Anybody care to give a discourse on the performance comparison of Uponor JoistTrac and the McDuffco UltraFin?
JoistTrac is an extruded aluminum 6″ width strip with an integral PEX tube track, into which the PEX snaps. The strips, 4′ long, are stapled up or screwed up to the bottomside of the floor sheathing, between joist bays.
UltraFin is a stamped thin aluminum part, looking like a piece of a louvered vent, that clamps onto PEX lines that are mounted to run a small distance below the subfloor.
Each product is essentially a heat emitter, meant to transfer the heat from the water moving in the PEX lines to either the surrounding air or the adjacent subfloor.
Water temps might run at 175 for the UltraFin setup, and as low as 110 if using JoistTrac. Results above-floor, however, need to be the same.
I am looking for info on efficiency, cost, long term payback, etc.
Replies
For every 3 degrees you can drop system temp you save 1% fuel costs.
At 170 you are stuck with an 80% boiler.
At 140 and less you can use a condensing boiler.
Make it a modulating boiler and you get max system efficency.
A mod/con can also do domestic hot water.
For every 3 degrees you can drop system temp you save 1% fuel costs.
Never heard this before. Can you provide us with some research?
This is an old rule of thumb related to conventional boiler temperatures. It is not scientific, but I believe in other discussions I've seen that it has some merit for high temperature boilers.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
here is tekmars brochure.
http://www.tekmarcontrols.com/literature/acrobat/p022.pdf
more.
http://www.hvacwebconnection.com/temperature_compensator.htm
and more
http://www.mncee.org/pdf/tech_pubs/84-2.pdf
Edited 1/1/2007 1:18 pm ET by rich1
Edited 1/1/2007 1:28 pm ET by rich1
Gene,
I haven't done RFH in a couple of years, but it's better to have contact with the subfloor than to heat the air between the joists.
Me? In my own home I have simple staple-up, no plates, with foil-faced polyiso friction fit between the joists (TJIs) right under the tubing,
I circulate about 115 degree water under 3/4" subfloor, 1/2" underlayment, then wood flooring (brazilian cherry) on top of that.
Works like a champ.
Happy New Year,
Mongo
First, Joist Trak is 4" wide, not 6" wide. The widest and thickest plate out there is Radiant Engineering's "Thermofin", at 5" wide.
"thinfin" is their lighter (yet still heavy gauge extruded) plate, and it prices well with joist trak, and is IMHO superior.. it has a smooth tubing groove instead of a faceted one, for slightly better conduction, but more importantly the groove holds the PEX tighter, so I regard it as superior from an installation standpoint.
"UltraFin" is not in the same league as any of these plates. It's better than not using plates, but it's not a fair comparison.
The lower your load and the lower your finish floor r values, the less difference it makes. Typically though I would opt for joist trak or thinfin every single time.
High temperature systems are less efficient. They are also much more restrictive for choices of heat source, as another poster noted... these days, if you can get the temps down I would opt for a mod/con boiler every time if possible, which are significantly more efficient than conventional boilers or water heaters. I would consider it on high temp systems as well for the modulating ability, or at least use more advanced firing controls if you use a regular boiler.
Or, if you like, later you can use solar, geothermal, wood, electric.. anything that heats water.
You still have choices with High temp, but you have less of them for sure.
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Thanks, that clears it up for me.
In the last job my excellent plumbing and heating sub did for me, Uponor JoistTrac was used everywhere, Runtal baseboard panels and a towel warmer rad supplied supplemental heat in areas of glass concentration, and the whole thing was fired by a W-M LP Ultra.
But I did a walkthrough yesterday of a new high-end spec being done two lots away, and saw the UltraFin installation, with the plant being a Buderus GA244 series, and then went home to do the price compare on UF versus JoistTrac. When I saw the savings in material, I thought I was missing something really big.
Sounds as if that spec house with its great big price tag is getting a ho-hum low cost radiant heating system.
Heh.. it's a spec house. They get their payoff saying "Radiant floor", not by saying "LOW TEMP MOD/CON RADIANT SYSTEM!". Unfortunately. I yearn for the day when energy usage becomes standard, required disclosure on real estate appraisals and sales. At the very least you'd think that monthly energy costs would have an impact on the mortgage application!ah well. Obviously all projects are different and you can't claim solid numbers yada yada yada.. but, I would not be at all surprised to see a 20% or more differential in energy usage between a high temp, conventional boiler system and a low temp. modulated system, AFUE ratings or not. The anecdotal evidence over there on "The Wall" where you cross posted would seem to indicate the opportunities for modulation at least are quite significant, and condensing just sweetens the whole deal. In fact if I saw less, I would give serious kudos for an above-average conventional install. We can see pretty efficient conventional systems, but we're putting $1000 in firing controls and electronics on the boilers typically. It works, but it kind of eats up a chunk of that price differential!One more thing is if you need wiggle room.. that is, if your calcs aren't perfect, and sometimes they aren't, or the homeowners unexpected fall in love with an oriental rug.. you have a LOT more "room to grow" in output with extruded plates.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
NRT Rob,There is an energy efficient mortgage out there and there has been for over ten years. In some areas it is just now being utilized. In my area however the banks have been using the program to get larger mortgages for homes that do not qualify/are not rated or certified. It's just a means to write a larger loan than the customer qualifies for. Garett
NO KIDDING???any links or resources? I'd be very, very interested in that.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
I Googled "energy efficiency mortgage" and got this from one of the first hits:
To qualify for an EEM, the property must have a HERS report. Home Energy Rating Systems (HERS) evaluate the subject property's energy-efficiency. A HERS report is prepared by a trained Energy Rater. Factors such as window types, local climate, appliance efficiencies, insulation and utility rates are used to rate the home and calculate energy costs. Contact Lee O'Neal of NSpects at (703) 222-4925 or email: [email protected]. For more information about HERS, contact NSpects' website at: http://www.nspects.com .
Looks like Gene found it....The basic idea is with less monthy heating/cooling expense the owner can afford a higher monthly payment.I think it allows for 2-4% additional. Garett