Help! Does this in floor radiant install look right?

Harvey Ramer

Or just insulate the tubing at the ends.

Zman

Heat source ?!?!?!...

Audio27

@Zman - condensing propane boiler.

Zman

Excellent,
Make sure they wire the outdoor sensor at setup the outdoor reset so you can maximize the efficiency you gained with those plates.
They should be piping it per manufactures instructions with no mixing valves.

Alan (California Radiant) Forbes

That installation wouldn't work in San Francisco let alone Juneau!

I'm with Gennady; use Ultra-Fin with a modulating boiler. That **** really works!

Gordy

Harvey Ramer said:

Or just insulate the tubing at the ends.

I agree that is an easy alternative Harvey. However not knowing the rim joist detail which with TJI joists is probably 1/2" osb to match exterior wall sheeting. How the exterior of that is treated with xps don't know that detail.

I would rather have that tubing inside the interior rim joist insulating detail.

ProblemSolver

What is the true purpose of the aluminum transfer plates? What is their duty? HePex does not transfer the heat from the water inside as well as copper does, meaning that HePex has a higher resistance of heat transfer than copper piping. That would lead me to believe that the aluminum plate’s duty is to increase the heat transfer through the HePex tubing, thus increase the output at a lower operating temperature and reduce the number of operating cycles per 24 hour period. Or is the aluminum transfer plate’s duty to increase the transfer of heat to the subfloor quicker? If heat transfer to the subfloor is its’ duty, then that would lead me to believe the subfloors temperature above the plate would be higher than the subfloor’s temperature between the plates during an on cycle, and the subfloor’s temperature would eventually even-out during the off cycle. I am asking this question because the contractor I have worked with over the last 15 years (now retired) never used the aluminum transfer plates; we only used the 1” standoff clips, then we stapled the two-layer bubble duct wrap material (which has a thin aluminum face) 1” down below the HePex tubing, thus creating a duct space to hold the heat in; then we insulated under the bubble material with 3.5” insulation. Never once did we get a complaint about operating cost or discomfort. This is why I am asking - What is the Plates main duty?

SWEI

The plates transfer more heat at lower temperatures -- roughly 175% more according to one study.

ProblemSolver

Another thing you need to consider, Audio27, is what are your finished floors going to be. If you are using wood floors, then your floor guy needs to use staples that will not reach the tubing. Also, is the installer using regular thermostats, or are radiant (Tekmar) thermostats being used. Wood floors cannot be heated beyond 76 degrees, therefore a floor sensor must be used to protect the wood floors. In any case, radiant should not be installed without the use of the floor sensor and radiant thermostats.

SWEI

ProblemSolver said:

Wood floors cannot be heated beyond 76 degrees

Huh?

ProblemSolver

Something also to consider, Audio27, is that Navien Boiler. Navien boilers have the lowest flow rating out of all the other boilers I have used. Even though the BTU's could be what is necessary, the flow rate may not be enough with all zones calling at the same time. Navien has redesigned their boilers recently, and maybe they increased the flow rate; I don't know, but it should be looked into.

Audio27

We are using the new NHB series boiler and not the older combination boilers.

Gordy

ProblemSolver said:

What is the true purpose of the aluminum transfer plates? What is their duty? HePex does not transfer the heat from the water inside as well as copper does, meaning that HePex has a higher resistance of heat transfer than copper piping. That would lead me to believe that the aluminum plate’s duty is to increase the heat transfer through the HePex tubing, thus increase the output at a lower operating temperature and reduce the number of operating cycles per 24 hour period. Or is the aluminum transfer plate’s duty to increase the transfer of heat to the subfloor quicker? If heat transfer to the subfloor is its’ duty, then that would lead me to believe the subfloors temperature above the plate would be higher than the subfloor’s temperature between the plates during an on cycle, and the subfloor’s temperature would eventually even-out during the off cycle. I am asking this question because the contractor I have worked with over the last 15 years (now retired) never used the aluminum transfer plates; we only used the 1” standoff clips, then we stapled the two-layer bubble duct wrap material (which has a thin aluminum face) 1” down below the HePex tubing, thus creating a duct space to hold the heat in; then we insulated under the bubble material with 3.5” insulation. Never once did we get a complaint about operating cost or discomfort. This is why I am asking - What is the Plates main duty?

The whole radiant enchilada is conduction. Conduction of the btus to the tube wall, the btus from the tube wall to the plate, and the btus from the plate to the floor. The more seamless that connection the more efficient the transfer.

Convection as in suspended tube you refer to is not as efficient. You are heating the air in the joist bay, and that air is heating the floor. It requires higher AWT which when coupled with a mod/con is not conducive to getting its highest efficiency.

Also suspended tube has much lower output at its highest deliverable temperature. This may not fulfill the load in certain designs.

