bloomingtonmike
Well-known member
How long should the pex be for a temp probe? I don't own a thermostat or temp probe for one yet but they are on the list. My pex was laid recently and I need to add a length for the probe.
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Pex for temp probe
- Thread starter bloomingtonmike
- Start date
anthony666
Well-known member
you wanna bring it to about mid slab .. tape the end to keep the concrete out, make sure it lays nice and flat, spaced evenly between two runs and dont forget a conduit elbow where it comes up
rburke65
Well-known member
This is the one thing I forgot to install when I did my pex install. I'm hoping I didnt screw up too bad!
anthony666
Well-known member
did you do expansion cuts mr b ?? just run it that-a-way in a pinch, and a pinch is what you're in
rburke65
Well-known member
The slab was saw cut in 10' x 10' sections.m Wow.....that's a great idea anthony666! I assume that I only need a 2 conductor thermostat wire for an input. I think I have taken enough photos that I can miss the pex. So is this just a sensor in contact with the concrete? I, like others, don't want to hi-jack the thread. Thanks.
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Highbeam
Well-known member
You want the stat at center of slab but you can always run the sleeve a little longer just in case a little concrete leaks in. You will want to measure the wire as you insert it to be sure of location.
rburke65
Well-known member
When you sat the "center" of the slab, are you referring to the thickness of the slab or the center of the floor area?
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Highbeam
Well-known member
Floor area. You will experiment to find the slab temp that provides the desired air temp. This will vary a little depending on outside air temp but it's not an absolute since your buildings insulation level is a factor.
rburke65
Well-known member
Thanks for replying Highbeam.
rburke65
Well-known member
What size wire do we run for the temp. sensor probe ?
OP
bloomingtonmike
Well-known member
How long a temp sensor are you running?? My floor is 40X64. Why center of floor area when I have nine loops running through it in one zone? Why would center floor be a better place to check temp than say 10' in?
rburke65
Well-known member
Well that was my thought. I have 6- 300' loops and one would think that the slab temps. would be somewhat uniform.
Highbeam
Well-known member
Because the heat loss from the slab is highest at the edges, the middle will be the warmest spot and most representative of the overall slab temp. The edges of the slab might be really cold when the outside temps are really low.
If you're stuck with only a 10' sleeve because you didn't think to place the probe in the center of mass then use what you've got. That's pretty good too.
Think how you will be using this temperature reading. Only to turn the boiler on and off. An air temp stat will do a decent job too.
If you're stuck with only a 10' sleeve because you didn't think to place the probe in the center of mass then use what you've got. That's pretty good too.
Think how you will be using this temperature reading. Only to turn the boiler on and off. An air temp stat will do a decent job too.
OP
bloomingtonmike
Well-known member
Are you wiring you own thermister then t get it 20' then to get to the middle?