Insulation under staple up

RascalOrnery

What's the best way to insulate under staple up radiant heat in a basement? (tubing is heating first floor)

I know the whole 'reflective radiant barrier' is known by some to simply be a 'scam'. What R value ranges yield most effective to force the heat upward?

I'm running 140 degree water under hardwood floors with the 'sheet metal' transfer plates (not the really good ones). This heat is supplemented when temperatures drop considerably so possibly in the future I will go to better quality transfer plates.

My basement does get 70-75 in the winter due to the boiler heat so the question is, do I insulate better under the plates to force the heat upward? Or do I leave it open to allow the basement heat to help push up into the house?

My gut says, insulate, force the radiant heat up and through the floor and possibly drop some degrees on the mixing valve in return...my floor joist are 100 years old and have some cross bracing and other items running in between so I was thinking of possibly trying to cut rockwool to fit that way I could remove it if needed and it would be easier since many sections will be custom fitted.

It seems to me that even with the plates, I'm going to get 50% downward since on the upside I'm 'conducting' through the floor but on the downside I'm 'conducting' (and much easier) to the air...

Thoughts?

hot_rod

Insulation limits the downward heat loss, it doesn’t really force heat up

The amount of R value you use will determine how much goes down

How deep are the floor joists? That would dictate how much R value you can get below the plates. 6” batts at the very least

I would spray foam the rim joist  It can be a big infiltration loss area, air leaks

Unfaced fiberglass batts may be easier to install and remove. Rockwool seems to break up easily

ethicalpaul

This is my own dumb opinion based on zero evidence, just thought and a little observation/experience.

Your plates are physically attached to the underside of the floor. That Conduction is by far handling the majority of the heat transfer. There is a little bit that radiates and/or convects off of the plates and the pex to the adjacent basement air.

Of that, a LOT of it will rise/stay to/at the very top of the joist bay anyway. What would make it go down?

Well it will admittedly mix and convect a little with the air in the basement, but presumably it's not very windy down there and as you said it's already 70-75 degrees so the loss there is going to be minimal anyway.

I installed screwed 1/8" aluminum plates myself under my living room and I haven't gotten around to insulating them yet. The warmth in the floor is there, the basement isn't any warmer (it's also around 70 like yours, before and after I added this loop), and my heating bills have not gone up (I'm using a hot water loop from my steam boiler).

So don't sweat it too much. Get some appropriately-sized rolls of fiberglass and put it up there. You don't have to be in contact with the plates, you are just trying to stop that little bit of heat transfer to the basement air.

hot_rod

Is the basement warm from the plates radiating down, or the boiler equipment.
Hot goes to cold, so wherever the larger delta T is, is where the heat will want to go.

If the plates are 120F and the basement 60, that is a 60 delta. The transfer downward will be radiant, long-wave radiation traveling in the line of site. Any air warming (convection) will stratify up in the joist bay near the plate. Unless as @ethicalpaul mentioned you have some fans forcing convection currents?

Transfer upward is conduction, the strongest, some convection.
Once the floor is warmed it transfers to the objects in the room by radiation.

Conduction transfer also when your foot is in contact with a warmer surface.

If the basement is too warm due to the plates, insulate.

Teemok

I have done this for a couple coastal homes. 50F and foggy semi-exposed under floor houses. I staple up radiant barrier directly to the sub-floor covering it in contact with tube and plates with one side flap that goes down 2" and folds back across and tacks to the other joist. This gives the air gap needed for a real radiant barrier. The top silver face facing down is a barrier in that it is a poor emitter. Silver tea kettles hold heat better than black ones. The lower reflects back up. Fiberglass below and foil bubble bubble foil under stapled. The last one had typar house rap under instead of bubble foil. I've seen rigid foil faced foam held off the bottom of the sub-floor with blocks or on top tji cord with foam gun sealed edges. Over kill for a basement but money well spent for coastal windy wet spot. Insulate, it's worth it. Rats love the space created it so wire mesh is sometimes done. No, I won't do it again. Other trade just love it.

