Welcome to the The Garage Journal Board forums.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   The Garage Journal Board > The Garage > Heating and A/C

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Search this Thread Display Modes
Old 07-28-2009, 05:04 PM   #1
chadman
Senior Member
 
chadman's Avatar
 
Join Date: Feb 2008
Location: Wakeman, OH
Posts: 219
Default How much PEX do I need?

I am going to be installing PEX in the floor of my new garage and I have a few questions. Garage will be approx. 1000 square ft. with R-14 walls and R-29 ceilings. One 16ft. and one 10ft. door both R-11. There will be 2" of XPS insulation under the slab. My questions are:

1) 1/2" or 3/4" PEX?
2) how many feet of PEX do I need?
3) how long per loop?
chadman is offline   Reply With Quote
Old 07-28-2009, 05:35 PM   #2
walrus
Senior Member
 
walrus's Avatar
 
Join Date: Nov 2008
Location: Maine
Posts: 4,075
Default Re: How much PEX do I need?

Quote:
Originally Posted by chadman View Post
I am going to be installing PEX in the floor of my new garage and I have a few questions. Garage will be approx. 1000 square ft. with R-14 walls and R-29 ceilings. One 16ft. and one 10ft. door both R-11. There will be 2" of XPS insulation under the slab. My questions are:

1) 1/2" or 3/4" PEX?
2) how many feet of PEX do I need?
3) how long per loop?
I;m sure someone will protest but the rule of thumb is 1 ft of pex for every sq ft of slab, 1/2 pex no more than 300 ft in a loop.

Where are you located, might make quite a difference?
walrus is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 07-28-2009, 05:49 PM   #3
chadman
Senior Member
 
chadman's Avatar
 
Join Date: Feb 2008
Location: Wakeman, OH
Posts: 219
Default Re: How much PEX do I need?

Thanks for the reply. I am in notheast Ohio between Sandusky and Cleveland.
chadman is offline   Reply With Quote
Old 07-28-2009, 08:14 PM   #4
Dragster Racer
Senior Member
 
Join Date: Feb 2008
Location: Morrison, IL
Posts: 1,497
Default Re: How much PEX do I need?

I would agree with Walrus from what I have read, and what we did in our home. If anything, you could go a little more than 1/sq since you have a little less insulation than a home and quicker recovery would be nice. Just set your tubes less than the suggested 1' apart. There isn't a lot of science to it. It's pretty forgiving.
Dragster Racer is offline   Reply With Quote
Old 07-28-2009, 11:15 PM   #5
Rob_b
Member
 
Join Date: Jul 2009
Location: Ontario Canada
Posts: 87
Default Re: How much PEX do I need?

Quote:
Originally Posted by chadman View Post
Thanks for the reply. I am in notheast Ohio between Sandusky and Cleveland.
Chad, I saw on a show we have here north of the border that the contractor installing the in floor heating used a styrofoam that had disks where the pex would be routed through and be lower than the tile or whatever other flooring was used. He used this stuff as a thermal break so your not heating below the surface and all the heat travels upwards where its needed. It wasn't very thick but very effective and required zero clamps to hold the pex piping. It held it by friction. Also if you use a manifold, it may make it more even heating but I assume you were going to use it anyways. Good luck
Rob_b is offline   Reply With Quote
Old 07-29-2009, 09:46 AM   #6
GearBeer
Senior Member
 
Join Date: Jun 2009
Posts: 252
Default Re: How much PEX do I need?

There's no substitute for laying out your tubing pattern to figure out how much you need. I made a spreadsheet to guesstimate this and came within 1' of what we used.

I made every other column and row thin and used colors to fill them to denote the routing. In the wide columns I inserted the distance center-to-center of each pair of adjacent tubes.
GearBeer is offline   Reply With Quote
Old 07-29-2009, 02:26 PM   #7
baugie
Senior Member
 
baugie's Avatar
 
Join Date: Jan 2009
Location: Ontario, Canada
Posts: 111
Default Re: How much PEX do I need?

Hey Chadman:

I'm due north of you on the other side of Lake Erie.
1/2" pex will do....make sure it is the oxygen barrier type. To calculate how much pex you need........use this formula....square footage of the floor + 20% = amount of linear feet of pex needed......divide that number by the amount of feet per roll and that's how many rolls you will need. I just finished my garage and the formula was quite accurate.
NOTE: do not have in splices in the concrete. My loops were 250 ft long.
baugie is offline   Reply With Quote
Old 07-29-2009, 02:49 PM   #8
walrus
Senior Member
 
walrus's Avatar
 
Join Date: Nov 2008
Location: Maine
Posts: 4,075
Default Re: How much PEX do I need?

You want to keep each loop within 10% in length also
walrus is offline   Reply With Quote
Old 07-29-2009, 04:05 PM   #9
chadman
Senior Member
 
chadman's Avatar
 
Join Date: Feb 2008
Location: Wakeman, OH
Posts: 219
Default Re: How much PEX do I need?

Thanks for the info. What spacing are you all using?
chadman is offline   Reply With Quote
Old 07-29-2009, 04:19 PM   #10
baugie
Senior Member
 
baugie's Avatar
 
Join Date: Jan 2009
Location: Ontario, Canada
Posts: 111
Default Re: How much PEX do I need?

first two outside loops 6" apart. then you can go from 8" to 12" as you get closer to the center.
baugie is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 11:15 AM.