Absolutely Lost

[StupidSheet]

I'm building a 26x48 shop which is 1248sq'. I bought 4 rolls of 300' pex and finished laying it out tonight. Looks like I'm going to be short about 150'. After reading on here I know that all loops need to be close to the same length. I don't even know what to do now. Do I change the layout to try get closer to all even loops? I'm just totally lost and frustrated. To top it off I was supposed to pir this Saturday but my concrete guy cancelled on me. Another month it it will be getting cold here. I need some help!

 

[D.J.]

If it was me I would think about buying another roll (300') and making the spacing closer together on the existing loops or leaving the shortage in the center rectangle away from all walls. As long as you use insulation under and a vapor barrier above insulation and under pex you should be ok, but the professionals will be along soon with the real info soon.

 

[StupidSheet]

Thanks for the reply. I have no problem buying another roll. The left over area is in the centre. I'm just wondering what the pots and cons will be if I run the shorter loop.

 

[sands35]

I would suggest that you grab some graph paper, draw the outline and start trying different layouts. It took me ~8-10 iterations to get the loop lengths within a few %. Only 30 minutes of my time and I was done. That's a lot faster then messing with PEX on a garage floor.

 

[wedge40]

Up to you, but I used a program called loopCAD. It's free to try for 30 days. Took about 4 hours to learn, but well worth it. I agres with other replies, go get another 300' roll. This should give 5 250' loops (give or take).

Wedge

 

[egads74]

http://www.garagejournal.com/forum/showthread.php?t=13286&highlight=zurn&page=5

Good thread on pex... vapor barrier on top of stone... then foam... foam on walls too or 30 percent loss there... foam at garage door threshold or heat the outside apron... loop lenghts within 10% or hot/cold effect in spots.... hope you didnt home run all the runs... supposed to minimize crossing of control breaks in cement... there are patterns to use as well... also suggest pex at 8 inch on center as max... can go tighter at doors, windows and walls (example go 6" oc near 3 garage doors as that's where heat loss is... there was a good thread on here somewhere about the thermal break at garage doors (or did I see a drawing on this when I searched the WWW). Fiber in cement... slab 4-6 inches or more... rebar...
I modeled after this thread... did about 8" cement and pex about 6 oc... graph paper and tv... successful so far... and make sure they set up lights first or they will do a crappy job in the dark from others I read....

 

[egads74]

search yahoo.... zurn ZPM02101
this is a great document... shows patterns to use...
well worth your time...

 

[2005UltraClassic]

I don't think your short. What you have installed will work just fine. Otherwise, if it were me, I would install 4 rolls of 1/2" X 300 PEX. I would divide the area to install the PEX into 4 equal sections. I would install the PEX keeping each loop length at 300 feet. If you need help to see layout concepts go to: http://www.radiantmadesimple.com/su...ple.com/PDF/RMS Installation Instructions.pdf
and search for page 9. This will assist you with the PEX layout.

Should you have questions about the product contact me through the support page at:
http://www.radiantmadesimple.com/support.php

It takes more than luck. It takes knowledge.

Reg

 

[egads74]

also if your doing 2nd story you can heat under a wood floor... above subfloor... see floor panel system here... www.blueridgecompany.com I bought pex from these guys.. helpful w/ questions I had... I did 36x44 barn 2 story... woodshop on top... pex under wood floor and in cement on floor 1.

 

[Highbeam]

Woops, failure to plan ahead. In a garage application, you won't notice the cold spot.

Not sure how you placed the pex but if you used 4 loops of 300' you have enough pipe but you'll need to space it out to cover the slab with 12" spacing.

I would rather have 14" spacing than deal with a single short loop.

 

[theoldwizard1]

I don't think your short. What you have installed will work just fine. Otherwise, if it were me, I would install 4 rolls of 1/2" X 300 PEX. I would divide the area to install the PEX into 4 equal sections. I would install the PEX keeping each loop length at 300 feet.

Yep ! Multiple shorter loops are better, otherwise you will cold spots at the end of a long loop. You can still control them as 1 zone if you want.

 

[StupidSheet]

Thanks for all the posts guys. I guess I'll be starting over with a little more preparation. I did use LoopCad and kind've followed that but it didn't work out as nice.

Now do any of you want to come help me pour my concrete next weekend? LOL.

 

[tdkkart]

I don't think you're lost at all, you just missed the calculation somewhere.
When I did mine I think kit was the BlueRidge folks that suggested a figure of 1.1' of tube for every square foot of floor, so at 1248ft of floor you should have had 1372ft of tubing.
You only bought 1200 ft and you came up 150ft short, 'magine that.

 

[98ssuck]

Radiant in floor heating is a science. To have a efficient system that works as intended you will need to do a lot of math. Start with a heat loss calculation. Then design your loops to give you the required heat to overcome your heat loss. Then Size your circulator pump to overcome your pressure drop of piping. Then size your boiler, to big of boiler is just as bad as to small of a boiler. A simple explational of run 1/2" heat pex 16" on centre and all you are doing is hoping your system will work.

 

[StupidSheet]

Haha, I figured it out guys. After going back to the drawing board (graph paper) I went and tried again. Followed my drawing and it still wasn't working out. Then I remembered a friend told me the pipe has the lengths on it so I checked that. To my surprise I thought I purchased 4-300' rolls when I actually got 250' rolls. I bought them awhile ago and had myself convinced I bought 300' rolls. Then I remembered that I changed my mind at the last second and got 250' rolls. I only bought 4 because we were coming back from a trip to the US and didn't have anymore room.

So yesterday I reconfigured for the 250' loops and got 4 installed matching my drawing almost perfectly. I just need to pick one more up and all we be good.

Thanks for the help guys!