RascalOrnery

Thanks everyone, adding insulation (even fiberglass) underneath the floor would add up to good chunk of change...it is hard to actually know whether the heat in the basement is from the exposed plates or just the boiler working more due to being winter.

I was mainly asking to see if there were any strong trends or truths to help steer me, conduction being key seems to be the strongest point of information to make decisions from.

hot_rod

Does the upstairs heat adequately? Even on the coldest days?
Worse case you are using more energy then you need to warm the living space, if the basement is overheating due to lack of insulation. Its hard to put a dollar amount on that.

But you already know that😉

EdTheHeaterMan

ethicalpaul said:

This is my own dumb opinion based on zero evidence, just thought and a little observation/experience.

Sorry Paul, I must disagree

You may be offering incorrect information and I want to be sure that @RascalOrnery is not misinformed.
Heat is transferred in three different ways.

Convection
Conduction
Radiation

The first two are easy to understand.

Convection is when you heat something (like water or air) in one location (like a boiler or furnace) and move it to another place (like a radiator or duct outlet). This is what Paul is talking about when he says the heat will rise to the top of the room. That is because hot air or hot water is lighter than cold air or cold water. Gravity will move the heated medium to the top of the room or the top of a boiler system. The colder water or colder air will move down to replace the heated air or water that is going up. You can also use pumps or fans to move the heated medium up, down, or sideways to get it to remote places that are not directly above the heat source.

Conduction is when heat moves from one hot item to another hot item that are touching each other. This happens on an electric range in your kitchen. The heating element (sometimes incorrectly called a burner) gets hot from the electricity. The pot that is on the hot element gets heat transferred very efficiently because the pot is touching the element. The pot then gets hot and transfers that heat to what is being cooked or boiled in the pot. Because they are all touching... in direct contact, the heat transfers from one item to the next and to the next very efficiently. Insulation slows this transfer... like using a pot holder to remove the pot from the stove.

Paul is correct again with the aluminum plate that is touching the PEX tubing and also touching the underside of the floor. As the hot water is convected to the PEX tubing by a pump, the heat from that water conducts to the plastic tube. The plastic tube conducts the heat to the aluminum plate. Then the aluminum plate and the plastic tube conducts the heat to the underside of the floor. The underside of the floor conducts the heat to the upper side of the floor and the floor is now heated.

The Radiation part is harder to grasp for some. Radiation is actually Infrared light rays that travel through space without heating anything except for objects and people that the light shines on. That means that the air temperature may not change but you can actually feel warmer if you are hit with Infrared Radiation. Infrared light travels in all directions, even down. Think of the sunlight that is up in the sky 93 million miles away. That is definitely not going UP from our perspective. I would argue that it is actually going down.

This is where Paul might be misinforming us. You see, without insulation shielding the basement from the radiant tubing and the aluminum plates, the conduction and the convection will not go down to the basement. However the radiant heat will make the basement hotter. This all depends on the water temperature in the tubing. And Paul has this awesome steam boiler in the basement that is also radiating gobs and gobs of heat into that area making it 70°F, so maybe a little more heat from his radiant project might not amount to much more temperature. But I have first hand experience with an overheated basement due to no insulation below the tubing.

Read this thread I posted a few years back for an example of the effects of not insulating below the tubing. https://forum.heatinghelp.com/discussion/comment/1712589#Comment_1712589

RascalOrnery

hot_rod said:

Does the upstairs heat adequately? Even on the coldest days?

Not on the coldest days, but this is due to air infiltration via older windows etc. I knew the radiant would not be able to fully heat my downstairs when I did the math. However, our entire house is hardwood floors, which I love, but also get a little chilly in the winter. I decided the radiant (vs fin baseboards) would keep air movement to a minimum and keep the floors from feeling cold - that is until it gets cold, then the baseboard kicks in and it is what it is.

