In-floor temperature sensor.

[RayBob58]

I'm looking for a pics and details of radiant in-floor temperature sensors. I'm trying to narrow down my choices of mini-boilers. Some require sensors & some don't. My 28x36ft garage has <1000ft of barrier Pex in a single zone with 4 loops. A really simple closed system. I worked with Nibco in laying it out, and I think I'm going with their RHP-1 panel, but they don't sell boilers. What's involved with the temp sensors?

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[chinboys]

I think the in-floor sensor feeds the temperature signal to the boiler's thermostat circuit which works with the modulation circuit (another outdoor temperature circuit based on the minimum outdoor temp you input) if it has one.
Or it feeds the signal to a thermostat that sends 24v to the boiler's start, steady state and shutdown circuit that works a modulation circuit.
Or in my case, my concrete slab sensor feeds a thermostat that controls a 3 zone controller and the controller controls the zone value, main system pump as well as tells my modulating boiler to fire up. Again, the modulation circuit tells the boiler how hot to make the water as well as making it in steady state mode (boiler detects return water temperature and decreases the fire burn from high to low).

Yes, the more your boiler can do along with your controller's functions makes your designing more complex.
I purchased my heating equipment from Supplyhouse.com and they were very helpful to answer my questions.

good luck.

 

[Firebrick43]

The boiler itself needs no slab sensor nor any other sensor. Some boilers can control the temp based on outdoor sensor (lower outside temp equals higher boiler water temp) called an out door reset.

The thermostat reads temp, some slab, some air, some can do both and use one or the other depending on programming. The themostat then calls for heat. This signal can be used directly with relays to actuate the pumps and call the boiler on. However it's much easier to use a controller.

A controller is prepackaged to actuate the pumps, the boiler, and the zone valves if used. It also connects the themostat and can prioritize things such as dhw if you have that on the system. Some controllers also exercise pumps one a week for 30 sec to keep them from locking up.

I have a caleffi controller a 6 zone. You would only need a one zone controller

https://www.supplyhouse.com/Caleffi-ZSR101-1-Zone-Expandable-Switching-Relay-w-Priority

Taco makes one as well and is well known in the industry.
https://www.supplyhouse.com/Taco-SR501-4-1-Zone-Switching-Relay

Grundfos version, not as common around here

https://www.supplyhouse.com/Grundfos-98996400-UPZCP-1-Single-Zone-Pump-Control

I am sure Honeywell and others have one as well.

The only thing your boiler needs is call terminal (**)

An outdoor reset is just an optional feature that can save fuel if you have a modulating condensing boiler

 

[RayBob58]

I was hoping to see a pic of the sensor itself, and how it enters the floor. I didn't plan for that when I poured. Can I simply drill for it?

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[Firebrick43]

I was hoping to see a pic of the sensor itself, and how it enters the floor. I didn't plan for that when I poured. Can I simply drill for it?

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Use a hammer or better yet rotary hammer and drill a hole. Make sure it not where a tube is! Maybe have someone with an IR camera locate the tubes.

https://www.supplyhouse.com/Tekmar-079-Slab-Sensor-10-wire-4170000-p

Depending on tubing layout just using air temp thermostat will be fine.