Before I close up the walls, is my in-slab radiant useless?

PWCSteve

I recently purchased a split level home... bottom-most floor is the main family room TV media room which is 4 foot subterrain and 4 foot above grade... on the other side of the split 5 stairs up is the kitchen dining room, then another 5 stairs up back to the other side above the family room is 2 bedrooms and a bathroom, and then back to the other side above the kitchen dining room is a large master bedroom suite.

i gutted the entire house to the max starting from scratch. only thing left was exterior walls and foundation, put up dormer, removed all plumbing and heating back and only have a water main sticking up currently, removed all electrical all bathrooms, EVERYTHING.

the bottom media room half underground i had the slab broken up and removed, new rebar and mesh put down and mason guy secrured 1/2" pex to the mesh and poured a new concrete slab... he swore up and down he's done it tons of times no problem trust him just buy a roll and he'll do it for me...

the room is 14' x 21'.... i bought a 300 foot roll of 1/2" pex wanting every foot of it to be in that concrete for good heat in the homes cold spot... he only installed 200' of it about 12+ " apart in a loop in about 4" of concrete secured to the mesh at the bottom...

Should i plan on this room still being a cold spot with inadequate heat? i'm very concerned there's not enough pex in the slab... i dont have a boiler or running water in the house yet, it's just undergoing final phase of sheetrock. should i plan on running a strip of baseboard to assist the floor to keep room temps in a subterrtain room at a comfortable level?



Thanks so much.

Steve

PWCSteve

additional info

to further add.... the floor will be porcelain tile. there is NO insulation underneath or on the sides of the slab... only a plastic vapor barrier laid down before the cement pour.

there are 7' ceilings in this room.

the "boiler room" is due to be IN this den room in one of the corners in a closet

i'm located on Long Island, NY.

the second floor will be radiant also with pex, on top of the subfloor i'm doing a mudjob and tile there

then the 3rd and 4th floors which are all bedrooms im doing slant-fin baseboard

the house is very "open" in that the staircases were all removed and all the floors are adjoining and see-through riserless floating stairs stagger and join each side of the split level house... so the air will move ALOT. i guess i am worried all the heat rising to the top floor and leaving a chilly downstairs tv room on the slab with inadequately tubed floor.

hope this more info helps.



thanks in advance

furnacefigher15

No insulation?

I doubt that will never heat right. You might get lucky, but you might not.



If the room in question has very few windows, and well insulated walls, you may be okay.

Gordy

Lack of tubing

Looks like he stayed away from the perimeter a couple of feet, or cheated on the 1+ foot spacing with only 200' of tubing. Did you purchase O2 barrier pex?



   Its not that it probably will not work. It will just take warmer water temps, and slab will be less responsive with out the insulation. Plenty of old uninsulated radiant basement slabs out there that do work. A lot of the energy goes to earth though. Not saying what he did was correct its just old school, and not how its done in modern times



Gordy

Slimpickins

I would

before doing anything else, get a heat loss calculation done on the house. It kinda sounds like you're winging it by having a masonry guy lay down your tubing. Do you have a heating guy lined up that is familiar with a multi temp system? To me, fin tube baseboard and zone valves are so primitive with the comfort technology that is out there. If you're in Long Island area, there are really knowledgeable and great craftsman on this site and you can find them by clicking, 'Find a Contractor' at the top of this page. As far as the work already done, you may want to consider running some heat lines for supplemental heat if needed. Good luck!

Jean-David Beyer

I am pretty sure my slab is uninsulated.

The house was built in 1950 and has mostly 1/2 inch copper tubing in the concrete. THe concrete is pretty thick and I do not know how deep the tubing is from the top. The house had very little insulation in it when I bought it ("builder's batts"), but I had solid foam injected to fill all the available space in the walls, and 6 inches or more of blown-in fiberglass in the ceiling. The one good thing is that the water table, in May, anyway, is 6 feet down from the surface. I am in New Jersey.



It heats just fine even when it gets 8F below design temperature. Windows are gas-filled double stuff (Marvin). But it heated just fine before the insulation and new windows.