heat transfer plates

hot_rod · August 2003

I have used the ThermoFin and the Radiant Technology products.

Some times Radiantec gets confused with RTI (Radiant Technology)of Bellport, NY.

Being a contractor that sells and installs, I see Radiantec as more of a competitor, as they sell mainly to DIYers without a contractor involved. I'm not familiar with their products, listings, design, or warranty procedures. As long as they are willing to stop by the jobsite and assure the design and installation is correct.... it's your choice :)

hot rod

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John Smith · July 2003

Heat transfer plates

I am looking for heat transfer plates that have high output per sq-ft for a retrofit job. I have heard some good and bad things about aluminum. Any recomendations would be appreciated?

Alan(CaliforniaRadiant)Forbes · July 2003

Thermofin

is an excellent product; thick extruded aluminum that effectively pulls heat out of the water in the tubing.

http://www.radiantengineering.com

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Dave_13 · July 2003

What is the thickness and does it have any effect that the underside of the tubing is not in contact with the plate? What O.D. tubing do they accept? Thanks.

Alan(CaliforniaRadiant)Forbes · July 2003

You can

call them at: (406)587-6036; x105 Bob Knebel (co-owner), x102 Dale Pickard (co-owner).

Sure, the plates would perform better if there was aluminum all the way around the tubing, but there would be no way to get the tubing in there; it's a very tight fit.

Thermofin is made for 3/8" and 1/2" PEX.

Alan

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John Smith · July 2003

Nice pic. I've heard of some other plates that had problems associated with them. I think that the tubing was falling out of them. Are these the same plates?

hydronicsmike · July 2003

Hey Alan,

how are things?

Those transfer plates look neat. Is it right to assume that you mount those first and then push the pipe into the groove provided?

It would appear to me that once they are well insulated from below, you wouldn't loose much heat transfer, if any at all.

Is this another one of Dale Pickards great ideas? Another 'one of the greatest' people I've talked to.

Mike

Dave_13 · July 2003

Good question from J Smith! Ever had any problems with tubing falling out(Expansion and contraction)??

Alan(CaliforniaRadiant)Forbes · July 2003

When we

install the tubing, we have to use an air-driven palm nailer with a plastic head to get it in the groove; there's no way that tubing is going to fall out. Any expansion and contraction is taken up in the looped ends.

We don't do a lot of staple-up because it's so expensive (about 10 jobs in the last 5 years), but we've had no problems with Thermofin and it's the only product we've ever used.

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Troy_3 · July 2003

sloppy plates

That would be RTI. Also sold by Wirsbo. I heard they had worn dies on the extruder or something.Can't tell you if it is still a problem. It cost me so much they will never get another look from me. I also use Thermofin. They are 20% heavier and really hold the tube. I've installed over 30,000 feet and never had a problem with Thermofin.

Steve Ebels · July 2003

Had problems with RTI myself

And we wholesale their line! Guess that doesn't make me exempt. It wasn't a big deal to remedy though. We just crimped the channel ever so slighty about every 2-3 ft with a pliers. Haven't had any trouble since.

One thing that I think is very important regardless of whose plates you are using is to run them on constant circ with variable water temp. Doing that eliminates any noise that may occur in an on/off system, solves a lot of comfort problems and just makes for a nicer working system.

hydronicsmike · July 2003

Excellent point.

Thats why outdoor reset helps a great deal. Not does it only save energy, it also eliminates expansion noises and temperature swings in the space. If the water temperature is hotter than required, it forces the zones to come ON for a shorter period of time and OFF for a longer period. This usually causes those expansion noises and the temperature swings.

So there are plenty of reasons for outdoor reset, aren't there?

Mike

John Smith · July 2003

RTI plates

Troy mentioned that the RTI plates had a problem with them in the past. Is that problem fixed? Has anybody used them recently? Thank you for all of your responses.

hot_rod · July 2003

Loose fit

can be a function of the plate, or the o.d. of the tube. I like the PAP tube for use with plates. It has a tad larger o.d. and with it's memory it likes to stay put better. Less expansion movement with the aluminum wrap inside.

I agree with the others, the ThermoFin brand has a very consistent and tight fit. I also like the 8 foot lengths. It is a combination of the gauge of the aluminum and construction or the extrusion at the tube groove, that provides the superior "fit."

