In Floor Heating

What are the assumptions? 

1. The loop temperature is maintained whether it is maintained using the 75F hot water mixing package (HMP) or if the boilers regulate the outlet water temp the point is the same. 
2. There is a valve or pump (or both) isolating any individual slab loop from the core loop. 

Since a concrete slab carries so much thermal inertia you would not use a typical space temperature sensor to monitor the space temp. The best option is to embed the sensor in the floor so you get the most accurate temperature reading and do not have heavy swings in the actual space temperature. So, what is the best way to control it?

Read about the importance of the CCU here

Operation

With our assumptions in place, all in floor heating really is, is opening or closing a loop to heat or cool a space based on slab temp. 

• When the slab is cold - Let the hot water flow to heat it up. 
• When the slab is warm - Close the valve or turn the pump off and isolate that slab until it cools back down. 

With a properly installed slab temp you will see nice long smooth heating cycles like below. 

Unlike with a misplaced slab sensor like this next image. Notice the short sporadic rises in temp. 

Controlling these valves is a Single Stage Equipment SSE package.

Read more about the SSE package here.