Radiant floor heating education ?

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webie

Minister of Fire
Feb 21, 2009
651
Wisconsin
Hi guys . I am looking for a little help. I am hopeing to do a DIY radiant job .
What I am planning is a staple up under floor radiant heating to my down stairs under my bathroom , kitchen , dining , computer area and foyer , roughly about 15 X 32 feet with 2 by 10 floor stringers 16" on center , all of which have inlaid floor covering . Its all open in the basement and the floor is very chilly all the time so I thought this would be a great application and use for my tax return. I have baseboard heat now but could use that in addition to the radiant floor heat if it doesnt keep up . I already have a supply and return plumbed down there with shut offs so I need to continue from there.
I think I have enough skills to do the project but I need to be made smart on how to do it , as to do it right the first time . Is there any sites with some great education and know how ? Or maybe there is some suppliers that do planning help . I think I was kinda planning on getting most parts at menards but if there are supply houses on line that could do better with shipping that would be an option . Also I need to figure a rough cost estimate as an idea not to get to excited and find that its way over my budget . Maybe you guys have great ideas to how and whats best . I have never worked with pex so this would be a new challange .
Thanks in advance .
 
Plenty of online project planners on pex. Iv been reading about it myself. You will need a lot of heat dispursiing panels., FInd a good source. Some are staple up with a channel to pop in the pex .THey disperse the heat over a wide area of floor. Usually aluminum .You will need to separate runs and returns every few joist runs. You will need controls to regulate the water temp going out to the runs,usually about 90Deg.
And a manifold to separate the runs. May have to close up those bays and insulate after installation unless you want to heat the basement as well. Iv never done one but i will be doing one in my next house. Dont forget to include the price of the pex tools. I have about $250 in pex tools and i still need more.
 
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When you are drilling your holes in the joists for pex, keep in mind that you want the holes in the center of the 2x10. Avoid drilling near the bottom. If you need to avoid wiring or other plumbing err towards the top of the joist
 
A lot of different systems out there for that application, most all my jobs have been topside in Mud...once topside under Walnut and carpet using Stadler system. I would think you would need some type of reflective material over the Pex to push the heat upward...also lower temp than your baseboard...keep reading, plenty of info out there, pex is pretty much straight forward, system design, not so much....
 
If you have a source for PEX-a I'd recommend that. PEX-a is made by several manufacturers ie. Wirsbo/Uponor, Mr.Pex etc. It is more flexible which is a big plus when trying to work it around through floor joists and pulling it like wire. Do not exceed 300' with 1/2" pex. And there is no reason to use anything larger than 1/2".

PEX-a is able to use the expansion-joining system, but I always use the copper crush rings. The S.S. side clamp chich rings are the last resort IMHO.

TS
 
webie said:
Hi guys . I am looking for a little help. I am hopeing to do a DIY radiant job .
What I am planning is a staple up under floor radiant heating to my down stairs under my bathroom , kitchen , dining , computer area and foyer , roughly about 15 X 32 feet with 2 by 10 floor stringers 16" on center , all of which have inlaid floor covering . Its all open in the basement and the floor is very chilly all the time so I thought this would be a great application and use for my tax return. I have baseboard heat now but could use that in addition to the radiant floor heat if it doesnt keep up . I already have a supply and return plumbed down there with shut offs so I need to continue from there.
I think I have enough skills to do the project but I need to be made smart on how to do it , as to do it right the first time . Is there any sites with some great education and know how ? Or maybe there is some suppliers that do planning help . I think I was kinda planning on getting most parts at menards but if there are supply houses on line that could do better with shipping that would be an option . Also I need to figure a rough cost estimate as an idea not to get to excited and find that its way over my budget . Maybe you guys have great ideas to how and whats best . I have never worked with pex so this would be a new challange .
Thanks in advance .
Click to expand...
What temperature water are you using?
Do you get enough heat with the existing baseboard?
It *might* make sense to insulate the subfloor well rather than run pex and insulate.