I also heard RTI corrected the loose fit. Criming the plate to keep the tube, or using silicone overhead, shouldn't be required. If the tight tube connection to the plate is not there, either is the "conduction" heat transfer! Which is what you are spending the money for

hot rod

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Steve Ebels · July 2003

We've expeienced

No problems in plates installed in the last year. They are a good heavy extruded plate. Reasonably priced as plates go. Lot's of labor to put up like any other plate system. We welded up a jig made of smooth rod that snaps into the groove of 2 plates at a time and holds them parallel as you put them up. It has a spacer on the side to center the plates in the joist bay. This has cut time involved by about 25%. Does get a little crowded with one guy holding the jig and 2 guys screwing all in the same spot. (Yikes! that's one of those sentences that could be taken out of context!!)

hot_rod · July 2003

You might try Slant Fin, also

I think they now offer the heavy gauge aluminum plates. You may find them stocked in your area. Shipping adds up, even on aluminum!

hot rod

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Alan(CaliforniaRadiant)Forbes · July 2003

Used to be

that Radiant Engineering would pay the freight if you ordered a "run" of plates, but I forget how much that is. If you plan on using a lot and have a place to put it, that's a good incentive to order in bulk.

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Unknown · July 2003

See Slant/Fin's plates here....

http://www.slantfin.com/tt technical/products/accesssories/accessories04.html

Noel

Dave H_2 · July 2003

Radiant-Trak Tolerances and other things ----- (DH)

OK, I just gotta jump in!!!

To follow up on all of the inquiries to all;

Problems experienced with Radiant-Traks in the past. What was occurring is that Radiant-Trak was and is being used with all other brands of PEX tubing while we had designed the Radiant-Traks to RTI Heat-PEX tolerances. What we had found out when other brands were used is that their tolerances to tubing size are not as controlled as ours (even though still within the standards and this standard has a wwiiiddddeee discrepancy).

Unfortunately, we could not control what tubing would be used in the Radiant-Traks so we had the tolerances tightened up to allow just about any PEX tubing to be used.

Just another note, neatness also counts when installing underfloor Radiant-Trak systems and others. By this I mean when the tubing is to exit one end of the Trak, it should go straight into the other. (See attached)

Another note, when the tubing is passing through the joists, the Radiant-Traks should be a small distance away to allow the tubing to guide itself into the Trak end, you dont want the tubing to enter into the middle of the Trak. This installation style will let the tubing pop out in certain sections as it heats up because of the expansion of PEX. (See second attachment).

So to summarize, the Radiant-Traks have been corrected. We thought we had worn dies but was not the case, so we went to the drawing board and really snug up the plates to fit everyones tubing.

Hope this clears the air.

Dave H.

John Smith · July 2003

Steve, which are you using? Are you using RTI or Thermofin?

Jed_2 · July 2003

Extruded vs. formed Aluminum

I am convinced extruded plates are the way to go. Can anyone point me to a source to compare performance data
between the two. I have seen some formed Aluminum plates
recently thinner than flashing, and I,m just not convinced about them. Some of the formed plates at least have some mass to them. The ones I saw were like feathers. And I can only wonder how Contractors can install these without dimpling.

Thanks,

Jed

Steve Ebels · July 2003

John

We've been using RTI plates all along. What Dave Holdorf said is interesting. We had RTI tube in the RTI plates and had trouble on the one job. Have not run into it since. That was late fall of 2001.

John Ruhnke1 · August 2003

Slant Fin.............

Hot Rod,

Slant Fin is Thermofin with holes in it. Slant Fin buys the Thermofin plates from Radiant Engineering and punches holes in them with a press. I think thermofin is the best too. It has the highest heat transfer rate.

JR

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Dale Pickard · August 2003

ThermoFin / TRAK

The tube falls out of the RTI product because the design is misguided and uninformed. It's what happens when something is just copied by the clueless. People who build knock off Rolex watches couldn't make a real one if they wanted to.

We recommend that the tubing be placed directly into the snap channel. It is not necessary to bring it straight out of the end of the extrusion. We have no problems with disengagement.

The attached photos illustrate why the tubing falls out of the Trak.

Dale Pickard

John Felciano · August 2003

Plates

We've used RTI plates on several jobs with no problems at all untill one job in 2001,I think, and did experience some tubing dropping out.It was simple to fix with a squeeze of the channels.We've used RTI since than with no problems.

