Yeah, I was thinking of something like that... not any kind of super-insulation strategy (unless you want to be a certified insulation hero) but enough to allow the heat to build up for the water or water/glycol fluid.

The fastener issue is not a big deal, metal roofs go on over much thicker insulation than you are considering, all the time.

But where on the metal roofing will your fasteners go? Will that intrude onto your PEX channel?

-AC

Here is what I am imagining:
Roof joists->OSB sheeting->3/4" foil board.
Hero-style R-26 minimum insulation between the joists below the OSB :D
there is a 1.5"x1.5" nailed around the roof perimeter, nailed to the OSB sheeting. The 3/4" foil is inside that.
Now we have a 3/4" space for pex. 3/4" pex might not be needed, but the dimension works for many reasons.
Lay out the pex and clip it down with U-clips and fasteners.
Use a horizontal pattern so you can see the pex. Don't worry about roof fastening yet.
Use small pieces of insulation to block between loops. Lay roofing over that, and shoot the screws down to the OSB. The standing seam roofing only gets screws on one edge, then the next sheet clips onto that piece and hides the screw.
It is easy to put in screws and not hit your tubing. Nothing is covering it.
Finish out the metal as normal.

R-26 for vaulted roofs isn't even code anymore in our fair PNW states. But since it's a shop, you should be due your proper respect.

Otherwise, it all sounds quite reasonable.

-AC

I'll have a 15' by 56' roof pitch to work with, more or less. one 500' roll will give me a 14" spacing between runs. That's $400, the 3/4" foil backed board is another $400.
Under a grand difference. I will look at some charts and see if it would pay. We really don't do solar well up here :)

$400? how do you break that down?

I'd like to see what the charts tell you.

Roger that... but we do get low quality solar. You need to have a goodly amount of temperature difference between your heated water and your radiating structure. It just so happens that a homemade heat pump can extract the heat and give you the delta-T, quite happily. The question is, will it supply heat at the rate you require. This is where reducing infiltration and increasing insulation becomes so important.

Also, if you have the land and the gumption, a ground source loop field can provide heat for you during the chill months, but during warm months, your PEX in the roof can gather warmth that you can stash in the ground (assuming you don't have serious water movement in the ground)... and it will cool your roof at the same time.

randen used the loop field to heat his shop near Toronto, and he built a homemade heat pump for that purpose.

He left a fairly well-documented trail...

BTW, I've kind of come into this thread in the middle... does your shop exist already? Are you building new? Are you renovating or are you planning out your ultimate shop?

-AC

The Solar Study I was Referring To...
 

Hey skyking,

I was able to locate the study that I was referring to previously...



HERE IT IS!

It should provide much food for thought.

-AC

as they say "you are the man"!
To summarize, they were able to extract about half as much as an exposed collector. I don't believe it was an evacuated tube high efficiency system they were comparing to though.
This shop is in planning stages. It will not be heated to the extent our house is.
I am very familiar with ground loop systems.
This is my brother's system in Yakima. I did all the ground work there.
http://ecorenovator.org/forum/geothe...m-install.html
I am contemplating that as well. He jacks solar heat into his ground system too.

That 400 was for just the tubing and nothing more. Same for the insulation. I was talking about the bare bones that went under the metal.

[QUOTE=skyking;33144}...That 400 was for just the tubing and nothing more...[/QUOTE]

I can understand if you want to buy local and support your community, however there are some pretty good prices HERE.

-AC

Sorry; I'm a bit late to this party. The above statement disagrees with every scientific source I've checked. One source:
Thermal radiation - Wikipedia, the free encyclopedia

The concept of more efficient emission from a 'black' surface is supported even by the instructions for using non-contact thermometers, which say that more accurate readings can be obtained by painting the target black.

Can you back up your statement with scientific sources?

Charlie

I was thinking about this. Sometimes people wake up on the wrong side of the bed. I think both I and MnRenovator did on the particular day this interchange came up. I don't hold any grudges here and don't want to rehash this, though I appreciate the support for my view, regardless. But let's all let it go and move on and continue to be friends.;)