General Radiant Question

[Rick Stanley]

Whether it's a staple-up, high mass, low mass or whatever, if you put the same pex tubing, in the same way, in a wall or even a ceiling, rather than in the floor, will it heat the room as well as it would if it were in the floor?
Thanks

 

[heaterman]

I've put tube practically anywhere you can think of and probably some you can't .........and it works well. The physics of radiant heat are the same regardless of whether the tube is on the bottom, top or sides of the room. Here's a few articles on the in's and out's of walls, ceilings and other surfaces. And lot's of other radiant stuff for that matter.
One of the nice things about a radiant wall or ceiling is that you can drive the surface temperature quite a bit higher than a floor because you don't have to worry about overheating your feet.

(broken link removed to http://www.healthyheating.com/home-heating-system-design.htm)

And here's an article about one that the boys and I did. The panels you see on the fireplace wall are made by Viega and go by the product name "Climate Panel".

(broken link removed to http://www.healthyheating.com/Newsletters/Radiant_Walls.htm)

 

[Chris Hoskin]

No. Heat rises and a radiant floor heats evenly across the whole room.

 

[woodsmaster]

Hot air rises. Heat radiates

 

[sdrobertson]

Hot air rises. Heat radiates

I'm guessing that's the same principle as those glowing heaters on the ceiling that I have seen at 84 lumber above the help counter. The building was cold, but when you stepped up to the counter, you could feel the heat immediately.

 

[sdrobertson]

And here's an article about one that the boys and I did. The panels you see on the fireplace wall are made by Viega and go by the product name "Climate Panel".

(broken link removed to http://www.healthyheating.com/Newsletters/Radiant_Walls.htm)

This is a cool idea that I had talked to my dad about a couple months ago. I was looking at my large fireplace that is never used, and I thought what a great place to radiant some heat. Unfortunately, I can't figure out a way to update a existing 14' by 8' stone hearth. :-S

 

[benjamin]

My uneducated guess is that there will be a noticable difference at the margins, that is when trying to heat a drafty (cold air sweeping across the floor) room with low temp water (relatively higher percentage of conduction than radiant transfer) the tubing in the floor will be more comfortable than the tubing in the walls or cieling.

On the other hand if it's easier to add more tubing in all of the walls than the floor, then that system could be made to work just fine.

 

[woodsmaster]

Lots of older houses ,I think 70s had elec. heat cables in the cieling and worked fine untill the plaster started falling down from all the heat cycles. I agree that heat in the floor would be better if an option.

 

[Fred61]

I've put tube practically anywhere you can think of and probably some you can't .........and it works well. The physics of radiant heat are the same regardless of whether the tube is on the bottom, top or sides of the room. Here's a few articles on the in's and out's of walls, ceilings and other surfaces. And lot's of other radiant stuff for that matter.
One of the nice things about a radiant wall or ceiling is that you can drive the surface temperature quite a bit higher than a floor because you don't have to worry about overheating your feet.

(broken link removed to http://www.healthyheating.com/home-heating-system-design.htm)

And here's an article about one that the boys and I did. The panels you see on the fireplace wall are made by Viega and go by the product name "Climate Panel".

(broken link removed to http://www.healthyheating.com/Newsletters/Radiant_Walls.htm)

Is a medium or high head circ needed to move water through the 5/16" Climate Panel tubing? I'm thinking about installing it in the next room I redo which now has under floor and don't want to invest in another pump.

 

[heaterman]

I've put tube practically anywhere you can think of and probably some you can't .........and it works well. The physics of radiant heat are the same regardless of whether the tube is on the bottom, top or sides of the room. Here's a few articles on the in's and out's of walls, ceilings and other surfaces. And lot's of other radiant stuff for that matter.
One of the nice things about a radiant wall or ceiling is that you can drive the surface temperature quite a bit higher than a floor because you don't have to worry about overheating your feet.

(broken link removed to http://www.healthyheating.com/home-heating-system-design.htm)

And here's an article about one that the boys and I did. The panels you see on the fireplace wall are made by Viega and go by the product name "Climate Panel".

(broken link removed to http://www.healthyheating.com/Newsletters/Radiant_Walls.htm)

Is a medium or high head circ needed to move water through the 5/16" Climate Panel tubing? I'm thinking about installing it in the next room I redo which now has under floor and don't want to invest in another pump.

Short answer, No. I have never used anything other than a Grundfos 15-58 or Wilo S21 usually on speed 2. The issue is how you design the panel layout. Obviously, one wants to keep the Climate Panel manifold on it's own circ if you are using it in conjunction with another type of radiation like panel rads or baseboard. The head will be less for the rads or BB.
Keep loop length at 175-200 max and you'll be fine. The amount of flow you need to make the stuff work is very small. Low 1/10th's of a gallon per minute per loop. My living room floor operates with a 21* temp drop on 200 foot loops and the circ set on speed 1.

The home with the fireplace for example uses a combination of panel rads and Climate Panel in the radiant floors/walls. The rads (14) are on two manifolds served by one pump (15-58) and piped reverse return with the furthest manifold getting back to the boiler first. The Climate Panel manifold has it's own circ which is again a 15-58. Both pumps run on warm weather shut down via the boiler control. The floors are also cycled off/on by a room thermostat and the panel rads all have their own TRV to allow various temps in all the rooms. The whole house (about 5,600 sq ft) is heated by two circs drawing a total of around 135 watts.

 

[in hot water]

Here are some homemade radiant wall systems. The beauty of radiant wall or ceiling is the high output per square foot. As there is no floor covering or furniture on walls So you can run a higher surface temperature, which = more output.

