slab sensor

ed m

are they needed in a thin slab pour over plywood. and if so are they connected to the EG.tekmar t-stat or control board EG. tekmar 260. just looking for some insight on how they work.
thanks eddie

Unknown

needed? maybe not.

if you are using a tekmar thermostat with an aux sensor input (almost, but not quite, all of them), the 079 sensor is a cheap add on, giving you control over floor temp and air temp.

that's pretty sweet. guaranteed minimum floor temps, good PID logic for precise temperature control. Hard to beat.

Gerry May

If you don't use the slab sensor for the in-floor radiant, you'll be in trouble. You'll experience big temperature swings.The purpose of the slab sensor is to maintain a minimum slab temperature when there is no call for heat (room temperature) I like to set that to about 68 - 70 deg F. The room will not cool off too much that on the "off" cycle will be shorter. The slab temperature also will limit the maximum floor surface temperature which is very important if you are using hardwood floors. Manufacturers spec out 85 deg max. That's what i set it for regardless of the floor covering....it's comfortable and also extends the heat cycle length. After you set everything up, confirm the floor surface temp with the display temp using an infrared thermometer. they may be a few degrees apart, in which case you'll have to adjust the setting accordingly. Tekmar makes the best thermostat for this application. If you have multiple zones you should consider the tN4 system which has communication between thermostats.......P.S. I would install the Tekmar 072 sensor. It's more expensive but it has a PVC sheild around it. The 079 is stainless steel, but I've had a couple of them fail over the years, possibly because of the chemical content of the overpour. We've had absolutly no issues with the 072. That's the one we use and it's more robust.

Unknown

we use the 079 in a pex conduit for easy future replacement. sealing the end of the conduit is a good idea.

not all thinslab systems are at risk for swings. In well insulated homes with improper water temperature control, it can be an issue. full thickness slabs, it's more critical in solar gain situations.

Gerry May

Have ever replaced aa slab sensor in a PEX conduit after initial installation? I would think that it's no problem to get the old one out, but how would you get a new one in?
I would think it would be pretty tough.I've never done it.

Bob Bona_4

electrical tape

piano wire to it as a snake for insertion and extraction. I like to "blunt" the sharp end of the wire where it meets the sensor bulb by bending it sharply back on itself. Don't need a bulb penetration

Mike Dunn

Bow down

and use the sacrificial fish tape.

ed m

sensor

the slab sensor hooks up to the t-stat or the control board

Bob Bona_4

stat

nm

Nron_13

refitting a sensor

Take some 1/4 plastic tubing and tape it to the back of the sensor and slide it into the 1/2 pex and cut off the rest of the roll and leave it with the sensor , it slides in real easy and will even go around corners