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Adding hot water heat to a small bathroom

djt Member Posts: 1
Our house was built in the 1920's and uses a Triangle Prestige Excellence to run the original radiators.  The house is located near San Francisco CA. 


I'm remodeling a bathroom and am exploring various ways to heat this space by tapping into our existing system (the bathroom did not have heat before).  The space is 3x6 feet with an 8 foot ceiling.  The walls are insulated to R-13 and the ceiling to R30.  One 3 foot and one 6 foot wall are exterior walls.  There is a steel casement single glazed window of about 4 square feet.  The floor is a concrete slab elevated over a garage space.  The garage is partially submerged in a hill and so the volume under the bathroom never falls below 50F.  I calc'ed the heat loss to be about 900 BTU/hr.

Choices for heat are a radiator such as the Runtal HX-14, the Burnham slenderized unit and...a wiggly copper pipe.  The hot water feed comes through the floor from the garage and I was considering just creating a 20 foot long zig zag of 3/4 copper pipe in an interior wall that is covered by sheet rock to be a "radiator".

Looking for thoughts on the wiggly copper pipe concept as well as the two proposed radiators.  If I use the radiator in the room, I would use a thermostatic valve to keep the room from overheating. 


  • Snowmelt
    Snowmelt Member Posts: 1,414
    No post

    So I will do it.

    It's a small bathroom. Just put some radiant in the floor or walls, or rads like you said.
  • icesailor
    icesailor Member Posts: 7,265
    Bathroom Heat:

    For the gymnastics and expense you are going to go through, you could put in more than enough electric heat and still be ahead of the cost game for the rest of your life.
  • hot_rod
    hot_rod Member Posts: 22,105
    Electric radiant

    is ideal for small areas like that, glue it down, tile over it. There are plenty of cable and mesh options for small rooms like that. No need to fire that boiler to keep a nice warm bathroom floor. Nice control options also, setback, floor and air sensors,etc.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream