I presently have a cast iron radiator in my upstairs bath, about 96 sf gross area. 90 year old house. New insulation in walls and in attic above. One exterior wall (insulated) with two new windows.
Am considering tying a simple hydronic radiant floor system into this line, i.e. when the heat comes on, the floor and the radiator both get warm. No separate zones. I would fasten 5/16″ He pex loops (about 6″ apart) to the new 3/4 subfloor, pour self leveling mix on top of that. Then thinset and ceramic over that. The loop would only run in the open floor area (minus shower, toilet, tub, vanity): about 50sf net. I’v done some research and talked to an intenet supplier, but I figure that I’d run this by some field experts.
My boiler is a about 9 years old, with a pump. No issues with heating capacity for the home.
My main objective is just to provide a warm floor, but I wonder if I can eliminate the radiator altogether and just rely on the radiant floor loops to heat the bath.
Any comments would be appreciated.
Thank you,
DIA
Replies
Someone with more knowledge will be along to answer your question ... but until then here are my thoughts.
I'm pretty sure the water temperature used for cast iron radiators is generally much higher than that used for radiant floor heat. Your radiant loop may need to be tempered somehow.
In our tiled bathroom (1920's) we have a small section of the floor where the piping for our cast iron radiator must run through the tile's mud bed. In the middle of winter this section of floor gets too hot to stand on in your bare feet.
Dan
No replies so I give ya my input, for what it's worth.
I am doing something very simalur, except I any inbedding 1/2" pex al pex in a self leveling mix on a small bathroom floor to carry the heat load. You will need some sort of mixing valve to choke down that temp. Running 160 - 180 degree water threw the floor is pretty hot.
I removed a CI rad from my bath and the floor will take up the load.
Check on SlantFin's web site, they offer a free heat loss software and do the math, see how many BTU's to will need.
visit the guys at Heatinghelp.com, the forum the wall is great.
I'm no expert but here's my thoughts, for what they're worth. I see several issues.
The first having been pointed out in a previous post -- radiant floors are generally run at lower temps than rads.
Second, how are you gonna feed the radiant loop? In order to get circulation, it would need to be on its own pump (or zone valve), or in series with the rad, and the latter option would pretty much choke off flow to the rads in the zone, since the flow rate for 5/16" pex is far lower than needed for cast iron rads. So you'd pretty much have to have the radiant floor on its own zone.
All that said, you may wanna consider WarmBoard or Quick Trak if you do go for the radiant floor. Just a thought.
Mike Hennessy
Pittsburgh, PA