Recently we used Dales plates on a couple jobs and have found them to be a bit tighter fitting.I also like the 8' length better than RTI's 4'

Our only difficulty is getting Dales plates.None of the local suppliers stock them.Luckily Wheels was able to personally deliver a bunch to me here in Connecticut from Pennsylvania,thanks again pal.

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JudeNY · August 2003

Thermofin

I am a DIY and planning on using Thermofin in lieu of staple up and was really glad to get the positive feedback on Tfin from you guys. The design I have is for 1/2" pex staple up. If I replace the staple up with Tfin can I go down to 3/8 pex (easier to handle) ? My understanding is that Tfin produces more than 2x the btu of staple up at the same temp.

JudeNY · August 2003

Thermofin has greater btu output ?

I am a DIY and planning on using Thermofin in lieu of staple up and was really glad to get the positive feedback on Tfin from you guys. The design I have is for 1/2" pex staple up. If I replace the staple up with Tfin can I go down to 3/8 pex (easier to handle) ? My understanding is that Tfin produces more than 2x the btu of staple up at the same temp.

Unknown · August 2003

To deliver twice the BTUHs to the plates

on the same length loop, at the same temperature, you need BIGGER tube, not smaller tube.

Noel

JudeNY · August 2003

I think my question was unclear. I will be replacing the staple up aluminum with Thermofin which supposedly transfers more than 2x the btu's of the aluminum staple up sheets. So it seems that I would get more btu output with Thermofin and 3/8 pex than with staple up aluminum sheets and 1/2 pex. No ?

Unknown · August 2003

The pex only delivers the BTUHs

If you expect a plate to transfer MORE BTUHs, because it is better, you need to deliver MORE BTUH through the pex pipe.

If you intend to deliver the SAME BTUH with LESS tubing, or LESS temperature, you still need the size pipe that delivers the SAME BTUHs to the floor, or the SAME size pipe.

Smaller pipe at the same temperature, and dropping the same number of degrees through the loop, will deliver fewer BTUHs

Make the pipe smaller, and you need to make the loop shorter, all other things being the same. The plates don't have anything to do with how many BTUHs a pipe size can carry, only how fast you run out of them.

Noel

Wayco Wayne · August 2003

Yeah

if you go plates definetly go to 3/8s tubing. Much easier to play with. Plates give you a lot more btu's. WW

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Unknown · August 2003

Let me give an example

Let's say that we do an open concept kitchen and dining room together, and because we cannot use the whole floor size for tubing, we figure for the BTUH load of the room, divide by what is available for floor space, and come up with a BTUH per square foot.

We figure that with the thin plates at a certain temperature, we can meet that requirement with 30,000 BTUH, which is EXACTLY the limit of the size tubing we plan to run, at a ten degree drop across the length of the tubing.

If I go back and put plates on that tubing that draw twice the btuh out of the water, that loop will have dropped it's whole ten degrees halfway through the run. It'll drop twice the degrees the thin plates would. The second half of the run will be at a lower water temperature.

So, with the new thick plates, do you refigure the pumps and boiler temp rise, or do you run a bigger pipe to carry the doubled amount of BTUHs that you have installed plates to recieve, to keep the ten degree drop that we need?

Either can work. Only changing your plates, and not the pump or the tubing, will change your temperature drop across the length of the loop. Lower temps at the end of the loop means lower output (even with the plates) at the end of the loop, than at the beginning of the loop.

In your case, you need to figure out how many BTUHs per square foot of floor you need to do the job, and what temperature and plate arrangement will deliver that.

Then loop length and pump size can be determined. Do you want to deliver a ten degree drop at 20 GPM, or a twenty degree drop at 10 GPM? The two are equal at BTUH delivery.

If you change to a twenty degree drop at 20 GPM, you will put twice the heat into the plates, but only if the pipe is big enough to pass it.

Noel

JudeNY · August 2003

I think I understand. I didn't mention that if I dropped to 3/8" pex with the Tfin I intend to double the number of circuits (loops?) so I should *not* get double the water temperature drop you describe, maybe less loss than with 1/2" pex. Is that right ?

After talking to Dale at Thermofin, I got the impression that the heat transfer with the fin was more effective than with aluminum sheets due to better contact, so that the heat transfer by conduction is increased and that more heat is lost to inefficient convection with the sheets. What do you think ?

