(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 15 of 15

Thread: radiant question

Hybrid View

  1. #1
    DIY Junior Member phillymaster's Avatar
    Join Date
    Nov 2009
    Location
    Philadelphia PA
    Posts
    5

    Default radiant question

    newbie here.

    i just put radiant heat on the my first floor and i love it. i put 3 zones in. two of them are less than 100 square feet, and one is about 500 square feet. my 2nd floor has old fashioned radiators, 3rd floor has nothing right now.

    anyways, the rooms warm up nice (and i haven't even insulated the joist bays yet ) but i noticed when i go in the basement and feel the pex loops (i put in pex between the joists with transfer plates), all of them get fully up to temp except for the return on the larger loop. my house is almost 100 years old. it's a pretty darn long loop for the living/dining room. it doesn't really bother me that much, but i'm curious as to why that return isn't heating up fully on the one loop. i'm using a taco mixing valve and a 007, with 3 zone valves. i'm not using a manifold with metering gauges because i figure that the 1st floor will be self-correcting, although some zones may heat up a little quicker. but even when i only run the big zone by itself, the return only gets up to probably 100 or so, whereas it's supply is 140ish. the other zones get even return and supply temps. maybe it's losing some heat as it gets to the end of the loop?? maybe insulating the joist bays with reflector and r19 would help?

    i guess this long loop is just too far away from the boiler (in linear pipe)??? maybe it should have been two loops?

    thanks for any input!
    Last edited by phillymaster; 11-16-2009 at 06:17 PM.

  2. #2
    DIY Senior Member zl700's Avatar
    Join Date
    Aug 2009
    Location
    Texas
    Posts
    235

    Default

    600 sq ft of residential with one loop is a poor design especially with plates. Who did the design? Split up the loops, lower the water temp to get an even and efficient system.

  3. #3
    DIY Junior Member phillymaster's Avatar
    Join Date
    Nov 2009
    Location
    Philadelphia PA
    Posts
    5

    Default

    Quote Originally Posted by zl700 View Post
    600 sq ft of residential with one loop is a poor design especially with plates. Who did the design? Split up the loops, lower the water temp to get an even and efficient system.
    everything seems to work well. it's a pretty simple system. feels like it heats up evenly from above. i designed it but am teaching this stuff to myself right now so that's why i'm posting here to get some help. can you elaborate on any of what you wrote, or give some more recommendations? i'm guessing i should have one loop for each room? what's the maximum sq ft for one loop?

  4. #4
    Previous member
    Join Date
    Jul 2009
    Location
    North of the Mason dixon Line
    Posts
    1,150

    Default

    600' with 1/2" is way way too long. I like to keep them to 200' or less.

  5. #5
    DIY Senior Member zl700's Avatar
    Join Date
    Aug 2009
    Location
    Texas
    Posts
    235

    Default

    Loop lengths are designed based on way it is attached, flow rate, water temp, floor material, thickness of floor, tube size and a few other factors besides heat loss and room size.

  6. #6
    DIY Junior Member phillymaster's Avatar
    Join Date
    Nov 2009
    Location
    Philadelphia PA
    Posts
    5

    Default

    cool. so what's the ideal temperature for pex with plates between joists? the floor boards are 7/8" pine. 120? what about in the back room where i have 3/4 plywood and 1/2 hardibacker, and then 1/4" tile? does that require hotter temps? thanks again!

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •