Outdoor Wood Furnace Info

General => DIY remodeling with Hydronics => Topic started by: mlappin on January 25, 2020, 12:26:21 PM

Title: Copper tubing for wall heat?
Post by: mlappin on January 25, 2020, 12:26:21 PM
Years ago we remodeled our bedroom, if it had been recently I probably would have used Ultra fin, would have been tricky as it would have had to be installed from the top before the subfloor. Its not even a crawl space under that part of the house, I honestly think that room used to be a porch that was enclosed. Or maybe I would have done radiant walls then, no duct to that room at all. Fieldstone walls so don’t even want to tackle getting a duct thru em.

Going to remodel the office next, it shares a wall with our bedroom, I’m seriously thinking of taking two rolls of 1/2’ or 5/8” copper and placing fifty foot in a stud bay then doing another for a total of 100’. Place a small register at the bottom and another at the top and see what happens. New windows and siding and we filled any voids when we tore the lathe and plaster down. It doesn’t do bad most of the time, although on colder nights it does get chilly about 4am, a small window unit takes care of AC in the summer.

I figure why not, I already have several other zones set up in the house and have a spot left in the zone controller, just need another zone valve and other miscellaneous supplies.
Title: Re: Copper tubing for wall heat?
Post by: slimjim on January 25, 2020, 01:53:41 PM
Here’s a thought Marty, years ago I made some towel racks for a bathroom in an old house out of copper, it warmed the room as well as the towels, I know, it’s your bedroom but putting tomorrow’s clothes on it tonight warms them up nice for tommorow morning!
Title: Re: Copper tubing for wall heat?
Post by: juddspaintballs on January 26, 2020, 10:18:19 AM
What about radiant baseboard heaters?
Title: Re: Copper tubing for wall heat?
Post by: wreckit87 on January 26, 2020, 11:59:04 AM
Bare copper doesn't emit very much radiant heat, in a baseboard scenario we'd be talking ~50 BTU per foot with 3/4" type L and 180 degree water. I wonder what the actual output would be in a wall like this
Title: Re: Copper tubing for wall heat?
Post by: slimjim on January 26, 2020, 02:36:30 PM
I gather Marty that you don’t want to give up any space?
Title: Re: Copper tubing for wall heat?
Post by: juddspaintballs on January 26, 2020, 07:55:10 PM
Bare copper doesn't emit very much radiant heat, in a baseboard scenario we'd be talking ~50 BTU per foot with 3/4" type L and 180 degree water. I wonder what the actual output would be in a wall like this

Ideally, it would be finned copper tubing, as in a real hydronic baseboard heater. 
Title: Re: Copper tubing for wall heat?
Post by: E Yoder on January 27, 2020, 04:01:37 AM
I've got a small (12'x12') office that I use for shipping, etc. Basically a storage shed. I put 100' pex under the floor and insulated it. That would barely keep above 50F in really cold weather. So I put approx. 100' coiled ½" pex under the counter, zip tied to the wall.
Now it'll stay any temp I set it at.
I think a bunch of pex in a stud bay would do pretty good. The more the better, the hotter the air the better the convection current will work.
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 27, 2020, 07:17:33 AM
Yah, dont want to loose any space and the wife hates baseboard heaters. I thought about a radiant wall or two, but then all the baseboard trim and crown moulding has to be torn torn and resized. Baseboards is easy, crown mounding not so much.

I do have some baseboard in the basement but it’s ran behind the water heater, well pressure tank, water softener, etc so she doesn’t lose any space to it.

I even thought about a kickspace heater in a wall kit but my other ideal is silent. If it doesn’t work I’m out some pex and a 100’ of soft copper tubing. I’ll try it before hanging the drywall in the office, if it’s a flop I can at least repurpose the copper for something else.
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 27, 2020, 07:25:24 AM
Bare copper doesn't emit very much radiant heat, in a baseboard scenario we'd be talking ~50 BTU per foot with 3/4" type L and 180 degree water. I wonder what the actual output would be in a wall like this

Ideally, it would be finned copper tubing, as in a real hydronic baseboard heater.