EdTheHeaterMan said:

The Radiation part is harder to grasp for some. Radiation is actually Infrared light rays that travel through space without heating anything except for objects and people that the light shines on. That means that the air temperature may not change but you can actually feel warmer if you are hit with Infrared Radiation. Infrared light travels in all directions, even down. Think of the sunlight that is up in the sky 93 million miles away. That is definitely not going UP from our perspective. I would argue that it is actually going down.

Read this thread I posted a few years back for an example of the effects of not insulating below the tubing. https://forum.heatinghelp.com/discussion/comment/1712589#Comment_1712589

I do have a 'reflective' barrier underneath but wonder if I should rip it out and just put in standard insulation, not like this is a suspended tube system! I have noticed in the basement it kind of feels like the 'sun is shining on me', so I know the radiation is gettin' me!

Thanks for the link, it was helpful, would I be better off using foam board or fiberglass? I am correct in saying fiberglass is only as good as it is tight and dry, right?

hot_rod

The radiant may cover your upstairs load if you insulate it Even 3-1/2 batts will help.
I think fiberglass will be cheaper than foamboard. Easier to work with also.

EdTheHeaterMan

My customer I spoke of in that link used Fiberglass. The foam idea I used for my own. The foam was professionally applied, They also did my attic ceiling at the time in order to make my home tighter.

Bob Rohr (hot_rod) indicated earlier that you might use foam (Like Great Stuff cans) at the edges to seal the box plates and sill plates. You can then use fiberglass for the joist space under the tubing.

another observation... I had a customer with foam boards cut to fit in the crawlspace joist spaces below their tubing. They also had some of the zone pumps located there. it was a real Pain in the Butt trying to place those insulation blocks back in the joist spaces after working on one of those pumps. I would go with Fiberglass!

RascalOrnery

Thanks guys! Once it gets cold I'll run the test by putting some fiberglass I have under a section that's uncovered, then from upstairs with the IR gun I can at least see if it's doing a better job pushing more heat compared to it's neighboring section, I'll try to post the results to help anyone in the future who might stumble upon this!

Rich_49

Of that, a LOT of it will rise/stay to/at the very top of the joist bay anyway. What would make it go down?

Well , the whole , HOT GOES to COLD thing . Maybe physics has changed since I laid down to take a nap

Teemok

Can we say radiant. It's electromagnetic energy and it cares not about air or it's tendency to stratify. The energy comes out of the bottom side of the sub-floor, plates and tubes in the bays like light, at the speed of light. It hits objects below and is absorbed or reflected. Some hits the joists on the way out and is absorbed exciting wood molecules that transfer that energy via conduction to cooler areas of the joist joists where it is emitted as radiant again or transferred by convection heating to cooler moving air molecules.
The greater the difference in energy states (temperature) of the different objects the greater the heat transfer rate from hot to cold regardless of up and down. If the mass below is large and ground connected ( almost infinite loss) it won't heat up much ever yet heat is flowing out of the structure/space to the earth.
An above floor IR gun test will show a difference from the top surface. Especially at early warm up but it won't show what % of heat is going down in the open bays. Conduction from the plates can keep the floor mass warm above while radiating loss down below at the same time. Top performance informs little of bottom loss.

EdTheHeaterMan

Rich_49 said:

Of that, a LOT of it will rise/stay to/at the very top of the joist bay anyway. What would make it go down? see below for this answer

Well , the whole , HOT GOES to COLD thing . Maybe physics has changed since I laid down to take a nap

Radiant heat goes in all directions. Think the SUN that is UP in the sky... If ALL heat goes up, then explain how the SUN's heat gets here from Up in the sky?

I believe I explained it very well here: https://forum.heatinghelp.com/discussion/comment/1763779#Comment_1763779
EDIT: I might add ...What % of the heat is conduction and convection, and what % is Radiant when we are talking about RADIANT FLOOR HEAT?

