I have a 16' X 16' single floor addition off my kitchen space. Currently
we have a wood stove for heat but it really over heats the space. Just off
the end of the kitchen is a 10 X 20 room that had roughly 25 ft of standard
baseboard style radiators. I have removed them from that zone entirely. I
should also mention that the 25 ft of radiator ahd a return from the end of
the radiator to the same spot...so 50 ft of tubing...half was radiator half
was simply to get back to the rest of the house. My feeling is that zone
now has plenty of extra energy for me to add some baseboard radiators to the
addition. Heck I took off 25 feet I should be able to add 15 without any
The addition is on a slab though. It does have R-19 fiberglass in the joist
spaces under the floor. My thoughts are to run approximately 7 feet in the
first joist bay and surface into the room to run 8 feet to the corner and
then another 8 to 10 feet down the far wall before going back under the
floor and running 16 ft back to the loop in the cellar space. This would
eliminate a section of pipe in the cellar equal to the 8 to 10 foot run on
the far wall.
My son (the engineer) and I have reasoned through the facts that if the
original circulating pump was fine before the 50 feet was removed adding
this 32 feet should be ok. After all 32 IS less than 50. The issue we are
both worried about is the under floor tubing is going to be in "unheated"
space unless you consider the fact it is surrounded by the R-19 fiberglass.
His firm says NEVER put water pipes in unheated spaces. I agree but what
The rafter bays are 14.5" wide with 11.25" depths ( 2 X 12's were used for
the joists) I would run the pipes as close as I can to center or the width
and perhaps 1" below the subfloor. I would then line the edges of the space
with 1.5" thick foam insulation. Then I would force the fiberglass R-19
back in and seal the bottom with another piece of 1.5" foam. All joints
taped and sealed. What this should accomplish is a sealed "room" with R-19
Fiberglass PLUS R-10 to 12 Foam on 3 sides all around the pipe. The
"exposed side is actually the underside of the room's floor. My feeling is
that the zone will call for heat often enough so that the supply pipes
carrying the 160 to 180 degree water would heat the spaces well above
freezing. The insulation should keep them from dropping much at all between
Obviously a power outage in severe cold is the flaw.
Are there any other solutions? As the room is laid out there really is no
way to enter above the floor in the heated space.
Thanks in advance to all.