I thought about buying just some replacement elements. Could place em at a diagonal from corner to corner in a stud bay.  Even thought about cutting them down and using a ton of elbows. More I thought about a stack of foot long finned elements in the wall and a ton of elbows the less I liked it.

It doesn’t need much, coolest I’ve seen it so far was 65 with the rest of the house at 67.
Title: Re: Copper tubing for wall heat?
Post by: slimjim on January 27, 2020, 08:13:25 AM
How about a nice ornate cast iron radiator then?
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 27, 2020, 12:59:38 PM
How about a nice ornate cast iron radiator then?


Yah, I’ve thought about a few of those if we ever enclose the porch. Would loose a bit of space in the bedroom. Only real spot for it would be where one of her aquariums is at now, the chances of moving the angels for a radiator are nil to none.
Title: Re: Copper tubing for wall heat?
Post by: wreckit87 on January 27, 2020, 04:00:03 PM
Just thinking out loud, but what if you were to grab a roll of 1/2" pex and zip tie it into a slinky, like they do for geothermal trench loops, and bury that in the stud bays? Say maybe 100-150 feet per stud bay? Then you'd have a lot more coverage than trying to fight copper, as the slinky loops would simply overlap each other and get you a lot of emitter in a not so big area.. Might be kind of a bugger to get coiled, but should do nicely once in the cavity I'd think
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 27, 2020, 05:04:02 PM
That’s what I was figuring to do with the copper, figure 50ft of copper probably radiates as much as 100’ of pex.
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 27, 2020, 06:19:00 PM
And thank you, a slinky is the best analogy of what I planned with the soft copper tubing. Suppose soft expands and contracts more than hard copper tubing?
Title: Re: Copper tubing for wall heat?
Post by: E Yoder on January 28, 2020, 03:21:08 AM
Emissivity of pex is actually higher than copper. I think so anyway because of coppers shiny surface.
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 28, 2020, 07:33:14 AM
Emissivity of pex is actually higher than copper. I think so anyway because of coppers shiny surface.

Really? I kinda figured its backwards, pex with 180 degree water in it can be grabbed, don’t want to grab copper with the same water in it.

Hmmm, course pour cement over pex all the time, Ultra fin and staple up all use pex...
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 28, 2020, 07:44:17 AM
Good ole engineering tool box, shiny (polished)  copper has a emissitivity of .023-.025 while heavily oxidized copper is .78.

They don’t list pex, but most plastics are over .90.


https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html
Title: Re: Copper tubing for wall heat?
Post by: hoardac on January 28, 2020, 02:35:22 PM
You could always hide a good sized loop of it behind a homemade frame art work thing. They can print just about anything on material toady. It will be right in the room for maximum heat transfer.
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 28, 2020, 05:11:38 PM
You could always hide a good sized loop of it behind a homemade frame art work thing. They can print just about anything on material toady. It will be right in the room for maximum heat transfer.

Thats an interesting suggestion, except we are taking the lathe and plaster off the office side anyways.

Want numerous outlets, along with ethernet and phone jacks on every wall.
Title: Re: Copper tubing for wall heat?
Post by: juddspaintballs on January 28, 2020, 06:06:52 PM
Just thinking out loud here, but what about 2 or 3 water to air heat exchangers mounted in that stud space, tied together in series and use those as your copper slinky?  That should offer a ton of surface area for the air to convect across and probably transfer more heat. 
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 29, 2020, 07:37:40 AM
I’ve got to thinking about this, before I redid all my plumbing in the basement had maybe 50’ of 1” pex down there. Have almost twice that in copper now, had to add baseboard heaters down there, was never chilly before with the pex. Course, I moved quite a bit around and the longest loop is a secondary to the furnace HX.