Just sayin' @Rich_49

hot_rod

Radiant ceiling output is lower than walls for example. Due to stratification at the ceiling level. It raises the ambient against the ceiling radiant panel, delta lessens, and so does output.

Radiant surfaces do increase the air temperature, else the thermostat would never satisfy. It’s not reading that long wave radiation.

EdTheHeaterMan

Agree @hot_rod with the thermostat not reading the long wave radiation. I do believe that my customer that didn't insulate the basement ceiling under the tubing was getting more of the radiant heat from the tubing that the upstairs room was getting. That radiant heat was hitting the floor and the washing machine and all the other objects in the basement. Once they heated up those surfaces were convecting heat into the air in that basement. All I remember is when I was doing the burner maintenance in that basement it was exceptionally hot. Like 85°+ hot in the middle of the winter. When you are wearing layers of clothes to keep warm. I have forgotten about my overcoat and left it there more than once, over the years.

Teemok

If 40% of a radiant floor panels output/flux is convective, I would think the lower ceiling panel flux is due to the loss of air circulation currents of heat from below that help keep surface and air delta t's high. The lower delta T of the air and the surface of the ceiling accounts for loss of flux. Radiant emission output is unchanged by hot air at the ceiling. As all the objects in the room warm and begin to radiate more themselves the balance of emission and absorption in the room changes. All objects and surfaces are radiating energy, reflecting, absorbing. As the whole room warms the absorption of the ceiling increases compared to it's emission making over all output of the ceiling in the radiant spectrum lower. Air is warmed by surface contact. Objects are warmed by radiant, air contact and physical contact.

hot_rod

heat like water will take the path of least resistance. Wherever the larger delta is will be the highest transfer, up or down.

This guy understood that in the 1800s. A slide from Robert Beans recent presentation.

Rich_49

EdTheHeaterMan said:

Rich_49 said:

Of that, a LOT of it will rise/stay to/at the very top of the joist bay anyway. What would make it go down? see below for this answer

Well , the whole , HOT GOES to COLD thing . Maybe physics has changed since I laid down to take a nap

Radiant heat goes in all directions. Think the SUN that is UP in the sky... If ALL heat goes up, then explain how the SUN's heat gets here from Up in the sky?

I believe I explained it very well here: https://forum.heatinghelp.com/discussion/comment/1763779#Comment_1763779
EDIT: I might add ...What % of the heat is conduction and convection, and what % is Radiant when we are talking about RADIANT FLOOR HEAT?

Just sayin' @Rich_49

I guess I am misunderstanding you addressing me Ed . This first sentence from my post was written by someone else , " Of that, a LOT of it will rise/stay to/at the very top of the joist bay anyway. "

My answer was this , " Well , the whole , HOT GOES to COLD thing . Maybe physics has changed since I laid down to take a nap "

Just sayin Ed .

Teemok

What's the direction of the greatest heat flow, is not the question I get asked. How much is going where I don't want it to, is much more popular. Radiant flux is not air temperature dependent. Estimating the direction of majority energy flow isn't all that valuable. If it's 51/49 that sucks, now what? Yes, insulate with r value and you force a lot of heat to the path of least resistance. Considering delta T and R value alone ignores the difference between black-body and shiny, The different flux rates of radiant, conduction and convection, active air currents and stagnant air stratification. Sure I can simple talk with just temperature but that's not a complete picture. A "heat engine" usually converts a difference of temperature into mechanical force. I'm not clear on how that relates to sub-floor energy transfer to a basement.

hot_rod

I just think you are barking up the wrong tree with the reflective approach under radiant. The staple up systems I open up to find staple holes had a layer of construction and sheetrock dust on the foil. I think that would be the case on most any applications

I don’t think any one is ignoring reflective  concepts, I see little to any advantage in floor radiant?

