EcoRenovator  

Go Back   EcoRenovator > Improvements > Renovations & New Construction
Advanced Search
 


Blog 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 07-08-18, 05:25 PM   #1
Drake
DIY Guy
 
Join Date: Jan 2011
Location: Mpls,MN
Posts: 315
Thanks: 2
Thanked 17 Times in 17 Posts
Default More pex loops better???

I'm putting hydronic pex heating in a high mass concrete slab 14' x 30'. It is for an open room floor plan so it could easily be done with just two loops and meet 1/2 pex length recommendations(approx two 200' loops) spaced from 6" apart near exterior to 12" in the interior. But would increasing number of and shortening the length be better for supplying more and quicker heating if needed(worst case demand). It certainly wouldn't over complicate the system to have 3 or 4 loops in the manifold to any great cost. Structure is super insulated to R50 walls and R80 ceilings. and all the details of Hi-R construction built into the design. Once the slab is poured its too late for any should have's, lol.

Drake is offline   Reply With Quote
Old 07-09-18, 10:43 PM   #2
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,004
Thanks: 303
Thanked 723 Times in 534 Posts
Default

Quote:
Originally Posted by Drake View Post
I'm putting hydronic pex heating in a high mass concrete slab 14' x 30'. It is for an open room floor plan so it could easily be done with just two loops and meet 1/2 pex length recommendations(approx two 200' loops) spaced from 6" apart near exterior to 12" in the interior. But would increasing number of and shortening the length be better for supplying more and quicker heating if needed(worst case demand). It certainly wouldn't over complicate the system to have 3 or 4 loops in the manifold to any great cost. Structure is super insulated to R50 walls and R80 ceilings. and all the details of Hi-R construction built into the design. Once the slab is poured its too late for any should have's, lol.
The closer the PEX runs, the more efficient it will be.

Old School Amreican rule of thumb is 12" spacing; from my research, Northern Europeans favor closer spacings, with 6" not being unusual. European energy is much more expensive than ours is now.

Sounds like you have a handle on PEX run lengths, and headers, etc.

I'd advise closer PEX runs, similar to the Northern European practice.

You are right about quicker temperature increase, but temperature decrease will be no different.

The real benefit to you will be lower fuel cost over the life of your system.

Hope this helps.

Regards,

-AC_Hacker
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Old 08-03-18, 12:18 PM   #3
Drake
DIY Guy
 
Join Date: Jan 2011
Location: Mpls,MN
Posts: 315
Thanks: 2
Thanked 17 Times in 17 Posts
Default

Decided to go with three shorter loops because my local Menard's store was clearing out 250' rolls of 1/2 of non-O2 pex 75% off to go to 300' rolls. I have three 200' runs in the layout plan now so no splices and Big savings. Most manifolds I've seen start at three anyway and about same as two price.
Drake is offline   Reply With Quote
Old 08-25-18, 11:28 AM   #4
Zwerius
Helper EcoRenovator
 
Zwerius's Avatar
 
Join Date: Aug 2014
Location: The Netherlands
Posts: 70
Thanks: 18
Thanked 26 Times in 14 Posts
Default

6" is more or less "old school" overhere in the Netherlands. 4" (or even less!!) is favourable, especially when you are using a heatpump. Or if you are planning to use one in the future.
More tubelength (so closer tubing), means lower watertemperature for the same amount of heat.
And lower watertemperature means a more efficient heatpump.
The difference in e-consumption is about 2,5% per °C.
So if you ar planning a hydronic heating right now, please do it right the first time.....
Zwerius is offline   Reply With Quote
Old 08-29-18, 08:35 AM   #5
BillG
Lurking Renovator
 
Join Date: Jul 2016
Location: Minneapolis
Posts: 16
Thanks: 2
Thanked 3 Times in 2 Posts
Default

Drake, I'm with you. I think some of the responses were thinking you were talking about spacing between the pipes, but I think you were talking about the length of the run.

Shorter runs will give you a warmer temperature at the return, so should heat everything more uniformly and more quickly. Heck, if you piped it that way and poured the slab, then decided later that you wanted fewer, longer runs, you could series connect a couple of runs at the manifold location. You could probably even valve it such that you could switch on a whim.
BillG is offline   Reply With Quote
Old 11-30-19, 10:59 PM   #6
n7mog
Lurking Renovator
 
Join Date: Sep 2011
Location: Deadwood, SD
Posts: 3
Thanks: 0
Thanked 1 Time in 1 Post
Default

Radiantec is a good site to look at radiant heating systems.

n7mog is offline   Reply With Quote
Reply


Thread Tools
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


All times are GMT -5. The time now is 06:48 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design