Just thinking out loud here, but wonder if it changes how much heat copper would give off if it was painted black like car radiators?
Title: Re: Copper tubing for wall heat?
Post by: wreckit87 on January 30, 2020, 03:45:09 PM
Copper definitely has more conductivity than pex, but emissivity I don't know. I'd think it's also more or they'd be making radiators out of plastic by now instead of copper? Same theory for the paint, I'd think that would hurt emission more than help. I was always under the impression that copper/brass automotive radiators were painted solely for corrosion purposes. Notice most aluminum rads in today's vehicles are unpainted
Title: Re: Copper tubing for wall heat?
Post by: mlappin on January 30, 2020, 08:59:21 PM
Copper definitely has more conductivity than pex, but emissivity I don't know. I'd think it's also more or they'd be making radiators out of plastic by now instead of copper? Same theory for the paint, I'd think that would hurt emission more than help. I was always under the impression that copper/brass automotive radiators were painted solely for corrosion purposes. Notice most aluminum rads in today's vehicles are unpainted


https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html
Title: Re: Copper tubing for wall heat?
Post by: E Yoder on January 31, 2020, 06:18:56 AM
Thinking carefully hree, are there actual copper radiators? I think the reason copper baseboard works is the convection currents that go up through the aluminum fins. Copper conducts very efficiently to the fins so it works, same with a hot air coil.
Title: Re: Copper tubing for wall heat?
Post by: RSI on January 31, 2020, 07:34:06 AM
Copper definitely has more conductivity than pex, but emissivity I don't know. I'd think it's also more or they'd be making radiators out of plastic by now instead of copper? Same theory for the paint, I'd think that would hurt emission more than help. I was always under the impression that copper/brass automotive radiators were painted solely for corrosion purposes. Notice most aluminum rads in today's vehicles are unpainted


https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html

That list is at 80 degrees. I am guessing the copper would be a lot higher at 180 than pex.
Title: Re: Copper tubing for wall heat?
Post by: RSI on January 31, 2020, 07:51:24 AM
https://insulationinstitute.org/wp-content/uploads/2015/11/CI226.pdf
Title: Re: Copper tubing for wall heat?
Post by: mlappin on February 01, 2020, 10:08:30 AM
I’m thinking doing two bays anyways, i’ll do one in copper and the other in pex and measure the output at the top register. I was going to line the bays with foil insulation anyways, can staple some over the bays  to close em off for a quick test before the drywall goes on.
Title: Re: Copper tubing for wall heat?
Post by: mlappin on February 06, 2020, 10:17:56 PM
Just thinking out loud here, but what about 2 or 3 water to air heat exchangers mounted in that stud space, tied together in series and use those as your copper slinky?  That should offer a ton of surface area for the air to convect across and probably transfer more heat.

Actually I was messing around on Supplyhouse and came across replacement H1 elements with jumbo fins, stack em three high and output is over 1700btu/ft instead of 580ish/foot. Wonder what the diminishing returns are? Would a fourth one in the stack add any more BTU’s or do they figure by time the air hits the top one its as hot as it’s gonna get?

Didn’t want to mess around with dozens of elbows to do that, however I have a swedging tool somewhere for an air chisel.
Title: Re: Copper tubing for wall heat?
Post by: mlappin on March 13, 2020, 10:59:15 AM
Still working on finishing up the office, did three stud bays with a minimum of 75’ of 1/2” pex in each one then have a 4x10 register in the top and bottom of each bay, all I can say is it works better than I could have hoped. Room is slightly under 12’ x 15’ and raised it 5 degrees in just over an hour.
Title: Re: Copper tubing for wall heat?
Post by: E Yoder on March 14, 2020, 10:42:48 AM
Very interesting.
Is there a noticable breeze coming out of the top register? What temps?
Title: Re: Copper tubing for wall heat?
Post by: mlappin on March 15, 2020, 08:22:10 PM
You can definitely feel the heat coming out, like 116-118 degrees out of each one. Much to my wife’s horror there was a cobweb above the one you could visibly see getting moved around when it was on.

Once I have the Mac back up and running I’ll post some pictures, trying to do it from my smart phone is a bad joke at best.
Title: Re: Copper tubing for wall heat?
Post by: mlappin on March 31, 2020, 08:42:59 PM
Middle stud bay, only one that came close to a standard width, at one time there was a door in two different spots in that wall. Placed a piece of lathe between the pex and the foil insulation as it was heating the wall up pretty good on the bedroom side. Wasn’t sure if it would cause issues with the drywall later.
 
