using them in new construction though.

hot_rod

I have some infrared pics of an UltraFin system I installed probably 20 years ago. Back when the assembled with a pneumatic pop rivet gun
I'll see if I can find that file. As I recall the floor temperature was nice and even from bay to bay. Whereas with transfer plates you see the higher temperature striping over all the plates, much cooler a few inches off the sides of the plate.

The ideal radiant panel for both output and comfort would be an even temperature spread. While heating the air space may not be as powerful of a transfer mechanism, if you can cover the load, that would be the goal.

I wonder that the majority of UF goes through box store DIY channels?

I think adding some radiant floor area onto a fin tube system is an excellent use, throw a few monoflo tees on the circuit, a loop of pex with UF.
Or in @Alan(CaliforniaRadiant)Forbes climate it may work just fine