Teemok

That's anecdotal. Just because you found sheet rock dust on top of foil doesn't mean all foil facing up under a sub floor is covered in dust and rendered completely useless. I have already discounted the reflective principle anyway. I see how dust does make the long term cost benefit questionable. The tree I'm barking up is the value of the high quality low emisivity side facing down with an air gap below it. It is not contaminated with dust. I get that you and others see little advantage to a low emisivity approach. That's not science, it's opinion.
I have a few clients who have foil facing up of diferant ages years I have not found them dirty. The shinny of the bubble foil or FG scrim might not be that good but there's no dust layer that I find. I might wipe a couple square feet of it with tact cloth and see what comes off. Pulling two 8' bays: One with bubble foil facing up removed. One treated with good barrier facing down with air gap below and measuring the difference between them and the existing bubble foil facing up with air gap up, might be be informative.

The idea that warm undisturbed air, in an un-insulated under floor application, negates a lot of downward losses because the delta T of the air in the bay and the sub-floor is low, is ignoring... radiant emissions, the known majority of radiant panel heat delivery. Opinions will always differ, your hot_rod has high value. Good science is what I'm barking about. If I find the cost benefit of face down barrier with air gap low, I'll come to agree it's not worth it. If someone can put down some good math or tests showing it isn't worth it I'll attempt to understand it and add it to my assessment. I'll refrain from polluting threads with the question.

hot_rod

Yeah, I don't think we will ever see two identical systems, homes, jobsites. This was an owner builder, they stapled their own rubber tube, hence the staples eventually leaking and the need to keep opening the ceiling. Takes a year or more for staples to rust away and start leaking, I've found.

The amount of dust surprised me to the point of taking pictures. Somewhere on an old floppy disc

Possibly they swept their floors more often then most builders during construction. It sure looked like fine sandings from sheetrock.

Maybe they did their own sheetrock also, 5 pounds of mud on, 3 lbs sanded off That is how I finish sheetrock.

Your OP asked for thoughts, that's what you'll get here.

RascalOrnery

So I don't know why I didn't think of this...but this morning was a 'heat worthy' kind of day, I noticed the floors get the chilly tinge a bit. I took the IR gun around the 1st floor and checked various spots where the was either no barrier between the pex and basement air, and other spots where there is the reflective barrier that is 'slightly' insulative...(probably very slightly! )

I saw no difference in temperature, which means, as the basement was at 70 degrees, it's pretty unlikely it's contributing any significant amount of heat and I'm probably better off with insulation than without.

My goal is to document the delta T on the manifold before any insulating as well as the basement air temp, then insulate one bay with the insulation I do have and see if anything changes substantially. Proof should be in the pudding! Also trying to better insulate the boiler area to retain it's own heat without stifling fresh air intake.... Can't wait till real winter!

hot_rod

An IR camera is a better device for looking at warm surfaces. You can get inexpensive ones that adapt onto a smart phone.

All sorts of things you can see with IR, air leaks, moisture leaks insulation leaks, nigh time prowlers, arthritic joints

RascalOrnery

hot_rod said:

An IR camera is a better device for looking at warm surfaces. You can get inexpensive ones that adapt onto a smart phone.

All sorts of things you can see with IR, air leaks, moisture leaks insulation leaks, nigh time prowlers, arthritic joints

OOooooohhh didn't know they can adapt to a fart phone! Any recomendations?

hot_rod

RascalOrnery said:

hot_rod said:

An IR camera is a better device for looking at warm surfaces. You can get inexpensive ones that adapt onto a smart phone.

All sorts of things you can see with IR, air leaks, moisture leaks insulation leaks, nigh time prowlers, arthritic joints

OOooooohhh didn't know they can adapt to a fart phone! Any recomendations?

I have heard good and bad about the Flir. Maybe google for a comparison report out there on various brands. or start a thread here and on IG for actual user feedback.