(https://live.staticflickr.com/65535/49722716632_775e2b2514_c.jpg) (https://flic.kr/p/2iKPVkN)Wall heat on the Cheap (https://flic.kr/p/2iKPVkN) by Marty Lappin (https://www.flickr.com/photos/143335218@N06/), on Flickr

One of the narrow ones, still managed to get at least 75’ of pipe in it, just kept the coils closer together.

(https://live.staticflickr.com/65535/49721862658_4ecfa3f420_c.jpg) (https://flic.kr/p/2iKKxu7)Wall heat on the Cheap (https://flic.kr/p/2iKKxu7) by Marty Lappin (https://www.flickr.com/photos/143335218@N06/), on Flickr

First one I did, have a 4”x10” register top and bottom on the bedroom side of the wall. Used a piece of insulation board caulked in place top and bottom to seal the stud bay off.

(https://live.staticflickr.com/65535/49721862653_2679b95efc_c.jpg) (https://flic.kr/p/2iKKxu2)Wall heat on the Cheap (https://flic.kr/p/2iKKxu2) by Marty Lappin (https://www.flickr.com/photos/143335218@N06/), on Flickr

Irwin 1” speed bit with a 10-12” extension was just barely long enough to get thru the beam into the basement.

(https://live.staticflickr.com/65535/49721862448_33ee23c849_c.jpg) (https://flic.kr/p/2iKKxqu)Wall heat on the Cheap (https://flic.kr/p/2iKKxqu) by Marty Lappin (https://www.flickr.com/photos/143335218@N06/), on Flickr

Those speed bits just eat batteries once they grab hold.

(https://live.staticflickr.com/65535/49722401906_8f4e9d2eeb_c.jpg) (https://flic.kr/p/2iKNiMu)Wall heat on the Cheap (https://flic.kr/p/2iKNiMu) by Marty Lappin (https://www.flickr.com/photos/143335218@N06/), on Flickr
Title: Re: Copper tubing for wall heat?
Post by: mlappin on March 31, 2020, 08:55:20 PM
Stripped the lathe and plaster on the walls then just the plaster on the ceiling as it had 6” of blown in above it. Screwed strips of 1/2” plywood to the ceiling joists to keep the lathe tight and act as a spacer, then added a 1” foil faced polystyrene insulation board, then screwed 2x4’s over the insulation and fastened the drywall to that so ended up with a double dead airspace to add to the insulation value.


(https://live.staticflickr.com/65535/49722402036_d3df1660d8_c.jpg) (https://flic.kr/p/2iKNiPJ)Wall heat on the Cheap (https://flic.kr/p/2iKNiPJ) by Marty Lappin (https://www.flickr.com/photos/143335218@N06/), on Flickr


Picture of the temps partway thru a heating cycle. Diminishing returns seem to add up faster with this than say baseboard. 64 to 70 is pretty fast actually, little more than an hour on a room thats a little under 12’ x 15’,  out of curiosity once its over 73 it takes a LONG time to keep gaining any, might take as long to gain another degree once its over 73 as it did to get it from 64 to 70.

(https://live.staticflickr.com/65535/49722716562_24f1d57a68_c.jpg) (https://flic.kr/p/2iKPVjA)Wall heat on the Cheap (https://flic.kr/p/2iKPVjA) by Marty Lappin (https://www.flickr.com/photos/143335218@N06/), on Flickr


(https://live.staticflickr.com/65535/49721862618_57f9d3df25_c.jpg) (https://flic.kr/p/2iKKxtq)Wall heat on the Cheap (https://flic.kr/p/2iKKxtq) by Marty Lappin (https://www.flickr.com/photos/143335218@N06/), on Flickr
Title: Re: Copper tubing for wall heat?
Post by: E Yoder on April 01, 2020, 04:47:49 AM
Im getting ready to start a similar project this summer if it slows down enough. I'll post some pictures when I get done. Have a room with a cast iron rad, but would like the wall space, so I'm thinking radiant wall. Floor is concrete so no radiant there.
Thanks for the pictures!