Here's how I did mine, wood and tile finish floor, 3/4 inch subfloor, 1/2" Uponor hepex, Thermofin C 8" on center. I used a cordless drill and 3/4" self piercing sheet metal screws to secure the plates. Grundfos Alpha pump that runs all the time on the low constant speed setting. Longest run is 350', and the rest are throttled to match. If you are drilling holes for your pex use a 1 1/8" bit, and take the time to align the holes with a chalk line and carpenter's square. Pulling pex gets a LOT easier and smoother when the holes are aligned. You can see the black pockmarks from the angle grinder that I took the hardwood floor nail points off with. The floor is not noticably warm to the touch, unless it is below -15F. Just not cool or cold. Outdoor reset, maximum water temperature is 140F at -20F outdoors. Thermofin C is expensive, but I was replacing electric baseboard and wanted to deliver as much heat through the floor as possible without having to install radiators on this floor.

I will be putting up faced fiberglass insulation but it won't be this season.

Even the second story wood floors are cool with bare feet. My six year old son came down this morning, stepped on the tile, and told my wife that I should install heat under the stairway steps and the upstairs floor.

Retrofit1.jpg




Retrofit2.jpg
 
arbutus said:
What temperature water are you using?
Do you get enough heat with the existing baseboard?
It *might* make sense to insulate the subfloor well rather than run pex and insulate.
Click to expand...

Your photos look like just what I would be dealing with . I can use whatever temp that is necessary for this application. My boiller temps run up near 190 and I am sure I will have to run a mixer and mix this down, not sure on what type of mixer . My baseboard easily keeps up , it just would be nice to have warm floors in this area because this is where we spend most of our awake time , and if I can heat this area with low temperature water in the shoulder season That would be a plus . Just want to make sure that I do the best job possible and have the area all roughly the same temp , avoiding hot and cold spots . I know from what little I read its labor intensive , thats why I have been thinking of doing it myself . I am not to worried about heat loss in my basement I heat that at 65 anyways , but if it makes a whole lot of difference I can insulate or ??? after the install . I have one area under my bathroom that was done with a couple of runs of slantfin emitters suspended a few inches below the subfloor and just tied into the rest of the baseboard and thats great haveing a warm floor .
I have somewhat of an idea what I would be doing but ???? not sure on the best way to control temp , I heat with a solo 60 and storage so I have a fluctuation in supply temps , also not sure on what I should make my run lengths at and I guess what I have read someplace its just as much of an advatage to build my own manifolds ,again not sure if there is or not. Also do have to be worried about someway to balance the circuits if they are all the same length . I have an idea from what I have read and seen is to make the runs 8 inches on center , also not sure on fittings and tools although I really dont want to be buying a whole pile of expensive tools for a one time job and a few connections , then again maybe I can rent them for a day , dont know on that one either . I thought I read some place that it was best to drill the holes near the upper edge of the floor stringers but what you guys have said its best to be near the center and error up if necessary .
 
velvetfoot said:
Do you have to run it hot then?
Click to expand...
It's under floor and house has been extensively reworked which resulted in the floors being 2 1/4" thick including the hardwood so I run 140 degree but will maintain 70 degree room temperature with water temperature down to 110 when outdoor temperatures are 10 degrees or above. Be aware though that my house is insulated way beyond normal. Also residual heat emmiting from the boiler , stack and close boiler piping from my daily 4 hour burn stratifies up to the living space giving the storage a break for three or so hours where the zones do not run at all.
 
velvetfoot said:
Do you have to run it hot then?
Click to expand...
Mine runs at 145 or so. Throw rugs, dog beds, no issues. I don't even have transfer plates. it's stapled up using these wide staples that let the pipe move, but keep it in contact with the subfloor. Inch of air space, then 2" foil faced foam beneath. been happy with the setup. Plenty of warmth. My pipes are 8" on center. Three runs per 24" 'bay' between floor trusses.

JP
 
Uponor's Complete Design Assistance Manual is available free in pdf form. Zurn also has a radiant design guide. Viega too. These will have curves for btu/hr with various R values, with various emitters.

The floor will start to feel "not cool" about 78F.

Menards has 2, 3, and 4 place copper crimp ring manifolds with and without valves and with and without balancing screws. I have four loops and used a valved and balancing manifold for supply and a valved manifold for return. Temperature balancing is done with a Taco I series 3 way outdoor reset valve.

I bought a 1/2 inch crimper for $70, but the local hardware store rents for $7 per day, and that was the only specialized tool I needed.
 
