heat gain from metal plates?

Steve_75

What should I figure for heat gain and water temp loss using the metal staple-up plates? Also, do you run them continous or do you leave a space between? I plan to run them cont. under the bathroom tile, every oter one under the other living space and not under the closet space.

I have a couple 300' runs of 1/2 PEX - will these plates reduce the water temp to much?

Weezbo

Howdy Steve.

it doesnt sound like you have had many bad experiences with this type of work. you are sorta lucky as doing things right helps eliminate a great many side adventures on the path..This is the easiest way to describe my limited experience with staple ups... plates help distribute heat ,and it would be a good idea to use them...i like to use low water temps rather than high water temps..there is alot of aspects to what your doing that i cannot help you with ...perhaps some other voice will make it clear or fill in some of the blank spaces in this reply.

MarkH

run 'em continuous

Running them continuously is supposed to make them quieter.
I guess if there is too much space, there is all the more room for them to get out of alignment.
I am not done with my system yet, so I can't tell you for sure first-hand.

Tony_8

I have

installed plates and leave a 1/4 inch space between for any possible expansion. I also use them under all the floors I want heated to reduce the water temp as much as possible. Cooler water = higher efficiency.

hr

You can't really gain

heat by using transfer plates.

Energy can neither be created nor destroyed, just moved around efficiently. Or inefficiently

Plates merely increase the heat transfer efficiency.

Think of trying to boil a pan of water with it suspended above the burner 2" or with the pan in contact with the actual burner element... this is a good analogy for explaining heat transfer "accelerator" plates. (An Alan Forbes term

Transfer plates are good for allowing reduced supply temperatures and getting better heat spread across the panel, in addition to being a good mechanism for placing the tube in the space

hot rod

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Steve Eayrs

Steve

The heat you can suck out of the tubing is basically the temp. difference between the supply and return piping, or what we call the "delta T".

Most staple up systems have a problem with getting enough delta T, not too much. The heat transfer plates will maintain a bigger delta, and therefore heat the space better and quicker.

Of course the flow rate, (pump speed relating to tubing length), also has something to do with this.


Ah..........Now what was the question????


Steve

Steve_75

OK now I am confused - yes I understand basic physics that the plates are not creating energy (heat) but they do transfer it to the floor right? I mean if all they did was hold the pipe up then why use them. So - if they do effectively transfer heat to the floor they are indeed taking energy that would have been returning to the boiler and adding heat to the room. If they are adding heat to the room in a more effecient manner then it seems this would be a critical in sizing.

Sorry but as I have said radiant is new to me. I do know that by adding more aluminum fins to a baseboard job will have a dramatic effect on btu output to the room - you ignore any bare copper return pipe as the heat transfer is negligable. I would never firgue a heat output into a room the same for bare pipe compared to finned. Isn't the same true for these plates?

hr

You will just get their quicker!

or get their at the same time with less fuel consumption, as you are using a lower supply temperature.

The heat given off to the room depends on the temperature difference between the floor surface and the room temperature.

Regardless of how you get the floor surface to say 80° you will output a certain BTU/ sq. ft. per hour.

Generally @ 2 btu per degree difference between the air and floor surface. 80° floor- 68° air would output about 24 BTU/ square foot / hr. Just a rule of thumb, windows, insulation, infiltration, etc all drive the load.

Remember the heat loss calc figure is JUST a point in time. It is ever changing. We pick a realistic "worse case" number to design to.

So think of the plates as accelerators IF you use the same temperature as a less efficient transfer, say suspended tube. Or a equal speed emitter IF you use a lower supply temperature.

It behoves you to heat you home with the lowest possible supply temperature from an efficiency point of view. Why boil water to heat a space if you could do it with 100° water and good thermal conduction transfer?

A Kia will get you from A to B about the same amount of time as a 300 hp BMW. Just depends how comfortably you want to get their.

Or a wood stove in the middle of the living room will heat the home vs a top line condensing, modulating, transfer plated, multi zoned, indoor/outdoor resetable radiant system. You decide

Does this make sense?

hot rod

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hr

You will just get their quicker!

or get their at the same time with less fuel consumption, as you are using a lower supply temperature.

