Number of loops/length

[iagsxr]

Messing around tonight drawing Pex layout for my floor;

36' x 48', 1728 sq. ft., one zone

Looks like you could do it with either 6, 7, or 8 loops.

My take is that eight shorter loops will heat more evenly. Is that correct or even matter?

What's the percentage the loops can vary in length?

There''ll be like a 6' x 8' bathroom in the one corner. Other than staying away from the toilet a bit and not running under the vanity I don't think it needs any special consideration it's so small.

 

[dieselgarage]

What size tube are you planning on using? Makes a difference in the length and number of loops needed. I can tell you I had my design done for me my building is 3800 square feet. The design is 8 loops of 5/8, the loops are 350 to 370 in length. The first joker that did the design had 17 loops of 1/2 tube.

 

[iagsxr]

1/2" pex, 12" on center

My North wall will have 18' overhead door and a couple windows so I'm thinking a pattern that favors that wall a little bit.

 

[koditten]

Try to keep the loops 250' to 300'. This stuff only comes in 300's. Its not that critical as long as you are roughly 12" on center. I did one dedicated loop around the perimeter at 6" centers. More heat is lost on the edges.

Spend the little bit extra to have loops with valves that can be throttled.

 

[Highbeam]

Under 300 feet per loop of 1/2" and keep the loops within 10% of each other. This, plus the valves will allow you to evenly heat the slab. 6 loops is plenty. You don't get bonus points for more loops and you don't need to worry about going under a vanity.

8 shorter loops will provide less head loss so less money spent on pumping but this is not a large loss.

 

[iagsxr]

Around the perimeter, 12" from slab edge, from finished wall or what?

Thinking about just once the insulation and mesh are down taking six 300 ft pieces and laying them out however works. I mean I have an idea but it'd be easier for me to see the pattern in real life than on graph paper.

 

[APPLETREE]

I am in the framing stage of building a garage 36 x 50 with an area (also garage) 17 x 14 attached to a house. All new construction. I used 7 loops of 1/2" pex about 250 to 275 feet each. I bought 2 - 1000 ' rolls from pexuniverse, a standup pex stapler and staples to attach to the 2" foam put down under all the slab. BTW, I dont need the stapler any more. Anyhow, I was pulling my hair out trying to do the layout when I ran across a radiant web site, I cant remember what site it was at the moment. I PDF'ed my plans to him after I picked his brain for awhile he did my layout and sent back a layout to me within the hour. He charged me $100 to do it. Well worth it. If I had bought my supplies from his company, he may have done it for free. I will try to post the layout if I can. You may be able to use it since your garage is similar size

 

[anthony666]

appletree .. what do you want for the stapler, shipped to canada ??

 

[Highbeam]

12" spacing is between the pipes. Many folks start their first loop 6" from the wall but I stayed at 12". The metal mesh is like a big graph paper with 6" squares makes this easy however, you really should put the mesh on top of the tubes and not below.

This is not a swiss watch. Get it close to 12" spacing and do not bend the pipe too sharply to prevent kinks.

 

[A_Pmech]

Before you spend a bunch of money, get a copy of Zurn's radiant heat design guide and read it. Loop sizing is all laid out in a very easy to understand process.

 

[APPLETREE]

Heres the layout

 

[iagsxr]

Before you spend a bunch of money, get a copy of Zurn's radiant heat design guide and read it. Loop sizing is all laid out in a very easy to understand process.

Printed it off last night, looking at it today. Lots to take in, thanks.

Heres the layout

That's awesome, thank you. Are any of your walls higher heat loss?

Think I need to favor my North wall with the big overhead door and windows quite a bit.

 

[APPLETREE]

I framed the entire garage with 2 x 8's. I am about to order a R-16 garage door, but I limited the remaining garage to 2 exterior pedestrian doors & 3 windows

 

[iagsxr]

Thanks to those that replied.

Ended up having a supplier do a diagram. They were having trouble making the six loops work out too so they upsized the PEX to 5/8" so only four loops.

I'll post the diagram here at some point it's not on this computer.

The PEX was in 450' rolls. We set a step ladder up with a piece of PVC across the legs to hold the rolls and spool them out. Worked well with two guys, better with three.







^^^^ All these pics are pre-rebar.

Used the little plastic boxes Menards sells for where the tubing comes out of the floor;



Temporarily mounted the manifolds to air test. They will be closer to the floor;



In this pic the lighting and trowel marks make the floor look wavy, it's not;

 

[anthony666]

nice work sir

 

[iagsxr]

nice work sir

Thanks, my concrete guy said I'm a little pickier than most.

Have to add this;

Panic is the Mother of invention. At 7:00 a.m. Friday the insulation and mesh were about 75% done. No tubing had been laid. The rebar needed done as well. Where my concrete guy gets his concrete had a huge order for a road Saturday. They told him if he wanted any the first load had to be there at 7:00 a.m. Sat.

We're getting towards late afternoon and it dawns on me I have no way to air test the tubing. My McGyver buddy was hanging around so I put him in charge of it. He cobbed the fill valve off my portable air tank, went to my car wash found some fittings. The gauge was broken on my air tank. He took the one off the compressor at the car wash and ta-da.



He left the hose on for effect;

 

[Beefbuzz]

I like your manifolds, where did you get them?