Cast Iron Radiators and radiant heat manifolds

ivanator2

Currently adding cast iron radiators to first floor for a separate zone. I will be putting in supply and return manifolds with 1/2 inch pex to the radiators.



I would like to put in a quality system, but don't know if, in this case, simple is better.



I'm undecided on two approaches:



1. The nice looking solution.



Radiant heat manifolds like Watts and Rehau with their nice dials and fine-tuning, and pex-al-pex.



2. Off-the-shelf solution.



Menards copper manifolds with shut-off valves, oxygen barrier pex with crimp fittings. I already have the crimping tool and experience from a bathroom renovation.



Are there compelling reasons to choose one over the other, excluding price? Are their fitting compatibility issues if I went with one of the nice manifolds from Rehau or Watts?

Ironman

#1

The Rehau or Watts manifolds would be my choice. They make it much easier to purge and balance the system. Also, if you're running 1/2" tubing on each rad, the RS20 manifold connectors will fit pex or pex-al-pex. You can use pex-al-pex compression adapters on the rads if you don't want to purchase a pex-al-pex pressing tool. If you're running 5/8" or 3/4" pex-al-pex, then you'll need manifold connectors made for that; they are readily available.



Pex-al-pex is much easier to install: it stays where you put it , stays the way you bend it and requires much less support. It won't sag or expand linearly like pex will.

Eric_32

I've done the same....

Using 3/4" Viega fosta pex.  to a home made mainifold. I terminated the pex below the floor using pex X female DE 90° and had 3/4" black nipples thru the floor to the radiator valve and union 90°. Worked great.

Gordan

3/4" is probably overkill

Not that it'll hurt anything.



One thing to watch with Fostapex is that it is not the same size as "other" PEX-AL-PEX, so you can't use compression fittings. You have to use their prep tool to strip out the outer layers, and use Viega's crimp fittings. Learned this the hard way. Rifeng, MrPex, and even Uponor are all in the same ballpark (bigger than Fostapex); of course, you're best off using the fittings by the same manufacturer as the tubing.

kcopp

I would just do....

the copper headers that Sioux Chief uses. They have them w/ mini ball valves and are pretty sharp looking. To get more control I would do some TRV's on each radiator

bob eck

CI radiators & radiant heating manifolds

I have a Triamgle Tube PE110 condensing gas boiler. Last winter I added three used cast iron radiators. made my own little copper header with Viega propress fittings and ran 1/2" viega fostapex pipe out and back to each radiator. I used 1/2" IP radiator ells and 1/2" black nipples to go through the floor into the basement and black 1/2" 90DEG ells and then 1/2" fostapex viega pex MIP adapters. This worked great. Viega fostapex is a full size pex tubing the same size as the viega radiant pex and their pex tubing used for potable water systems. The highest temp that ran through the fostapex tubing was about 170*F last year when the outside temp was down around 5*F. The fostapex does not droop and will not grow when running hot boiler water through it. This summer I will replace 2" black steel supply and return mains with a Legend Hydronics radiant manifold and I will be running 1/2" fostapex to each radiator. With the Legend Hydronics radiant manifold I will be able to control the flow to each CI radiator and balance the system just right. Happy Heating.