The heat given off to the room depends on the temperature difference between the floor surface and the room temperature.

Regardless of how you get the floor surface to say 80° you will output a certain BTU/ sq. ft. per hour.

Generally @ 2 btu per degree difference between the air and floor surface. 80° floor- 68° air would output about 24 BTU/ square foot / hr. Just a rule of thumb, windows, insulation, infiltration, etc all drive the load.

Remember the heat loss calc figure is JUST a point in time. It is ever changing. We pick a realistic "worse case" number to design to.

So think of the plates as accelerators IF you use the same temperature as a less efficient transfer, say suspended tube. Or a equal speed emitter IF you use a lower supply temperature.

It behoves you to heat you home with the lowest possible supply temperature from an efficiency point of view. Why boil water to heat a space if you could do it with 100° water and good thermal conduction transfer?

A Kia will get you from A to B about the same amount of time as a 300 hp BMW. Just depends how comfortably you want to get their.

Or a wood stove in the middle of the living room will heat the home vs a top line condensing, modulating, transfer plated, multi zoned, indoor/outdoor resetable radiant system. You decide

Does this make sense?

hot rod

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Leo G_99

Steve,

the brand I use, recommends a 4-6" gap between the plates, and at least 18" from center of the bend.

Leo G

Unknown

DO NOT LET THEM TOUCH!!!!!

If you want it quiet, keep your runs shorter, your water temps lower, let the tubing expand using larger joist penetrations, and staple the piss out of the plates! Using PAP is an option as well.

Steve, you're making me nervous. Your questions about dropping the water temp "too much" makes me think you are going to run boiler temp water into the plates and then run it straight back into the boiler. Chances are greater that your supply temp will be too hot for the radiant rather than the return will be too cool for the boiler.

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jp_2

look again hot rod

"" What should I figure for heat gain and water temp loss using the metal staple-up plates?"""

thats a valid statment! the room will 'gain' more heat if the tubing has better transfer!

it all prespective, i saw him as saying 'room will "gain more heat"' compared to non plate application.

I agree, words do not always explain things well, I think thats why they invented math!

Weezbo

from what i have read in these posts....You have had your ?'s

answered...thinking clearly and considering what was said will have improved almost every conceivable variation within the realm on your install.Remember, close delta "T" ,plates,low water temps,heat loss, water temps "mixed " back up ahead of return to boiler to optomise its preformance,and hey your in business. dont overlook insulation in the project. box beam and rim joist insulation is extremely important,how much the aluminum plates will "lose" heat is going to be pretty much answered in what amount you deliver to them and the amount they can lose to the environment. speaking of environment,...Wind does tend to have some profound abilities to carry away heat. so type of insulation ,infiltration ,vapor barrier, wind sheathings all play a part in the equasion. that is pretty much the parameters of staple up in a nut shell. before you ask what temp to introduce into the system,or how much is too much loss,think...what did i read about requirements of heat and comfort, staying within the boundaries of the info of these numbers will keep things together...like i said though,i like lower temps than most.dont get me wrong here in 60 70 +/- below zero i would rather have more heat than not enough

Kritz_3

Vapor barrier

How about installing Tyvek vapor barrier under the insulation?
Just put the print side down away from the fiberglass, that will
stop air infiltration. What do ya think?
Steve K.

Weezbo

Tyveck honestly isnt a vapor barrir as i understand ....

not to say there arent different products by the same manufacture for different climatic zones and weather conditions ...the building wrap we use is designed more as a wind brake,we use vapor barriers as the Building envelope first.then the insulation..osb or ply wood thenthe tyveck the vyinil siding or whatever. i try to send you a picture or thwee computer been berry berry PITA i edited the photos so you wouldnt have to defy gravity to see them...and the POS turned them some other way on me:)))

Steve_75

Thanks guys for all of the help this has been very informative and helpful!
No worries on the water temp and direct to the boiler. I am new to radiant but not to heating systems or heat loss (IBR certified and had a master oil license for #1 and 2 oils up to 15GPH)

I am using a heat exchanger off the boiler with mixing valves - one for the slab one for the staple up. This is a new construction with more then adequate insulation -with the staple up over a heated area. Still using a radiant reflective barrier and 9" of fiberglass.