Radiant energy travels in any direction, and becomes heat energy when it strikes a surface. Just like walking out into the sunlight on a cold winters day with the heat source 93 millions miles away. As soon as the energy hits your body you feel the warmth..

Photo courtesy John Siegenthaler Appropriate Design,

 

[in hot water]

radiant wall installation

 

[heaterman]

And here's an article about one that the boys and I did. The panels you see on the fireplace wall are made by Viega and go by the product name "Climate Panel".

(broken link removed to http://www.healthyheating.com/Newsletters/Radiant_Walls.htm)

This is a cool idea that I had talked to my dad about a couple months ago. I was looking at my large fireplace that is never used, and I thought what a great place to radiant some heat. Unfortunately, I can't figure out a way to update a existing 14' by 8' stone hearth. :-S

I can get you one of these.

http://www.hydro-to-heat-convertor.com/index.html

Not a bad price for what they do. Some of the heat is released into the area via normal fireplace radiation but a larger percentage is transferred into the water connected to your system.

 

[tom in maine]

One thing to remember is that tubing embedded in concrete or a thin slab on the room side is going to require relatively cool water for most heat loads~90-120F max. If it is a staple up system underneath the floor, it could need 140-180F depending on what the heat load is and how insulating the floor covering might be.
A staple up system definitely requires insulation underneath the tubing.

A system with sleepers on the room side with tubing requires water temps in between, depending on whether aluminum fins are there and tube spacing.

There are design tools online. I suspect Gary has some on www.builditsolar.com.

Radiant walls will use higher temp water and emit higher btus/sq ft.

We installed mostly radiant walls except for one radiant slab in the bathroom. The usual water temp is low (120-140F) and the btu output is low, but the heat load is quite low as well.

 

[rkusek]

radiant wall installation

HR's wall install pic

This looks like a great way to finish my basement space. I wonder if some aluminum inserts could be molded (comercially not DIY) that would fill the space between the drywall and the pex and be thick enough to provide accidental pex damage from someone hanging a picture, etc. I suppose it would transfer too much heat the that one area. I wonder if it could be something other than aluminum that would still protect the pex but transfer most of the heat to the plates. Maybe plastic with a steel plate thick enough to resist nail penetration. Would this be overkill?

Whether you put out strict orders on hanging pictures, followed standard tube heights that could be remembered easily down the road, I know there would still be a very good chance it would still happen down the road and in fact, I would be the one to probably do it. What a mess it would be to fix too.

 

[in hot water]

often times, to meet the load, all you need to heat is the bottom 3 feet of wall. So you stay out of the picture hanging. Plus by heating the lower 1/2 it aligns with where people sit, so you feel that radiant warmth.

hr

 

[rkusek]

Sounds even better. That install looks pretty straight forward but leads to another question. My basement will have close to 9' walls except were to HVAC trunk runs where it is more like 7.5' if I remember correctly. If I ran the heat only on the lower 3 or 4', does anyone have a good suggestion on how to transition the wall or would I need to put the OSB and reflective insulation from top to bottom. It doesn't seem like it would serve any purpose. Do you think it would be possible to use 2x6s on the interior walls and rip out the approx 1.25" on the lower 4' of the wall studs with a tabel saw when framing? However, I suppose that would not be up to code. I would really want smooth walls when done.

My end goal eventually would be staple up radiant with homemade plates under the main floor and to finish the basement with wall radiant. I would still have the Water-Air HX available to supplement heat in extreme cold, maintain humidity, or for quicker warmups with a cold house. It would be nice to be able to still get heat from a battery/inverter setup powering just a few circs instead of relying on 240V to run that air handler during a power outage. The wife and I actually decided to keep the tsat at 70 this past January when we went on vacation for a week with the thought that during a power outage it would take that much longer to freeze the water lines, etc. The power did indeed go out for about 4 hours.

 

[sdrobertson]

Sounds even better. That install looks pretty straight forward but leads to another question. My basement will have close to 9' walls except were to HVAC trunk runs where it is more like 7.5' if I remember correctly. If I ran the heat only on the lower 3 or 4', does anyone have a good suggestion on how to transition the wall or would I need to put the OSB and reflective insulation from top to bottom. It doesn't seem like it would serve any purpose. Do you think it would be possible to use 2x6s on the interior walls and rip out the approx 1.25" on the lower 4' of the wall studs with a tabel saw when framing? However, I suppose that would not be up to code. I would really want smooth walls when done.

You could just shim out the studs to the same thickness above where the radiant would stop. A sheet of plywood cut into 1 1/2" stripes would cover allot of studs.

 

[Willman]

I would be using steel studs in a basement enviroment. Foam board glued to the concrete walls. Check out buildingscience.com for basement remodeling good and bad approaches.

Will

 

[jimbom]

Whether it's a staple-up, high mass, low mass or whatever, if you put the same pex tubing, in the same way, in a wall or even a ceiling, rather than in the floor, will it heat the room as well as it would if it were in the floor?
Thanks

Floor and wall panel heat(radiant + convective) transfer are equivalent. Ceiling panel radiant transfer is equivalent, but the ceiling convective component is nil. Details in 1987 ASHRAE Handbook, HVAC Systems and Applications, Chapter 7, figure 1 and figure 3. For example: if panel surface temperature 90 F and room average temp 70 F then => Radiant transfer for floor, wall and ceiling is the same 20 BTUH/ft^2 of panel. Natural convection transfer for floor and wall is ~ 15 BTUH/ft^2. Natural convection transfer for ceiling is ~ 3 BTUH/ft^2.

If you raise the ceiling panel temperature to 100 F, you would transfer about the same amount of heat into the space as 90 F surface temperature floor or wall panel. For the same square foot.