JudeNY · August 2003

Noel, I think I understand. I didn't mention that if I dropped to 3/8" pex with the Tfin I intend to double the number of circuits (loops?) so I should *not* get double the water temperature drop you describe, maybe less loss than with 1/2" pex. Is that right ?

After talking to Dale at Thermofin, I got the impression that the heat transfer with the fin was more effective than with aluminum sheets due to better contact, so that the heat transfer by conduction is increased and that more heat is lost to inefficient convection with the sheets. What do you think ?

(I keep messing up where I should be posting)

JudeNY · August 2003

I think I understand. I didn't mention that if I dropped to 3/8" pex with the Tfin I intend to double the number of circuits (loops?) so I should *not* get double the water temperature drop you describe, maybe less loss than with 1/2" pex. Is that right ?

After talking to Dale at Thermofin, I got the impression that the heat transfer with the fin was more effective than with aluminum sheets due to better contact, so that the heat transfer by conduction is increased and that more heat is lost to inefficient convection with the sheets. What do you think ?

I am really messing up with posting in the wrong place. Sorry

JudeNY · August 2003

Thanks Wayco Wayne. I'm having a conversation(above) with Noel where he points out that the heat loss will be faster with the fin so the water temp at the end of the circuit will be 2x as great. I didn't mention that I intended to double the number of circuits if I went down to 3/8".

My understanding after talking to Dale at Thermofin was that due to more heat being conducted with the fin as opposed to loss through so convection with the aluminum plates, that would give me more heat actually delivered with the fins. What do you think ? Do you use the fins ?

Unknown · August 2003

I guess the bottom line on pipe size is this. The bigger the diameter, the longer the run you can have on the pipe. The same exact floor, same temperature water, 1/2" pipe will carry more plates than 3/8" tubing will. Better plates or more plates, same thing. 1/2" delivers more BTUs than 3/8" tubing. Higher output plates require higher output from the tubing. If 1/2" can carry 50 thin plates and you put thick plates on that run, it will carry fewer of them before the BTUs are all gone. Smaller tubing would hurt that scene.

I agree completely with Dale. But for the TFin to deliver more heat, there needs to be MORE HEAT in the tubing, not less. Not smaller. To get more out, you need to put more in.

Smaller, properly engineered, is MUCH easier to work with. Size from the start for 3/8" tube and it'll turn out great!

Noel

hot_rod · August 2003

> Thanks Wayco Wayne. I'm having a

> conversation(above) with Noel where he points out

> that the heat loss will be faster with the fin so

> the water temp at the end of the circuit will be

> 2x as great. I didn't mention that I intended to

> double the number of circuits if I went down to

> 3/8".

>

> My understanding after talking to Dale

> at Thermofin was that due to more heat being

> conducted with the fin as opposed to loss through

> so convection with the aluminum plates, that

> would give me more heat actually delivered with

> the fins. What do you think ? Do you use the

> fins ?

hot_rod · August 2003

The main issue with 3/8

is to keep your loop lengths in the 200 foot range, as there is a bit more pressure drop in the smaller id tube.

The heavier gauge plates do contact the floor bettewr with less fasteners than the thin flashing gauge, and are less prone to noise.

It could be argued that the heavier gauge also conducts heat better across the fin width. Probably not a huge number between the RTI or ThermoFin brand.

When it comes down to it you are buying a tight fit, both to the tube, and the plate to the subfloor. Hence the best conduction transfer.

I like the Wirsbo 3/8" hepex best for plate work. It seems to be the most flexible, and easiest to "fix" should you kink a section or two.

He are some iR pics I took in my shop with various installation methods. You should be able to pick out the difference between the suspended tube, staple up and ThermoFin installs, and the difference in temperature applied to the floor.

The RPA has a CD available with more pics like this and narration. And many other great seminars.

hot rod

JudeNY · August 2003

Thanks hotrod. Dale told me that you had experience with Tfin. I was going to use the pex and the rest of the equipment supplied by Radiantec. Feedback from DIYers was positive and I found them responsive and their literature and installation information very complete and understandable and they are available for phone support during install. Do you know of any reason I should not go this route ?

JudeNY · August 2003

Thanks Noel.

heat transfer plates

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