Artubus, From the photo your tubing appears to be within 3 or 4 inches from the rim joist. I'm assuming that's the rim joist from the black condensation stains. I have read and also have been told that it's very important to super insulate that surface so I left about 6 inches of clearance for foam. I had a large supply of 2 inch thick cut-offs of isocyanurate laying around so I friction fit a double layer in the cavity giving me a full four inch thickness. Hope you have space for a good amount of insulation there.
 
While they are obviously trying to sell you their stuff, this place is refreshingly DIY oriented and has lots of info (just a so-far-happy customer)

http://www.radiantcompany.com

One thing they promote (which makes sense to me) is, where possible, using larger PEX so the pump requirements are lower.
 
webie said:
Hi guys . I am looking for a little help. I am hopeing to do a DIY radiant job .
What I am planning is a staple up under floor radiant heating to my down stairs under my bathroom , kitchen , dining , computer area and foyer , roughly about 15 X 32 feet with 2 by 10 floor stringers 16" on center , all of which have inlaid floor covering . Its all open in the basement and the floor is very chilly all the time so I thought this would be a great application and use for my tax return. I have baseboard heat now but could use that in addition to the radiant floor heat if it doesnt keep up . I already have a supply and return plumbed down there with shut offs so I need to continue from there.
I think I have enough skills to do the project but I need to be made smart on how to do it , as to do it right the first time . Is there any sites with some great education and know how ? Or maybe there is some suppliers that do planning help . I think I was kinda planning on getting most parts at menards but if there are supply houses on line that could do better with shipping that would be an option . Also I need to figure a rough cost estimate as an idea not to get to excited and find that its way over my budget . Maybe you guys have great ideas to how and whats best . I have never worked with pex so this would be a new challange .
Thanks in advance .
Click to expand...


Another easy option is the Ultra-Fin product. It can run at the same temperature as the baseboard. Great for low load floor warming and nice to install if the floor had a lot of nails protruding.
 
Fred61 said:
Artubus, From the photo your tubing appears to be within 3 or 4 inches from the rim joist. I'm assuming that's the rim joist from the black condensation stains. I have read and also have been told that it's very important to super insulate that surface so I left about 6 inches of clearance for foam. I had a large supply of 2 inch thick cut-offs of isocyanurate laying around so I friction fit a double layer in the cavity giving me a full four inch thickness. Hope you have space for a good amount of insulation there.
Click to expand...


You saw those stains correctly. The rim joist ends were originally stuffed with fiberglass, and condensation happened.
I'll be spraying an inch of closed cell foam in each cavity. There is about 6 inches of room between the pex and the inner edge of the rim.
 
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mmudd,
Thanks for the link to Tom Sullivan's site. Great source for aluminum absorber plates. One of my goals is to build my own solar collector to just heat my hot water.
I also see that you are a Jonsered owner. My best saw is a red.
 
I used the absorbers from Tom Sullivan for a homemade solar collector and also for some wall radiant. Those he makes are way better and I think cheaper than the menards crap available in my area. Tom is a good source of info on DIY solar and helped me out a lot when I built the 8'x8'collector (on right in pic) several years back. He can roll the absorber plates out to various sizes based on what you are doing. upon request, he can make them such that when you take the time to clamp the absorber around the pipe, you have close to 90% contact of the alum to the pipe, which is important for solar collectors.

Jonsered saws are my first choice. Someone told me the are made by Husqvarna? This could start a range war, but I own both sthil and jonsered saws, and pound for pound, they start easier and run better than the Stihl. I always reach for the red one first.
 

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Could the idea with Tom's product be to get a custom two pipe plate that would fill the joist space? Is it 'the more plate, the better'?
 
You could call and ask him. Not sure what his machine shop is capable of, but he is a good guy to deal with and always looking for new ways to do things. The plates I ordered were 6" wide, so if you put two pipe runs in a typical floor framed 16" joist space, there would only be 2.5" not covered by aluminum. Seems like it could be a pain trying to get two pex floppy pipes into one absorber plate, but it might work. See the pic below. The plates on the bottom part of the wall are the 2' long plates for 1/2 pex. He also makes the absorbers in 32" length and for larger diameter pex pipe as well. I used the 4" x48" extruded plates on upper part of the wall to deter picture hangers form puncuting pipe. The wall radiant works great with 120 degree water!
 

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