Gordy

ProblemSolver said:

Another thing you need to consider, Audio27, is what are your finished floors going to be. If you are using wood floors, then your floor guy needs to use staples that will not reach the tubing. Also, is the installer using regular thermostats, or are radiant (Tekmar) thermostats being used. Wood floors cannot be heated beyond 76 degrees, therefore a floor sensor must be used to protect the wood floors. In any case, radiant should not be installed without the use of the floor sensor and radiant thermostats.

Wood floors most certainly can take 82* surface temps. Wood floor manufactors agree on this.

Humidity control plays a much higher role in adverse effects to wood flooring. Along with dimensional width used narrower the more stable., and how the floor is milled. 1/4 sawn to be superior. Acclimation to environment before installation is another.

How many wood floors go over 82* with the sun beating in on them in the summer, and winter through windows.

All this stems from poorly designed, and controlled RFH systems that run wild at high temps. So now the wood floor manufactors have to step in to protect their product.

ProblemSolver

Erin Holohan Haskell said:

Here's the John Siegenthaler article that @Stephen Minnich is talking about. Thanks for sharing, Stephen!

I read the paper and got my answer. Holy smokes, all those radiant joist jobs are working, but using more energy than what they should use. Now that the other guy has retired, I am doing a lot of my own engineering and I am finding that some of our past work wasn't as correct as I was convinced to believe. Never stop learning!!!

ProblemSolver

Thanks Gordy, as always.

hot_rod

The best way to fasten down T&G hardwood is with a cleat. These are blunt pointed, tapered, serrated fasteners designed just for T&G flooring. They grab the subflooring extremely well and allow the flooding to move due to humidity change, without working the fastener loose.

They are available in various lengths and you can angle the driver to assure they do not reach the plate or tube.

Excellent flooring info at www.radiantengineering.com, maybe sent the hardwood installer by the site for tips and techniques.

Gordy

Depends who you talk to which is better staples, or cleats. Staples are cheaper, and give two fastening points for every staple. Cleats are more expensive, and as you describe them. There really is no definitive evidence which is better. My flooring nailer takes either type. The heads of cleats can work through the board from movement. Where a staple will not work through a board, but can work out of the sub floor. Either way the fastener can fail. Controlling movement is a better option. That boils down to humidity, and temperature.

Audio27

We will not have hard wood, but thanks for the info.

Terry_23

I would suggest looking at the Uponor/Wirsbo website and see the different installation methods that are recommended by Uponor. If designed and installed correctly joist heating WILL work. I have sold many jobs with joist space heating. The correct installation, including insulation and air space are imperative...
Plates are a great product and give you a better pick up time and lower water temps. It depends on what the design says you need to use. Is your contractor Uponor/Wirsbo trained?

Tinman

Terry said:

It depends on what the design says you need to use.

I've been using their Advanced Design Suite since its inception and I always pick my design. Not once have I chosen plateless because, in my opinion, I'd being doing my customer a disservice.

Mark Eatherton

No offense meant to anyone that does it that way, but why?

It's noisier than all get out, and requires significantly higher water temperatures to overcome the resistance value of the floor and sub floor materials. Is it because it doesn't require any skills that people use it?

Wait, I did it in my own house as an experiment, and decided I never would attempt to do it that way for a customer... ever.

I know the manufacturers LOVE it because it sells a LOT of PEX tubing, but from a professional, efficiency stand point, it makes absolutely no sense. Yes, it can be used, but at a trade off in efficiency.

One mans opinion, matching numerous others.

ME

PS, I've NEVER been the low bidder either. Never wanted to be. I always wanted to be the most comprehensive, which meant I was also the most expensive.

ME

Gordy

There is something to be said, and shown by a true craftsman.

Stet

I do a heat loss on every heat job I do. Even if it's a boiler or furnace replacement. It's the FIRST thing you do, and I show it to my customer. If you don't do a heat loss calculation you are guessing. And they are guessing with your money. $1200 for a heat loss calculation is absurd! The heat loss calculation is what matches your boiler and heating apparatus to the needed heating whether it's radiant or baseboard. You can't properly design the system without it.

I also agree about having one gas boiler and an indirect tank. I personally install the Slant Fin CHS boiler and Super Stor Ultra tank.

Paul Pollets

Stet said:

$1200 for a heat loss calculation is absurd!

Where do you get $1200 for a residential heatloss calc?

Tinman

Audio27 said:

Well now my head is spinning. I talked to the plumber directly and he was good at walking me through his design and why he said this design has worked in Juneau. He also said that a heat loss assessment is available by only one person in town and it would cost upwards of $1200.



He also explained that his system is designed to work at 130 - 140, and they have never had striping issues. He feels that for the additional cost of aluminum channels they are a pain to install and may only gain me 10 degrees output on the boiler, so he'll still need to run at about 120. The City & Borough of Juneau inspects and approves these plateless installations, so apparently everyone else in the chain seems ok with it.



I don't know how the IECC is applied here but it seems to be UgetwhatUC, unless you have more money.